Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1	Feb 2, 2015	S	482,469	$29.50	D	1,958,824	I	See Footnote
Common Stock^F2	Feb 2, 2015	S	9,403	$29.50	D	38,178	I	See Footnote
Common Stock^F3	Feb 2, 2015	S	3,304	$29.50	D	13,419	I	See Footnote
Common Stock^F4	Feb 2, 2015	S	4,824	$29.50	D	19,588	I	See Footnote

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein.
F2The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Flint and McGuire are the managing members of PVM V. Each of Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein.
F3The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Flint and McGuire are the managing members of PVM V. Each of Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein.
F4The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Flint and McGuire are the managing members of PVM V. Each of Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein.