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:

BLUEPRINT MEDICINES CORPORATION

(Name of Registrant as Specified in Its certificateits Certificate of incorporation)

Incorporation)

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

Payment of Filing Fee (Check the appropriate box):

BLUEPRINT MEDICINES CORPORATION

3845 Sidney Street Suite 200

Cambridge, Massachusetts 02139

(617) 374-7580

374‑7580

NOTICE OF 20162020 ANNUAL MEETING OF STOCKHOLDERS

To Be Held On June 21, 2016

23, 2020

Dear Stockholders:

You are cordially invited to attend the 20162020 annual meeting of stockholders of Blueprint Medicines Corporation to be held on Tuesday, June 21, 201623, 2020 at 3:0030 p.m., Eastern Daylight Time, atTime. The annual meeting will be held entirely online this year due to the officesemerging public health impact of Goodwin Procter LLP, 53 State Street, Boston, Massachusetts 02109.the coronavirus (COVID‑19) pandemic.  You will be able to attend and participate in the annual meeting online by visiting http://www.virtualshareholdermeeting.com/BPMC2020, where you will be able to vote electronically and submit questions. You will not be able to attend the annual meeting in person. You will need the 16‑digit control number included with these proxy materials to attend the annual meeting. At the annual meeting, stockholders will consider and vote on the following matters:

The foregoing items of business are more fully described in the proxy statement accompanying this notice.

Stockholders of record at the close of business on April 25, 201624, 2020 will be entitled to notice of and to vote at the annual meeting or any adjournment or postponement thereof.

We encourage you to access the annual meeting before it begins. Online check-in to access the meeting will start shortly before the meeting on June 23, 2020. If you attend the annual meeting at http://www.virtualshareholdermeeting.com/BPMC2020, you may vote electronically during the meeting even if you have previously returned a proxy. Stockholders will also have the opportunity to submit questions during the annual meeting through http://www.virtualshareholdermeeting.com/BPMC2020. A technical support telephone number will be posted on the log-in page of http://www.virtualshareholdermeeting.com/BPMC2020 that you can call if you encounter any difficulties accessing the virtual meeting during the check-in or during the meeting.

We have elected to provide access to our proxy materials over the Internet under the Securities and Exchange Commission’s “notice and access” rules. We believe that providing our proxy materials over the Internet expedites stockholders’ receipt of proxy materials, lowers costs and reduces the environmental impact of our annual meeting.

We encourage all stockholders to attend the annual meeting in person.online. However, whether or not you plan to attend the annual meeting in person,online, we encourage you to read this proxy statement and submit your proxy or voting instructions as soon as possible. Please review the instructions on each of your voting options described in the proxy statement.

Thank you for your ongoing support and continued interest in Blueprint Medicines Corporation.

Boston, Massachusetts

April 28, 2016

Important Notice Regarding Internet Availability of Proxy Materials: ThisWe are furnishing proxy materials to our stockholders primarily via the Internet. On April 29, 2020, we mailed to our stockholders a Notice of Internet Availability, or Notice, containing instructions on how to access our proxy materials, including this proxy statement and our 20152019 annual report. The Notice also instructs you on how to submit your proxy or voting instructions through the Internet or to request a paper copy of our proxy materials, including a proxy card or voting instruction form that includes instructions on how to submit your proxy or voting instructions by mail or telephone. Other stockholders, in accordance with their prior requests, have received e-mail access to our proxy materials and instructions to submit their vote via the Internet, or have been mailed paper copies of our proxy materials and a proxy card or voting instruction form.

A copy of this proxy statement and our 2019 annual report to stockholders which consists of our Annual Report on Form 10-K for the fiscal year ended December 31, 2015, are available at www.proxyvote.com. These documents are also available

Internet distribution of our proxy materials is designed to any stockholder who wishesexpedite receipt by stockholders, lower the cost of the annual meeting, and conserve natural resources. However, if you would prefer to receive a paper copy by calling 1-800-579-1639, by emailing sendmaterial@proxyvote.comor by submitting a request overprinted proxy materials, please follow the Internet at www.proxyvote.com.  instructions included in the Notice. If you have previously elected to receive our proxy materials electronically, you will continue to receive these materials via e-mail unless you elect otherwise.

TABLE OF CONTENTS

3845 Sidney Street Suite 200

Cambridge, Massachusetts 02139

(617) 374-7580

374‑7580

PROXY STATEMENT

20162020 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on June 21, 2016

TO BE HELD ON JUNE 23, 2020

INFORMATION CONCERNING SOLICITATION AND VOTING

This proxy statement and the enclosed proxy card are being furnished in connection with the solicitation of proxies by the board of directors of Blueprint Medicines Corporation for use at the annual meeting of stockholders to be held online on Tuesday, June 21, 201623, 2020 at 3:0030 p.m., Eastern Daylight Time, at the offices of Goodwin Procter LLP, 53 State Street, Boston, Massachusetts 02109, and at any adjournment thereof.

The annual meeting will be held entirely online this year at http://www.virtualshareholdermeeting.com/BPMC2020 due to the emerging public health impact of the COVID‑19 pandemic. We encourage all stockholders to attend the annual meeting online. However, whether or not you plan to attend the annual meeting online, we encourage you to read this proxy statement and submit your proxy or voting instructions as soon as possible. Additional details regarding attending the virtual annual meeting and voting at the meeting are provided below.

