As filed with the Securities and Exchange Commission on August 10, 2020

Registration No. 333-                

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

Under

The Securities Act of 1933

NantKwest, Inc.

(Exact name of Registrant as specified in its charter)

3530 John Hopkins Court

San Diego, California 92121

(Address of principal executive offices, including zip code)

2015 Equity Incentive Plan

(Full title of the plan)

Patrick Soon-Shiong, M.D., FRCS (C), FACS

Chairman and Chief Executive Officer

NantKwest, Inc.

3530 John Hopkins Court

San Diego, California 92121

(858) 633-0300

(Name, address and telephone number, including area code, of agent for service)

Copies to:

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☒

CALCULATION OF REGISTRATION FEE

PART I

INFORMATION REQUIRED IN THE PROSPECTUS

This Registration Statement on Form S-8 (the “Registration Statement”) registers 3,000,000 additional shares of the common stock of NantKwest, Inc. (the “Registrant”) to be issued pursuant to the Registrant’s 2015 Equity Incentive Plan, as amended and restated (the “2015 Plan”).

In accordance with General Instruction E to Form S-8, the contents of the previous Registration Statements on Form S-8  filed by the Registrant with the Securities and Exchange Commission (the “Commission”) on July 30, 2015 (File No. 333-205942) and August 7, 2019 (File No. 333-233082) (the “Previous Form S-8s”) is incorporated by reference into this Registration Statement.

PART II

INFORMATION REQUIRED IN REGISTRATION STATEMENT

The Registrant hereby incorporates by reference into this Registration Statement the following documents previously filed with the Commission:

All documents filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act on or after the date of this Registration Statement and prior to the filing of a post-effective amendment to this Registration Statement that indicates that all securities offered have been sold or that deregisters all securities then remaining unsold shall be deemed to be incorporated by reference in this Registration Statement and to be part hereof from the date of filing of such documents; provided, however, that documents or information deemed to have been furnished and not filed in accordance with the rules of the Commission shall not be deemed incorporated by reference into this Registration Statement. Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any subsequently filed document which also is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.

Under no circumstances will any information furnished under current items 2.02 or 7.01 of Form 8-K be deemed incorporated herein by reference unless such Form 8-K expressly provides to the contrary.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of San Diego, State of California, on August 10, 2020.

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Patrick Soon-Shiong and Barry J. Simon, and each of them, as his or her true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities (including his or her capacity as a director and/or officer of NantKwest, Inc.), to sign the Registration Statement on Form S-8 of NantKwest, Inc., and any or all amendments thereto (including post-effective amendments), and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully for all intents and purposes as they, he, or she might or could do in person, hereby and about the premises hereby ratifying and confirming all that said attorneys-in-fact and agent, proxy and agent, or his, her or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

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Exhibit 5.1

OPINION OF WILSON SONSINI GOODRICH & ROSATI

PROFESSIONAL CORPORATION

August 10, 2020

NantKwest, Inc.

3530 John Hopkins Court

San Diego, California 92121

Ladies and Gentlemen:

We have examined the Registration Statement on Form S-8 (the “Registration Statement”) to be filed by NantKwest, Inc., a Delaware corporation, with the Securities and Exchange Commission on or about the date hereof, in connection with the registration under the Securities Act of 1933, as amended, of an aggregate of 3,000,000 shares of the Company’s common stock, par value $0.0001 per share (the “Shares”) reserved for future issuance pursuant to the NantKwest, Inc. 2015 Equity Incentive Plan, as amended and restated (the “Plan”). As your legal counsel, we have examined the proceedings taken and are familiar with the actions proposed to be taken by you in connection with the issuance and sale of the Shares under the Plan and pursuant to the agreements related thereto.

It is our opinion that the Shares, when issued and sold in the manner referred to in the Plan and pursuant to the agreements that accompany the Plan, will be legally and validly issued, fully paid and nonassessable.

We consent to the use of this opinion as an exhibit to the Registration Statement, and further consent to the use of our name wherever appearing in the Registration Statement and any amendments thereto.

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the 2015 Equity Incentive Plan of NantKwest, Inc. of our report dated March 25, 2020, with respect to the consolidated financial statements of NantKwest, Inc. included in its Annual Report (Form 10-K) for the year ended December 31, 2019, filed with the Securities and Exchange Commission.