X0306 4 2020-03-23 0 0001597264 Blueprint Medicines Corp BPMC 0001690460 Dorsch Marion C/O BLUEPRINT MEDICINES CORPORATION 45 SIDNEY STREET CAMBRIDGE MA 02139 0 1 0 0 Chief Scientific Officer Common Stock 2020-03-23 4 S 0 199 55.14 D 16265 D Common Stock 2020-03-23 4 S 0 241 53.43 D 16024 D Common Stock 2020-03-23 4 S 0 774 51.52 D 15250 D Effected pursuant to a trading plan adopted on April 3, 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 $55.00 to $55.27 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 in footnotes (2) through (4) to this Form 4. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $53.41 to $53.58 per share. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $51.01 to $51.93 per share. /s/ Christopher Frankenfield, Attorney-in-Fact 2020-03-25