Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2020

Total accounts receivable consists of the following (in thousands):

	June 30,		December 31,
	2020		2019
U.S. Food and Drug Administration	$	156	$	176
Vifor (International) Ltd., and/or its affiliates, or collectively, Vifor		72		—
	$	228	$	176

Summary of Numerator and Denominator Used in Calculation of Basic and Diluted Net Income (Loss) Per Share

The following table is a reconciliation of the numerator and denominator used in the calculation of basic and diluted net income (loss) per share (in thousands):

	Three Months Ended June 30,					Six Months Ended June 30,
	2020		2019			2020			2019
Numerator:
Net income (loss)	$	20,267	$	(15,150	)	$	(1,420	)	$	(27,099	)
Denominator:
Weighted average shares outstanding - basic		63,282		58,056			62,289			55,226
Dilutive stock options, RSUs and RSAs		6,134		—			—			—
Weighted average shares outstanding - diluted		69,416		58,056			62,289			55,226
Net income (loss) per common share
Basic	$	0.32	$	(0.26	)	$	(0.02	)	$	(0.49	)
Diluted	$	0.29	$	(0.26	)	$	(0.02	)	$	(0.49	)

Potentially Dilutive Securities Excluded from Calculation of Diluted Net Income (Loss) per Share Due to Anti-Dilutive Effect

The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Options to purchase common stock, including purchases from contributions to ESPP		860		11,001		7,730		11,001
Restricted stock units		14		402		400		402
Restricted stock awards		14		41		14		41
Warrants to purchase common stock		—		150		150		150
		888		11,594		8,294		11,594