ACLX Arcellx Inc

As filed with the Securities and Exchange Commission on January 3, 2025

Registration No. 333-   

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

ARCELLX, INC.

(Exact name of registrant as specified in its charter)

800 Bridge Parkway

Redwood City, CA 94065

(240) 327-0630

(Address of principal executive offices, including zip code)

2022 Equity Incentive Plan

2022 Employee Stock Purchase Plan

(Full title of the plan)

Rami Elghandour

President, Chief Executive Officer and Chairman of the Board of Directors

Arcellx, Inc.

800 Bridge Parkway

Redwood City, CA 94065

(240) 327-0630

(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. ☐

EXPLANATORY NOTE

Arcellx, Inc. (the “Registrant”) is filing this Registration Statement with the Securities and Exchange Commission (the “Commission”) to register (i) 2,714,041 additional shares of common stock under the Registrant’s 2022 Equity Incentive Plan (the “2022 Plan”), pursuant to the provision of the 2022 Plan providing for such automatic increase in the number of shares reserved for issuance, and (ii) 312,500 additional shares of common stock under the Registrant’s 2022 Employee Stock Purchase Plan (the “2022 ESPP”), pursuant to the provision of the 2022 ESPP providing for such automatic increase in the number of shares reserved for issuance.

Accordingly, contents of (i) the previous Registration Statement on Form S-8 filed by the Registrant with the Securities and Exchange Commission (the “Commission”) on February 7, 2022 (File No. 333-262571) (the “2022 Form S-8”), (ii) the previous Registration Statement on Form S-8 filed by the Registrant with the Commission on January 3, 2023 (File No. 333-269105) (the “2023 Form S-8”) and (iii) the previous Registration Statement on Form S-8 filed by the Registrant with the Commission on January 2, 2024 (File No. 333-276346) (the “2024 Form S-8”, and together with the 2022 Form S-8 and 2023 Form S-8, the “Previous Forms S-8”), including the information incorporated by reference therein and the periodic reports filed after the Previous Forms S-8 to maintain current information about the Registrant, are incorporated by reference into this Registration Statement pursuant to General Instruction E of Form S-8 (the “Registration Statement”).

PART I

INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

The information specified in Item 1 and Item 2 of Part I of Form S-8 is omitted from this Registration Statement in accordance with the provisions of Rule 428 under the Securities Act of 1933, as amended (the “Securities Act”) and the introductory note to Part I of Form S-8. The documents containing the information specified in Part I of Form S-8 will be delivered to the participants in the equity benefit plans covered by this Registration Statement as specified by Rule 428(b)(1) under the Securities Act. These documents and the documents incorporated by reference in this Registration Statement pursuant to Item 3 of Part II of Form S-8, taken together, constitute a prospectus that meets the requirements of Section 10(a) of the Securities Act.

PART II

INFORMATION REQUIRED IN THE 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 a 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.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, 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 Redwood City, California, on January 3, 2025.

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.

Exhibit 5.1

		Wilson Sonsini Goodrich & Rosati Professional Corporation   650 Page Mill Road Palo Alto, California 94304-1050   O: 650.493.9300 F: 866.974.7329

January 3, 2025

Arcellx, Inc.

800 Bridge Parkway

Redwood City, CA 94065

Ladies and Gentlemen:

We have examined the Registration Statement on Form S-8 (the “Registration Statement”) to be filed by Arcellx, Inc., a Delaware corporation (the “Company”), 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 3,026,541 shares (the “Shares”) of the Company’s common stock, par value $0.001 per share (“Common Stock”), consisting of (i) 2,714,041 shares of Common Stock reserved for future issuance under the Company’s 2022 Equity Incentive Plan (the “2022 Plan”), and (ii) 312,500 shares of Common Stock reserved for issuance under the Company’s Amended and Restated 2022 Employee Stock Purchase Plan. As the Company’s legal counsel, we have reviewed the actions proposed to be taken by the Company in connection with the issuance and sale of the Shares to be issued under such plans (which plans are referred to herein as the “Plans”).

