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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2020	May 08, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Trading Symbol	NK
Entity Registrant Name	NANTKWEST, INC.
Entity Central Index Key	0001326110
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		98,508,958
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-37507
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	43-1979754
Entity Address, Address Line One	3530 John Hopkins Court
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	633-0300
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 16,952	$ 15,508
Prepaid expenses and other current assets (including related parties)	3,910	4,105
Marketable debt securities, available-for-sale	23,263	36,144
Total current assets	44,125	55,757
Marketable debt securities, noncurrent	0	1,497
Property, plant and equipment, net	58,539	60,501
Operating lease right-of-use assets, net (including related parties)	11,055	11,729
Equity investment	9,253	9,253
Other assets (including related parties)	4,051	4,386
Total assets	127,023	143,123
Current liabilities:
Accounts payable	3,148	1,749
Accrued expenses	6,634	5,343
Due to related parties	853	486
Other current liabilities (including related parties)	3,613	3,981
Total current liabilities	14,248	11,559
Operating lease liability, less current portion (including related parties)	10,180	10,885
Total liabilities	24,428	22,444
Commitments and contingencies (Note 8)	0	0
Stockholders’ equity:
Common stock, $0.0001 par value; 500,000,000 shares authorized; 98,498,432 and 98,460,404 issued and outstanding as of March 31, 2020 and December 31, 2019	10	10
Additional paid-in capital	783,287	782,965
Accumulated other comprehensive loss	(128)	(105)
Accumulated deficit	(680,574)	(662,191)
Total stockholders’ equity	102,595	120,679
Total liabilities and stockholders’ equity	$ 127,023	$ 143,123

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	98,498,432	98,460,404
Common stock, shares outstanding	98,498,432	98,460,404

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenue	$ 21	$ 5
Operating expenses:
Research and development (including amounts with related parties)	13,234	12,598
Selling, general and administrative (including amounts with related parties)	5,373	5,742
Total operating expenses	18,607	18,340
Loss from operations	(18,586)	(18,335)
Other income (expense):
Investment income, net	178	370
Interest expense	(7)	(3)
Other income, net (including amounts with related parties)	32	47
Total other income	203	414
Loss before income taxes	(18,383)	(17,921)
Income tax benefit	0	36
Net loss	$ (18,383)	$ (17,885)
Net loss per share:
Basic and diluted	$ (0.19)	$ (0.22)
Weighted-average number of shares during the period:
Basic and diluted	98,472,641	81,261,302

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (18,383)	$ (17,885)
Other comprehensive (loss) income, net of income taxes:
Net unrealized (losses) gains on available-for-sale securities	(24)	61
Reclassification of net realized losses on available-for-sale securities included in net loss	1	0
Total other comprehensive (loss) income	(23)	61
Comprehensive loss	$ (18,406)	$ (17,824)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2018	$ 146,006	$ 8	$ 741,246	$ (267)	$ (594,981)
Beginning Balance, Shares at Dec. 31, 2018		79,087,734
Stock-based compensation expense	1,351	$ 0	1,351	0	0
Exercise of warrants	35,151	$ 2	35,149	0	0
Exercise of warrants, Shares		17,589,250
Exercise of stock options	4,070	$ 0	4,070	0	0
Exercise of stock options, Shares		1,986,300
Vesting of restricted stock units (RSUs)	0	$ 0	0	0	0
Vesting of restricted stock units (RSUs), Shares		49,775
Employee payroll taxes withheld related to vesting of RSUs and exercise of stock options	(26)	$ 0	(26)	0	0
Employee payroll taxes withheld related to vesting of RSUs and exercise of stock options, Shares		(38,906)
Cumulative effect of the adoption of the new standard \| Accounting Standards Update 2016-02	(920)	$ 0	0	0	(920)
Other comprehensive (loss) income, net	61	0	0	61	0
Net loss	(17,885)	0	0	0	(17,885)
Ending Balance at Mar. 31, 2019	167,808	$ 10	781,790	(206)	(613,786)
Ending Balance, Shares at Mar. 31, 2019		98,674,153
Beginning Balance at Dec. 31, 2019	$ 120,679	$ 10	782,965	(105)	(662,191)
Beginning Balance, Shares at Dec. 31, 2019	98,460,404	98,460,404
Stock-based compensation expense	$ 445	$ 0	445	0	0
Vesting of restricted stock units (RSUs)	0	$ 0	0	0	0
Vesting of restricted stock units (RSUs), Shares		63,750
Employee payroll taxes withheld related to vesting of RSUs and exercise of stock options	(123)	$ 0	(123)	0	0
Employee payroll taxes withheld related to vesting of RSUs and exercise of stock options, Shares		(25,722)
Other comprehensive (loss) income, net	(23)	$ 0	0	(23)	0
Net loss	(18,383)	0	0	0	(18,383)
Ending Balance at Mar. 31, 2020	$ 102,595	$ 10	$ 783,287	$ (128)	$ (680,574)
Ending Balance, Shares at Mar. 31, 2020	98,498,432	98,498,432

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Operating activities:
Net loss	$ (18,383)	$ (17,885)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,217	2,395
Non-cash lease expense related to operating lease right-of-use assets	674	624
Stock-based compensation expense	445	1,351
Amortization of net premiums and discounts on marketable debt securities	45	41
Non-cash interest items, net	17	(95)
Loss on sales of marketable debt securities	1	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	244	80
Operating lease right-of-use assets, net	0	(247)
Other assets	335	8
Accounts payable	1,270	670
Accrued expenses and other liabilities	997	797
Due to related parties	300	(162)
Operating lease liabilities	(758)	(655)
Net cash used in operating activities	(12,596)	(13,078)
Investing activities:
Purchases of property, plant and equipment	(146)	(2,104)
Purchases of marketable debt securities, available-for-sale	(10,300)	(50,273)
Sales/maturities of marketable debt securities	24,609	32,918
Net cash provided by (used in) investing activities	14,163	(19,459)
Financing activities:
Proceeds from exercises of stock options and warrants	0	39,221	$ 39,200
Net share settlement for restricted stock unit vesting and option exercises	(123)	(26)
Net cash (used in) provided by financing activities	(123)	39,195
Net increase in cash, cash equivalents, and restricted cash	1,444	6,658
Cash, cash equivalents, and restricted cash, beginning of period	15,687	17,000	17,000
Cash, cash equivalents, and restricted cash, end of period	17,131	23,658	15,687
Reconciliation of cash, cash equivalents, and restricted cash at end of period:
Cash and cash equivalents	16,952	22,279	15,508
Restricted cash	179	1,379
Cash, cash equivalents, and restricted cash, end of period	17,131	23,658	$ 15,687
Supplemental disclosure of cash flow information:
Interest	7	3
Income taxes	0	0
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment purchases included in accounts payable, accrued expenses, and other liabilities	182	2,031
Conversion of Viracta convertible notes and accrued interest into investment in equity securities of Viracta (Note 4)	0	751
Unrealized (losses) gains on marketable debt securities	(23)	118
Cashless exercise of stock options	$ 0	$ 29

Description of Business

3 Months Ended

Mar. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Description of Business

1. Description of Business

Organization

NantKwest, Inc., or NantKwest, was incorporated in Illinois on October 7, 2002 under the name ZelleRx Corporation. On January 22, 2010, the company changed its name to Conkwest, Inc., and on July 10, 2015, the company changed its name to NantKwest, Inc. In March 2014, the company redomesticated from the State of Illinois to the State of Delaware and the Illinois company ceased to exist. We are a pioneering clinical-stage immunotherapy biotechnology company headquartered in San Diego, California with certain operations in Culver City and El Segundo, California and Woburn, Massachusetts. In these notes, the terms “we,” “our,” “the company” and “us” refer to NantKwest.

We are focused on harnessing the power of the innate immune system by using its natural killer cells, or NK cells, to treat cancer and viral infectious diseases. A critical aspect of our strategy is to invest significantly in innovating new therapeutic candidates, based upon our proprietary activated NK, or aNK, cell platform, and conducting clinical testing and scale manufacturing of our most promising biologic product candidates.

We hold the exclusive right to commercialize aNK cells, a commercially viable NK cell line, and a wide range of genetically modified derivatives capable of killing cancer and virally infected cells. We own corresponding United States, or U.S., and foreign composition and methods-of-use patents and applications covering the cells, improvements, methods of expansion and manufacture and use of aNK cells and their improvements as therapeutics to treat a spectrum of clinical conditions.

We also license exclusive commercial rights to a high-affinity CD16 receptor expressing enhancement of our aNK cell platform, covered in a portfolio of U.S. and foreign composition and methods-of-use patents and applications covering both the clinical use as a therapeutic to treat cancers in combination with antibody products, as well as the non-clinical use in laboratory testing of monoclonal antibodies. We have non-exclusively licensed or sub-licensed our high-affinity CD16 bearing aNK cell platform and corresponding intellectual property to numerous pharmaceutical and biotechnology companies for such non-clinical uses.

Liquidity

As of March 31, 2020, the company had an accumulated deficit of approximately $680.6 million. We also had negative cash flow from operations of approximately $12.6 million during the three months ended March 31, 2020. The company will likely need additional capital to further fund development of, and seek regulatory approvals for, our product candidates, and to begin to commercialize any approved products.

We are currently focused primarily on the development of immunotherapeutic treatments for cancers and debilitating viral infections using targeted cancer and viral killing cell lines, and we believe such activities will result in the company’s continued incurrence of significant research and development and other expenses related to those programs. If the clinical trials for any of the company’s product candidates fail or produce unsuccessful results and those product candidates do not gain regulatory approval, or if any of our product candidates, if approved, fail to achieve market acceptance, we may never become profitable. Even if the company achieves profitability in the future, it may not be able to sustain profitability in subsequent periods. We intend to cover our future operating expenses through cash and cash equivalents and marketable debt securities on hand and through a combination of equity offerings, debt financings, government or other third-party funding, marketing and distribution arrangements and other collaborations, strategic alliances, and licensing arrangements. Additional financing may not be available to us when needed and, if available, financing may not be obtained on terms favorable to the company or its stockholders.

While we expect our existing cash, and cash equivalents and marketable debt securities, together with the ability to borrow from affiliated entities, will enable us to fund operations and capital expenditure requirements for at least the next 12 months, we may not have sufficient funds to reach commercialization. Failure to obtain adequate financing when needed may require us to delay, reduce, limit, or terminate some or all of our development programs or future commercialization efforts or grant rights to develop and market product candidates that we might otherwise prefer to develop and market ourselves, which could adversely affect our ability to operate as a going concern. If we raise additional funds from the issuance of equity securities, substantial dilution to existing stockholders may result. If we raise additional funds by incurring debt financing, the terms of the debt may involve significant cash payment obligations, as well as covenants and specific financial ratios that may restrict our ability to operate our business.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

There have been no material changes in our significant accounting policies other than the adoption of accounting pronouncements described below under Application of New or Revised Accounting Standards – Adopted, as compared to the significant accounting policies described in our Annual Report on Form 10‑K for the year ended December 31, 2019.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP. The condensed consolidated financial statements reflect all adjustments which are, in the opinion of management, necessary to present fairly the results for the interim periods presented and have been prepared on the same basis as the audited consolidated financial statements for the fiscal year ended December 31, 2019.