Unless otherwise stated, all references to “us,” “our,” “Blueprint,” “Blueprint Medicines,” “we,” the “Company” and similar designations refer to Blueprint Medicines Corporation and its consolidated subsidiary, Blueprint Medicines Security Corporation.

subsidiaries. References to our website are inactive textual references only, and the contents of our website are not incorporated by reference into this proxy statement.

This proxy statement summarizes information about the proposals to be considered at the meeting and other information you may find useful in determining how to vote. The proxy card is the means by which you actually authorize another person to vote your shares in accordance with your instructions. We are making this proxy statement, the related proxy card and our 2019 annual report to stockholders for the fiscal year ended December 31, 2015 available to stockholders for the first time on or about April 28, 2016.

29, 2020.

A copy of our Annual Report on Form 10-K10‑K for the fiscal year ended December 31, 2015,2019, as filed with the Securities and Exchange Commission, or SEC, except for exhibits, will be furnished without charge to any stockholder upon written or oral request to Blueprint Medicines Corporation, 3845 Sidney Street, Suite 200, Cambridge, Massachusetts 02139 or by calling 1-800-579-1639,1‑800‑579‑1639, by emailing sendmaterial@proxyvote.com or by submitting a request over the Internet at www.proxyvote.com. This proxy statement and our Annual Report on Form 10-K10‑K for the fiscal year ended December 31, 20152019 are also available on the SEC’s website at www.sec.govand the “Investors & Media —SEC Filings” section of our website, which is located at www.blueprintmedicines.comhttp://ir.blueprintmedicines.com.

Implications of Being an “Emerging Growth Company”

We are an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. We will remain an emerging growth company until the earlier of (i) December 31, 2020; (ii) the last day of the fiscal year in which we have total annual gross revenues of $1 billion or more; (iii) the date on which we have issued more than $1 billion in nonconvertible debt during the previous three years; or (iv) the date on which we are deemed to be a large accelerated filer under the rules of the SEC, which means the market value of our common stock that is held by non-affiliates exceeds $700 million as of the prior June 30th. For so long as we remain an emerging growth company, we are permitted and intend to rely on exemptions from certain disclosure requirements that are applicable to other public companies that are not emerging growth companies. These exemptions include reduced disclosure obligations regarding executive compensation. In addition, as an emerging growth company, we are not required to conduct votes seeking approval, on an advisory basis, of the compensation of our named executive officers or the frequency with which such votes must be conducted. We have taken advantage of certain reduced reporting obligations in this proxy statement. Accordingly, the information contained herein may be different than the information you receive from other public companies in which you hold stock.

IMPORTANT INFORMATION ABOUT THE ANNUAL MEETING AND VOTING

Q.Why did I receive these proxy materials?

A.    Our board of directors hasWe have made these materials available to you on the Internet in connection with the solicitation of proxies for use at our 20162020 annual meeting of stockholders to be held at the offices of Goodwin Procter LLP, 53 State Street, Boston, Massachusetts 02109,online on Tuesday, June 21, 201623, 2020 at 3:0030 p.m., Eastern Daylight Time.Time, at http://www.virtualshareholdermeeting.com/BPMC2020. As a holder of common stock, you are invited to attend the annual meeting online and are requested to vote on the items of business described in this proxy statement. This proxy statement includes information that we are required to provide to you under SEC rules and that is designed to assist you in voting your shares.

Q.    Why did I receive a notice in the mail regarding the Internet availability of proxy materials instead of a full set of proxy materials?

A.In accordance with the SEC rules, we may furnish proxy materials, including this proxy statement and our annual report, to our stockholders by providing access to such documents on the Internet instead of mailing printed copies. If you would like to receive a paper copy of our proxy materials, you should follow the instructions for requesting such materials in the notice.

Notice.

Q.    What is the purpose of the annual meeting?

A.At the annual meeting, stockholders will consider and vote on the following matters:

Q.Who can vote at the annual meeting?

A.   To be entitled to vote, you must have been a stockholder of record at the close of business on April 25, 2016,24, 2020, the record date for our annual meeting. As of the record date, there were 27,237,95054,188,423 shares of our common stock outstanding and entitled to vote at the annual meeting.

Q.How many votes do I have?

A.Each share of our common stock that you own as of the record date will entitle you to one vote on each matter considered at the annual meeting.

Q.How do I vote?

A.If you are the “record holder” of your shares,meaning that your shares are registered in your name in the records of our transfer agent, Computershare Trust Company, N.A., and not in the name of a bank, brokerage firm or other nominee, you may vote your shares at the meeting in person or by proxy as follows:

If your shares are held in “street name,” meaning they are held for your account by an intermediary, such as a bank, brokerage firm or other nominee, then you are deemed to be the beneficial owner of your shares, and the bank, brokerage firm or other nominee that actually holds the shares for you is the record holder and is required to vote the shares it holds on your behalf according to your instructions. The proxy materials, as well as voting and revocation instructions, should have been forwarded to you by the bank, brokerage firm or other nominee that holds your shares. In order to vote your shares, you will need to follow the instructions that your bank, brokerage firm or other nominee provides you. Many banks, brokerage firms or other nominees solicit voting instructions over the Internet or by telephone.

If you do not give instructions to your bank, brokerage firm or other nominee, they will still be able to vote your shares with respect to certain “discretionary” items. The ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm (Proposal 2)3) is considered a discretionary item. Accordingly, your bank, brokerage firm or other nominee may vote your shares in its discretion with respect to that matter even if you do not give voting instructions on Proposal 2.

3.