It is our opinion that the Shares, when issued and sold in the manner referred to in the Plans and pursuant to the agreements that accompany the Plans, 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.

AUSTIN BEIJING BOSTON BOULDER BRUSSELS HONG KONG LONDON LOS ANGELES NEW YORK PALO ALTO

SALT LAKE CITY SAN DIEGO SAN FRANCISCO SEATTLE SHANGHAI WASHINGTON, DC WILMINGTON, DE

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the Registration Statement (Form S-8), dated January 3, 2025, pertaining to the 2022 Equity Incentive Plan and the 2022 Employee Stock Purchase Plan of Arcellx, Inc. of our reports dated February 28, 2024, with respect to the consolidated financial statements of Arcellx, Inc. and the effectiveness of internal control over financial reporting of Arcellx, Inc. included in its Annual Report (Form 10-K) for the year ended December 31, 2023, filed with the Securities and Exchange Commission.

/s/ Ernst & Young LLP

Tysons, Virginia

January 3, 2025

Exhibit 24.1

POWER OF ATTORNEY – ARCELLX, INC DIRECTORS

KNOW ALL PERSONS BY THESE PRESENTS, that each of the undersigned directors of ARCELLX, INC., a Delaware corporation (the “Company”), hereby nominates and appoints RAMI ELGHANDOUR, MICHELLE GILSON and MARYAM ABDUL-KAREEM, and each of them acting or signing singly, as such director’s agents and attorneys-in-fact, in his or her respective name and in the capacity or capacities indicated below, to execute and/or file, with all exhibits thereto, and other documents filed in connection therewith or constituting a part thereof:

(1) a registration statement on Form S-8 under the Securities Act of 1933, as amended (the “Securities Act”), in connection with the registration under the Securities Act of additional shares of Common Stock of the Company (“Common Stock”) that may be issued, effective as of January 1, 2025, pursuant to (i) Section 3(b) of the Arcellx, Inc. 2022 Equity Incentive Plan (the “2022 Plan”), and (ii) Section 13(a) of the Arcellx, Inc. 2022 Employee Stock Purchase Plan (as amended and restated September 27, 2022) (the “2022 ESPP”); and

(2) any one or more amendments to any part of the foregoing registration statement, including any post-effective amendments, or appendices or supplements that may be required to be filed under the Securities Act to keep such registration statement effective or to terminate its effectiveness.

Section 3(b) of the 2022 Plan provides that the maximum aggregate number of shares of Common Stock that may be issued under the 2022 Plan will be increased on January 1, 2025, by a number of shares of the Company’s Common Stock equal to the lesser of (i) 4,296,875 shares of Common Stock, (ii) five percent (5%) of the total number of shares of all classes of Common Stock of the Company outstanding on the last day of the immediately preceding fiscal year, and (iii) a lesser number of shares of Common Stock determined by the Company’s Board of Directors (or a committee thereof).

Section 13(a) of the 2022 ESPP provides that that the total number of shares of Common Stock reserved and available for issuance under the 2022 ESPP will be increased on January 1, 2025, by a number of shares of the Company’s Common Stock equal to the lesser of (i) 312,500 shares of Common Stock, (ii) one percent (1.0%) of the outstanding shares of Common Stock on the last day of the immediately preceding fiscal year, or (iii) an amount determined by the Company’s Board of Directors (or a committee thereof).

Further, the undersigned do hereby authorize and direct such agents and attorneys-in-fact to take any and all actions and execute and file any and all documents with the Securities and Exchange Commission (the “SEC”) or state regulatory agencies, necessary, proper or convenient in their opinion to comply with the Securities Act and the rules and regulations or orders of the SEC, or state regulatory agencies, adopted or issued pursuant thereto, to the end that the registration statement of the Company shall become effective under the Securities Act and any other applicable law.

Finally, each of the undersigned does hereby ratify, confirm and approve each and every act and document which the said appointment agents and attorneys-in-fact may take, execute or file pursuant thereto with the same force and effect as though such action had been taken or such documents had been executed or filed by the undersigned respectively.

This Power of Attorney shall remain in full force and effect until revoked or superseded by written notice filed with the SEC.