X0306 4 2020-09-23 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 2020-09-23 4 M 0 4600 37.11 A 19850 D Common Stock 2020-09-23 4 S 0 4600 89 D 15250 D Stock Option (Right to Buy) 37.11 2020-09-23 4 M 0 4600 0 D 2026-11-21 Common Stock 4600 57200 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. This option was granted on November 21, 2016. This option vested with respect to 25% of the shares underlying the option on November 21, 2017 and vests as to an additional 1/48th of the shares underlying the option each month thereafter. /s/ Christopher Frankenfield, Attorney-in-Fact 2020-09-25