SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Haviland Kate (Last) (First) (Middle) C/O BLUEPRINT MEDICINES CORPORATION 45 SIDNEY STREET (Street) CAMBRIDGE MA 02139 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Blueprint Medicines Corp [ BPMC ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) Chief Operating Officer
	3. Date of Earliest Transaction (Month/Day/Year) 03/01/2019
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/01/2019		M(1)		14,144	A	$16.28	20,018	D
Common Stock	03/01/2019		M(1)		7,500	A	$36.05	27,518	D
Common Stock	03/01/2019		S(2)		21,644	D	$85.05(3)	5,874	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	$86.6	03/01/2019		A		32,500		(4)	03/01/2029	Common Stock	32,500	$0	32,500	D
Restricted Stock Units	(5)	03/01/2019		A		8,750		(6)	(6)	Common Stock	8,750	$0	8,750	D
Stock Option (Right to Buy)	$16.28	03/01/2019		M(1)			14,144	(7)	02/01/2026	Common Stock	14,144	$0	33,495	D
Stock Option (Right to Buy)	$36.05	03/01/2019		M(1)			7,500	(8)	02/16/2027	Common Stock	7,500	$0	24,000	D

Explanation of Responses:

1. The exercises reported on this Form 4 was effected pursuant to a trading plan adopted on December 21, 2017 pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended (the "Exchange Act").

2. The sales reported on this Form 4 were effected pursuant to a trading plan adopted on December 21, 2017 pursuant to Rule 10b5-1 under the Exchange Act.

3. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $85.00 to $85.58 per share. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.

4. This option vests with respect to 1/48th of the shares underlying the option on April 1, 2019 and as to an additional 1/48th of the shares underlying the option each month thereafter.

5. Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

6. The restricted stock units vest in four equal annual installments on March 1, 2020, 2021, 2022 and 2023.

7. This option was granted on February 1, 2016. This option vested with respect to 25% of the shares underlying the option on January 5, 2017 and as to an additional 1/48th of the shares underlying the option each month thereafter.

8. This option was granted on February 16, 2017. This option vested with respect to 1/48th of the shares underlying the option on March 16, 2017 and as to an additional 1/48th of the shares underlying the option each month thereafter.

	/s/ Christopher Frankenfield, Attorney-in-Fact	03/05/2019
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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