Related party transactions	12 Months Ended
Dec. 31, 2019
Related party transactions
Related party transactions	13. Related party transactions Apple Tree Life Sciences, Inc. During 2018, the Company issued 8,000,000 shares of Series A Preferred Stock and 880,568 shares of Series B Preferred Stock to entities affiliated with Apple Tree Life Sciences, Inc. ("Apple Tree") and a principal of Apple Tree was elected to the board of directors. The Company's founders, including the current Executive Vice President and Chief Operating Officer and Chief Scientific Officer, were formerly employees of Apple Tree until April 2017. During the years ended December 31, 2019 and 2018, the Company incurred fees for certain general and administrative services from Apple Tree totaling $20 and $0, respectively. As of December 31, 2019 and 2018, the Company did not owe any amounts to Apple Tree. Atlas Venture Life Science Advisors, LLC During 2018, the Company issued 10,666,667 shares of Series A Preferred Stock and 722,737 shares of Series B Preferred Stock to entities affiliated with Atlas Venture ("Atlas") and a principal of Atlas was elected to the board of directors. During the years ended December 31, 2019 and 2018, the Company incurred fees for certain research and development consulting services from Atlas totaling $0 and $23, respectively. In August 2018, the Company entered into a use and occupancy agreement for office space in Cambridge, Massachusetts with Atlas (See Note 12). The parties terminated the agreement in September of 2019. During the years ended December 31, 2019 and 2018, the Company incurred fees under the use and occupancy agreement with Atlas totaling $22 and $8, respectively. As of December 31, 2019, the Company did not owe any amounts to Atlas. As of December 31, 2018, the Company owed $12 to Atlas, which was included in accounts payable on the Company’s consolidated balance sheet. Versant Venture Capital VI, L.P. During 2018, the Company issued 10,666,667 shares of Series A Preferred Stock and 722,737 shares of Series B Preferred Stock to entities affiliated with Versant Venture Capital VI, L.P. ("Versant") and a principal of Versant at that time was elected to the board of directors. During the years ended December 31, 2019 and 2018, the Company incurred fees for certain general and administrative services from Versant totaling $0 and $4, respectively. As of December 31, 2019 and 2018, the Company did not owe any amounts to Versant. venBio Global Strategic Fund II, L.P. During 2018, the Company issued 10,666,667 shares of Series A Preferred Stock and 722,737 shares of Series B Preferred Stock to entities affiliated with venBio Global Strategic Fund II, L.P. ("venBio"). A principal of venBio served on the Company’s board of directors from June 2018 to August 2019. During the years ended December 31, 2019 and 2018, the Company incurred fees for certain general and administrative services from venBio totaling $0 and $35, respectively. As of December 31, 2019, the Company did not owe any amounts to venBio. As of December 31, 2018, the Company owed $35 to venBio, which was included in accounts payable on the Company’s consolidated balance sheet.

13. Related party transactions

Apple Tree Life Sciences, Inc.

During 2018, the Company issued 8,000,000 shares of Series A Preferred Stock and 880,568 shares of Series B Preferred Stock to entities affiliated with Apple Tree Life Sciences, Inc. ("Apple Tree") and a principal of Apple Tree was elected to the board of directors. The Company's founders, including the current Executive Vice President and Chief Operating Officer and Chief Scientific Officer, were formerly employees of Apple Tree until April 2017. During the years ended December 31, 2019 and 2018, the Company incurred fees for certain general and administrative services from Apple Tree totaling $20 and $0, respectively. As of December 31, 2019 and 2018, the Company did not owe any amounts to Apple Tree.

Atlas Venture Life Science Advisors, LLC

During 2018, the Company issued 10,666,667 shares of Series A Preferred Stock and 722,737 shares of Series B Preferred Stock to entities affiliated with Atlas Venture ("Atlas") and a principal of Atlas was elected to the board of directors.

During the years ended December 31, 2019 and 2018, the Company incurred fees for certain research and development consulting services from Atlas totaling $0 and $23, respectively. In August 2018, the Company entered into a use and occupancy agreement for office space in Cambridge, Massachusetts with Atlas (See Note 12). The parties terminated the agreement in September of 2019. During the years ended December 31, 2019 and 2018, the Company incurred fees under the use and occupancy agreement with Atlas totaling $22 and $8, respectively. As of December 31, 2019, the Company did not owe any amounts to Atlas. As of December 31, 2018, the Company owed $12 to Atlas, which was included in accounts payable on the Company’s consolidated balance sheet.

Versant Venture Capital VI, L.P.

During 2018, the Company issued 10,666,667 shares of Series A Preferred Stock and 722,737 shares of Series B Preferred Stock to entities affiliated with Versant Venture Capital VI, L.P. ("Versant") and a principal of Versant at that time was elected to the board of directors. During the years ended December 31, 2019 and 2018, the Company incurred fees for certain general and administrative services from Versant totaling $0 and $4, respectively. As of December 31, 2019 and 2018, the Company did not owe any amounts to Versant.

venBio Global Strategic Fund II, L.P.

During 2018, the Company issued 10,666,667 shares of Series A Preferred Stock and 722,737 shares of Series B Preferred Stock to entities affiliated with venBio Global Strategic Fund II, L.P. ("venBio"). A principal of venBio served on the Company’s board of directors from June 2018 to August 2019. During the years ended December 31, 2019 and 2018, the Company incurred fees for certain general and administrative services from venBio totaling $0 and $35, respectively. As of December 31, 2019, the Company did not owe any amounts to venBio. As of December 31, 2018, the Company owed $35 to venBio, which was included in accounts payable on the Company’s consolidated balance sheet.