The condensed consolidated financial statements have been prepared assuming the company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or amounts and classification of liabilities that may result from the outcome of the uncertainty discussed in the Liquidity section of Note 1. We believe our existing cash, cash equivalents, and investments in marketable debt securities, and our ability to borrow from affiliated entities, will be sufficient to fund operations through at least the next 12 months following the issuance date of the financial statements based upon our Chairman and CEO’s intent and ability to support the company’s operations with additional funds, including loans from affiliated entities, as required. We may also seek to sell additional equity, through one or more follow-on public offerings, or in separate financings, or obtain a credit facility. However, we may not be able to secure such financing in a timely manner or on favorable terms. Without additional funds, we may choose to delay or reduce our operating or investment expenditures. Further, because of the risk and uncertainties associated with the commercialization of the company’s product candidates in development, we may need additional funds to meet our needs sooner than planned. To date, the company’s primary sources of capital were its initial public offering and the concurrent private placement of common shares. In addition, during the year ended December 31, 2019, our Chairman and CEO exercised warrants and options resulting in aggregate cash proceeds of $39.2 million.

The unaudited condensed consolidated financial statements do not include all information and notes necessary for a complete presentation of results of income, comprehensive income, financial position, and cash flows in conformity with U.S. GAAP. Accordingly, these financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the fiscal year ended December 31, 2019 included in our Annual Report on Form 10‑K. Interim operating results are not necessarily indicative of operating results for the full year. The year-end consolidated balance sheet data was derived from our audited financial statements, but does not include all disclosures required by U.S. GAAP.

Principles of Consolidation and Equity Investments

The condensed consolidated financial statements include the accounts of NantKwest and its wholly owned subsidiaries. All intercompany amounts have been eliminated.

We apply the variable interest model under Accounting Standards Codification, or ASC, Topic 810, Consolidation, to any entity in which we hold an equity investment or to which we have the power to direct the entity's most significant economic activities and the ability to participate in the entity's economics. If the entity is within the scope of the variable interest model and meets the definition of a variable interest entity, or VIE, we consider whether we must consolidate the VIE or provide additional disclosures regarding our involvement with the VIE. If we determine that we are the primary beneficiary of the VIE, we will consolidate the VIE. This analysis is performed at the initial investment in the entity or upon any reconsideration event.

For entities we hold as an equity investment that are not consolidated under the VIE Model, we consider whether our investment constitutes ownership of a majority of the voting interests in the entity and therefore should be considered for consolidation under the voting interest model.

Unconsolidated equity investments in the common stock or in-substance common stock of an entity under which we are able to exercise significant influence, but not control, are accounted for using the equity method. Our ability to exercise significant influence is generally indicated by ownership of 20 to 50 percent interest in the voting securities of the entity.

All other unconsolidated equity investments on which we are not able to exercise significant influence will be subsequently measured at fair value with unrealized holding gains and losses included in other income, net on the condensed consolidated statements of operations. In the instance the equity investment does not have a readily determinable fair value and does not qualify for the practical expedient to estimate fair value in accordance with ASC 820, Fair Value Measurement, or ASC 820, we will apply the measurement alternative under ASC 321, Investments—Equity Securities, or ASC 321, pursuant to which we will measure the investment at its cost less impairment, adjusted for observable price changes in an orderly market for an identical or similar investment of the same issuer.

We own non-marketable equity securities that are accounted for using the measurement alternative under ASC 321 because the preferred stock held by us is not considered in-substance common stock and such preferred stock does not have a readily determinable fair value. All investments are reviewed on a regular basis for possible impairment. If an investment's fair value is determined to be less than its net carrying value, the investment is written down to its fair value. Such an evaluation is judgmental and dependent on specific facts and circumstances. Factors considered in determining whether an impairment indicator is present include: the investees’ earnings performance and clinical trial performance, change in the investees’ industry and geographic area in which it operates, offers to purchase or sell the security for a price less than the cost of the investment, issues that raise concerns about the investee's ability to continue as a going concern, and any other information that we may be aware of related to the investment. Factors considered in determining whether an observable price change has occurred include: the price at which the investee issues equity instruments similar to those of our investment and the rights and preferences of those equity instruments compared to ours.

Use of Estimates

The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, we evaluate our estimates, including those related to valuation of equity-based awards, deferred income taxes and related valuation allowances, preclinical and clinical trial accruals, impairment assessments, useful lives of long-lived assets, loss contingencies, and fair value measurements. We base our estimates on historical experience and on various other market-specific and relevant assumptions that we believe to be reasonable under the circumstances. Estimates are assessed each period and updated to reflect current information, such as the economic considerations related to the impact that the recent coronavirus disease (COVID‑19) could have on our significant accounting estimates. Actual results could differ from those estimates.

Risks and Uncertainties

In March 2020, the World Health Organization declared the novel strain of coronavirus disease (SARS‑CoV‑2) outbreak a pandemic. To date, our operations have not been significantly impacted by the COVID‑19 outbreak. However, we cannot at this time predict the specific extent, duration, or full impact that the COVID‑19 outbreak may have on our financial condition and results of operations, including ongoing and planned clinical trials. The impact of the COVID‑19 coronavirus outbreak on the financial performance of the company will depend on future developments, including the duration and spread of the outbreak and related governmental advisories and restrictions. These developments and the impact of COVID‑19 on the financial markets and the overall economy are highly uncertain. If the financial markets and/or the overall economy are impacted for an extended period, our results may be adversely affected.

Contingencies

We record accruals for loss contingencies to the extent that we conclude it is probable that a liability has been incurred and the amount of the related loss can be reasonably estimated. We evaluate, on a quarterly basis, developments in legal proceedings and other matters that could cause a change in the potential amount of the liability recorded or of the range of potential losses disclosed. Additionally, we record our rights to insurance recoveries, limited to the extent of incurred or probable losses, as a receivable when such recoveries have been agreed to with our third-party insurers and when receipt is deemed probable. This includes instances when our third-party insurers have agreed to pay, on our behalf, certain legal defense costs and settlement amounts directly to applicable law firms and a settlement fund.

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments that potentially subject us to concentrations of risk consist principally of cash and cash equivalents and marketable debt securities.

Our cash and cash equivalents are held by one major financial institution in the U.S. and one in Korea.

Product candidates developed by us will require approvals or clearances from the U.S. Food and Drug Administration, or FDA, or international regulatory agencies prior to commercial sales. There can be no assurance that any of our product candidates will receive any of the required approvals or clearances. If we were to be denied approval or clearance or any such approval or clearance was to be delayed, it would have a material adverse impact on us.

Basic and Diluted Net Loss per Share of Common Stock

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period. Diluted loss per share is computed similarly to basic loss per share except that the denominator is increased to include the number of additional shares that would have been outstanding if the potential common shares had been issued and if the additional common shares were dilutive.

For all periods presented, potentially dilutive securities are excluded from the computation of fully diluted loss per share as their effect is anti-dilutive. The following table details those securities that have been excluded from the computation of potentially dilutive securities:

	As of March 31,
	2020		2019
Outstanding options		4,506,950		4,506,950
Outstanding RSUs		1,102,528		821,936
Total		5,609,478		5,328,886

Amounts in the table above reflect the common stock equivalents of the noted instruments.

Recent Accounting Pronouncements

Application of New or Revised Accounting Standards – Adopted

In December 2019, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2019‑12, Simplifying the Accounting for Income Taxes, or ASU 2019‑12. The amendments in ASU 2019‑12 include removing the exception to the incremental approach for intraperiod tax allocation when there is a loss from continuing operations and income, or a gain, from other items (e.g., discontinued operations or other comprehensive income) and the exception to the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. ASU 2019‑12 also amends other aspects of accounting for income taxes to help simplify and promote consistent application of U.S. GAAP. The guidance is effective for interim and annual periods beginning after December 15, 2020, with early adoption permitted. We early adopted ASU 2019‑12 effective January 1, 2020, and it did not have a material impact on our consolidated financial statements. Although our adoption of ASU 2019‑12 did not have a material impact on our consolidated financial statements during the first quarter of 2020, it may have a material impact on our consolidated financial statements in future periods due to the removal of the exceptions discussed above. The amendments related to intraperiod tax allocation were applied prospectively, and the amendment related to calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year will be applied prospectively.

Application of New or Revised Accounting Standards – Not Yet Adopted

In June 2016, the FASB issued ASU 2016‑13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The FASB subsequently issued amendments to ASU 2016‑13, which have the same effective date and transition dates as described below. The new guidance supersedes existing U.S. GAAP for measuring and recording of credit losses on financial assets measured at amortized cost by replacing the incurred-loss model with an expected-loss model. Accordingly, these financial assets will be presented at the net amount expected to be collected. This new standard also requires that credit losses related to available-for-sale debt securities be recorded as an allowance through net income rather than reducing the carrying amount under the current, other-than-temporary-impairment model. For public business entities that meet the definition of a SEC filer, except entities that are eligible to be a smaller reporting company as defined by the SEC, the standard is effective for annual periods beginning after December 15, 2019, and interim periods therein. For all other entities, the standard is effective for annual periods beginning after December 15, 2022, and interim periods therein. Early adoption is permitted for all entities for annual periods beginning after December 15, 2018. With certain exceptions, adjustments are to be applied using a modified-retrospective approach by reflecting adjustments through a cumulative-effect impact on retained earnings as of the beginning of the fiscal year of adoption. We are currently evaluating the impact that this new standard and its related amendments will have on our consolidated financial statements and we have not yet determined when we will adopt this new standard.

Other recent authoritative guidance issued by the FASB (including technical corrections to the ASC), the American Institute of Certified Public Accountants, and the Securities and Exchange Commission during the three months ended March 31, 2020 did not, or are not expected to, have a material effect on our consolidated financial statements.

Financial Statement Details

3 Months Ended

Mar. 31, 2020

Financial Statement Details [Abstract]

Financial Statement Details

3. Financial Statement Details

Prepaid expenses and other current assets

As of March 31, 2020 and December 31, 2019, prepaid expenses and other current assets were made up of (in thousands):

	March 31, 2020		December 31, 2019
	(Unaudited)
Prepaid preclinical and clinical trial services - with related party (Note 9)	$	1,249	$	1,021
Prepaid supplies - with related party (Note 9)		410		467
Prepaid rent		393		392
Insurance premium financing asset		381		757
Prepaid services		344		440
Prepaid insurance		288		372
Prepaid equipment maintenance		262		251
Interest receivable - marketable debt securities		205		222
Prepaid license fees		157		78
Due from related parties		114		47
Insurance claim receivables		29		34
Other		78		24
	$	3,910	$	4,105

Property, plant and equipment, net

As of March 31, 2020 and December 31, 2019, property, plant and equipment, net, was made up of (in thousands):

	March 31, 2020			December 31, 2019
	(Unaudited)
Leasehold improvements	$	33,430		$	33,406
Buildings		22,690			22,690
Equipment		21,640			21,434
Software		1,195			1,195
Furniture & fixtures		408			383
		79,363			79,108
Accumulated depreciation		(20,824	)		(18,607	)
	$	58,539		$	60,501

Depreciation expense related to property, plant and equipment was $2.2 million and $1.8 million for the three months ended March 31, 2020 and 2019, respectively.

Other assets

As of March 31, 2020 and December 31, 2019, other assets were made up of (in thousands):

	March 31, 2020		December 31, 2019
	(Unaudited)
Prepaid preclinical and clinical trial services - with related party (Note 9)	$	3,739	$	4,075
Restricted cash		179		179
Security deposit		113		113
Other		20		19
	$	4,051	$	4,386

Restricted cash is comprised of a certificate of deposit that serves as collateral for a letter of credit required by our landlord as a security deposit related to our facility in San Diego, California.