However, under applicable stock exchange rules that regulate voting by registered banks, brokerage firms or other nominees, the election of our nominees to serve as Class III directors (Proposal 1) and a non-binding, advisory vote on the compensation paid to our named executive officers (Proposal 2) is not considered to be a discretionary item. Accordingly, if you do not give your bank, brokerage firm or other nominee voting instructions on ProposalProposals 1 or 2 they may not vote your shares with respect to this matter and your shares will be counted as “broker non-votes” with respect to the proposal. A “broker non-vote” occurs when shares held by a bank, brokerage firm or other nominee are not voted with respect to a particular proposal because the bank, brokerage firm or other nominee does not have or did not exercise discretionary authority to vote on the matter and has not received voting instructions from its clients.

Regardless of whether your shares are held in street name, you are welcome to attend the meeting.annual meeting online. You may not vote shares held in street name in person at the annual meeting, however, unless you obtain a legal proxy, executed in your favor, from the holder of record (i.e., your bank, brokerage firm or other nominee). A legal proxy is not the form of proxy included with this proxy statement. You will not be able to vote shares you hold in street name in person at the annual meeting unless you have a legal proxy from your bank, brokerage firm or other nominee issued in your name giving you the right to vote your shares.

Q.How do I attend the annual meeting online?

A.    Our 2020 annual meeting will be held entirely online due to the emerging public health impact of the COVID‑19 pandemic and to support the health and well-being of our partners, employees, and stockholders. Stockholders of record as of April 24, 2020 will be able to attend and participate in the annual meeting by accessing http://www.virtualshareholdermeeting.com/BPMC2020. To join the annual meeting, you will need to have your 16‑digit control number, which is included on your Notice and your proxy card. Stockholders will also have the opportunity to submit questions during the annual meeting through http://www.virtualshareholdermeeting.com/BPMC2020. A technical support telephone number will be posted on the log-in page of http://www.virtualshareholdermeeting.com/BPMC2020 that you can call if you encounter any difficulties accessing the virtual meeting during the check-in or during the meeting.

Even if you plan to attend the annual meeting online, we recommend that you also vote by proxy as described herein so that your vote will be counted if you decide not to attend the annual meeting.

Log in Instructions. To attend the online annual Meeting, log in at http://www.virtualshareholdermeeting.com/BPMC2020. Stockholders will need their unique 16‑digit control number, which appears on the Notice and the instructions that accompanied the proxy materials. In the event that you do not have a control number, please contact your broker, bank, or other nominee as soon as possible and no later than June 22, 2020, so that you can be provided with a control number and gain access to the meeting.

Q.Can I change my vote?

A. If your shares are registered directly in your name,you may revoke your proxy and change your vote at any time before the vote is taken at the annual meeting. To do so, you must do one of the following:

If your shares are held in “streetstreet name,” you may submit new voting instructions by contacting your bank, brokerage firm or other nominee. You may also vote in person at the annual meeting online if you obtain a legal proxy as described in the answer above.

Q.How many shares must be represented to have a quorum and hold the annual meeting?

A.A majority of our shares of common stock outstanding at the record date must be present in person or represented by proxy to hold the annual meeting. This is called a quorum. For purposes of determining whether a quorum exists, we count as present any shares that are voted over the Internet, by telephone, by completing and submitting a proxy by mail or that are represented in person at the meeting. Further, for purposes of establishing a quorum, we will count as present shares that a stockholder holds even if the stockholder votes to abstain or only votes on one of the proposals. In addition, we will count as present shares held in “street name”street name by banks, brokerage firms or other nominees who indicate on their proxies that they do not have authority to vote those shares. If a quorum is not present, we expect to adjourn the annual meeting until we obtain a quorum.

The presence at the annual meeting, online or by proxy, of holders representing a majority of our outstanding common stock as of the record date, April 24, 2020, or approximately 27,094,212 shares, constitutes a quorum at the meeting and permits us to conduct the business of the meeting.

Q.    What vote is required to approve each matter and how are votes counted?

A.Proposal 1—Election of Class III Directors

A nomineeThe three nominees for director to receive the highest number of votes FOR election will be elected as directors. This is called a director atplurality. Proposal 1 is a non-discretionary matter. Therefore, if your shares are held by your brokerage firm in street name and you do not timely provide voting instructions with respect to your shares, your brokerage firm cannot vote your shares on Proposal 1. Shares held in street name by banks, brokerage firms or other nominees who indicate on their proxies that they do not have authority to vote the annual meeting ifshares on Proposal 1 will not be counted as votes FOR or WITHHELD from any nominee. As a result, such “broker non-votes” will have no effect on the nominee receivesvoting on Proposal 1. You may:

☐    vote FOR all nominees;

☐    vote FOR one or more nominees and WITHHOLD your vote from the other nominees; or

☐    WITHHOLD your vote from all nominees.

Votes that are withheld will not be included in the vote tally for the election of directors and will not affect the results of the vote.

Proposal 2— Non-Binding Advisory Vote on the Compensation Paid to Named Executive Officers

To approve Proposal 2, holders of a pluralitymajority of the votes cast “for” the applicable seat on the matter must vote FOR the proposal. Proposal 2 is a non-discretionary matter. Therefore, if your shares are held by your brokerage firm in street name and you do not timely provide voting instructions with respect to your shares, your brokerage firm cannot vote your shares on Proposal 2. If you ABSTAIN from voting on Proposal 2, your shares will not be voted FOR or AGAINST the proposal and will also not be counted as votes cast or shares voting on the proposal. As a result, such “broker non-votes” and abstentions will have no effect on the voting on Proposal 2. Proposal 2 is non-binding. Because this vote is advisory and not binding on us or our board of directors.

in any way, our board may decide that it is in our and our stockholders’ best interests to compensate our named executive officers in an amount or manner that differs from that which is approved by our stockholders.

