| Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block] |
The following table summarizes amounts charged to expense for stock-based compensation related to employee and director stock-option grants and stock-based compensation recorded in connection with stock options granted to non-employee consultants:
| | | Three Months Ended
September 30, | | Nine Months Ended
September 30, | | Cumulative
Development-
Stage Period
from
November 7,
2002 through
September 30, | | | | | 2013 | | 2012 | | 2013 | | 2012 | | 2013 | | | Employee and director stock option grants: | | | | | | | | | | | | | | | | | | Research and development | | $ | 84,949 | | $ | 78,627 | | $ | 297,561 | | $ | 234,816 | | $ | 1,105,822 | | | General and administrative | | | 206,449 | | | 249,562 | | | 782,731 | | | 747,808 | | | 3,941,523 | | | | | | 291,398 | | | 328,189 | | | 1,080,292 | | | 982,624 | | | 5,047,345 | | | Non-employee consultant stock option grants: | | | | | | | | | | | | | | | | | | Research and development | | | 5,812 | | | 3,896 | | | 10,134 | | | 85,265 | | | 126,170 | | | General and administrative | | | 464 | | | 4,351 | | | 11,039 | | | 92,022 | | | 286,120 | | | | | | 6,276 | | | 8,247 | | | 21,173 | | | 177,287 | | | 412,290 | | | | | | | | | | | | | | | | | | | | | Total stock-based compensation | | $ | 297,674 | | $ | 336,436 | | $ | 1,101,465 | | $ | 1,159,911 | | $ | 5,459,635 | |
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| Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] |
The following table summarizes weighted-average values and assumptions used for options granted to employees, directors and consultants in the periods indicated:
| | | Three Months
Ended
September 30,
2013 | | | Nine Months
Ended
September 30,
2013 | | | Three and Nine
Months Ended
September 30, 2012 | | | Volatility | | | 109 | % | | | 109 | % | | | 115 | % | | Risk-free interest rate | | | 1.82 | % | | | 0.915% - 1.82 | % | | | 0.925 | % | | Expected life (years) | | | 6.0 | | | | 6.0 | | | | 6.0 | | | Dividend | | | 0 | % | | | 0 | % | | | 0 | % | | Weighted-average exercise price | | $ | 0.43 | | | $ | 0.47 | | | $ | 1.00 | | | Weighted-average grant-date fair value | | $ | 0.36 | | | $ | 0.39 | | | $ | 0.85 | |
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| Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] |
A summary of stock option activity under stock option plans is as follows:
| | | Number of
Shares
Issuable Upon
Exercise of
Outstanding
Options | | Weighted
Average
Exercise Price | | Weighted
Average
Remaining
Contracted
Term in
Years | | Aggregate
Intrinsic
Value | | | Outstanding at December 31, 2012 | | | 6,439,188 | | $ | 1.52 | | | | | | | | | Granted | | | 160,000 | | $ | 0.47 | | | | | | | | | Forfeited | | | (338,386) | | $ | 0.81 | | | | | | | | | Expired | | | (156,135) | | $ | 2.47 | | | | | | | | | Outstanding at September 30, 2013 | | | 6,104,667 | | $ | 1.51 | | | | | | | | | | | | | | | | | | | | | | | | Vested, September 30, 2013 | | | 3,674,390 | | $ | 1.96 | | | 7.95 | | $ | — | | | Unvested, September 30, 2013 | | | 2,430,277 | | $ | 0.83 | | | 8.67 | | $ | — | | | Exercisable at September 30, 2013 | | | 3,674,390 | | $ | 1.96 | | | 7.95 | | $ | — | |
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