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Commitment and Contingencies - Additional Information (Detail) |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Sep. 30, 2015 USD ($) $ / shares shares | Jul. 31, 2015 USD ($) | Jul. 08, 2015 USD ($) | Jun. 30, 2015 USD ($) ft² | Dec. 31, 2014 USD ($) shares | Mar. 31, 2014 USD ($) shares | Sep. 30, 2015 USD ($) $ / shares shares | Sep. 30, 2014 USD ($) | Sep. 30, 2015 USD ($) $ / shares shares | Sep. 30, 2014 USD ($) | Dec. 31, 2014 USD ($) | Apr. 30, 2014 USD ($)
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease Expiration Date |  |  |  |  |  |  |  |  |  |  | Aug. 31, 2016 |  |  |
Number of square foot of facility leased. | ft² |  |  |  |  |  | 44,681 |  |  |  |  |  |  |  |
Extended lease term |  |  |  |  |  |  |  |  |  |  | 7 years |  |  |
Base rent |  |  |  |  |  |  |  |  |  |  | $ 179,000 |  |  |
Percentage of annual increase of base rent |  |  |  |  |  |  |  |  |  |  | 3.00% |  |  |
Rent expense |  |  |  |  |  |  |  |  | $ 667,000 | $ 59,000 | $ 825,000 | $ 158,000 |  |
Research and development |  |  |  |  |  |  |  |  | 3,950,000 | 328,000 | 6,328,000 | 691,000 |  |
Issuance of common stock |  |  |  |  |  |  |  |  |  |  | 77,975,000 |  |  |
Consideration for the sale of the licensed patents |  |  |  |  |  |  |  |  |  |  | $ 75,000 |  |  |
Notes payable |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,000,000
Ownership interest of the total outstanding common shares |  |  |  |  |  |  |  |  |  |  | 7.00% |  |  |
Warrant exercise term |  |  |  |  |  |  |  |  |  |  | 10 years |  |  |
Class of warrant or right outstanding number of shares exercised | shares |  |  |  |  |  |  |  |  |  |  | 37,030 |  |  |
Proceeds from issuance of common stock net of issuance costs |  |  |  |  | $ 7,000,000 | $ 70,976,000 |  | $ 3,000,000 |  |  |  |  |  |
Percentage of equity owned by partners |  |  |  |  |  |  |  | 7.00% |  |  |  |  |  |
Expense earned or paid |  |  | $ 0 |  |  |  |  |  | 6,000 | 6,000 | $ 19,000 | 44,000 |  |
Milestone payments |  |  |  |  |  |  |  |  |  |  | $ 0 | 0 |  |
License agreement termination notice period |  |  |  |  |  |  |  |  |  |  | 60 days |  |  |
Fox Chase Cancer Center License Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expense earned or paid |  |  |  |  |  |  |  |  | $ 0 | $ 29,000 | $ 51,000 | $ 149,000 |  |
Rush University Medical Center License Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for the sale of the licensed patents |  |  |  |  |  |  |  |  |  |  |  |  | $ 250,000,000 |
Period of license agreement |  |  |  |  |  |  |  |  |  |  |  |  | 12 years |
Minimum annual royalty payment |  |  |  |  |  |  |  |  |  |  |  |  | $ 25,000 |
Payments in license agreement |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,500,000 |
Common Class A |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exchanged warrants, in share | shares |  |  | 123,433 |  |  |  |  |  | 123,433 |  | 123,433 |  |  |
Stock price of warrants | $ / shares |  |  | $ 2.44 |  |  |  |  |  | $ 2.44 |  | $ 2.44 |  |  |
Warrants exchange to purchase common stock | shares |  |  |  |  |  |  |  | 156,109 |  |  |  |  |  |
Purchase of fully-vested incentive stock option | shares |  |  |  |  |  |  |  | 740,600 |  |  |  |  |  |
Private Placement One |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of common stock net of issuance costs |  |  |  | $ 17,000,000 |  |  |  |  |  |  |  |  |  |
Private Placement One | Sorrento | Common Class A |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common stock, Shares | shares |  |  |  |  |  |  | 4,557,537 |  |  |  | 4,557,537 |  |  |
Proceeds from issuance of common stock gross of issuance costs |  |  |  |  |  |  | $ 8,000,000 |  |  |  | $ 8,000,000 |  |  |
Private Placement Two | Common Class A |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common stock, Shares | shares |  |  |  |  |  |  | 26,252,262 |  |  |  |  |  |  |
Proceeds from issuance of common stock gross of issuance costs |  |  |  |  |  |  | $ 49,495,000 |  |  |  |  |  |  |
Private Placement Two | Sorrento | Common Class A |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common stock, Shares | shares |  |  |  |  |  |  | 1,060,789 |  |  |  | 1,060,789 |  |  |
Issuance of common stock |  |  |  |  |  |  | $ 2,000,000 |  |  |  | $ 2,000,000 |  |  |
2013 Securities Purchase Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Notes payable |  |  | $ 1,000,000 |  |  |  |  |  | $ 1,000,000 |  | 1,000,000 |  |  |
2013 Securities Purchase Agreement | Common Class A |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Notes payable |  |  | $ 950,000 |  |  |  |  |  | $ 950,000 |  | 950,000 |  |  |
Scenario Forecast |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Research and development | $ 2,000,000 | $ 2,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Sub Lease Agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rent expense |  |  |  |  |  |  |  |  |  |  | $ 0 |  |  |

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