X0206 3 2023-08-11 0 0001819133 Tango Therapeutics, Inc. TNGX 0001931056 Third Rock Ventures VI, L.P. C/O THIRD ROCK VENTURES, LLC 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 1 0 0 0 0001977499 Third Rock Ventures GP VI, L.P. C/O THIRD ROCK VENTURES, LLC 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 1 0 0 0 0001990716 TRV GP VI, LLC C/O THIRD ROCK VENTURES, LLC 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 1 0 0 0 Common Stock 194174 D The shares of common stock were acquired by the Reporting Person pursuant to a securities purchase agreement in a private placement offering of shares of the Issuer's common stock, which offering closed on August 11, 2023. These shares are directly held by Third Rock Ventures VI, L.P. ("TRV VI"). The general partner of TRV VI is Third Rock Ventures GP VI, L.P. ("TRV GP VI"). The general partner of TRV GP VI is TRV GP VI, LLC ("TRV GP VI LLC"). Each of TRV GP VI and TRV GP VI LLC disclaims beneficial ownership of the shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares. Reid Huber, a partner at Third Rock Ventures, LLC, has been deputized to represent the Reporting Persons (and other funds affiliated with Third Rock Ventures, LLC that hold shares of the Issuer's stock) on the board of directors of the Issuer. By virtue of Mr. Huber's representation, for purposes of Section 16 of the Securities Exchange Act of 1934, each of the Reporting Person may be deemed directors by deputization of the Issuer. /s/ Kevin Gillis, Chief Operating Officer of TRV GP VI, LLC, general partner of Third Rock Ventures GP VI, L.P., general partner of Third Rock Ventures VI, L.P. 2023-08-22 /s/ Kevin Gillis, Chief Operating Officer of TRV GP VI, LLC, general partner of Third Rock Ventures GP VI, L.P. 2023-08-22 /s/ Kevin Gillis, Chief Operating Officer of TRV GP VI, LLC 2023-08-22