X0306 4 2021-12-07 0 0001597264 Blueprint Medicines Corp BPMC 0001683600 McCain Tracey L C/O BLUEPRINT MEDICINES CORPORATION 45 SIDNEY STREET CAMBRIDGE MA 02139 0 1 0 0 EVP and Chief Legal Officer Common Stock 2021-12-07 4 M 0 5000 28.36 A 38441 D Common Stock 2021-12-07 4 S 0 4328 97.46 D 34113 D Common Stock 2021-12-07 4 S 0 572 96.38 D 33541 D Common Stock 2021-12-07 4 S 0 100 95.54 D 33441 D Stock Option (Right to Buy) 28.36 2021-12-07 4 M 0 5000 0 D 2026-10-03 Common Stock 5000 55000 D Effected pursuant to a trading plan adopted on February 22, 2021 pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. Includes 167 shares that were previously acquired under the Issuer's employee stock purchase plan. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $96.97 to $97.91 per share. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $95.87 to $96.73 per share. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein. This option was granted on October 3, 2016 and fully vested as of the date hereof. /s/ Ariel Hurley, Attorney-in-Fact 2021-12-09