Accrued expenses

As of March 31, 2020 and December 31, 2019, accrued expenses were made up of (in thousands):

	March 31, 2020		December 31, 2019
	(Unaudited)
Accrued bonus	$	2,611	$	2,002
Accrued compensation		1,631		1,064
Accrued professional and service fees		1,097		975
Accrued laboratory equipment, supplies and related services		559		640
Accrued preclinical and clinical trial costs		511		281
Accrued franchise, sales/use and property taxes		168		200
Other		57		181
	$	6,634	$	5,343

Other current liabilities

As of March 31, 2020 and December 31, 2019, other current liabilities were made up of (in thousands):

	March 31, 2020		December 31, 2019
	(Unaudited)
Operating lease liability - current portion (including amounts with related parties, Note 9)	$	3,154	$	3,206
Financing obligation - current portion		381		757
Other		78		18
	$	3,613	$	3,981

Investment income, net

Net investment income is as follows for the three months ended March 31, 2020 and 2019 (in thousands):

	Three Months Ended March 31,
	2020			2019
	(Unaudited)
Interest income	$	224		$	410
Investment amortization expense, net		(45	)		(40	)
Net realized losses on investments		(1	)		—
	$	178		$	370

Interest income includes interest from marketable debt securities, notes receivable, other assets, and interest from bank deposits. We did not recognize an impairment loss on any investments during the three months ended March 31, 2020 and 2019.

Viracta Investment

3 Months Ended

Mar. 31, 2020

Investments All Other Investments [Abstract]

Viracta Investment

4. Viracta Investment

In March 2017, we participated in a Series B convertible preferred stock financing and invested $8.5 million in Viracta Therapeutics, Inc., or Viracta, a clinical stage drug development company. In May 2017, we executed an exclusive worldwide license with Viracta to develop and commercialize Viracta’s proprietary histone deacetylase inhibitor drug candidate for use in combination with natural killer cell therapy and possibly additional therapies. At March 31, 2020, our investment in Viracta totaled $9.3 million. Our investment in Viracta is reflected in equity investment on the condensed consolidated balance sheets.

In June 2018, Viracta executed a 2018 Note and Warrant Purchase Agreement with existing and new investors, including us. The initial closing under the Purchase Agreement occurred in June 2018, at which point we purchased a convertible note for $0.4 million, which under certain circumstances was convertible into preferred stock of Viracta, and a warrant to purchase Viracta’s common shares. The convertible note accrued interest at 8% and had a one-year maturity date. In September 2018, a milestone closing under the Purchase Agreement occurred, at which point we purchased an additional convertible note for $0.4 million, which under certain circumstances was convertible into preferred stock of Viracta, and a warrant to purchase Viracta’s common shares. The convertible note accrued interest at 8% and had a one-year maturity date. We classified the convertible notes as held-to-maturity notes receivable on the consolidated balance sheets. Effective January 31, 2019, the notes, together with accrued interest then outstanding, were converted to Series B preferred stock resulting in an increase to our investment in Viracta’s Series B convertible preferred stock of $0.8 million. In May 2019, we exercised warrants to acquire 253,120 shares of Viracta common stock. At December 31, 2019, our investment in Viracta totaled $9.3 million.

Based on the level of equity investment at risk, Viracta is not a VIE and therefore is not consolidated under the VIE Model. In addition, we do not hold a controlling financial interest in Viracta and therefore we do not consolidate Viracta under the voting interest model. As the preferred stock is not considered in-substance common stock, the investment is not within the scope of accounting for the investment under the equity method. As the preferred stock does not have a readily determinable fair value and does not qualify for the practical expedient to estimate fair value in accordance with ASC 820, we have elected to apply the measurement alternative under ASC 321, pursuant to which we measure our investment in Viracta at cost, less impairment, adjusted for observable price changes in an orderly market for an identical or similar investment of the same issuer.

As of March 31, 2020, our qualitative impairment assessment did not indicate there were events or changes in circumstances that may have had a significant adverse effect on the fair value of the investment. We have not recorded any impairments as of March 31, 2020, or on a cumulative basis. Further, we have not identified any downward or upward adjustments due to observable price changes in the investment as of March 31, 2020, or on a cumulative basis.

Financial Instruments Investments in Debt Securities

3 Months Ended

Mar. 31, 2020

Cash Equivalents And Marketable Securities [Abstract]

Financial Instruments Investments in Marketable Debt Securities

5. Financial Instruments – Investments in Marketable Debt Securities

At March 31, 2020, our investments in available-for-sale debt securities are detailed below (in thousands):

	March 31, 2020
	(Unaudited)
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Corporate debt securities	$	19,534	$	—	$	(30	)	$	19,504
Foreign government bonds		1,001		—		—			1,001
Government sponsored securities		2,751		7		—			2,758
Current portion		23,286		7		(30	)		23,263
Total	$	23,286	$	7	$	(30	)	$	23,263

As of March 31, 2020, the weighted-average remaining contractual life of our available-for-sale securities was approximately 0.2 years.

At December 31, 2019, our investments in available-for-sale debt securities are detailed below (in thousands):

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Corporate debt securities	$	32,382	$	10	$	(3	)	$	32,389
Foreign government bonds		1,007		—		—			1,007
Government sponsored securities		2,752		—		(4	)		2,748
Current portion		36,141		10		(7	)		36,144
Noncurrent:
Corporate debt securities		1,501		—		(4	)		1,497
Noncurrent portion		1,501		—		(4	)		1,497
Total	$	37,642	$	10	$	(11	)	$	37,641

Accumulated unrealized losses on debt securities classified as available-for-sale that have been in a continuous loss position for less than 12 months and for more than 12 months at March 31, 2020 and December 31, 2019 were as follows (in thousands):

	March 31, 2020
	(Unaudited)
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Corporate debt securities	$	19,504	$	(30	)	$	—	$	—
Total	$	19,504	$	(30	)	$	—	$	—

	December 31, 2019
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Corporate debt securities	$	11,021	$	(3	)	$	1,497	$	(4	)
Government sponsored securities		—		—			2,748		(4	)
Total	$	11,021	$	(3	)	$	4,245	$	(8	)

At March 31, 2020, 23 of the securities were in an unrealized loss position. We evaluated our securities for other-than-temporary impairment and concluded that the decline in value was primarily caused by current economic and market conditions. We do not intend to sell the investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases. Therefore, we did not recognize any other-than-temporary impairment loss during the three months ended March 31, 2020.

Realized gains and losses on sales of available-for-sale debt securities during the three months ended March 31, 2020 and 2019 were immaterial.

Fair Value Measurements

3 Months Ended

Mar. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

6. Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, based on our principal or, in absence of a principal, most advantageous market for the specific asset or liability.

We use a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires us to use observable inputs when available, and to minimize the use of unobservable inputs, when determining fair value. The three tiers are defined as follows:

•

Level 1— Observable inputs that reflect quoted market prices (unadjusted) for identical assets or liabilities in active markets at the measurement date. Since valuations are based on quoted prices that are readily and regularly available in an active market, valuation of these products does not entail a significant degree of judgment. Our Level 1 assets consist of bank deposits and money market funds.

•

Level 2— Observable inputs other than quoted prices in active markets that are observable either directly or indirectly in the marketplace for identical or similar assets and liabilities. Our Level 2 assets consist of corporate debt securities including commercial paper, government sponsored securities and corporate bonds, as well as foreign municipal securities.

•

Level 3— Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

During the periods presented, no transfers were made into or out of the Level 1, 2 or 3 categories. We will continue to review the fair value inputs on quarterly basis.

We utilize a third-party pricing service to assist in obtaining fair value pricing for our investments in marketable debt securities. Inputs are documented in accordance with the fair value disclosure hierarchy.

Recurring Valuations

Financial assets and liabilities measured at fair value on a recurring basis are summarized below at March 31, 2020 and December 31, 2019 (in thousands):

	Fair Value Measurements at March 31, 2020
	(Unaudited)
	Total		Level 1		Level 2		Level 3
Assets:
Current:
Cash and cash equivalents	$	16,952	$	16,952	$	—	$	—
Corporate debt securities		19,504		—		19,504		—
Foreign government bonds		1,001		—		1,001		—
Government sponsored securities		2,758		—		2,758		—
Total assets measured at fair value	$	40,215	$	16,952	$	23,263	$	—

	Fair Value Measurements at December 31, 2019
	Total		Level 1		Level 2		Level 3
Assets:
Current:
Cash and cash equivalents	$	15,508	$	15,508	$	—	$	—
Corporate debt securities		32,389		—		32,389		—
Foreign government bonds		1,007		—		1,007		—
Government sponsored securities		2,748		—		2,748		—
Noncurrent:
Corporate debt securities		1,497		—		1,497		—
Total assets measured at fair value	$	53,149	$	15,508	$	37,641	$	—

Non-recurring Valuations

Non-financial assets and liabilities are recognized at fair value subsequent to initial recognition when they are deemed to be other-than-temporarily impaired. There were no material non-financial assets and liabilities deemed to be other-than-temporarily impaired and measured at fair value on a non-recurring basis for the three months ended March 31, 2020.

Collaboration and License Agreements

3 Months Ended

Mar. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaboration and License Agreements

7. Collaboration and License Agreements

Collaborative Arrangements

A collaborative arrangement is a contractual arrangement that involves a joint operating activity. These arrangements involve two or more parties who are (i) active participants in the activity, and (ii) exposed to significant risks and rewards dependent on the commercial success of the activity.

Cost Sharing Agreement

In January 2020, we entered into a Cost Allocation Agreement, or the Agreement, with ImmunityBio, Inc. and its subsidiaries, or ImmunityBio. The Agreement became effective on October 1, 2019. ImmunityBio is a related party, as it is an affiliate of NantWorks (Note 9). Under the Agreement and related work order, the parties agreed to conduct a joint study for the clinical research trial being conducted pursuant to the protocol titled QUILT 3.063: A phase 2 study of combination therapy with an IL‑15 superagonist (N‑803), off-the-shelf CD16‑targeted natural killer cells (haNK), and avelumab without cytotoxic chemotherapy in subjects with Merkel Cell Carcinoma (MCC) that has progressed on or after treatment with a checkpoint inhibitor. The ImmunityBio study drug included in the joint study is ImmunityBio’s proprietary IL‑15 superagonist known as N‑803 and our study drug is our proprietary “off-the-shelf” CD16-targeted natural killer cell therapy known as haNK.

We will act as the sponsor of this joint study for purposes of regulatory matters, including submissions, correspondence, and communications. Additionally, we are designated as the contracting party to execute agreements with third and related parties relating to the joint study. We and ImmunityBio will split certain joint study costs equally in accordance with the terms of the Agreement and related work order. Shared joint study costs include cost related to conducting the joint study development activities, such as personnel related costs, as well as all costs associated with regulatory matters. Costs and expenses incurred in connection with the development, manufacturing, supply, delivery, and pre-patient administration dosing mechanism of each party’s study drug, are excluded from the shared joint study costs.

Under the Agreement, each of ImmunityBio and the company will receive exclusive rights to any new intellectual property developed that relates solely to its respective study drug, and the parties will have joint co-equal rights in any other intellectual property. The Agreement expires upon the second anniversary of the effective date with the option to renew for additional successive one-year terms, but work orders for any joint studies still in process at the time of termination will continue until the applicable study is completed.

During the three months ended March 31, 2020, we incurred $0.1 million in costs related to the joint study that are subject to joint cost sharing under the Agreement which have been recorded as a reduction in research and development expense on the condensed consolidated statements of operations. At March 31, 2020, we have recorded a receivable of $0.1 million from ImmunityBio related to ImmunityBio’s share of joint study costs under the Agreement, which is included in prepaid and other current assets on the condensed consolidated balance sheets.

