Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F6,F2,F7,F8	Jul 20, 2015	S	282	$16.0522	D	39,017	I	See Footnotes
Common Stock^F6,F3,F7,F8	Jul 20, 2015	S	99	$16.0522	D	58,372	I	See Footnotes
Common Stock^F6,F4,F7,F8	Jul 20, 2015	S	144	$16.0522	D	80,384	I	See Footnotes
Common Stock^F6,F5,F7,F8	Jul 20, 2015	S	14,474	$16.0522	D	2,085,091	I	See Footnotes
Common Stock^F9,F2,F7,F8	Jul 21, 2015	S	282	$15.4209	D	38,735	I	See Footnotes
Common Stock^F9,F3,F7,F8	Jul 21, 2015	S	99	$15.4209	D	58,273	I	See Footnotes
Common Stock^F9,F4,F7,F8	Jul 21, 2015	S	144	$15.4209	D	80,240	I	See Footnotes
Common Stock^F9,F5,F7,F8	Jul 21, 2015	S	14,474	$15.4209	D	2,070,617	I	See Footnotes
Common Stock^F10,F2,F7,F8	Jul 22, 2015	S	282	$15.2243	D	38,453	I	See Footnotes
Common Stock^F10,F3,F7,F8	Jul 22, 2015	S	99	$15.2243	D	58,174	I	See Footnotes
Common Stock^F10,F4,F7,F8	Jul 22, 2015	S	144	$15.2243	D	80,096	I	See Footnotes
Common Stock^F10,F5,F7,F8	Jul 22, 2015	S	14,474	$15.2243	D	2,056,143	I	See Footnotes

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting persons on May 22, 2015.
F10The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $15.00 to $15.46. The reporting persons undertake to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F2By Polaris Venture Partners Entrepreneurs' Fund V, L.P.
F3By Polaris Venture Partners Founders' Fund V, L.P.
F4By Polaris Venture Partners Special Founders' Fund V, L.P.
F5By Polaris Venture Partners V, L.P.
F6The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $15.85 to $16.49. The reporting persons undertake to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F7Each of Polaris Venture Partners V, L.P., Polaris Venture Partners Special Founder's Fund V, L.P., Polaris Venture Partners Founders' Fund V, L.P. and Polaris Venture Partners Entrepreneurs' Fund V, L.P. (collectively, the "Funds") has the sole voting and investment power with respect to the shares directly held by it. The general partner of each of the Funds is Polaris Venture Management Co. V, LLC, or Polaris Management. Polaris Management may be deemed to have sole voting and investment power with respect to the shares held by the Funds and disclaims beneficial ownership of all the shares held by the Funds except to the extent of its proportionate pecuniary interest therein.
F8The members of North Star Venture Management 2000, LLC, Terrence McGuire and Jonathan Flint, collectively the Management Members, are also members of Polaris Management, and as members of the general partner, they may be deemed to share voting and investment power over the shares held by the Funds. The Management Members disclaim beneficial ownership of such shares, except to the extent of their proportionate pecuniary interest therein.
F9The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $15.14 to $15.85. The reporting persons undertake to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.