Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (9,434,135)	$ (10,962,916)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	33,190	40,963
Change in fair value of warrant liability	(545,698)	(926,671)
Financing expense	0	31,231
Stock-based compensation	323,895	480,947
Derecognition of CIRM liability	(7,719,440)	0
Accrued interest on CIRM award	882,683	546,823
Write-off of supplies for clinical trials	2,349,404	0
Changes in assets and liabilities:
Other assets	157,967	595,679
Supplies for clinical trials	146,430	(293,100)
Accounts payable	2,843,974	(531,531)
Accrued compensation and benefits	(908,221)	(459,562)
Accrued liabilities	2,346,767	284,005
Net cash used in operating activities	(9,523,184)	(11,194,132)
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	691,187
Proceeds from the exercise of warrants	41,000	0
Deferred offering costs	(140,929)	(148,663)
Net cash (used in) provided by financing activities	(99,929)	542,524
(Decrease) in cash and cash equivalents	(9,623,113)	(10,655,623)
Cash and cash equivalents, beginning of period	11,437,118	22,604,481
Cash and cash equivalents, end of period	1,814,005	11,948,858
Supplemental cash flows disclosures:
Interest expense paid	0	0
Income taxes paid	0	0
Supplemental non-cash disclosures:
Financing costs included in accounts payable	89,726	79,440
Deposits reclassified to other current assets	1,922,218	0
CIRM liability reclassified to other current assets	$ 108,984	$ 0