Exclusive Co-Development Agreement

In August 2016, we entered into an exclusive Co‑Development Agreement, or the Co‑Development Agreement, with Altor BioScience, LLC, or Altor. Altor is a related party, as it is a wholly owned subsidiary of ImmunityBio (Note 9). Under the Co‑Development Agreement, the parties agreed to exclusively collaborate on the development of certain therapeutic applications combining our proprietary NK cells with Altor's N‑801 and/or N‑803 products with respect to certain technologies and intellectual property rights as may be agreed between the parties for the purpose of jointly developing therapeutic applications of certain effector cell lines.

We are the lead developer for each product developed by the parties pursuant to the Co‑Development Agreement unless otherwise agreed to under a given project plan. Under the terms of the Co‑Development Agreement, both parties granted a co-exclusive, royalty free, fully paid-up, worldwide license, with the right to sublicense (only to a third-party contractor assisting with research and development activities under this Co‑Development Agreement and subject to prior consent, not to be unreasonably withheld), under the intellectual property, or IP, including the parties interest in the joint IP, solely to conduct any development activities agreed to by the steering committee as set forth in any development plan. Unless otherwise mutually agreed by the parties in the development plan for a project, we are responsible for all costs and expenses incurred by either party related to conducting clinical trials and other activities under each development program, including costs associated with patient enrollment, materials and supplies, third-party staffing and regulatory filings. Altor supplies free of charge, sufficient amounts of Altor products for all pre-clinical requirements and certain clinical requirements for up to 400 patients in phase I and/or phase II clinical trials, as required under the development plan for a project per the Co‑Development Agreement.

Each company owns an undivided interest in and to all rights, title and interest in and to the joint product rights. The Co‑Development Agreement expires upon the fifth anniversary of the effective date. We have dosed patients with N‑803, an IL‑15 superagonist, in several phase Ib/II trials. No charges for supplies by Altor were incurred in association with the above trials during the three months ended March 31, 2020 and 2019.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and contingencies

8. Commitments and Contingencies

Contingencies

We record accruals for loss contingencies to the extent that we conclude it is probable that a liability has been incurred and the amount of the related loss can be reasonably estimated. We evaluate, on a quarterly basis, developments in legal proceedings and other matters that could cause a change in the potential amount of the liability recorded or of the range of potential losses disclosed. Additionally, we record our rights to insurance recoveries, limited to the extent of incurred or probable losses, as a receivable when such recoveries have been agreed to with our third-party insurers and when receipt is deemed probable. This includes instances where our third-party insurers have agreed to pay, on our behalf, certain legal defense costs and settlement amounts directly to applicable law firms and a settlement fund.

Securities Litigation

In March 2016, a putative securities class action complaint captioned Sudunagunta v. NantKwest, Inc., et al., No. 16‑cv‑01947 was filed in federal district court for the Central District of California related to the company’s restatement of certain interim financial statements for the periods ended June 30, 2015 and September 30, 2015. A number of similar putative class actions were filed in federal and state court in California. The actions originally filed in state court were removed to federal court, and the various related actions were consolidated. Plaintiffs asserted causes of action for alleged violations of Sections 11 and 15 of the Securities Act of 1933 and Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b‑5 promulgated thereunder. Plaintiffs sought unspecified damages, costs and attorneys’ fees, and equitable/injunctive or other relief on behalf of putative classes of persons who purchased or acquired the company’s securities during various time periods from July 28, 2015 through March 11, 2016. In September 2017, the court denied defendants' motion to dismiss the third amended consolidated complaint. On August 13, 2018, the district court granted plaintiffs’ motions for class certification and to strike plaintiffs’ claims under the Securities Exchange Act of 1934 and Rule 10b‑5. On August 24, 2018, at the district court’s direction, plaintiffs filed a fourth amended consolidated complaint. On August 27, 2018, defendants petitioned the U.S. Court of Appeals for the Ninth Circuit to authorize interlocutory appeal of the class certification order. On September 7, 2018, defendants answered the fourth amended consolidated complaint. On September 21, 2018, the parties informed the Ninth Circuit that they had reached a settlement in principle, and the parties moved to stay appellate proceedings. On September 24, 2018, the parties notified the district court that they had reached a settlement in principle. On November 9, 2018, the plaintiffs filed an unopposed motion for preliminary approval of the settlement and notice to class members. On January 9, 2019, the district court granted the motion for preliminary approval. A final approval hearing was held on April 29, 2019, and the district court granted final approval and entered judgment on May 31, 2019.

Under the terms of the settlement, we paid $12.0 million to the plaintiffs as full and complete settlement of the litigation. We were responsible for $1.2 million of the settlement amount, which was recognized in selling, general and administrative expense during 2018, while the remaining $10.8 million was fully funded by our insurance carriers under our directors’ and officers’ insurance policy. We and the insurance carriers paid the settlement amount into a settlement fund in January 2019. Subsequent to receiving final approval of the settlement on May 13, 2019, the aforementioned settlement accrual, associated insurance claim receivable and restricted cash were released and are no longer reflected on the accompanying condensed consolidated balance sheets.

Stipulation of Settlement

In early April 2019, following board approval, which occurred in late March 2019, we entered into a settlement agreement, or the Stipulation of Settlement, with three stockholders of the company, each of whom had submitted a stockholder demand for the board to take action to remedy purported harm to the company resulting from certain alleged wrongful conduct concerning, among other things, disclosures about Dr. Soon-Shiong’s compensation and a related-party lease agreement. The Stipulation of Settlement called for us to adopt certain governance changes, and for the three stockholders to file a stockholder derivative action in the Superior Court of the State of California, County of San Diego, followed by an application for court approval of the Stipulation of Settlement. On May 31, 2019, the court entered an order preliminarily approving the Stipulation of Settlement and scheduling the final settlement hearing for August 9, 2019. Pursuant to the Stipulation of Settlement, we have provided stockholders with notice of the settlement and the final settlement hearing.

Under the terms of the Stipulation of Settlement, which received final approval by the court on August 9, 2019, we paid an attorney’s fee of $0.5 million to the plaintiffs as part of the settlement. Of that amount, we were responsible for half, which was recognized in selling, general and administrative expense on the condensed consolidated statements of operations during the first quarter of 2019, while the other half was funded by our insurance carrier. We and the insurance carrier paid the settlement amount into a settlement fund in June 2019. Subsequent to receiving final approval of the settlement on August 9, 2019, the aforementioned settlement accrual, associated insurance claim receivable and restricted cash were released and are no longer reflected on the accompanying condensed consolidated balance sheets.

Insurance Recoveries

We have reflected our right to insurance recoveries, limited to the extent of incurred or probable losses, as a receivable when such recoveries have been agreed to with our third-party insurers and receipt is deemed probable. This includes instances where our third-party insurers have agreed to pay, on our behalf, certain legal defense costs and settlement amounts directly to applicable law firms and a settlement fund. The amount of such receivable recorded at March 31, 2020 and December 31, 2019 was $30,000 and $34,000, respectively, and is included in prepaid expenses and other current assets on our consolidated balance sheets.

Contractual Obligations - Leases

Substantially all of our operating lease right-of-use assets and operating lease liabilities relate to facilities leases. We lease: (i) a research facility and office space in San Diego, California; (ii) a research and manufacturing space in Culver City, California, from a related party; (iii) a research and manufacturing facility in El Segundo, California, also from a related party; (iv) a research facility in Torrance, California; and (v) a research facility in Woburn, Massachusetts. See Note 9 – Related Party Agreements for further information.

For the three months ended March 31, 2020 and 2019, $1.3 million and $1.2 million, respectively, including variable lease costs of $0.3 million and $0.2 million, respectively, was recorded in operating expenses on the condensed consolidated statements of operations. The weighted-average remaining lease term as of March 31, 2020 and December 31, 2019 was 4.3 years and 4.5 years, respectively. The weighted-average discount rate as of March 31, 2020 and December 31, 2019 was 9%. For the three months ended March 31, 2020 and 2019, cash outflows from operating leases, excluding variable lease costs, was $1.0 million and $1.3 million, respectively.

Future minimum lease payments at March 31, 2020 are presented in the following table (in thousands). Common area maintenance costs and taxes are not included in these payments.

Years ending December 31:	Operating Leases (a)
2020 (excluding the three months ended March 31, 2020)	$	3,221
2021		3,754
2022		3,671
2023		2,545
2024		1,083
Thereafter		1,730
Total future minimum lease payments		16,004
Less: Interest		2,671
Present value of operating lease liabilities	$	13,333

(a)

Operating lease payments include $3.3 million related to options to extend lease terms that are reasonably certain of being exercised.

In August 2018, NantBio, Inc., or NantBio, a related party (Note 9), assigned an agreement to us for the use of a third-party research facility, which provides us with the exclusive right to use and access to a portion of the third party’s laboratory and vivarium premises. In conjunction with the assignment, we reimbursed NantBio for upfront payments which it had made to the third party of $0.9 million, and paid $0.5 million directly to the third party for an aggregate value of $1.4 million. The assigned agreement is for a term of ten years and expires in June 2027. The agreement may be terminated by us at any time, with or without cause. In case of termination of the agreement, the third party will reimburse us for a pro-rata amount based upon the passage of time.

In September 2016, we entered into a lease agreement with 605 Doug St, LLC, a related party (Note 9), for approximately 24,250 square feet in El Segundo, California, which has been converted to a research and development laboratory and a current good manufacturing practice, or cGMP, manufacturing facility. The lease runs from July 2016 through July 2023. We have the option to extend the lease for an additional three year term through July 2026. The monthly rent is $0.1 million with annual increases of 3% beginning in July 2017.

In March 2016, we entered into a lease agreement for an approximately 7,893 square foot facility in Woburn, Massachusetts, for a research and development laboratory, related office and other related uses. The initial lease term runs for 48 months from April 29, 2016 through May 31, 2020. In June 2016, the lease was amended to add 260 square feet, for a total of 8,153 square feet. Base rent for the initial term of the lease is $19,000 per month with a $1 per square foot annual increase on each anniversary date. In August 2019, we exercised our right pursuant to the lease agreement to extend the term of the lease for an additional two years through May 31, 2022. Consequently, during the third quarter of 2019 we recognized an increase of $0.6 million in both operating lease right-of-use assets and operating lease liabilities on the condensed consolidated balance sheets.

In November 2015, we entered into a facility license agreement with NantWorks LLC, or NantWorks, a related party (Note 9), for approximately 9,500 square feet of office space in Culver City, California, which has been converted to a research and development laboratory and a cGMP manufacturing facility. The license was effective in May 2015 and extends through December 2020. The monthly rent is $47,000, with annual increases of 3% beginning in January 2017.

In June 2015, we entered into a lease agreement for an approximately 44,700 square foot facility in San Diego, California, for a research and development laboratory, related office and other related uses. The term of the lease extends for seven years commencing on August 1, 2016. The base rent is $0.2 million per month with 3% annual increases on each anniversary date.

Commitments

We did not enter into any significant contracts during the three months ended March 31, 2020, other than those disclosed in these unaudited condensed consolidated financial statements.

Related Party Agreements

3 Months Ended

Mar. 31, 2020

Related Party Agreements

9. Related Party Agreements

Our Chairman and CEO founded and has a controlling interest in NantWorks, which is a collection of multiple companies in the healthcare and technology space. As described below, we have entered into arrangements with NantWorks, and certain affiliates of NantWorks, to facilitate the development of new genetically modified NK cells for our product pipeline. Affiliates of NantWorks are also affiliates of the company due to the common control by and/or common ownership interest of our Chairman and CEO.

