Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (5,824,987)	$ (5,633,345)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	16,595	20,370
Change in fair value of warrant liability	(102,776)	(481,011)
Financing expense	0	14,636
Stock-based compensation	171,966	227,435
Accrued interest on CIRM award	452,659	264,827
Changes in assets and liabilities:
Other assets	297,297	185,052
Supplies for clinical trials	55,281	(356,182)
Deposits	34,620	413,402
Accounts payable	(518,434)	(249,821)
Accrued compensation and benefits	(875,762)	(575,079)
Accrued liabilities	223,184	818,795
Net cash used in operating activities	(6,070,357)	(5,350,921)
Cash flows from investing activities:
Purchase of property and equipment	0	(4,015)
Net cash used in investing activities	0	(4,015)
Cash flows from financing activities:
Proceeds from the issuance of common stock through controlled equity offering	0	264,668
Deferred financing costs	(25,328)	0
Net cash (used in) provided by financing activities	(25,328)	264,668
(Decrease) in cash and cash equivalents	(6,095,685)	(5,090,268)
Cash and cash equivalents, beginning of period	11,437,118	22,604,481
Cash and cash equivalents, end of period	5,341,433	17,514,213
Supplemental cash flows disclosures:
Interest expense paid	0	0
Income taxes paid	0	0
Supplemental non-cash disclosures:
Financing costs included in accounts payable	$ 90,881	$ 8,593