Research and License Agreements	12 Months Ended
Dec. 31, 2017
Licensing Agreements [Abstract]
Research and License Agreements	14. Research and License Agreements Contract Research Agreement In December 2013, the Company entered into a contract research agreement with a contract manufacturing organization (“CMO”) under which the CMO provides research and development services to the Company in exchange for cash and convertible preferred shares. For the years ended December 31, 2017 and 2016, no shares were issued to the CMO. For the year ended December 31, 2015, the Company issued 70,028 Series B convertible preferred shares to the CMO with a fair value of $1.1 million. The number of convertible preferred shares contractually issuable to the counterparty was determined by dividing a fixed monetary amount by the issuance-date fair value of the issued shares. These services are expensed as research and development costs in accordance with the fair value of the consideration paid and as the services are rendered. The Company was obligated to issue a variable number of shares of convertible preferred stock upon the completion of certain milestones related to the research and development of the Company’s products. In June 2015, the contract research agreement was amended to convert the remaining unmet milestone awards from share-based payments to cash. As of December 31, 2017, 2016, and 2015, all related obligations payable in convertible preferred stock under the agreement have been satisfied. University Research Agreement In December 2013, the Company entered into a research agreement with the University of Texas at Austin (the “University”). Under the terms of this research agreement, the Company engaged the University to perform certain nonclinical research activities related to the systemic depletion of amino acids for cancer and rare genetic disease therapy. Under the research agreement, the Company was required to pay the University an annual amount not to exceed $386,000 during the one-year term of the agreement from the effective date. Pursuant to subsequent amendments to the research agreement, the term and maximum expenditure limitation were extended and increased through August 31, 2018 for a combined $2.5 million, including an amendment in October 2017 which increased the maximum expenditure limitation by $375,000 for additional research to be performed by the University. For the years ended December 31, 2017, 2016, and 2015, the Company paid $563,000, $832,000, and $563,000, respectively, to the University under the research agreement. License Agreements In December 2013, two of the Company’s wholly owned subsidiaries, AECase, Inc. (“AECase”) and AEMase, Inc. (“AEMase”), entered into license agreements with the University under which the University granted to AECase and AEMase exclusive, worldwide, sublicenseable licenses. The University granted the AECase license under a patent application relating to the right to use technology related to the Company’s AEB3103 product candidate. The University granted the AEMase license under a patent relating to the right to use technology related to the Company’s AEB2109 product candidate. In January 2017, the Company entered into an Amended and Restated Patent License Agreement (the “Restated License”) with the University which consolidated the two license agreements, revised certain obligations, and licensed additional patent applications and invention disclosures to the Company. Pursuant to the terms of the Restated License, the Company may be required to pay the University up to $6.4 million in milestone payments based on the achievement of certain development milestones, including clinical trials and regulatory approvals, the majority of which are due upon the achievement of later development milestones, including a $5.0 million payment due on regulatory approval of a product and a $500,000 payment payable on final regulatory approval of a product for a second indication. In addition, the Company is required to pay the University a low single-digit royalty on worldwide-net sales of products covered under Restated License, together with a revenue share on non-royalty consideration received from sublicensees. The rate of the revenue share ranges from 6.5% to 25% depending on the date the sublicense agreement is signed. For the years ended December 31, 2017 and 2016, the Company paid $30,000 and $10,000, respectively, in annual license fees. For the year ended December 31, 2015, there were no license fees due or paid.

14. Research and License Agreements

Contract Research Agreement

In December 2013, the Company entered into a contract research agreement with a contract manufacturing organization (“CMO”) under which the CMO provides research and development services to the Company in exchange for cash and convertible preferred shares.

For the years ended December 31, 2017 and 2016, no shares were issued to the CMO. For the year ended December 31, 2015, the Company issued 70,028 Series B convertible preferred shares to the CMO with a fair value of $1.1 million. The number of convertible preferred shares contractually issuable to the counterparty was determined by dividing a fixed monetary amount by the issuance-date fair value of the issued shares. These services are expensed as research and development costs in accordance with the fair value of the consideration paid and as the services are rendered.

The Company was obligated to issue a variable number of shares of convertible preferred stock upon the completion of certain milestones related to the research and development of the Company’s products. In June 2015, the contract research agreement was amended to convert the remaining unmet milestone awards from share-based payments to cash. As of December 31, 2017, 2016, and 2015, all related obligations payable in convertible preferred stock under the agreement have been satisfied.

University Research Agreement

In December 2013, the Company entered into a research agreement with the University of Texas at Austin (the “University”). Under the terms of this research agreement, the Company engaged the University to perform certain nonclinical research activities related to the systemic depletion of amino acids for cancer and rare genetic disease therapy.

Under the research agreement, the Company was required to pay the University an annual amount not to exceed $386,000 during the one-year term of the agreement from the effective date. Pursuant to subsequent amendments to the research agreement, the term and maximum expenditure limitation were extended and increased through August 31, 2018 for a combined $2.5 million, including an amendment in October 2017 which increased the maximum expenditure limitation by $375,000 for additional research to be performed by the University. For the years ended December 31, 2017, 2016, and 2015, the Company paid $563,000, $832,000, and $563,000, respectively, to the University under the research agreement.

License Agreements

In December 2013, two of the Company’s wholly owned subsidiaries, AECase, Inc. (“AECase”) and AEMase, Inc. (“AEMase”), entered into license agreements with the University under which the University granted to AECase and AEMase exclusive, worldwide, sublicenseable licenses. The University granted the AECase license under a patent application relating to the right to use technology related to the Company’s AEB3103 product candidate. The University granted the AEMase license under a patent relating to the right to use technology related to the Company’s AEB2109 product candidate.

In January 2017, the Company entered into an Amended and Restated Patent License Agreement (the “Restated License”) with the University which consolidated the two license agreements, revised certain obligations, and licensed additional patent applications and invention disclosures to the Company. Pursuant to the terms of the Restated License, the Company may be required to pay the University up to $6.4 million in milestone payments based on the achievement of certain development milestones, including clinical trials and regulatory approvals, the majority of which are due upon the achievement of later development milestones, including a $5.0 million payment due on regulatory approval of a product and a $500,000 payment payable on final regulatory approval of a product for a second indication. In addition, the Company is required to pay the University a low single-digit royalty on worldwide-net sales of products covered under Restated License, together with a revenue share on non-royalty consideration received from sublicensees. The rate of the revenue share ranges from 6.5% to 25% depending on the date the sublicense agreement is signed.

For the years ended December 31, 2017 and 2016, the Company paid $30,000 and $10,000, respectively, in annual license fees. For the year ended December 31, 2015, there were no license fees due or paid.