X0306 4 2020-09-22 0 0001597264 Blueprint Medicines Corp BPMC 0001663022 Haviland Kate C/O BLUEPRINT MEDICINES CORPORATION 45 SIDNEY STREET CAMBRIDGE MA 02139 0 1 0 0 Chief Operating Officer Common Stock 2020-09-22 4 M 0 3143 16.28 A 45981 D Common Stock 2020-09-22 4 S 0 3143 85.49 D 42838 D Stock Option (Right to Buy) 16.28 2020-09-22 4 M 0 3143 0 D 2026-02-01 Common Stock 3143 2 D Effected pursuant to a trading plan adopted on April 19, 2019 pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $85.32 to $85.84 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 range set forth herein. This option was granted on February 1, 2016. This option is fully vested as of the date hereof. /s/ Christopher Frankenfield, Attorney-in-Fact 2020-09-24