Exhibit 12.1

Computation of Deficiency in the Coverage of Fixed Charges by Earnings Before Fixed Charges and

Preferred Stock Dividends

	Year ended December 31,
	2010			2011			2012			2013			2014
Fixed charges:
Interest expense	$	94		$	90		$	86		$	82		$	108
Estimate of interest expense within rental expense		204			220			104			84			266
Total fixed charges	$	298		$	310		$	190		$	166		$	374
Earnings before fixed charges:
Net loss before provision for income taxes	$	(32,177	)	$	(2,318	)	$	(121,287	)	$	(111,985	)	$	(135,789	)
Add fixed charges		298			310			190			166			374
Total earnings (loss) before fixed charges	$	(31,879	)	$	(2,008	)	$	(121,097	)	$	(111,819	)	$	(135,415	)
Deficiency of earnings to cover fixed charges:	$	(32,177	)	$	(2,318	)	$	(121,287	)	$	(111,985	)	$	(135,789	)
Earnings before fixed charges and preferred stock dividends:
Net loss before provision for income taxes	$	(32,177	)	$	(2,318	)	$	(121,287	)	$	(111,985	)	$	(135,789	)
Add fixed charges		298			310			190			166			374
Add preferred stock dividends		—			—			—			—			—
Total earnings (loss) before fixed charges and preferred stock dividends	$	(31,879	)	$	(2,008	)	$	(121,097	)	$	(111,819	)	$	(135,415	)
Deficiency of earnings to cover fixed charges and preferred stock dividends:	$	(32,177	)	$	(2,318	)	$	(121,287	)	$	(111,985	)	$	(135,789	)