X0306 4 2019-12-20 0 0001750019 TCR2 THERAPEUTICS INC. TCRR 0001362054 Baeuerle Patrick TCR2 THERAPEUTICS INC. 100 BINNEY STREET CAMBRIDGE MA 02142 1 0 0 0 Common Stock 2019-12-20 4 S 0 32022 15.16 D 435693 I By APAK Solutions GmbH Common Stock 2019-12-23 4 S 0 84907 15.44 D 350786 I By APAK Solutions GmbH The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person. $15.16 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.00 to $15.87, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range. The reported securities are owned directly by APAK Solutions GmbH. The Reporting Person is managing director of APAK Solutions GmbH. The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein. $15.44 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.01 to $16.29, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range. /s/ Margaret Siegel as Attorney-in-Fact 2019-12-26