Atara Biotherapeutics Announces Fourth Quarter and Full Year 2014 Operating Results

South San Francisco, Calif., February 26, 2015 – Atara Biotherapeutics, Inc. (Nasdaq: ATRA), a biopharmaceutical company with a focus on developing innovative therapies for patients with debilitating diseases, today reported financial results for the fourth quarter and full year ended December 31, 2014.

“2014 was a significant year for Atara,” said Isaac Ciechanover, CEO of Atara. “This past year, we: continued to advance our lead clinical program, PINTA 745, in an ongoing randomized, blinded Phase 2 study in protein energy wasting associated with end-stage renal disease; initiated a Phase 1 trial of our second clinical program, STM 434, in ovarian cancer and other solid tumors; broadened our clinical pipeline through an exclusive option agreement with Memorial Sloan Kettering Cancer Center for the development and commercialization of three clinical stage allogeneic T-cell therapies for the treatment of certain cancers and persistent viral infections; and completed an initial public offering. In 2015, we look forward to the advancement of our diverse pipeline as well as a number of important milestones, including the un-blinding of our PINTA 745 Phase 2 study at the end of the year.”

Atara Biotherapeutics, Inc. is a biopharmaceutical company focused on developing innovative therapies for patients with debilitating diseases. Atara’s lead programs target myostatin and activin, members of the TGF-beta family of proteins that have demonstrated the potential to have therapeutic benefit in a number of clinical indications. In September 2014, Atara Biotherapeutics entered into an exclusive option agreement with Memorial Sloan Kettering Cancer Center (MSK) under which it has the right to license (pursuant to a negotiated form of license agreement) the exclusive, worldwide rights to three clinical stage T-cell programs, as well as other T-cell programs that are discovered or developed by MSK pursuant to sponsored research funded by the company.

This press release contains or may imply “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Because such statements deal with future events and are based on Atara’s current expectations, they are subject to various risks and uncertainties and actual results, performance or achievements of Atara could differ materially from those described in or implied by the statements in this press release. For example, forward-looking statements include statements regarding Atara’s expectations regarding the timing of reporting results from its Phase 2 clinical trial of PINTA 745. These forward-looking statements are subject to other risks and uncertainties, including those discussed under the heading "Risk Factors" in Atara’s registration statements on Form S-1, quarterly report on Form 10-Q for the quarter ended September 30, 2014 and subsequent filings with the Securities and Exchange Commission. Except as otherwise required by law, Atara 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.

	December 31,			December 31,
	2014			2013
Assets
Current assets
Cash and cash equivalents	$	21,897		$	51,615
Short-term available-for-sale investments		82,219			—
Prepaid expenses and other current assets		1,910			193
Total current assets		106,026			51,808
Property and equipment, net		48			8
Other assets		48			12
Total assets	$	106,122		$	51,828

Liabilities, convertible preferred stock and stockholders’ equity (deficit)
Current liabilities:
Accounts payable	$	440		$	606
Accrued compensation		1,225			331
Income tax payable		1			155
Other accrued liabilities		1,058			432
Total current liabilities		2,724			1,524
Other long-term liabilities		216			230
Total liabilities		2,940			1,754

Commitments and contingencies
Series A convertible preferred stock—$0.0001 par value, liquidation preference of $20,088 as of December 31, 2013		—			19,909
Series A-1 convertible preferred stock—$0.0001 par value, liquidation preference of $3,000 as of December 31, 2013		—			2,768
Series B convertible preferred stock—$0.0001 par value, liquidation preference of $52,000 as of December 31, 2013		—			38,414

Stockholders’ equity (deficit):
Common stock—$0.0001 par value, 19,692,937 and 12,003,891 shares issued and outstanding as of December 31, 2014 and 2013, respectively		2			1
Additional paid-in capital		144,169			2,200
Notes receivable from stockholder		—			(335	)
Accumulated other comprehensive loss		(100	)		—
Accumulated deficit		(40,889	)		(12,883	)
Total stockholders’ equity (deficit)		103,182			(11,017	)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$	106,122		$	51,828

	Three months ended						Year ended
	December 31,						December 31,
	2014			2013			2014			2013
Operating Expenses:
Research and development	$	5,048		$	2,249		$	14,380		$	4,306
Research and development costs paid to Amgen		—			3			1,066			553
General and administrative		5,548			1,164			12,710			3,756
Total operating expenses		10,596			3,416			28,156			8,615
Loss from operations		(10,596	)		(3,416	)		(28,156	)		(8,615	)
Interest income		66			3			125			12
Loss before provision for income taxes		(10,530	)		(3,413	)		(28,031	)		(8,603	)
Provision (benefit) for income taxes		(3	)		143			(25	)		170
Net loss	$	(10,527	)	$	(3,556	)	$	(28,006	)	$	(8,773	)
Other comprehensive loss, net of tax:
Unrealized losses on investments		(89	)		—			(100	)		—
Other comprehensive loss		(89	)		—			(100	)		—
Comprehensive loss	$	(10,616	)	$	(3,556	)	$	(28,106	)	$	(8,773	)
Net loss per common share:
Basic and diluted net loss per common share	$	(0.67	)	$	(3.15	)	$	(5.62	)	$	(9.08	)
Weighted-average common shares outstanding - basic and diluted		15,804,856			1,129,607			4,985,540			965,825