Subsequent Events	9 Months Ended
Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	11. Subsequent Events Collaboration Agreement with Seattle Genetics In November 2019, the Company and Seattle Genetics suspended further development under the Collaboration Agreement, including suspension of further dose-escalation of the ATTCK-17-01 Phase 1 clinical trial, and the Company is reviewing the next steps with this program. In accordance with ASC 606, the Company has concluded that the performance obligations were not modified during the three or nine months ended September 30, 2019, and that the Company will account for the suspension of research and development activities in the fourth quarter of the fiscal year ended December 31, 2019.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-URI http://asc.fasb.org/topic&trid=2122774

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