NantWorks

Under the NantWorks shared services agreement executed in November 2015, but effective August 2015, NantWorks provides corporate, general and administrative, manufacturing strategy, research and development, regulatory and clinical trial strategy, and other support services. We are charged for the services at cost plus reasonable allocations for indirect costs that relate to the employees providing the services. For the three months ended March 31, 2020 and 2019, we recorded $0.7 million and $0.6 million, respectively, to selling, general and administrative expense, and $0.5 million and $0.3 million, respectively, to research and development expense under this arrangement on the condensed consolidated statements of operations. These amounts exclude certain general and administrative expenses provided by third party vendors directly for our benefit, which have been reimbursed to NantWorks based on those vendors’ invoiced amounts without markup by NantWorks.

In June 2016, we amended the existing shared services agreement with NantWorks whereby we can provide support services to NantWorks and/or any of its affiliates. For the three months ended March 31, 2020 and 2019, we recorded expense reimbursements of $0.3 million and $0.2 million, respectively, to selling, general and administrative expense and $0.5 million and $0.5 million, respectively, to research and development expense.

We owed NantWorks a net amount of $0.7 million and $0.4 million for all agreements between the two affiliates at March 31, 2020 and December 31, 2019, respectively, which is included in due to related parties on the condensed consolidated balance sheets.

In November 2015, we entered into a facility license agreement with NantWorks, which became effective May 2015, for approximately 9,500 square feet in Culver City, California, which has been converted to a research and development laboratory and a cGMP manufacturing facility. Lease expense for this facility is recorded in research and development expense on the condensed consolidated statements of operations and was $0.1 million for each of the three months ended March 31, 2020 and 2019.

Immuno-Oncology Clinic, Inc.

Beginning in 2017, we entered into multiple agreements with Immuno-Oncology Clinic, Inc., or the Clinic, to conduct various clinical trials. The Clinic was formerly known as John Lee, M.D. and Leonard Sender, M.D., Inc., a professional medical corporation, dba Chan Soon-Shiong Institutes for Medicine, in El Segundo, California. The Clinic is a related party as it is owned by one officer of NantKwest and NantWorks manages the administrative operations of the Clinic. Prior to June 30, 2019, one of the company’s officers was an investigator or sub-investigator for all of the company’s trials conducted at the Clinic.

In July 2019, we entered into a new agreement with the Clinic which superseded our existing agreements with the Clinic, effective as of July 1, 2019. The new agreement, as amended on March 31, 2020, covers clinical trial and research related activities on a non-exclusive basis relating to our existing clinical trials, commenced prior to July 1, 2019, and prospective clinical trials and research projects. The new agreement also specifies certain services and related costs that are excluded from the new agreement. Prior to commencing any work under the new agreement, the parties have agreed to execute written work orders setting forth the terms and conditions related to specific services to be performed, including financial terms. For existing clinical trials, commenced prior to July 1, 2019, fees incurred for services performed after July 1, 2019 are covered under the new agreement and applied towards the below-mentioned prepayments. The initial term of the new agreement is for one year, but the agreement allows for an automatic renewal and additional extensions beyond the initial term. In July 2019, we executed a clinical trial work order under the new agreement with the Clinic for an open-label, phase I study of PD‑L1.t‑haNK for infusion in subjects with locally advanced or metastatic solid cancers.

In consideration of the services to be performed under the new agreement, as amended on March 31, 2020, we agreed to make payments of up to $7.5 million to the Clinic, of which $3.75 million and $1.875 million were paid in July 2019 and October 2019, respectively. As amended, a conditional payment of $1.875 million shall be due and payable at such time, if any, that the payments made in July 2019 and October 2019 have been earned by the Clinic through performance of services. Under the term of the new agreement, the outstanding balance of our prepayment shall be increased on a quarterly basis by an interest credit computed in accordance with terms specified in the new agreement.

To the extent any portion of the prepayments remain unearned by the Clinic on the third anniversary of the new agreement, we may elect at our sole discretion either to (i) not extend the term of the new agreement and have the Clinic reimburse us for the total amount of any remaining unused portion of the prepayments, or (ii) extend the term of the new agreement for up to three additional one year periods, at which time the Clinic will reimburse us for the total amount of any remaining unused portion of the prepayments plus interest if reimbursement is not made within 60 days of expiration. The Clinic may terminate this agreement upon each anniversary date upon sixty (60) days prior written notice and reimbursement in full to us of any outstanding unearned balance of the prepayments, provided that any such termination by the Clinic will not apply with respect to any work orders still in effect at the time of such termination.

During the three months ended March 31, 2020 and 2019, $0.1 million and $0.4 million, respectively, has been recognized in research and development expense on the condensed consolidated statements of operations related to our agreements with the Clinic. At March 31, 2020 and December 31, 2019, we owed the Clinic $0.1 million and $0.1 million, respectively, for services excluded from the new agreement, which are included in due to related parties on the condensed consolidated balance sheets. At March 31, 2020 and December 31, 2019, we had a prepaid balance with the Clinic of $5.0 million and $5.1 million, respectively, which are included in prepaid expenses and other currents assets, and other assets, on the condensed consolidated balance sheets. We anticipate that the remaining prepayment amount as of March 31, 2020 will be utilized in future periods as the Clinic provides additional services pursuant to the new agreement.

ImmunityBio

ImmunityBio, Inc., or ImmunityBio, is a related party, as it is an affiliate of NantWorks.

In January 2020, we entered into a cost sharing agreement with ImmunityBio as further described in Note 7 – Collaboration and License Agreements. During the three months ended March 31, 2020, we incurred $0.1 million in costs related to the joint study being conducted that are subject to joint cost sharing under the Agreement which have been recorded as a reduction in research and development expense on the condensed consolidated statements of operations. At March 31, 2020, we have a receivable of $0.1 million from ImmunityBio related to this agreement, which is included in prepaid expenses and other current assets on the condensed consolidated balance sheets.

In August 2016, we entered into an exclusive Co‑Development Agreement with Altor as described in Note 7 – Collaboration and License Agreements. Altor is a related party as it is a wholly owned subsidiary of ImmunityBio. No charges for supplies by Altor were incurred in association with the trials during the three months ended March 31, 2020 and 2019.

In June 2015, we entered into a supply agreement with ImmunityBio pursuant to which we have the right to purchase ImmunityBio’s proprietary bioreactors, made according to specifications mutually agreed to with ImmunityBio. We also have the right to purchase reagents and consumables associated with such equipment from ImmunityBio. When an upfront payment is made, it is included in prepaid expenses on the condensed consolidated balance sheets until the product is received. The agreement has an initial term of five years and renews automatically for successive one-year periods unless terminated earlier.

At each of March 31, 2020 and December 31, 2019, we had $1.8 million in capitalized equipment purchased from ImmunityBio, which is included in property, plant and equipment, net, on the condensed consolidated balance sheets. During each of the three months ended March 31, 2020 and 2019, we recorded research and development expense associated with reagents and consumables purchased from ImmunityBio of $0.1 million on the condensed consolidated statements of operations.

At March 31, 2020 and December 31, 2019 we had $0.4 million and $0.5 million, respectively, included in prepaid expenses and other current assets on the condensed consolidated balance sheets related to consumables purchased from ImmunityBio. At March 31, 2020 and December 31, 2019, no other balances were due between the parties.

605 Doug St. LLC

In September 2016, we entered into a lease agreement with 605 Doug St, LLC, an entity owned by our Chairman and CEO, for approximately 24,250 square feet in El Segundo, California, which has been converted to a research and development laboratory and a cGMP manufacturing facility. The lease runs from July 2016 through July 2023. We have the option to extend the lease for an additional three-year term through July 2026. The monthly rent is $0.1 million with annual increases of 3% beginning in July 2017. Lease expense for this facility is recorded in research and development expense on the condensed consolidated statements of operations and was $0.2 million for each of the three months ended March 31, 2020 and 2019, respectively. At March 31, 2020 and December 31, 2019, no balances were due between the parties.

NantBio

In August 2018, NantBio assigned an agreement to us for the use of a third-party research facility, which provides us with the exclusive right to use and access to a portion of the third party’s laboratory and vivarium premises. NantBio is a related party, as it is an affiliate of NantWorks. In conjunction with the assignment, we reimbursed NantBio for upfront payments which it had made to the third party of $0.9 million, and paid $0.5 million directly to the third party for an aggregate value of $1.4 million. The assigned agreement is for a term of ten years and expires in June 2027. The agreement may be terminated by us at any time, with or without cause. In case of termination of the agreement, the third party will reimburse us for a pro-rata amount based upon the passage of time.

At December 31, 2019, NantBio owed us $8,400, which is included in prepaid expenses and other current assets on the condensed consolidated balance sheets. At March 31, 2020, no balances were due between the parties.

In March 2016, NantBio and the National Cancer Institute entered into a cooperative research and development agreement. The initial five year agreement covers NantBio and its affiliates, including us. Under the agreement, the parties are collaborating on the preclinical and clinical development of proprietary recombinant natural killer cells and monoclonal antibodies in monotherapy and in combination immunotherapies. We benefited from the preclinical and clinical research conducted during the first four years under this agreement. In each of April 2016, April 2017, August 2018 and May 2019, we paid $0.6 million to the National Cancer Institute as a prepayment for services under the agreement. We recognize research and development expense related to this agreement ratably over a 12‑month period for each funding year and recorded $0.1 million and $0.1 million of expense associated with the agreement in each of the three months ended March 31, 2020 and 2019. At March 31, 2020, we have accrued $25,000 in anticipation of funding an additional $0.6 million related to the fifth year of the agreement in April 2020. As of December 31, 2019, we had a balance of $0.1 million included in prepaid expenses and other current assets related to this agreement, on the condensed consolidated balance sheets.

Stockholders' Equity

3 Months Ended

Mar. 31, 2020

Equity [Abstract]

Stockholders' Equity

10. Stockholders’ Equity

Stock Repurchase – In November 2015, the board of directors approved a share repurchase program, or the 2015 Share Repurchase Program, allowing the CEO or CFO, on behalf of the company, to repurchase from time to time, in the open market or in privately negotiated transactions, up to $50.0 million of our outstanding shares of common stock, exclusive of any commissions, markups or expenses. The timing and amounts of any purchases were and will continue to be based on market conditions and other factors, including price, regulatory requirements and other corporate considerations. The 2015 Share Repurchase Program does not require the purchase of any minimum number of shares and may be suspended, modified, or discontinued at any time without prior notice. We have financed, and expect to continue to finance, the purchases with existing cash balances. At March 31, 2020, $18.3 million remained authorized for repurchase under the 2015 Share Repurchase Program and no shares were repurchased during the three months ended March 31, 2020. The shares are formally retired through board approval upon repurchase.

Stock-Based Compensation

3 Months Ended

Mar. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

11. Stock-Based Compensation

The following table presents all stock-based compensation as included on the condensed consolidated statements of operations (in thousands):

	Three Months Ended March 31,
	2020		2019
	(Unaudited)
Stock-based compensation expense:
Employee stock options	$	105	$	997
Employee RSUs		290		250
Non-employee RSUs		50		104
	$	445	$	1,351
Stock-based compensation expense in operating expenses:
Research and development	$	128	$	111
Selling, general and administrative		317		1,240
	$	445	$	1,351

Stock Options

The following table summarizes stock option activity under all equity incentive plans for the three months ended March 31, 2020:

	Number of Shares		Weighted- Average Exercise Price		Aggregate Intrinsic Value (in thousands)		Weighted- Average Remaining Contractual Life (in years)
Outstanding at December 31, 2019		4,506,950	$	9.37	$	5,710		5.8
Outstanding at March 31, 2020		4,506,950	$	9.37	$	3,085		5.6
Vested and Exercisable at March 31, 2020		4,023,614	$	10.13	$	3,085		5.3

The total unrecognized compensation cost related to non-vested stock options as of March 31, 2020 is $1.0 million, which is expected to be recognized over a weighted-average period of 2.4 years.

