Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net loss	$ (12,790,814)	$ (9,377,533)	$ (8,800,563)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	36,193	47,656	50,402
Accrued Interest on CIRM award	133,905	0	0
(Gain) loss on disposal of assets	0	(4)	3,817
Change in fair value of warrant liability	(2,925,258)	(529,774)	(642,411)
Financing expense	88,939	62,683	0
Stock-based compensation	916,028	654,260	724,212
Changes in assets and liabilities:
Other assets	422,448	(9,097)	(426,640)
Supplies for clinical trials	(2,209,192)	(227,097)	0
Deposits	(3,657,913)	(339,259)	0
Accounts payable	805,320	(644,587)	128,175
Accrued liabilities	140,943	425,950	175,791
Net cash used in operating activities	(19,039,401)	(9,936,802)	(8,787,217)
Cash flows from investing activities:
Purchase of property and equipment	(169,750)	(28,975)	(44,372)
Proceeds from sale of property and equipment	0	400	0
Net cash used in investing activities	(169,750)	(28,575)	(44,372)
Cash flows from financing activities:
Proceeds from exercise of stock options	6,750	1,045,000	324,517
Proceeds from exercise of warrants	0	0	5,030,677
Deferred financing costs	(15,041)	0	0
Proceeds from CIRM award	4,000,000	0	0
Proceeds from issuance of common stock and warrants net of offering costs	14,599,627	4,496,322	4,906,078
Net cash provided by financing activities	18,591,336	5,541,322	10,261,272
Increase (decrease) in cash and cash equivalents	(617,815)	(4,424,055)	1,429,683
Cash and cash equivalents, beginning of period	23,222,296	27,646,351	26,216,668
Cash and cash equivalents, end of period	22,604,481	23,222,296	27,646,351
Supplemental cash flows disclosures:
Interest expense paid	0	0	0
Income taxes paid	0	0	0
Supplemental non-cash financing disclosures:
Warrant liability converted to additional paid-in capital	0	0	1,145,659
Common stock issued for license rights	0	0	75,000
Deferred offering costs	$ 33,936	$ 105,563	$ 0