X0306 4 2020-08-31 0 0001750019 TCR2 THERAPEUTICS INC. TCRR 0001556064 Menzel Garry E TCR2 THERAPEUTICS INC. 100 BINNEY STREET CAMBRIDGE MA 02142 1 1 0 0 President and CEO Common Stock 84527 I See Footnote Common Stock 2020-08-31 5 A 0 E 1132 10.098 A 3399 D Common Stock 2021-02-28 5 A 0 E 686 16.1245 A 4085 D Consists of 84,527 shares of common stock held by Dr. Garry Menzel, as Trustee of the Garry E. Menzel and Mary E. Henshall Family Trust, under instrument of trust dated July 29, 2010. Dr. Menzel is the trustee of the Garry E. Menzel and Mary E. Henshall Family Trust and may be deemed to beneficially own these securities. The reporting person is voluntarily reporting the acquisition of shares of the issuer's common stock pursuant to the issuer's 2018 Employee Stock Purchase Plan ("ESPP") for the ESPP purchase period of March 1, 2020 through August 31, 2020. This transaction is exempt under Rule 16b-3(c). In accordance with the ESPP, these shares were purchased based on 85% of the closing price of the issuer's common stock on February 28, 2020. The reporting person is voluntarily reporting the acquisition of shares of the issuer's common stock pursuant to the ESPP for the ESPP purchase period of September 1, 2020 through February 28, 2021. This transaction is exempt under Rule 16b-3(c). In accordance with the ESPP, these shares were purchased based on 85% of the closing price of the issuer's common stock on September 1, 2020. /s/ Margaret Siegel as Attorney-in-Fact 2021-03-08