SCHEDULE 13G/A

Under the Securities Exchange Act of 1934
(Amendment No. 2)*

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 783,407 shares held by VA4, 159,761 shares held by VP and 19,247 shares held by VEF4.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 6,423,748 shares of common stock held by the VHCP Entities. The Venrock IV Entities disclaim beneficial ownership over the shares held by the VHCP Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

2

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 783,407 shares held by VA4, 159,761 shares held by VP and 19,247 shares held by VEF4.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 6,423,748 shares of common stock held by the VHCP Entities. The Venrock IV Entities disclaim beneficial ownership over the shares held by the VHCP Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

3

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 783,407 shares held by VA4, 159,761 shares held by VP and 19,247 shares held by VEF4.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 6,423,748 shares of common stock held by the VHCP Entities. The Venrock IV Entities disclaim beneficial ownership over the shares held by the VHCP Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

4

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 783,407 shares held by VA4, 159,761 shares held by VP and 19,247 shares held by VEF4.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 6,423,748 shares of common stock held by the VHCP Entities. The Venrock IV Entities disclaim beneficial ownership over the shares held by the VHCP Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

5

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 783,407 shares held by VA4, 159,761 shares held by VP and 19,247 shares held by VEF4.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 6,423,748 shares of common stock held by the VHCP Entities. The Venrock IV Entities disclaim beneficial ownership over the shares held by the VHCP Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

6

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 783,407 shares held by VA4, 159,761 shares held by VP and 19,247 shares held by VEF4.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 6,423,748 shares of common stock held by the VHCP Entities. The Venrock IV Entities disclaim beneficial ownership over the shares held by the VHCP Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

7

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 962,415 shares of common stock held by the Venrock IV Entities. The VHCP Entities disclaim beneficial ownership over the shares held by the Venrock IV Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

8

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 962,415 shares of common stock held by the Venrock IV Entities. The VHCP Entities disclaim beneficial ownership over the shares held by the Venrock IV Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

9

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 962,415 shares of common stock held by the Venrock IV Entities. The VHCP Entities disclaim beneficial ownership over the shares held by the Venrock IV Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

10

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 962,415 shares of common stock held by the Venrock IV Entities. The VHCP Entities disclaim beneficial ownership over the shares held by the Venrock IV Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

11

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 962,415 shares of common stock held by the Venrock IV Entities. The VHCP Entities disclaim beneficial ownership over the shares held by the Venrock IV Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

12

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 962,415 shares of common stock held by the Venrock IV Entities. The VHCP Entities disclaim beneficial ownership over the shares held by the Venrock IV Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

13

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 962,415 shares of common stock held by the Venrock IV Entities. The VHCP Entities disclaim beneficial ownership over the shares held by the Venrock IV Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

14

(1)                     This Schedule 13G/A is being filed by (i) Venrock Associates IV, L.P. (“VA4”), Venrock Partners, L.P. (“VP”), Venrock Entrepreneurs Fund IV, L.P. (“VEF4”), Venrock Management IV, LLC (“VM4”), Venrock Partners Management, LLC (“VPM”) and VEF Management IV, LLC (“VEFM” and together with VA4, VP, VEF4, VM4 and VPM, the “Venrock IV Entities”) and (ii) Venrock Healthcare Capital Partners II, L.P. (“VHCP2”), VHCP Co-Investment Holdings II, LLC (“VHCP Co-2”), VHCP Management II, LLC (“VHCPM2”), Venrock Healthcare Capital Partners III, L.P. (“VHCP3”), VHCP Co-Investment Holdings III, LLC (“VHCP Co-3”), VHCP Management III, LLC (“VHCPM3”), Nimish Shah (“Shah”) and Bong Koh (“Koh” and together with VHCP2, VHCP Co-2, VHCPM2, VHCP3, VHCP Co-3, VHCPM3 and Shah, the “VHCP Entities”). The Venrock IV Entities and the VHCP Entities are collectively referred to as the “Reporting Persons.” The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G/A.

(2)                     Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                     The shares included on rows 6, 8 and 9 do not include an aggregate of 962,415 shares of common stock held by the Venrock IV Entities. The VHCP Entities disclaim beneficial ownership over the shares held by the Venrock IV Entities.

(4)                     This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

15

Introductory Note: This Schedule 13G/A is filed on behalf of the following entities and individuals in respect of shares of common stock of Bellerophon Therapeutics, Inc.:

·                  Venrock Associates IV, L.P., a limited partnership organized under the laws of the State of Delaware (“VA4”);

·                  Venrock Partners, L.P., a limited partnership organized under the laws of the State of Delaware (“VP”);

·                  Venrock Entrepreneurs Fund IV, L.P., a limited partnership organized under the laws of the State of Delaware (“VEF4”);

·                  Venrock Management IV, LLC, a limited liability company organized under the laws of the State of Delaware (“VM4”), the general partner of VA4;

·                  Venrock Partners Management, LLC, a limited liability company organized under the laws of the State of Delaware (“VPM”), the general partner of VP;

·                  VEF Management IV, LLC, a limited liability company organized under the laws of the State of Delaware (“VEFM”), the general partner of VEF4;

·                  Venrock Healthcare Partners II, L.P., a limited partnership organized under the laws of the State of Delaware (“VHCP2”);

·                  VHCP Co-Investment Holdings II, LLC, a limited liability company organized under the laws of the State of Delaware (“VHCP Co-2”);

·                  VHCP Management II, LLC, a limited liability company organized under the laws of the State of Delaware (“VHCPM2”), the general partner of VHCP2 and the manager of VHCP Co-2;

·                  Venrock Healthcare Partners III, L.P., a limited partnership organized under the laws of the State of Delaware (“VHCP3”);

·                  VHCP Co-Investment Holdings III, LLC, a limited liability company organized under the laws of the State of Delaware (“VHCP Co-3”);

·                  VHCP Management III, LLC, a limited liability company organized under the laws of the State of Delaware (“VHCPM3”), the general partner of VHCP3 and the manager of VHCP Co-3;

·                  Nimish Shah, a managing member of VHCPM2 and VHCPM3; and

·                  Bong Koh, a managing member of VHCPM2 and VHCPM3.

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18

(1)                       Consists of 783,407 shares held by VA4, 159,761 shares held by VP and 19,247 shares held by VEF4.

(2)                       Consists of 2,952,442 shares held by VHCP2, 1,196,936 shares held by VHCP Co-2, 2,067,631 shares held by VHCP3 and 206,739 shares held by VHCP Co-3.

(3)                       This percentage is calculated based upon 58,679,492 shares of common stock outstanding as of November 6, 2018, as reported in the issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2018.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Statement is true, complete and correct.

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EXHIBITS

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EXHIBIT A

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned agree to the joint filing on behalf of each of them of a statement on Schedule 13G (including amendments thereto) with respect to the Common Stock of Bellerophon Therapeutics, Inc. and further agree that this agreement be included as an exhibit to such filing. Each party to the agreement expressly authorizes each other party to file on its behalf any and all amendments to such statement. Each party to this agreement agrees that this joint filing agreement may be signed in counterparts.

In evidence whereof, the undersigned have caused this Agreement to be executed on their behalf this 14th day of February, 2019.

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