Proposal 2—3—Ratification of the Appointment of Independent Registered Public Accounting Firm

The affirmative vote of theTo approve Proposal 3, holders of shares of common stock representing a majority of the votes cast on the matter must vote FOR the proposal. Proposal 3 is requiredconsidered a routine matter. If your shares are held by your brokerage firm in street name and you do not provide voting instructions with respect to your shares, your brokerage firm may vote your unvoted shares on Proposal 3. If you ABSTAIN from voting on Proposal 3, your shares will not be voted FOR or AGAINST the proposal and will also not be counted as votes cast or shares voting on the proposal. As a result, voting to ABSTAIN will have no effect on the outcome of Proposal 3.

Although stockholder approval of our audit committee’s appointment of Ernst & Young LLP as our independent registered public accounting firm for the ratification offiscal year ending December 31, 2020 is not required, we believe that it is advisable to give stockholders an opportunity to ratify this appointment. If this proposal is not approved at the annual meeting, our audit committee will reconsider its appointment of Ernst & Young LLP as our independent registered public accounting firm for the year endedending December 31, 2015.2020.

Shares which abstain from voting and “broker non-votes” with respect to a matter will not be counted as votes in favor

Q.    Who will count the vote?

A.The votes will be counted, tabulated and certified by Broadridge Financial Solutions, Inc.

Q.    How does the board of directors recommend that I vote on the proposals?

A.Our board of directors recommends that you vote:

FOR the election of the three nominees to serve as Class III directors, each for a three yearthree-year term; and

FOR the approval, on a non-binding, advisory basis, of the compensation of our named executive officers; and

FOR the ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2016.2020.

BOARDPROPOSAL 1 — ELECTION OF DIRECTORS AND CORPORATE GOVERNANCE 

Election of Directors 

Our board of directors is divided into three classes, with membersone class of our directors standing for election each year. Directors in each class holding office for staggered three-year terms. There are currently three Class I directors (Jeffrey W. Albers, Mark Goldberg, M.D. and Nicholas Lydon, Ph.D.), whose terms expireelected at thisthe annual meeting of stockholders; threestockholders held in the year in which the term for their class expires and hold office for a three-year term and until their resignation or removal or their successors are duly elected and qualified. In accordance with our certificate of incorporation and bylaws, our directors may fill existing vacancies on the board of directors.

The term of office of our Class II directors, (AlexisAlexis Borisy, Charles A. Rowland, Jr. and Lonnel Coats), whose termsCoats, will expire at the 20172020 annual meeting of stockholders; and threestockholders. The nominees for Class IIIII directors (Daniel S. Lynch, George D. Demetri, M.D. and Lynn Seely, M.D.), whose terms expirefor election at the 20182020 annual meeting of stockholders are Messrs. Borisy, Rowland and Coats. If any of Messrs. Borisy, Rowland and Coats are elected at the 2020 annual meeting of stockholders, such individual will be elected to serve for a three-year term that will expire at our 2023 annual meeting of stockholders and until such individual’s successor is elected and qualified.

If no contrary indication is made, proxies in all cases, subjectthe accompanying form will be voted for Messrs. Borisy, Rowland and Coats or, in the event that any of Messrs. Borisy, Rowland and Coats is not a candidate or is unable to serve as a director at the time of the election and qualification(which is not currently expected), for any nominee who is designated by our board of such director’s successor ordirectors to such director’s earlier death, resignation or removal. Other than Dr. Goldberg, Mr. Coats and Dr. Seely, each of our directors was elected pursuant to a stockholders agreement that we entered into withfill the holders of our preferred stock that terminated upon the closing of our initial public offering.vacancy.

Information Regarding Directors

Set forth below are the names and certain information for each member of theour board of directors, including the nominees for election as Class III directors, as of April 15, 2016.March 31, 2020. The information presented includes each director’s and nominee’s principal occupation and business experience for the past five years, and the names of other public companies of which he or she has served as a director during the past five years. The information presented below regarding the specific experience, qualifications, attributes and skills of each director and nominee led our nominating and corporate governance committee and our board of directors to conclude that he or she should serve as a director. In addition, we believe that all of our directors and nominees possess the attributes or characteristics described in “—Director Nomination Process” the nominating and corporate governance committee expects of each director.

There are no family relationships among any of our directors or executive officers.

Other than Mr. Coats and Drs. Goldberg and Seely, each of our directors was initially elected pursuant to a stockholders agreement that we entered into with the holders of our preferred stock, which terminated upon the closing of our initial public offering.

Class I Director Nominees 

Jeffrey W. Albers has served as our president and chief executive officer and a member of our board of directors since July 2014. Mr. Albers has nearly a decade of experience in leadership roles in the biopharmaceutical industry. Prior to joining us, from January 2012 to April 2014, he was president of the U.S. subsidiary of Algeta ASA, or Algeta U.S., a Norwegian biopharmaceutical company, where he oversaw the commercial and business functions. At Algeta U.S., Mr. Albers was responsible for the U.S. launch of Radium-223 in metastatic castrate resistant prostate cancer. Prior to Algeta U.S., from July 2005 to November 2011, Mr. Albers was at Genzyme Corporation, or Genzyme, a biotechnology company that is now a wholly-owned subsidiary of Sanofi S.A., most recently as vice president of the U.S. hematology and oncology business unit. Mr. Albers received a B.S. from Indiana University and an M.B.A. and a

