X0306 4 2020-12-10 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 1 Common Stock 2267 D Stock Option (Right to Buy) 31.38 2020-12-10 4 A 0 245000 0.00 A 2030-12-09 Common Stock 245000 245000 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. 25% of this option shall vest and become exercisable on January 1, 2022, with the remainder vesting in thirty-six (36) equal monthly installments thereafter. /s/ Margaret Siegel as Attorney-in-Fact 2020-12-10