During the three months ended March 31, 2019, we recognized proceeds of $4.1 million from exercises of stock options by our Chairman and CEO. There were no option exercises during the three months ended March 31, 2020.

Restricted Stock Units

The following table summarizes the restricted stock units, or RSUs, activity under the 2015 Plan for the three months ended March 31, 2020:

	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested balance at December 31, 2019		1,139,428		$	2.23
Granted		33,500		$	6.43
Vested		(63,750	)	$	5.90
Forfeited		(6,650	)	$	2.71
Unvested balance at March 31, 2020		1,102,528		$	2.14

During the three months ended March 31, 2020, we granted 33,500 RSUs to employees. As of March 31, 2020, there was $1.3 million of unrecognized stock-based compensation expense related to RSUs that is expected to be recognized over a weighted-average period of 2.0 years. Of that amount, $1.2 million of unrecognized expense is related to employee grants with a remaining weighted-average period of 2.1 years and $0.1 million of unrecognized expense is related to non-employee grants with a remaining weighted-average period of 0.6 years.

Warrants

During the three months ended March 31, 2019, we recognized proceeds of $35.2 million upon the exercise of warrants by our Chairman and CEO. As of December 31, 2019 there were no warrants outstanding, and no warrants were issued during the three months ended March 31, 2020.

Income Taxes

3 Months Ended

Mar. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

12. Income Taxes

The difference between the federal statutory tax rate of 21% and our 0% tax rate is due to losses in jurisdictions from which we cannot benefit.

Prior to the adoption of ASU 2019‑12 in the first quarter of 2020, as described in Note 2, intraperiod tax allocation rules required us to allocate the provision for income taxes between continuing operations and other categories of earnings, such as other comprehensive income. In periods in which we had a year-to-date pre-tax loss from continuing operations and pre-tax income in other categories of earnings, such as other comprehensive income, we had to allocate the tax provision to the other categories of earnings. We then recorded a related tax benefit in continuing operations. However, with the adoption of ASU 2019‑12, we are no longer required to allocate the tax provision to the other categories of earnings and related benefit to continuing operations under these circumstances.

We recorded unrealized gains on marketable debt securities during the three months ended March 31, 2019. As a result, we recorded a tax benefit of $36,000 for the three months ended March 31, 2019 on the condensed consolidated statements of operations. We also recorded an increase to other comprehensive income of $0.1 million for the three months ended March 31, 2019 on the condensed consolidated balance sheets.

We are operating in Korea. During the three months ended March 31, 2020 and 2019, there was no tax expense or benefit related to Korea.

We currently file federal and state income tax returns in the U.S. and in Korea. Income tax expense consists of U.S. federal, state, and Korean income taxes. To date, we have not been required to pay U.S. federal income taxes and only minimum state income taxes because of current and accumulated net operating losses.

On March 27, 2020, the U.S. enacted the Coronavirus Aid, Relief and Economic Security Act, or the CARES Act. The CARES Act is an emergency economic stimulus package that includes spending and tax breaks to strengthen the U.S. economy and fund a nationwide effort to curtail the effect of COVID‑19. While the CARES Act provides sweeping tax changes in response to the COVID‑19 pandemic, some of the more significant provisions which are expected to impact our financial statements include removal of certain limitations on utilization of net operating losses, increasing the loss carryback period for certain losses to five years, and increasing the ability to deduct interest expense, as well as amending certain provisions of the previously enacted Tax Cuts and Jobs Act. Consistent with previous years, we expect to continue to generate net losses in the foreseeable future. We currently have significant federal and state deferred tax assets attributed to prior net operating losses and research and experimentation tax credits. These deferred taxes are fully reserved. As we have never generated taxable income, the CARES Act feature allowing net operating losses originating in 2018, 2019 or 2020 to be carried back five years is not expected to have a significant impact. Management does not expect any other provisions of the CARES Act to have a material impact on our financial position, results of operations or cash flows during 2020.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2020

Accounting Policies [Abstract]

Liquidity

Basis of Presentation

Principles of Consolidation and Equity Investments

The condensed consolidated financial statements include the accounts of NantKwest and its wholly owned subsidiaries. All intercompany amounts have been eliminated.

Use of Estimates

Risks and Uncertainties

Contingencies

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments that potentially subject us to concentrations of risk consist principally of cash and cash equivalents and marketable debt securities.

Our cash and cash equivalents are held by one major financial institution in the U.S. and one in Korea.

Basic and Diluted Net Loss Per Share of Common Stock

Basic and Diluted Net Loss per Share of Common Stock

	As of March 31,
	2020		2019
Outstanding options		4,506,950		4,506,950
Outstanding RSUs		1,102,528		821,936
Total		5,609,478		5,328,886

Amounts in the table above reflect the common stock equivalents of the noted instruments.

Recent Accounting Pronouncements

Application of New or Revised Accounting Standards – Adopted

Application of New or Revised Accounting Standards – Not Yet Adopted

Investment in Viracta

Fair Value Measurements

•

Level 3— Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

During the periods presented, no transfers were made into or out of the Level 1, 2 or 3 categories. We will continue to review the fair value inputs on quarterly basis.

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2020

Accounting Policies [Abstract]

Securities Excluded from the Computation of Potentially Dilutive Securities

The following table details those securities that have been excluded from the computation of potentially dilutive securities:

	As of March 31,
	2020		2019
Outstanding options		4,506,950		4,506,950
Outstanding RSUs		1,102,528		821,936
Total		5,609,478		5,328,886

Amounts in the table above reflect the common stock equivalents of the noted instruments.

Financial Statement Details (Tables)

3 Months Ended

Mar. 31, 2020

Financial Statement Details [Abstract]

Prepaid Expenses and Other Current Assets

As of March 31, 2020 and December 31, 2019, prepaid expenses and other current assets were made up of (in thousands):

	March 31, 2020		December 31, 2019
	(Unaudited)
Prepaid preclinical and clinical trial services - with related party (Note 9)	$	1,249	$	1,021
Prepaid supplies - with related party (Note 9)		410		467
Prepaid rent		393		392
Insurance premium financing asset		381		757
Prepaid services		344		440
Prepaid insurance		288		372
Prepaid equipment maintenance		262		251
Interest receivable - marketable debt securities		205		222
Prepaid license fees		157		78
Due from related parties		114		47
Insurance claim receivables		29		34
Other		78		24
	$	3,910	$	4,105

Property, Plant and Equipment, Net

As of March 31, 2020 and December 31, 2019, property, plant and equipment, net, was made up of (in thousands):

	March 31, 2020			December 31, 2019
	(Unaudited)
Leasehold improvements	$	33,430		$	33,406
Buildings		22,690			22,690
Equipment		21,640			21,434
Software		1,195			1,195
Furniture & fixtures		408			383
		79,363			79,108
Accumulated depreciation		(20,824	)		(18,607	)
	$	58,539		$	60,501

Other Assets

As of March 31, 2020 and December 31, 2019, other assets were made up of (in thousands):

	March 31, 2020		December 31, 2019
	(Unaudited)
Prepaid preclinical and clinical trial services - with related party (Note 9)	$	3,739	$	4,075
Restricted cash		179		179
Security deposit		113		113
Other		20		19
	$	4,051	$	4,386

Accrued Expenses

As of March 31, 2020 and December 31, 2019, accrued expenses were made up of (in thousands):

	March 31, 2020		December 31, 2019
	(Unaudited)
Accrued bonus	$	2,611	$	2,002
Accrued compensation		1,631		1,064
Accrued professional and service fees		1,097		975
Accrued laboratory equipment, supplies and related services		559		640
Accrued preclinical and clinical trial costs		511		281
Accrued franchise, sales/use and property taxes		168		200
Other		57		181
	$	6,634	$	5,343

Other Current Liabilities

As of March 31, 2020 and December 31, 2019, other current liabilities were made up of (in thousands):

	March 31, 2020		December 31, 2019
	(Unaudited)
Operating lease liability - current portion (including amounts with related parties, Note 9)	$	3,154	$	3,206
Financing obligation - current portion		381		757
Other		78		18
	$	3,613	$	3,981

Investment Income, Net

Net investment income is as follows for the three months ended March 31, 2020 and 2019 (in thousands):

	Three Months Ended March 31,
	2020			2019
	(Unaudited)
Interest income	$	224		$	410
Investment amortization expense, net		(45	)		(40	)
Net realized losses on investments		(1	)		—
	$	178		$	370

Financial Instruments Investments in Marketable Debt Securities (Tables)

3 Months Ended

Mar. 31, 2020

Cash Equivalents And Marketable Securities [Abstract]

Schedule of Investments in available-for-sale Debt Securities

At March 31, 2020, our investments in available-for-sale debt securities are detailed below (in thousands):

	March 31, 2020
	(Unaudited)
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Corporate debt securities	$	19,534	$	—	$	(30	)	$	19,504
Foreign government bonds		1,001		—		—			1,001
Government sponsored securities		2,751		7		—			2,758
Current portion		23,286		7		(30	)		23,263
Total	$	23,286	$	7	$	(30	)	$	23,263

At December 31, 2019, our investments in available-for-sale debt securities are detailed below (in thousands):

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Corporate debt securities	$	32,382	$	10	$	(3	)	$	32,389
Foreign government bonds		1,007		—		—			1,007
Government sponsored securities		2,752		—		(4	)		2,748
Current portion		36,141		10		(7	)		36,144
Noncurrent:
Corporate debt securities		1,501		—		(4	)		1,497
Noncurrent portion		1,501		—		(4	)		1,497
Total	$	37,642	$	10	$	(11	)	$	37,641

Accumulated Unrealized Losses on Debt Securities Classified as Available-for-Sale in Continuous Loss Position

	March 31, 2020
	(Unaudited)
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Corporate debt securities	$	19,504	$	(30	)	$	—	$	—
Total	$	19,504	$	(30	)	$	—	$	—

	December 31, 2019
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Corporate debt securities	$	11,021	$	(3	)	$	1,497	$	(4	)
Government sponsored securities		—		—			2,748		(4	)
Total	$	11,021	$	(3	)	$	4,245	$	(8	)

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2020

Fair Value Disclosures [Abstract]

Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

Financial assets and liabilities measured at fair value on a recurring basis are summarized below at March 31, 2020 and December 31, 2019 (in thousands):

	Fair Value Measurements at March 31, 2020
	(Unaudited)
	Total		Level 1		Level 2		Level 3
Assets:
Current:
Cash and cash equivalents	$	16,952	$	16,952	$	—	$	—
Corporate debt securities		19,504		—		19,504		—
Foreign government bonds		1,001		—		1,001		—
Government sponsored securities		2,758		—		2,758		—
Total assets measured at fair value	$	40,215	$	16,952	$	23,263	$	—

	Fair Value Measurements at December 31, 2019
	Total		Level 1		Level 2		Level 3
Assets:
Current:
Cash and cash equivalents	$	15,508	$	15,508	$	—	$	—
Corporate debt securities		32,389		—		32,389		—
Foreign government bonds		1,007		—		1,007		—
Government sponsored securities		2,748		—		2,748		—
Noncurrent:
Corporate debt securities		1,497		—		1,497		—
Total assets measured at fair value	$	53,149	$	15,508	$	37,641	$	—

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Summary of Future Minimum Lease Payments

Future minimum lease payments at March 31, 2020 are presented in the following table (in thousands). Common area maintenance costs and taxes are not included in these payments.

