X0306 4 2022-11-29 1 0001746473 PLIANT THERAPEUTICS, INC. PLRX 0001569705 Third Rock Ventures III, L.P. C/O THIRD ROCK VENTURES, LLC, 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02215 0 0 1 0 0001637300 Third Rock Ventures GP III, L.P. 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02115 0 0 1 0 0001637299 TRV GP III, LLC 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02115 0 0 1 0 0001192595 TEPPER ROBERT I 201 BROOKLINE AVE, SUITE 1401 BOSTON MA 02115 0 0 1 0 Common Stock 2022-11-29 4 J 0 2000000 D 1839160 D Common Stock 2132867 I See footnote Common Stock 229504 D On November 29, 2022, Third Rock Ventures III, L.P. ("TRV III") distributed for no consideration, 2,000,000 shares of Common Stock of the Issuer (the "Shares") to its limited partners and to Third Rock Ventures GP III, L.P. ("TRV GP III"), the general partner of TRV III, representing each such partner's pro rata interest in such Shares. On the same date, TRV GP III distributed, for no consideration, the Shares it received in the distribution by TRV III to its partners, representing each such partner's pro rata interest in such Shares. All of the aforementioned distributions were made in accordance with the exemptions afforded by Rules 16a-13 and 16a-9 of the Securities Exchange Act of 1934, as amended. These shares are directly held by TRV III. The general partner of TRV III is TRV GP III. The general partner of TRV GP III is TRV GP III, LLC ("TRV GP III LLC"). The individual manager of TRV GP III LLC is Dr. Robert Tepper ("Tepper"). Each of TRV GP III, TRV GP III LLC and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares. These shares are directly held by Third Rock Ventures IV, L.P. ("TRV IV"). The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Each of TRV GP IV and TRV GP IV 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. Each of the reporting persons disclaims the existence of a Section 13(d) "group" as between the TRV III related parties and the TRV IV related parties and this report shall not be deemed an admission that any of such parties is or may be part of such a group with any of the other parties. The shares are directly held by Tepper. Includes Shares received in the distributions described in footnote (1) above. /s/ Kevin Gillis, Chief Operating Officer of TRV GP III, LLC, general partner of Third Rock Ventures GP III, L.P., general partner of Third Rock Ventures III, L.P. 2022-12-01 /s/ Kevin Gillis, Chief Operating Officer of TRV GP III, LLC, general partner of Third Rock Ventures GP III, L.P. 2022-12-01 /s/ Kevin Gillis, Chief Operating Officer of TRV GP III, LLC 2022-12-01 /s/ Kevin Gillis, by power of attorney for Dr. Robert Tepper 2022-12-01