Medicine, Inc. From 2007 to 2012, Mr. Borisy served as chairman of FORMA Therapeutics, Inc., a biopharmaceutical company focused on discovering and developing medicines in cancer and other genetically-driven diseases. Mr. Borisy co-founded Foundation Medicine, Inc., or Foundation Medicine, where he served as its interim chief executive officer from 2009 to 2011 and has served as a member of its board of directors sincebetween 2009 and 2018, including as chairman of Foundation Medicine’s board of directors since 2011.from 2011 to February 2017. In 2000, Mr. Borisy founded CombinatoRx, Inc. (now EPIRUS Biopharmaceuticals, Inc.), a public drug development company, and served as its chief executive officer and on its board of directors from 2000 to 2009. Mr. Borisy received an A.B. in chemistry from the University of Chicago and an A.M. from Harvard University. We believe Mr. Borisy’s detailed knowledge of our company and long tenure with us, having served as one of our founders, along with his experience working with and serving on the boards of directors of life sciences companies and his experience working in the venture capital industry qualifies him to serve on our board of directors.

Charles A. Rowland, Jr., MBAhas served as a member of our board of directors since March 2015. SinceFrom April 2016 to February 2017, Mr. Rowland has served as president and chief executive officer of Aurinia Pharmaceuticals Inc., or Aurinia,

Professor of Medicine and serves as a co-director of the Ludwig Center at Harvard. At DFCI, Dr. Demetri is the senior vice president for Experimental Therapeutics, as well as an associate director for clinical sciences at the NCI-designated Dana-Farber/Harvard Comprehensive Cancer Center Consortium. Dr. Demetri’s research and clinical interests have centered on mechanism-based drug development for solid tumors, with a particularan emphasis on molecularly-defined subsets of sarcomas such as gastrointestinal stromal tumors. Dr. Demetri has contributed to the development of several new drugs for sarcomas and other malignancies, including imatinib, sunitinib, dasatinib, trabectedin, vemurafenib, everolimus, pazopanib and regorafenib. He was also a member of the scientific advisory board for Plexxikon Inc. and helped to develop the mutant BRAF inhibitor, vemurafenib. In addition, Dr. Demetri has served as a member of the board of directors of Translate Bio since July 2019. Dr. Demetri also previously served as a member of the board of directors and organization and compensation committee of Merrimack Pharmaceuticals, Inc. between December 2017 and October 2019. Dr. Demetri serves as chair of the medical advisory boardScience Policy and Government Affairs Committee for the Sarcoma Foundation of AmericaAmerican Association for Cancer Research as well as several other scientific and editorial advisory boards. With an interest in internet-based patient support, Dr. Demetri also serves on the Medical Advisory Board of ASCO’s CancerNet as well as CancerCommons.org. Dr. Demetri received an A.B. in biochemistry from Harvard College and an M.D. from Stanford University School of Medicine. We believe that Dr. Demetri’s more than 25 years of experience as an

product development board. Prior to joining Genzyme, Dr. Goldberg was a full-time staff physician at Brigham and Women’s Hospital and the Dana-Farber Cancer Institute, where he still holds appointments. Dr. Goldberg is a part-time Associate Professor of Medicine at Harvard Medical School. From 2010 to 2017, Dr. Goldberg served on the board of directors of the New England Division of the American Cancer Society. Since December 2017 he has chaired the eastern New England Board of the American Cancer Society and since January 2019 has been a member of the national board of directors of the American Cancer Society. Dr. Goldberg received an A.B. in biochemistry and molecular biology from Harvard University and an M.D. from Harvard Medical School. We believe Dr. Goldberg is qualified to serve on our board of directors due to his extensive healthcare and regulatory experience.

Nicholas Lydon, Ph.D., FRS is a scientific founder of Blueprint Medicines and has served as a member of our board of directors since April 2011. Dr. Lydon is a co-founder and scientific advisor of OncoSTAT, Inc. and has served as a member of its board of directors and scientific advisor since 2019. Dr. Lydon is a member of VB Therapeutics LLC, which he co-founded in 2019. In addition, Dr. Lydon currently serves as the manager of Staurus Biopharma, LLC, a privately held biopharmaceutical company that he co-founded. Dr. Lydon is a co-founder of AnaptysBio Inc. and served as a scientific advisor and member of its board of directors between 2006 and 2019. From 2003 to 2009, Dr. Lydon served as a scientific advisor and member of the board of directors of Ambit Biosciences Corp., a biopharmaceutical company. From 2000 to 2002, Dr. Lydon served as vice president, small molecule drug discovery, at Amgen, Inc., or Amgen. Prior to joining Amgen, in 1997, Dr. Lydon founded Kinetix Pharmaceuticals, Inc., or Kinetix, a biotechnology company focused on the discovery and development of selective protein kinase inhibitors, which was acquired by Amgen in 2000, and served as Kinetix’s chief executive officer and member of its board of directors. Prior to founding Kinetix, Dr. Lydon worked for Ciba-Giegy AG (now Novartis AG) where he was responsible for the tyrosine protein kinase program, including the discovery and preclinical development of imatinib. Dr. Lydon, has been awarded the Lasker-DeBakey Clinical Medical Research Award and the Japan Prize for his role in the development of imatinib. Dr. Lydon received a B.S. in biochemistry and zoology from the University of Leeds, England, and received a Ph.D. in biochemistry from the Medical Sciences Institute, University of Dundee, Scotland. We believe Dr. Lydon’s detailed knowledge of our company and long tenure with us, having served as one of our scientific founders, along with his experience working with and serving on the boards of directors of life sciences companies and his experience as a senior executive with several life sciences companies qualifies him to serve on our board of directors.

