CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue:
Government contracts	$ 0	$ 134	$ 0	$ 2,080
Research and development collaborations	6,732	2,371	12,412	4,643
Total revenue	6,732	2,505	12,412	6,723
Expenses:
Research and development	39,263	64,904	76,916	133,856
General and administrative	8,940	14,099	17,793	24,627
Total expenses	48,203	79,003	94,709	158,483
Loss from operations	(41,471)	(76,498)	(82,297)	(151,760)
Other income (expense):
Investment income	523	670	997	1,147
Interest expense	(3,516)	(3,512)	(7,029)	(5,946)
Other income (expense)	(1)	(11)	10	(44)
Net loss	$ (44,465)	$ (79,351)	$ (88,319)	$ (156,603)
Basic and diluted net loss per share	$ (0.16)	$ (0.29)	$ (0.32)	$ (0.58)
Basic and diluted weighted average number of common shares outstanding	283,444	270,760	278,836	270,469

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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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