Stockholder Notice: Robbins LLP Informs Investors of the Atara Biotherapeutics, Inc. Class Action Lawsuit

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1:37 PM on Monday, March 23

The Associated Press

SAN DIEGO--(BUSINESS WIRE)--Mar 23, 2026--

Robbins LLP informs stockholders that a class action was filed on behalf of all investors who purchased or otherwise acquired Atara Biotherapeutics, Inc. (NASDAQ: ATRA) securities between May 20, 2024 and January 9, 2026. Atara develops therapies for patients with solid tumors, hematologic cancers, and autoimmune diseases in the U.S. and the United Kingdom (“U.K.”). The Company’s lead product candidate is tabelecleucel (also referred to as tab-cel or EBVALLO), a T-cell immunotherapy program for the treatment of, inter alia, Epstein-Barr virus positive post-transplant lymphoproliferative disease (“EBV+PTLD”).

For more information, submit a form, email attorney Aaron Dumas, Jr., or give us a call at (800) 350-6003.

The Allegations: Robbins LLP is Investigating Allegations that Atara Biotherapeutics, Inc. (ATRA) Misled Investors Regarding its Drug Candidate

According to the complaint, during the class period, defendants failed to disclose that: (i) certain manufacturing issues, as well as deficiencies inherent in the ALLELE study, made it unlikely that the FDA would approve the tabelecleucel BLA; (ii) accordingly, tabelecleucel’s regulatory prospects were overstated; (iii) the aforementioned manufacturing issues also subjected Atara to a heightened risk of regulatory scrutiny, as well as jeopardized its ongoing clinical trials; (iv) all the foregoing was likely to have a significant negative impact on Atara’s business and financial condition; and (v) as a result, Defendants’ public statements were materially false and/or misleading at all relevant times.

Plaintiff alleges that on January 12, 2026, Atara issued a press release announcing that the FDA had issued another Complete Response Letter ("CLR") regarding the tabelecleucel BLA—which the Company had resubmitted to the FDA in July 2025—stating that “[t]he CRL indicates that the FDA is unable to approve the EBVALLO™ BLA in its present form” because “the single arm ALLELE trial . . .is no longer considered to be adequate to provide evidence of effectiveness for accelerated approval” and “the trial’s interpretability is confounded due to trial study design, conduct, and analysis.” On this news, Atara’s stock price fell $7.79 per share, or 56.99%, to close at $5.88 per share on January 12, 2026.

What Now: You may be eligible to participate in the class action against Atara Biotherapeutics, Inc. Shareholders who wish to serve as lead plaintiff for the class should contact Robbins LLP. The lead plaintiff is a representative party who acts on behalf of other class members in directing the litigation. You do not have to participate in the case to be eligible for a recovery. If you choose to take no action, you can remain an absent class member. For more information, click here.

All representation is on a contingency fee basis. Shareholders pay no fees or expenses.

About Robbins LLP: A recognized leader in shareholder rights litigation, the attorneys and staff of Robbins LLP have been dedicated to helping shareholders recover losses, improve corporate governance structures, and hold company executives accountable for their wrongdoing since 2002.

To be notified if a class action against Atara Biotherapeutics, Inc. settles or to receive free alerts when corporate executives engage in wrongdoing, sign up for Stock Watch today.

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View source version on businesswire.com:https://www.businesswire.com/news/home/20260323361785/en/

CONTACT: Aaron Dumas, Jr.

Robbins LLP

5060 Shoreham Pl., Ste. 300

San Diego, CA 92122

[email protected]

(800) 350-6003

www.robbinsllp.com

KEYWORD: UNITED STATES NORTH AMERICA CALIFORNIA

INDUSTRY KEYWORD: CLASS ACTION LAWSUIT PROFESSIONAL SERVICES LEGAL

SOURCE: Robbins LLP