Recommendation of the Board of Directors

Corporate Governance Matters OUR BOARD OF DIRECTORS RECOMMENDS THAT STOCKHOLDERS VOTE “FOR” THE ELECTION OF ALEXIS BORISY, CHARLES A. ROWLAND, JR. AND LONNEL COATS TO SERVE AS CLASS II DIRECTORS.

CORPORATE GOVERNANCE

General

Our board of directors believes that good corporate governance is important to ensure that our company is managed for the long-term benefit of stockholders. This section describes key corporate governance guidelines and practices that our board of directors has adopted. Complete copies of our corporate governance guidelines, committee charters and code of conduct are available on the “Investors —Corporate& Media — Corporate Governance” section of our website, which is located at www.blueprintmedicines.comhttp://ir.blueprintmedicines.com. Alternatively, you can request a copy of any of these documents by contacting us at Blueprint Medicines Corporation, 3845 Sidney Street, Suite 200, Cambridge, Massachusetts 02139, Attn: Investor Relations, telephone: (617) 714-6674,714‑6674, e-mail: ir@blueprintmedicines.com.

Code of Business Conduct and Ethics and Corporate Governance Guidelines

Our board of directors has adopted a written code of business conduct and ethics, as amended, that applies to our directors, officers and employees, including our principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. A copy of the code of business conduct and ethics is available on the “Investors—“Investors & Media — Corporate Governance” section of our website, which is located at www.blueprintmedicines.comhttp://ir.blueprintmedicines.com. We intend to disclose on our website any amendments to, or waivers from, the code of business conduct and ethics that are required to be disclosed pursuant to the disclosure requirements of Item 5.05 of Form 8-K.8‑K.

Our board of directors has also adopted corporate governance guidelines to assist in the exercise of its duties and responsibilities and to serve the best interests of our company and our stockholders. A copy of the corporate governance guidelines is available on the “Investors—“Investors & Media — Corporate Governance” section of our website, which is located at www.blueprintmedicines.comhttp://ir.blueprintmedicines.com.

Board Leadership Structure and Risk Oversight

Board Leadership Structure

As a general policy, our board of directors believes that separation of the positions of chairman and chief executive officer reinforces the independence of the board of directors from management, creates an environment that encourages objective oversight of management’s performance and enhances the effectiveness of the board of directors as a whole. Accordingly, we currently separate the roles of chief executive officer and chairman of the board of directors, with Mr. Albers serving as our president and chief executive officer and Mr. Lynch serving as chairman of the board of directors. As president and chief executive officer, Mr. Albers is responsible for setting the strategic direction for our company and the day-to-day leadership and performance of our company, while Mr. Lynch, as chairman of the board of directors, presides over meetings of the board of directors, including executive sessions of the board of directors, and

the Securities Exchange Act of 1934, as amended, or the Exchange Act. Audit committee members must also satisfy the independence criteria set forth in Rule 10A-310A‑3 under the Exchange Act, and compensation committee members must also satisfy the independence criteria set forth in Rule 10C-110C‑1 under the Exchange Act. Under Rule 5605(a)(2) of the NASDAQNasdaq Listing Rules, a director will only qualify as an “independent director” if, in the opinion of our board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director. In order to be considered independent for purposes of Rule 10A-3,10A‑3, a member of an audit committee of a listed company may not, other than in his or her capacity as a member of the audit committee, the board of directors, or any other committee of the board of directors, accept, directly or indirectly, any consulting, advisory, or other compensatory fee from the listed company or any of its subsidiaries or otherwise be an affiliated person of the listed company or any of its subsidiaries. In order to be considered independent for purposes of Rule 10C-1,10C‑1, the board of directors must consider, for each member of a compensation committee of a listed company, all factors specifically relevant to determining whether a director has a relationship to such company which is material to that director’s ability to be independent from management in connection with the duties of a compensation committee member, including, but not limited to: (1) the source of compensation of the director, including any consulting advisory or other compensatory fee paid by such company to the director; and (2) whether the director is affiliated with the company or any of its subsidiaries or affiliates.

Our board of directors undertook a review of the composition of our board of directors and its committees and the independence of each director. Based upon information requested from and provided by each director concerning his or her background, employment and affiliations, including family relationships, our board of directors has determined that each of our directors, with the exception of Jeffrey W. Albers, Alexis Borisy and Daniel S. Lynch, is an “independent director” as defined under Rule 5605(a)(2) of the NASDAQNasdaq Listing Rules. Mr. Albers is not an independent director under Rule 5605(a)(2) because he is our president and chief executive officer. Our board of directors also determined that Charles A. Rowland, Jr., Lonnel Coats and Mark Goldberg, who comprise our audit committee, Daniel S. Lynch, Charles A. Rowland, Jr., Mark Goldberg and Lynn Seely, who comprise our compensation committee, and Lonnel Coats, George D. Demetri, Lonnel Coats and Nicholas Lydon, who comprise our nominating and corporate governance

Nominating and Corporate Governance Committee

Our nominating and corporate governance committee’s responsibilities include:

committee and our board of directors also take into consideration the diversity (with respect to gender, race and national origin) of our board members but do not make any particular weighting of diversity or any other characteristic in evaluating nominees and directors. Our nominating and corporate governance committee’s and our board of directors’ priority in selecting board members is identification of persons who will further the interests of our stockholders.

