STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total revenues	$ 108,621	$ 59,288	$ 44,509
Costs and expenses:
Cost of product sales	895	906	287
Research and development	60,101	52,885	46,903
Selling, general and administrative	76,598	74,588	70,002
Total costs and expenses	137,594	128,379	117,192
Loss from operations	(28,973)	(69,091)	(72,683)
Interest income	582	2,532	2,203
Interest expense	(1,353)	(335)
Net loss	$ (29,744)	$ (66,894)	$ (70,480)
Net loss per share, basic and diluted
Net loss per share, basic and diluted (in dollars per share)	$ (0.18)	$ (0.40)	$ (0.44)
Weighted average shares used in computing net loss per share
Weighted average shares used in computing net loss per share, basic and diluted (in shares)	168,754	167,400	160,529
Product sales, net
Total revenues	$ 61,696	$ 43,772	$ 13,947
Contract revenues from collaborations
Total revenues	$ 46,925	$ 15,516	$ 30,562

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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