Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net loss	$ (22,085,702)	$ (12,790,814)	$ (9,377,533)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	75,114	36,193	47,656
Accrued Interest on CIRM award	1,311,836	133,905	0
(Gain) loss on disposal of assets	0	0	(4)
Change in fair value of warrant liability	(3,812,398)	(2,925,258)	(529,774)
Financing expense	498,520	88,939	62,683
Stock-based compensation	1,228,987	916,028	654,260
Changes in assets and liabilities:
Other assets	5,940	422,448	(9,097)
Supplies for clinical trials	(221,545)	(2,209,192)	(227,097)
Deposits	2,220,766	(3,657,913)	(339,259)
Accounts payable	125,363	805,320	(644,587)
Accrued liabilities	788,677	140,943	425,950
Net cash used in operating activities	(19,864,442)	(19,039,401)	(9,936,802)
Cash flows from investing activities:
Purchase of property and equipment	(4,015)	(169,750)	(28,975)
Proceeds from sale of property and equipment	0	0	400
Net cash used in investing activities	(4,015)	(169,750)	(28,575)
Cash flows from financing activities:
Proceeds from exercise of stock options	0	6,750	1,045,000
Proceeds from exercise of warrants	208,750	0	0
Deferred financing costs	(44,711)	(15,041)	0
Proceeds from CIRM award	1,500,000	4,000,000	0
Proceeds from issuance of common stock and warrants, net of offering costs	6,345,868	14,599,627	0
Proceeds from issuance of common stock through controlled equity offering	691,187	0	4,496,322
Net cash provided by financing activities	8,701,094	18,591,336	5,541,322
Decrease in cash and cash equivalents	(11,167,363)	(617,815)	(4,424,055)
Cash and cash equivalents, beginning of period	22,604,481	23,222,296	27,646,351
Cash and cash equivalents, end of period	11,437,118	22,604,481	23,222,296
Supplemental cash flows disclosures:
Interest expense paid	0	0	0
Income taxes paid	0	0	0
Supplemental non-cash financing disclosures:
Deferred offering costs included in accounts payable	$ 55,505	$ 0	$ 0