Stockholder Nominations

Stockholders may recommend individuals to our nominating and corporate governance committee for consideration as potential director candidates by submitting their names, together with appropriate biographical information and background materials and a statement as to whether the stockholder or group of stockholders making the recommendation has beneficially owned more than 5% of our common stock for at least a year as of the date such recommendation is made, to Blueprint Medicines Corporation, Attention: Nominating and Corporate Governance Committee, 3845 Sidney Street, Suite 200, Cambridge, Massachusetts 02139. Assuming that appropriate biographical and background material has been provided on a timely basis, the nominating and corporate governance committee will evaluate stockholder-recommended candidates by following substantially the same process, and applying substantially the same criteria, as it follows for candidates submitted by others. If the board determines to nominate a stockholder-recommended candidate and recommends his or her election, then his or her name will be included in our proxy card for the next annual meeting.

Stockholders also have the right under our bylaws to directly nominate director candidates, without any action or recommendation on the part of the nominating and corporate governance committee or our board of directors, by following the procedures set forth under “Stockholder Proposals for 2017 Annual Meeting.Proposals.”

In February 2016 and April 2016, respectively, Lonnel Coats and Lynn Seely were appointed by our board of directors as a new director.

Compensation Committee Interlocks and Insider Participation 

None of our executive officers currently serves, or in the past fiscal year has served, as a member of the board of directors or compensation committee, or other committee serving an equivalent function, of any entity that has one or more executive officers who serve as members of our board of directors or our compensation committee. None of the members of our compensation committee is an officer or employee of our company, and none of the members of our compensation committee has ever been an officer or employee of our company.

Policies and Procedures for Related Person Transactions 

Our board of directors has adopted a written related person transaction policy to set forth policies and procedures for the review and approval or ratification of related person transactions. This policy covers any transaction, arrangement or relationship, or any series of similar transactions, arrangements or relationships, in which we were or are to be a participant and any director or executive officer, director nominee, holder of 5% or more of any class of our voting securities or any member of the immediate family of or entities affiliated with any of the foregoing had or will have a direct or indirect material interest, including, without limitation, purchases of goods or services by or from the related person or entities in which the related person has a material interest, indebtedness, guarantees of indebtedness and employment by us of a related person. Any such transaction must be presented to our audit committee for review, consideration and approval. In approving or rejecting any such proposal, our audit committee is to consider the relevant facts and circumstances available and deemed relevant to the audit committee, including, but not limited to, the extent of the related party’s interest in the transaction, and whether the transaction is on terms no less favorable to us than terms we could have generally obtained from an unaffiliated third party under the same or similar circumstances.

Related Person Transactions 

Other than the compensation arrangements for our named executive officers and directors, which are described elsewhere in the “Executive Compensation” and “Director Compensation” sections of this proxy statement, set forth below is a description of transactions since January 1, 2015 to which we were or will be a party, and in which:

We believe the terms obtained or consideration that we paid or received, as applicable, in connection with the transactions described below were comparable to terms available or the amounts that would be paid or received, as applicable, from unrelated third parties.

Initial Public Offering

In April 2015, we entered into an underwriting agreement with Goldman, Sachs & Co. and Cowen and Company, LLC, as representatives of the several underwriters, relating to an underwritten public offering of shares of our common stock. Pursuant to the underwriting agreement, we sold an aggregate of 9,367,708 shares of our common stock to the underwriters, including 1,221,874 shares of common stock sold by us pursuant to the exercise in full by the underwriters of their option to purchase additional shares in connection with the offering, at a price to the public of $18.00 per share. The offering closed on May 5, 2015. Certain holders of more than 5% of our capital stock (including shares of common stock acquired in the offering) purchased shares of our common stock from the underwriters in the offering at the offering price of the shares to the public. The following table sets forth the number of shares of our common stock purchased and the aggregate cash purchase price paid by each of these stockholders.

Takeda Pharmaceutical Company Limited) from December 2005 to September 2014. Ms. Hurley began her career at Deloitte & Touche, LLP and has over 20 years of experience in finance and accounting roles of increasing responsibility. She earned her certified public accountant license in Massachusetts. Ms. Hurley received a B.S. in accounting from Providence College.

Michael Landsittel has served as our chief financial officer since January 2019. Mr. Landsittel previously served as our vice president, finance from February 2016 to January 2019 and as our senior director, finance from September 2014 to February 2016. Prior to joining us, from October 2012 to July 2014,our company, Mr. Landsittel served as senior director, finance at Algeta U.S. Priorfrom October 2012 to his timeJuly 2014, as director, finance at Algeta,Infinity Pharmaceuticals, Inc. from March 2012 to October 2012 Mr. Landsittel served as director, finance at Infinity Pharmaceuticals, Inc., and from August 2002 to March 2012, Mr. Landsittel held various business development and strategic planning roles of increasing responsibility at Genzyme including most recently as director, business planning.from August 2002 to March 2012. Mr. Landsittel began his career at Arthur Andersen LLP, and he earned his certified public accountant license in Illinois. Mr. Landsittel received a B.B.A from the University of Michigan and an M.B.A. from the Tuck School of Business at Dartmouth College.