Years ending December 31:	Operating Leases (a)
2020 (excluding the three months ended March 31, 2020)	$	3,221
2021		3,754
2022		3,671
2023		2,545
2024		1,083
Thereafter		1,730
Total future minimum lease payments		16,004
Less: Interest		2,671
Present value of operating lease liabilities	$	13,333

(a)

Operating lease payments include $3.3 million related to options to extend lease terms that are reasonably certain of being exercised.

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Based Compensation Expenses Included on Operations Statement

The following table presents all stock-based compensation as included on the condensed consolidated statements of operations (in thousands):

	Three Months Ended March 31,
	2020		2019
	(Unaudited)
Stock-based compensation expense:
Employee stock options	$	105	$	997
Employee RSUs		290		250
Non-employee RSUs		50		104
	$	445	$	1,351
Stock-based compensation expense in operating expenses:
Research and development	$	128	$	111
Selling, general and administrative		317		1,240
	$	445	$	1,351

Summarizes Stock Option Activity Under Equity Intensive Plan

The following table summarizes stock option activity under all equity incentive plans for the three months ended March 31, 2020:

	Number of Shares		Weighted- Average Exercise Price		Aggregate Intrinsic Value (in thousands)		Weighted- Average Remaining Contractual Life (in years)
Outstanding at December 31, 2019		4,506,950	$	9.37	$	5,710		5.8
Outstanding at March 31, 2020		4,506,950	$	9.37	$	3,085		5.6
Vested and Exercisable at March 31, 2020		4,023,614	$	10.13	$	3,085		5.3

Restricted Stock Units (RSUs) Activity

The following table summarizes the restricted stock units, or RSUs, activity under the 2015 Plan for the three months ended March 31, 2020:

	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested balance at December 31, 2019		1,139,428		$	2.23
Granted		33,500		$	6.43
Vested		(63,750	)	$	5.90
Forfeited		(6,650	)	$	2.71
Unvested balance at March 31, 2020		1,102,528		$	2.14

Description of Business - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accumulated deficit	$ (680,574)		$ (662,191)
Net cash used in operating activities	$ (12,596)	$ (13,078)

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Accounting Policies [Line Items]
Proceeds from exercise of stock options and warrants	$ 0	$ 39,221	$ 39,200
VIE \| Minimum
Accounting Policies [Line Items]
Percentage of ownership interest	20.00%
VIE \| Maximum
Accounting Policies [Line Items]
Percentage of ownership interest	50.00%

Summary of Significant Accounting Policies - Securities Excluded from the Computation of Potentially Dilutive Securities (Detail) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	5,609,478	5,328,886
Employee Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	4,506,950	4,506,950
Outstanding RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,102,528	821,936

Financial Statement Details - Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Statement Details [Abstract]
Prepaid preclinical and clinical trial services - with related party (Note 9)	$ 1,249	$ 1,021
Prepaid supplies - with related party (Note 9)	410	467
Prepaid rent	393	392
Insurance premium financing asset	381	757
Prepaid services	344	440
Prepaid insurance	288	372
Prepaid equipment maintenance	262	251
Interest receivable - marketable debt securities	205	222
Prepaid license fees	157	78
Due from related parties	114	47
Insurance claim receivables	29	34
Other	78	24
Total prepaid expenses and other current assets	$ 3,910	$ 4,105

Financial Statement Details - Property, Plant and Equipment, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 79,363	$ 79,108
Accumulated depreciation	(20,824)	(18,607)
Property, plant and equipment, net	58,539	60,501
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	33,430	33,406
Buildings
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	22,690	22,690
Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	21,640	21,434
Software
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,195	1,195
Furniture And Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 408	$ 383

Financial Statement Details - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financial Statement Details [Abstract]
Depreciation expense related to property, plant and equipment	$ 2,200,000	$ 1,800,000
Impairment loss on recognized investments	$ 0	$ 0

Financial Statement Details - Other Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Statement Details [Abstract]
Prepaid preclinical and clinical trial services - with related party (Note 9)	$ 3,739	$ 4,075
Restricted cash	179	179
Security deposit	113	113
Other	20	19
Other Assets Noncurrent	$ 4,051	$ 4,386

Financial Statement Details - Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Statement Details [Abstract]
Accrued bonus	$ 2,611	$ 2,002
Accrued compensation	1,631	1,064
Accrued professional and service fees	1,097	975
Accrued laboratory equipment, supplies and related services	559	640
Accrued preclinical and clinical trial costs	511	281
Accrued franchise, sales/use and property taxes	168	200
Other	57	181
Accrued Liabilities Current	$ 6,634	$ 5,343

Financial Statement Details - Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Statement Details [Abstract]
Operating lease liability - current portion (including amounts with related parties, Note 9)	$ 3,154	$ 3,206
Financing obligation - current portion	381	757
Other	78	18
Other current liabilities	$ 3,613	$ 3,981

Financial Statement Details - Investment Income, Net (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financial Statement Details [Abstract]
Interest income	$ 224	$ 410
Investment amortization expense, net	(45)	(40)
Net realized losses on investments	(1)	0
Investment income, net	$ 178	$ 370

Viracta Investment - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2020	Dec. 31, 2019	May 31, 2019	Jan. 31, 2019	Mar. 31, 2017
Schedule Of Investments [Line Items]
Equity securities			$ 9,253	$ 9,253			$ 8,500
2018 Note and Warrant Purchase Agreement
Schedule Of Investments [Line Items]
Equity securities				$ 9,300
Purchase of convertible note	$ 400	$ 400
Convertible note accrued interest rate	8.00%	8.00%
Debt instrument maturity date	1 year	1 year
2018 Note and Warrant Purchase Agreement \| Common Stock
Schedule Of Investments [Line Items]
Warrants exercised to acquire shares					253,120
Series B Preferred Stock \| 2018 Note and Warrant Purchase Agreement
Schedule Of Investments [Line Items]
Preferred stock value						$ 800

Financial Instruments Investments in Marketable Debt Securities - Schedule of Investments in available-for-sale Debt Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost		$ 37,642
Available-for-sale, Unrealized Gains		10
Available-for-sale, Unrealized Losses		(11)
Available-for-sale, Fair Value		37,641
Current Assets
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	$ 23,286	36,141
Available-for-sale, Unrealized Gains	7	10
Available-for-sale, Unrealized Losses	(30)	(7)
Available-for-sale, Fair Value	23,263	36,144
Current Assets \| Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	19,534	32,382
Available-for-sale, Unrealized Gains	0	10
Available-for-sale, Unrealized Losses	(30)	(3)
Available-for-sale, Fair Value	19,504	32,389
Current Assets \| Foreign Government Bonds
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	1,001	1,007
Available-for-sale, Unrealized Gains	0	0
Available-for-sale, Unrealized Losses	0	0
Available-for-sale, Fair Value	1,001	1,007
Current Assets \| Government Sponsored Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	2,751	2,752
Available-for-sale, Unrealized Gains	7	0
Available-for-sale, Unrealized Losses	0	(4)
Available-for-sale, Fair Value	$ 2,758	2,748
Noncurrent Assets
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost		1,501
Available-for-sale, Unrealized Gains		0
Available-for-sale, Unrealized Losses		(4)
Available-for-sale, Fair Value		1,497
Noncurrent Assets \| Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost		1,501
Available-for-sale, Unrealized Gains		0
Available-for-sale, Unrealized Losses		(4)
Available-for-sale, Fair Value		$ 1,497

Financial Instruments Investments in Marketable Debt Securities - Additional Information (Detail) - Security	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, weighted-average remaining contractual life	2 months 12 days
Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Number of available-for-sale securities in unrealized loss positions	23
Maximum
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, period of unrealized loss positions	12 months	12 months
Minimum
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, period of unrealized loss positions	12 months	12 months

Financial Instruments Investments in Marketable Debt Securities - Accumulated Unrealized Losses on Debt Securities Classified as Available-for-Sale in Continuous Loss Position (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	$ 19,504	$ 11,021
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(30)	(3)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	0	4,245
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	0	(8)
Government Sponsored Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value		0
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses		0
Available-for-Sale Investments, More than 12 months, Estimated Fair Value		2,748
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses		(4)
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	19,504	11,021
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(30)	(3)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	0	1,497
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	$ 0	$ (4)

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 40,215	$ 53,149
Current Assets \| Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	16,952	15,508
Current Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	19,504	32,389
Current Assets \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	1,001	1,007
Current Assets \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	2,758	2,748
Noncurrent Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value		1,497
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	16,952	15,508
Level 1 \| Current Assets \| Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	16,952	15,508
Level 1 \| Current Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Level 1 \| Current Assets \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Level 1 \| Current Assets \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Level 1 \| Noncurrent Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value		0
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	23,263	37,641
Level 2 \| Current Assets \| Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Level 2 \| Current Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	19,504	32,389
Level 2 \| Current Assets \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	1,001	1,007
Level 2 \| Current Assets \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	2,758	2,748
Level 2 \| Noncurrent Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value		1,497
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Level 3 \| Current Assets \| Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Level 3 \| Current Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Level 3 \| Current Assets \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Level 3 \| Current Assets \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 0	0
Level 3 \| Noncurrent Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value		$ 0

Collaboration and License Agreements - Additional Information (Detail)	1 Months Ended	3 Months Ended
	Jun. 30, 2015	Mar. 31, 2020 USD ($) Patient	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Licensing Agreement [Line Items]
Research and development		$ 13,234,000	$ 12,598,000
Due from related parties		114,000		$ 47,000
ImmunityBio
Licensing Agreement [Line Items]
Related party, agreement renewal term	1 year
Research and development		100,000	100,000
ImmunityBio \| Collaborative Arrangement
Licensing Agreement [Line Items]
Related party, agreement renewal term	1 year
Research and development		100,000
ImmunityBio \| Collaborative Arrangement \| Prepaid Expenses and Other Current Assets
Licensing Agreement [Line Items]
Due from related parties		$ 100,000
Altor
Licensing Agreement [Line Items]
Maximum number of patients in phase 1 and 2 for clinical trials \| Patient		400
Supplies and milestone charges for conducting clinical trials		$ 0	$ 0

