X0306 4 2017-11-06 0 0001624658 Allena Pharmaceuticals, Inc. ALNA 0001488495 Third Rock Ventures II, L.P. C/O THIRD ROCK VENTURES, LLC 29 NEWBURY STREET, 3RD FLOOR BOSTON MA 02116 0 0 1 0 0001614061 Third Rock Ventures GP II, L.P. C/O THIRD ROCK VENTURES, LLC 29 NEWBURY STREET, 3RD FLOOR BOSTON MA 02116 0 0 1 0 0001614073 TRV GP II, LLC C/O THIRD ROCK VENTURES, LLC 29 NEWBURY STREET, 3RD FLOOR BOSTON MA 02116 0 0 1 0 0001180428 LEVIN MARK J 29 NEWBURY STREET, 3RD FLOOR BOSTON MA 02116 0 0 1 0 0001192603 STARR KEVIN P 29 NEWBURY STREET, 3RD FLOOR BOSTON MA 02116 0 0 1 0 Common Stock 2017-11-06 4 C 0 2575964 A 2575964 D Common Stock 2017-11-06 4 P 0 215000 14.00 A 2790964 D Series A Preferred Stock 2017-11-06 4 C 0 6122448 0.00 D Common Stock 1466805 0 D Series B Preferred Stock 2017-11-06 4 C 0 4629630 0.00 D Common Stock 1109159 0 D Represents the total number of shares of Common Stock received by Third Rock Ventures II, L.P. ("TRV II") upon conversion of the Series A Preferred Stock and Series B Preferred Stock of the Issuer in connection with the closing of the Issuer's initial public offering. The Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 4.174-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The Preferred Stock had no expiration date. These shares are directly held by TRV II. The general partner of TRV II is Third Rock Ventures GP II, L.P. ("TRV GP II"). The general partner of TRV GP II is TRV GP II, LLC ("TRV GP II LLC"). The individual managers of TRV GP II LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP II, TRV GP II LLC, Levin, Starr and Tepper disclaims beneficial ownership of these 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. Represents shares of Common Stock purchased by TRV II in the Issuer's initial public offering. /s/ Kevin Gillis, Chief Financial Officer of TRV GP II, LLC, general partner of Third Rock Ventures GP II, L.P., general partner of Third Rock Ventures II, L.P. 2017-11-06 /s/ Kevin Gillis, Chief Financial Officer of TRV GP II, LLC, general partner of Third Rock Ventures GP II, L.P. 2017-11-06 /s/ Kevin Gillis, Chief Financial Officer of TRV GP II, LLC 2017-11-06 /s/ Kevin Gillis by power of attorney for Mark Levin 2017-11-06 /s/ Kevin Gillis by power of attorney for Kevin Starr 2017-11-06