Tracey L. McCain, Esq. has served as our executive vice president and chief legal officer since September 2016 and as our chief compliance officer since June 2017. Prior to joining us, from January 2016 to September 2016, Ms. McCain served as senior vice president and head of legal of Sanofi Genzyme, a global business unit of Sanofi. Ms. McCain held roles of increasing responsibility after joining Genzyme Corporation, or Genzyme, in May 1997, including becoming its general counsel after Genzyme was acquired by Sanofi in 2011. In her capacity as senior vice president and general counsel of Genzyme from May 2011 to December 2015, she oversaw all aspects of its legal department in the United States and Europe, including general corporate, commercial and intellectual property matters. Prior to joining Genzyme, Ms. McCain was an associate at the law firm Palmer & Dodge LLP. Ms. McCain has served as a member of the board of directors and audit committee of Kiniksa Pharmaceuticals, Ltd. since 2018. Ms. McCain holds a B.A. from the University of Pennsylvania with a major in political science and a J.D. from Columbia University School of Law.

Christopher K. Murray, Ph.D. has served as our senior vice president, technical operations since October 2017. Prior to joining us, from January 2014 to May 2017, Dr. Murray served as vice president, technical operations at ARIAD Pharmaceuticals, Inc., or ARIAD. In this role, Dr. Murray oversaw all aspects of commercial and clinical manufacturing, supply chain and logistics, process development, quality control and analytical chemistry for ARIAD’s approved products and product candidates, including Iclusig® (ponatinib) and Alunbrig® (brigatinib). From 2004 to December 2013, Dr. Murray held multiple roles of increasing responsibility at ARIAD related to process development, manufacturing and clinical supply. Prior to joining ARIAD, Dr. Murray served in various positions with Allos Therapeutics, Inc. and Hauser Inc. related to clinical and commercial manufacturing and supply of active pharmaceutical ingredient. Dr. Murray holds a B.S. from Hope College with a major in chemistry and a Ph.D. in chemistry from the University of Chicago.

Christina Rossi has served as our chief commercial officer since October 2018. Prior to joining us, from January 2015 to October 2018, Ms. Rossi served as the Multiple Sclerosis business unit head, North America, at Sanofi Genzyme. In this role, she was responsible for all aspects of the financial performance of Sanofi Genzyme’s multiple sclerosis franchise and increased market share for existing products, led the launch of new therapies and optimized operations to accelerate patient access. Previously, Ms. Rossi served as vice president, Multiple Sclerosis Sales at Sanofi Genzyme form May 2014 to December 2015 and vice president, Multiple Sclerosis Patient and Provider Services at Sanofi Genzyme from June 2012 to May 2014. Prior to joining Sanofi Genzyme, Ms. Rossi served in various roles at Biogen, Inc., including head, commercial strategy for Eidetica Biopharma GmbH, Biogen’s biosimilar-focused venture, and U.S. brand leader for TYSABRI® (natalizumab). In addition, Ms. Rossi consulted in the healthcare practice at the Boston Consulting Group. Ms. Rossi holds a B.S. in biology, cum laude, from Duke University and an M.B.A. from Harvard Business School.

Executive CompensationEXECUTIVE COMPENSATION

Compensation Discussion and Analysis

This section discussesOur compensation committee is responsible for reviewing and approving, or recommending for approval by the material elementsboard of our executivedirectors, the compensation policies for our “named executive officers” and the most important factors relevant to an analysis of these policies. For 2015, our named executive officers, are Jeffrey W. Albers,including base salary, cash and equity incentive compensation levels, severance arrangements, change-in-control benefits and other forms of executive compensation. This committee is also responsible for evaluating our presidentcompany’s performance against its goals and chief executive officer, andmaking related recommendations to our two other most highly compensated executive officers, Christoph Lengauer, our chief scientific officer, and Anthony Boral, our chief medical officer. In addition, this section provides qualitative information regardingboard of directors, assessing the manner and context in which compensation is awarded to and earned byperformance of our named executive officers, and ensuring our compensation program is intendedaligned with the objectives described below and competitive with those of other companies in our industry that compete with us for talent. This section discusses the principles underlying our compensation committee’s policies and decisions with respect to placethe compensation of our named executive officers.

For 2019, our named executive officers were as follows:

Executive Summary

We are a precision therapy company focused on genomically defined cancers, rare diseases and cancer immunotherapy. Our approach is to leverage our novel target discovery engine to systematically and reproducibly identify kinases that are drivers of diseases and to craft highly selective and potent therapies that may provide significant and durable clinical responses for patients without adequate treatment options. This integrated biology and chemistry approach enables us to identify, characterize and design drug candidates to inhibit novel kinase targets that have been difficult to selectively inhibit. We believe that our uniquely targeted, scalable approach empowers the rapid design and development of new treatments and increases the likelihood of success. We have one precision therapy approved by the U.S. Food and Drug Administration, or FDA, and are currently advancing multiple investigational medicines in perspectiveclinical development, along with multiple research programs.  In 2019, we worked towards our vision to leverage our scientific platform to design innovative first-in-class or best-in-class medicines targeting novel kinase biology and become a leading platform-enabled, fully-integrated, global precision therapy company focused on discovering, developing and commercializing a portfolio of precision therapies to patients with cancer and rare diseases. We achieved a number of significant goals in 2019, including the datafollowing:

As described in more detail below, based on the following tablesrecommendation of our chief executive officer and the corresponding narrative.significant advances that we made on our 2019 corporate performance goals (including the overachievement on some goals balanced against the underachievement of others), upon the recommendation of our compensation committee, our board of directors determined that we achieved our 2019 corporate performance goals at 107.0%.

Summary Compensation Table

The following table sets forth information regardingOur compensation earned bycommittee seeks to ensure that our compensation program is aligned with the interests of our stockholders and our business goals and that the total compensation paid to each of our named executive officers duringis fair, reasonable and competitive. As described in more detail below, key elements of our compensation program include the years indicated.following: