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Common Stock (Tables) | 12 Months Ended
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Dec. 31, 2017
Common Stock |
Schedule of Common Stock reserved for future issuance |
|  | As of December 31, |
|  | 2017 |  | 2016 |
Warrants for the purchase of Common Stock |  |  | 24,566 |  |  | 24,566 |
Options to purchase Common Stock |  |  | 3,669,791 |  |  | 2,939,968 |
Employee Stock Purchase Plan |  |  | 523,659 |  |  | 335,484 |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Total |  |  | 4,218,016 |  |  | 3,300,018 |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​

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