As filed with the Securities and Exchange Commission on February 27, 2018.

Registration No. 333-             

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

ATARA BIOTHERAPEUTICS, INC.

(Exact name of Registrant as specified in its charter)

611 Gateway Blvd., Suite 900

South San Francisco, CA 94080

(650) 278-8930

(Address, including zip code and telephone number, of Registrant’s principal executive offices)

Atara Biotherapeutics, Inc. Amended and Restated 2014 Equity Incentive Plan

Atara Biotherapeutics, Inc. 2014 Employee Stock Purchase Plan

Isaac E. Ciechanover, M.D.

Chief Executive Officer

611 Gateway Blvd., Suite 900

South San Francisco, California 94080

(650) 278-8930

(Name, address, including zip code 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, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Exchange Act of 1934.

Emerging growth company ☒

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

EXPLANATORY NOTE

Atara Biotherapeutics, Inc. (the “Registrant”) is filing this Registration Statement on Form S-8 for the purpose of registering (a) 145,000 shares of Common Stock granted to Kanya Rajangam on August 22, 2017 to induce her to accept employment as Senior Vice President and Chief Medical Officer of the Registrant (the “Inducement Award”), (b) an additional 1,536,516 shares of Common Stock issuable to eligible persons under the Atara Biotherapeutics, Inc. Amended and Restated 2014 Equity Incentive Plan, which Common Stock is in addition to the shares of Common Stock registered on the Registrant’s Form S-8 filed on October 21, 2014 (File No. 333-199508), Form S-8 filed on May 12, 2015 (File No. 333-204076), Form S-8 filed on March 4, 2016 (File No. 333-209961), Form S-8 filed on November 4, 2016 (File No. 333-214431) and Form S-8 filed on August 7, 2017 (File No. 333-219763), and (c) an additional 230,769 shares of Common Stock issuable to eligible persons under the Atara Biotherapeutics, Inc. 2014 Employee Stock Purchase Plan, which Common Stock is in addition to the shares of Common Stock registered on the Registrant’s Form S-8 October 21, 2014 (File No. 333-199508), Form S-8 filed on May 12, 2015 (File No. 333-204076), Form S-8 filed on March 4, 2016 (File No. 333-209961) and Form S-8 filed on August 7, 2017 (File No. 333-219763). The Inducement Award was approved by the Compensation Committee of the Registrant’s Board of Directors in reliance on the employment inducement exception to shareholder approval under NASDAQ Listing Rule 5635(c)(4), and therefore, was not granted under the Registrant’s shareholder-approved 2014 Plan.

PART II

ITEM 3.INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The following documents filed by the Registrant with the SEC are incorporated by reference into this Registration Statement:

(a)The contents of the earlier registration statements on Form S-8 relating to the 2014 Plan and 2014 ESPP, previously filed with the SEC on October 21, 2014 (File No. 333-199508), May 12, 2015 (File No. 333-204076), March 4, 2016 (File No. 333-209961), November 4, 2016 (File No. 333-214431) and August 7, 2017 (File No. 333-219763).

(b)The Registrant’s Annual Report on Form 10-K for the year ended December 31, 2017, which includes audited financial statements for the Registrant’s latest fiscal year, filed with the SEC on February 28, 2018.

(c)The Registrant’s Current Report on Form 8-K filed with the SEC on January 4, 2018.

(d)The description of the Registrant’s common stock which is contained in a registration statement on Form 8-A filed on July 16, 2014 (File No. 001-36548) under the Exchange Act of 1934, as amended, or the Exchange Act, including any amendment or report filed for the purpose of updating such description.

(e)All other reports and documents subsequently filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act (other than Current Reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits furnished on such form that relate to such items) on or after the date of this Registration Statement and prior to the filing of a post-effective amendment to this Registration Statement which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference herein and to be a part of this Registration Statement from the date of the filing of such reports and documents. 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 that 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.

ITEM 8.EXHIBITS

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 South San Francisco, State of California, on this 27^th day of February, 2018.

Know All Persons By These Presents, that each person whose signature appears below constitutes and appoints Isaac E. Ciechanover and John F. McGrath, Jr., and each of them, as his or her true and lawful attorneys-in-fact and agents, each with the full power of substitution, for him or her and in his or her name, place or stead, in any and all capacities, to sign any and all amendments to this Registration Statement (including post-effective amendments), and to sign any registration statement for the same offering covered by this Registration Statement that is to be effective upon filing pursuant to Rule 462(b) promulgated under the Securities Act, and all post-effective amendments thereto, and to file the same, with 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 and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or their, his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.