U.S. markets closed

Atara Biotherapeutics Announces Full Exercise of Underwriters’ Option to Purchase Additional Shares

Atara Biotherapeutics, Inc. (Nasdaq:ATRA), a pioneer in T-cell immunotherapy leveraging its novel allogeneic EBV T-cell platform to develop transformative therapies for patients with severe diseases including solid tumors, hematologic cancers and autoimmune disease, today announced that the underwriters of its recently closed underwritten offering of 12,633,039 shares of its common stock and pre-funded warrants to purchase 2,866,961 shares of its common stock have exercised in full their option to purchase an additional 2,325,000 shares of common stock at the public offering price less the underwriting discount. The aggregate net proceeds to Atara from the offering, including the shares sold pursuant to the underwriters’ option, after deducting underwriting discounts and commission and estimated offering expenses, were approximately $189.4 million. Pro forma cash, which is comprised of cash, cash equivalents and short-term investments as of March 31, 2020 of $214.6 million along with the aggregate net proceeds of $189.4 million from the offering, totals $404.0 million, and is expected to enable Atara to fund its planned operations into 2022.

Citigroup, Cowen and Evercore ISI acted as joint book-running managers for the proposed offering. Mizuho Securities acted as lead manager and Canaccord Genuity acted as co-manager for the proposed offering.

The securities described above were offered by Atara Biotherapeutics pursuant to a shelf registration statement on Form S-3, including a base prospectus, that was previously filed by Atara Biotherapeutics with the Securities and Exchange Commission (the "SEC") and that became automatically effective on February 27, 2018. A final prospectus supplement and accompanying prospectus relating to the proposed offering have been filed with the SEC and are available on the SEC’s website located at http://www.sec.gov. Copies of the final prospectus supplement and the accompanying prospectus relating to the proposed offering may be obtained from: Citigroup, by mail at Citigroup Global Markets Inc., c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, or by telephone at 1-800-831-9146; Cowen and Company, LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717, Attn: Prospectus Department, by telephone at (833) 297-2926, or by email at PostSaleManualRequests@broadridge.com; or Evercore Group L.L.C., Attention: Equity Capital Markets, 55 East 52nd Street, 35th Floor, New York, NY 10055, or by telephone at (888) 474-0200, or by email at ecm.prospectus@evercore.com.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such jurisdiction.

About Atara Biotherapeutics, Inc.

Atara Biotherapeutics, Inc. is a pioneer in T-cell immunotherapy leveraging its novel allogeneic EBV T-cell platform to develop transformative therapies for patients with severe diseases including solid tumors, hematologic cancers and autoimmune disease.

Forward-Looking Statements

This press release contains or may imply "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. For example, forward-looking statements include statements regarding the sufficiency of Atara’s cash, cash equivalents and short-term investments to fund operations into 2022. Because such statements deal with future events and are based on Atara Biotherapeutics’ current expectations, they are subject to various risks and uncertainties and actual results, performance or achievements of Atara Biotherapeutics could differ materially from those described in or implied by the statements in this press release. These forward-looking statements are subject to risks and uncertainties, including, without limitation, uncertainties related to the costs and timing of drug development, particularly clinical trials, which are difficult to predict, subject to substantial risks and delays and often vary depending on the particular disease and development strategy, as well as those risks discussed in Atara Biotherapeutics filings with the Securities and Exchange Commission (SEC), including in the "Risk Factors" and "Management’s Discussion and Analysis of Financial Condition and Results of Operations" sections of the Company’s most recently filed periodic reports on Form 10-K and Form 10-Q and subsequent filings and in the documents incorporated by reference therein. Except as otherwise required by law, Atara Biotherapeutics disclaims any intention or obligation to update or revise any forward-looking statements, which speak only as of the date hereof, whether as a result of new information, future events or circumstances or otherwise.

View source version on businesswire.com: https://www.businesswire.com/news/home/20200624005819/en/

Contacts

INVESTOR & MEDIA CONTACTS:

Media
Kerry Beth Daly
Head, Corporate Communications
Atara Biotherapeutics
516-982-9328
kdaly@atarabio.com

Investors
Eric Hyllengren
Vice President, Investor Relations and Finance
Atara Biotherapeutics
805-395-9669
ehyllengren@atarabio.com