Partner Fund Management Has Confidence In Blueprint Medicines Corp (BPMC)

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Page 2 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 2 of 13 Pages

1.

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Partner Fund Management, L.P.

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)    ¨

 

(b)    x

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

1,359,946 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX
IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES

CERTAIN SHARES                                                                                                                            ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

5.0%1

12.

TYPE OF REPORTING PERSON

IA; PN

1 The percentages reported in this Schedule 13G are based
upon 27,201,271 shares of common stock outstanding as of February 29, 2016 according to the Form 10-K filed by the issuer with
the Securities and Exchange Commission on March 11, 2016. All of the other numbers and percentages reported in this Schedule 13G
are as of 9:00 a.m. (PT) on the date of filing.

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