X0306 4 2020-03-09 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 2020-03-09 4 S 0 671 51.98 D 42838 D The sale reported on this Form 4 represents shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units.The sale occurred automatically to satisfy the tax withholding obligations to be funded by a "sell to cover" transaction and does not represent a discretionary trade by the Reporting Person. /s/ Christopher Frankenfield, Attorney-in-Fact 2020-03-11