UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.  )

Filed by the Registrant  ☒                            Filed by a Party other than the Registrant  ☐

Check the appropriate box:

☐	Preliminary Proxy Statement
☐	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
☐	Definitive Proxy Statement
☒	Definitive Additional Materials
☐	Soliciting Material Pursuant to §240.14a-12

BLUEPRINT MEDICINES CORPORATION

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

☒	No fee required.
☐	Fee paid previously with preliminary materials:
☐	Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

Your Vote Counts! BLUEPRINT MEDICINES CORPORATION ATTN: TRACEY L. MCCAIN 45 SIDNEY STREET CAMBRIDGE, MA 02139 BLUEPRINT MEDICINES CORPORATION 2025 Annual Meeting Vote by June 17, 2025 11:59 p.m. Eastern Time You invested in BLUEPRINT MEDICINES CORPORATION and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy materials for the Annual Meeting to be held on June 18, 2025. Vote Virtually at the Meeting* June 18, 2025 3:00 PM, Eastern Time Virtually at: www.virtualshareholdermeeting.com/BPMC2025 *Please check the meeting materials for any special requirements for meeting attendance. Smartphone users Point your camera here and vote without entering a control number For complete information and to vote, visit www.ProxyVote.com Control # V66985-P30356 Get informed before you vote View the Notice and Proxy Statement and Form 10-K online OR you can receive a free paper or email copy of the material(s) by requesting prior to June 4, 2025. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy.

THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming stockholder meeting. Please follow the instructions on the reverse side to vote these important matters. Vote at www.ProxyVote.com Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Delivery Settings”. Voting Items Board Recommends V66986-P30356 1. Election of class I directors each to serve for a three-year term, or until their successor has been duly elected and qualified For All nominees Nominees: 01) Jeffrey Albers 02) Mark Goldberg, M.D. 03) John Tsai, M.D. 2. Approval of a non-binding advisory vote on the compensation paid to our named executive officers. For 3. Ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2025. For NOTE: The proxies are authorized to vote, in their discretion, upon such other business as may properly come before the meeting or any adjournment or postponement thereof.