X0306 4 2021-06-24 0 0001419600 Flexion Therapeutics Inc FLXN 0001201580 COLELLA SAMUEL D C/O FLEXION THERAPEUTICS, INC. 10 MALL ROAD, SUITE 301 BURLINGTON MA 01803 1 0 0 0 Common Stock 2021-06-24 4 A 0 4500 0.00 A 11198 D Common Stock 1000 I The Samuel Colella Trust Common Stock 69837 I By the Colella Family Trust Common Stock 5000 I By the Colella Family Exempt Marital Deduction Trust Common Stock 994129 I By Versant Venture Capital III L.P. Common Stock 5871 I By Versant Side Fund III Common Stock 388683 I By Versant Development Fund III, LLC Common Stock 943 I By Colella Partners Common Stock 19653 I By Colella Partners II Common Stock 250 I By spouse Stock option (right to buy) 9.22 2021-06-24 4 A 0 7000 0.00 A 2031-06-23 Common Stock 7000 7000 D Represents a restricted stock unit award granted under the Issuer's 2013 Equity Incentive Plan. Reflects the transfer of 1,000 shares to The Samuel Colella Trust. The shares are held by the Colella Family Trust UTA Dtd. 9/21/92 ("Colella Trust"). The Reporting Person is a trustee and beneficiary of the Colella Trust. The shares are held by the Colella Family Exempt Marital Deduction Trust Dated 9/21/1992 ("Colella Exempt Trust"). The Reporting Person is a trustee and beneficiary of the Colella Exempt Trust. The shares are held by Versant Venture Capital III, L.P. ("VVC III"). The Reporting Person is a managing member of Versant Ventures III, LLC ("VV III"), the sole general partner of VVC III and shares voting and dispositive power over the shares held by VVC III; however, he disclaims beneficial ownership of the shares held by such entity except to the extent of his pecuniary interests therein. The shares are held by Versant Side Fund III, L.P. ("Side Fund III"). The Reporting Person is a managing member of VV III, the sole general partner of Side Fund III and shares voting and dispositive power over the shares held by Side Fund III; however, he disclaims beneficial ownership of the shares held by such entity except to the extent of his pecuniary interests therein. The shares are held by Versant Development Fund III, LLC ("Development III"). The Reporting Person is a managing member of VV III, a majority member of Development III and shares voting and dispositive power over the shares held by Development III; however, he disclaims beneficial ownership of the shares held by such entity except to the extent of his pecuniary interests therein. Shares held by Colella Partners. The Reporting Person is the general partner of Colella Partners. Shares held by Colella Partners II. The Reporting Person is the general partner of Colella Partners II. The stock option vests and becomes exercisable in 12 equal monthly installments following the date of grant. /s/ Mark S. Levine, Attorney-in-Fact 2021-06-28