UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) 

of the Securities Exchange Act of 1934

Date of Report (Date of Earliest Event Reported): December 6, 2016

Blueprint Medicines Corporation

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (617) 374-7580

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 1.01        Entry into a Material Definitive Agreement

On December 7, 2016, Blueprint Medicines Corporation  (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Goldman, Sachs & Co. and Morgan Stanley & Co. LLC, as representatives of the underwriters named therein (collectively, the “Underwriters”), relating to an underwritten public offering (the “Offering”) of 5,000,000 shares of the Company’s common stock, $0.001 par value per share (the “Common Stock”), at a price to the public of $25.00 per share (the “Offering Price”). After deducting the underwriting discounts and commissions and estimated offering expenses, the Company expects to receive net proceeds from the Offering of approximately $116.9 million. The Company has also granted the Underwriters a 30-day option to purchase up to an additional 750,000 shares of Common Stock at the Offering Price less the underwriting discounts and commissions.

The Offering was made pursuant to the Company’s effective shelf registration statement on Form S-3 (File No. 333-211266), including the prospectus dated July 25, 2016, as supplemented by a prospectus supplement dated December 7, 2016. The Offering is expected to close on December 13, 2016, subject to the satisfaction of customary closing conditions.

A copy of the Underwriting Agreement is attached as Exhibit 1.1 to this Current Report on Form 8-K and is incorporated herein by reference. The foregoing description of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to such exhibit.

A copy of the legal opinion of Goodwin Procter LLP relating to the legality of the issuance and sale of the shares in the Offering is attached as Exhibit 5.1 to this Current Report on Form 8-K.

Item 8.01        Other Events

On December 6, 2016, the Company issued a press release announcing the Offering, and on December 7, 2016, the Company issued a press release announcing the pricing of the Offering. Copies of these press releases are attached to this Current Report on Form 8-K as Exhibits 99.1 and 99.2, respectively, and are each incorporated herein by reference.

Item 9.01        Financial Statements and Exhibits.

(d) Exhibits.

See the Exhibit Index which immediately follows the signatures hereto, which Exhibit Index is incorporated herein by reference.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

EXHIBIT INDEX