Commitments and Contingencies - Additional Information (Detail)		1 Months Ended							3 Months Ended			12 Months Ended
	Aug. 09, 2019 USD ($)	Aug. 31, 2019	Aug. 31, 2018 USD ($)	Sep. 30, 2016 USD ($) ft²	Jun. 30, 2016 USD ($) ft² $ / ft²	Mar. 31, 2016 ft²	Nov. 30, 2015 USD ($) ft²	Jun. 30, 2015 USD ($) ft²	Mar. 31, 2020 USD ($) ft²	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)
Commitments And Contingencies [Line Items]
Litigation settlement amount									$ 12,000,000
Attorney's fee to plaintiffs	$ 500,000
Weighted average remaining lease term									4 years 3 months 18 days				4 years 6 months
Weighted average discount rate									9.00%				9.00%
Cash outflows from operating leases excluding variable lease cost									$ 1,000,000		$ 1,300,000
Woburn, Massachusetts
Commitments And Contingencies [Line Items]
Number of square foot of facility leased \| ft²					8,153	7,893
Base rent - monthly					$ 19,000
Initial term of lease arrangement						48 months
Lease commencement date						Apr. 29, 2016
Addition to number of square foot of facility leased \| ft²					260
Annual increase of base rent \| $ / ft²					1
Optional extended lease term		2 years
Lease agreement extended lease period		May 31, 2022
Increase in operating lease right-of-use assets										$ 600,000
Period of agreement									In June 2016, the lease was amended to add 260 square feet, for a total of 8,153 square feet. Base rent for the initial term of the lease is $19,000 per month with a $1 per square foot annual increase on each anniversary date
Commitment; San Diego
Commitments And Contingencies [Line Items]
Number of square foot of facility leased \| ft²								44,700
Base rent - monthly								$ 200,000
Percentage of annual increase of base rent								3.00%
Initial term of lease arrangement								7 years
NantBioScience
Commitments And Contingencies [Line Items]
Reimbursed upfront payment to third-party			$ 900,000
Related party transaction, amount paid to third-party			500,000
Related party transaction, aggregate value			$ 1,400,000
Initial term of agreement entered into with the related party by the entity			10 years			5 years
Related party agreement expiration date			2027-06
Doug St, LLC
Commitments And Contingencies [Line Items]
Period of agreement									The lease runs from July 2016 through July 2023. We have the option to extend the lease for an additional three year term through July 2026. The monthly rent is $0.1 million with annual increases of 3% beginning in July 2017
Optional extended lease term				3 years
Base rent - monthly				$ 100,000
Percentage of annual increase of base rent				3.00%
Annual percentage increases to base rent commencement date				Jul. 31, 2017
Doug St, LLC \| El Segundo California
Commitments And Contingencies [Line Items]
Number of square foot of facility leased \| ft²				24,250
NantWorks
Commitments And Contingencies [Line Items]
Number of square foot of facility leased \| ft²							9,500		9,500
Base rent - monthly							$ 47,000
Percentage of annual increase of base rent							3.00%
Annual percentage increases to base rent commencement date							Jan. 31, 2017
Period of agreement									The license was effective in May 2015 and extends through December 2020. The monthly rent is $47,000, with annual increases of 3% beginning in January 2017.
Prepaid Expenses and Other Current Assets
Commitments And Contingencies [Line Items]
Insurance claim receivable									$ 30,000				$ 34,000
Directors and Officers Insurance Policy
Commitments And Contingencies [Line Items]
Litigation settlement amount									10,800,000
Selling, General and Administrative
Commitments And Contingencies [Line Items]
Litigation settlement amount												$ 1,200,000
Operating Expenses
Commitments And Contingencies [Line Items]
Operating lease expense									1,300,000		1,200,000
Variable lease costs									$ 300,000		$ 200,000

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Detail) $ in Thousands	Mar. 31, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2020 (excluding the three months ended March 31, 2020)	$ 3,221
2021	3,754
2022	3,671
2023	2,545
2024	1,083
Thereafter	1,730
Total future minimum lease payments	16,004
Less: Interest	2,671
Present value of operating lease liabilities	$ 13,333

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Parenthetical) (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Operating lease payments related to options to extend lease terms	$ 3.3

Related Party Agreements - Additional Information (Detail)	1 Months Ended										3 Months Ended		12 Months Ended
	Oct. 31, 2019 USD ($)	Jul. 31, 2019 USD ($)	May 31, 2019 USD ($)	Aug. 31, 2018 USD ($)	Apr. 30, 2017 USD ($)	Sep. 30, 2016 USD ($) ft²	Apr. 30, 2016 USD ($)	Mar. 31, 2016	Nov. 30, 2015 USD ($) ft²	Jun. 30, 2015	Mar. 31, 2020 USD ($) ft² Officer	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Related Party Transaction [Line Items]
Selling, general and administrative expense											$ 5,373,000	$ 5,742,000
Research and development											13,234,000	12,598,000
Due to related parties											853,000		$ 486,000
Due from related parties											$ 114,000		47,000
NantWorks
Related Party Transaction [Line Items]
Number of square foot of facility leased \| ft²									9,500		9,500
Base rent - monthly									$ 47,000
Percentage of annual increase of base rent									3.00%
Annual percentage increases to base rent commencement date									Jan. 31, 2017
NantWorks \| Research and Development
Related Party Transaction [Line Items]
Lease expense											$ 100,000	100,000
NantWorks \| Shared Services Agreement
Related Party Transaction [Line Items]
Selling, general and administrative expense											700,000	600,000
Research and development											500,000	300,000
NantWorks \| Shared Services Agreement \| Reimbursements
Related Party Transaction [Line Items]
Selling, general and administrative expense											300,000	200,000
Research and development											500,000	500,000
Due to related parties											700,000		400,000
Immuno-Oncology Clinic, Inc. \| California
Related Party Transaction [Line Items]
Research and development											100,000	400,000
Due to related parties											$ 100,000		100,000
Number of officers \| Officer											1
Initial term of agreement		1 year
Related party transaction installment payment	$ 1,875,000	$ 3,750,000
Related party transaction conditional payment											$ 1,875,000
Prepayments remain unearned extension description											To the extent any portion of the prepayments remain unearned by the Clinic on the third anniversary of the new agreement, we may elect at our sole discretion either to (i) not extend the term of the new agreement and have the Clinic reimburse us for the total amount of any remaining unused portion of the prepayments, or (ii) extend the term of the new agreement for up to three additional one year periods, at which time the Clinic will reimburse us for the total amount of any remaining unused portion of the prepayments plus interest if reimbursement is not made within 60 days of expiration.
Notice period to terminate new agreement											60 days
Prepaid balance included in prepaid expenses and other current assets and other assets											$ 5,000,000		5,100,000
Immuno-Oncology Clinic, Inc. \| California \| Maximum
Related Party Transaction [Line Items]
Estimated cost for new agreement with clinic											7,500,000
ImmunityBio
Related Party Transaction [Line Items]
Research and development											100,000	100,000
Initial term of agreement entered into with the related party by the entity										5 years
Related party, agreement renewal term										1 year
Related parties, capitalized equipment amount											1,800,000		1,800,000
Prepaid expenses and other current assets											400,000		500,000
Due between parties											0		0
ImmunityBio \| Collaborative Arrangement
Related Party Transaction [Line Items]
Research and development											100,000
Related party, agreement renewal term										1 year
ImmunityBio \| Collaborative Arrangement \| Prepaid Expenses and Other Current Assets
Related Party Transaction [Line Items]
Due from related parties											100,000
Altor
Related Party Transaction [Line Items]
Supplies and milestone charges for conducting clinical trials											0	0
Doug St, LLC
Related Party Transaction [Line Items]
Due between parties											$ 0		0
Period of agreement											0
Base rent - monthly						$ 100,000
Percentage of annual increase of base rent						3.00%
Annual percentage increases to base rent commencement date						Jul. 31, 2017
Doug St, LLC \| El Segundo California
Related Party Transaction [Line Items]
Number of square foot of facility leased \| ft²						24,250
Doug St, LLC \| Research and Development
Related Party Transaction [Line Items]
Lease expense											$ 200,000	200,000
NantBioScience
Related Party Transaction [Line Items]
Research and development											100,000	100,000
Due to related parties											$ 25,000
Estimated cost for new agreement with clinic				$ 1,400,000
Initial term of agreement entered into with the related party by the entity				10 years				5 years
Related party transaction,reimbursement payment to a related-party				$ 900,000
Related party transaction, amount paid to third-party				500,000
Related party transaction, aggregate value				$ 1,400,000
Related party agreement expiration date				2027-06
Research and development expense, ratable payment period											12 months
Prepayment for services amount			$ 600,000	$ 600,000	$ 600,000		$ 600,000
Additional amount funded											$ 600,000
NantBioScience \| Prepaid Expenses and Other Current Assets
Related Party Transaction [Line Items]
Research and development												$ 100,000
Due between parties											$ 0		$ 8,400

Stockholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Nov. 30, 2015
Equity [Abstract]
Total amount authorized for repurchase		$ 50,000,000
Repurchase of common stock, shares	0
Remaining authorized repurchase amount	$ 18,300,000

Stock-Based Compensation - Stock Based Compensation Expenses Related to Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 445	$ 1,351
Employee Stock Option
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	105	997
Employee RSUs
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	290	250
Non-employee RSUs
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	50	104
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	128	111
Selling, General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 317	$ 1,240

Stock-Based Compensation - Stock Option Activity (Detail) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Number of Shares
Stock Options, Beginning Balance	4,506,950
Stock Options, Ending Balance	4,506,950	4,506,950
Stock Options, Vested and Exercisable	4,023,614
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding Beginning balance	$ 9.37
Weighted Average Exercise Price, Outstanding Ending balance	9.37	$ 9.37
Weighted Average Exercise Price, Vested and Exercisable	$ 10.13
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding, Beginning balance	$ 5,710
Aggregate Intrinsic Value, Outstanding, Ending balance	3,085	$ 5,710
Aggregate Intrinsic Value, Vested and Exercisable	$ 3,085
Weighted Average Remaining Contractual Life
Weighted Average Remaining Contractual Life, Outstanding	5 years 7 months 6 days	5 years 9 months 18 days
Weighted Average Remaining Contractual Life, Vested and Exercisable	5 years 3 months 18 days

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise of stock options		$ 4,070
Proceeds from exercises of warrants		$ 35,200
Number of warrants outstanding			0
Number of warrants issued	0
Chairman and CEO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from stock options exercised	$ 4,100
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost related to non-vested stock options	$ 1,000
Weighted-average period for recognition	2 years 4 months 24 days
Exercise of stock options	$ 0
Weighted-average period for recognition	2 years 4 months 24 days
Employee Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period for recognition	2 years 1 month 6 days
Grants of restricted stock	33,500
Unrecognized compensation cost related to non-vested stock options	$ 1,200
Unrecognized compensation cost related to non-vested stock options	$ 1,200
Weighted-average period for recognition	2 years 1 month 6 days
Outstanding RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period for recognition	2 years
Grants of restricted stock	33,500
Unrecognized compensation cost related to non-vested stock options	$ 1,300
Unrecognized compensation cost related to non-vested stock options	$ 1,300
Weighted-average period for recognition	2 years
Non Employee Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period for recognition	7 months 6 days
Unrecognized compensation cost related to non-vested stock options	$ 100
Unrecognized compensation cost related to non-vested stock options	$ 100
Weighted-average period for recognition	7 months 6 days

Stock-Based Compensation - Restricted Stock Units (RSUs) Activity (Detail) - Outstanding RSUs	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Unvested, Beginning balance \| shares	1,139,428
Number of Shares, Granted \| shares	33,500
Number of Shares, Vested \| shares	(63,750)
Number of Shares, Forfeited \| shares	(6,650)
Number of Shares, Unvested, Ending balance \| shares	1,102,528
Weighted-Average Grant Date Fair Value, Unvested, beginning balance \| $ / shares	$ 2.23
Weighted-Average Grant Date Fair Value, Granted \| $ / shares	6.43
Weighted-Average Grant Date Fair Value, Vested \| $ / shares	5.90
Weighted-Average Grant Date Fair Value, Forfeited \| $ / shares	2.71
Weighted-Average Grant Date Fair Value, Unvested, ending balance \| $ / shares	$ 2.14

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax [Line Items]
Federal statutory tax rate		21.00%
Company's effective tax rate		0.00%
Tax benefit		$ (36,000)
Tax benefit in other comprehensive income		(100,000)
Korea
Income Tax [Line Items]
Tax benefit	$ 0	$ 0