X0206 3 2020-10-01 0 0001671818 Oncorus, Inc. ONCR 0001609492 MPM BioVentures 2014, L.P. C/O MPM ASSET MANAGEMENT LLC 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001473930 Foley Todd C/O MPM ASSET MANAGEMENT LLC 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001609493 MPM BioVentures 2014 (B), L.P. C/O MPM ASSET MANAGEMENT LLC 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001609495 MPM Asset Management Investors BV2014 LLC C/O MPM ASSET MANAGEMENT LLC 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001765021 MPM BioVentures 2014 LLC C/O MPM ASSET MANAGEMENT LLC 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001765091 MPM BioVentures 2014 GP LLC C/O MPM ASSET MANAGEMENT LLC 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 0001263048 MPM ASSET MANAGEMENT LLC C/O MPM ASSET MANAGEMENT LLC 450 KENDALL STREET CAMBRIDGE MA 02142 0 0 1 0 Common Stock 115823 I See footnote Series A-1 Preferred Stock Common Stock 1783879 I See footnote Series B Preferred Stock Common Stock 775975 I See footnote Warrant (right to buy) 1.21 2031-03-31 Common Stock 42655 I See footnote The shares are held by MPM Asset Management LLC ("AM LLC"). Luke Evnin and Anbsert Gadicke are the members of AM LLC. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its pecuniary interest therein. Each share of Series A-1 Preferred and Series B Preferred Stock is convertible at any time at the option of the holder, without payment of additional consideration, into Common Stock, on a one-for-one basis, has no expiration date and will automatically convert into shares of Common Stock upon the closing of the Issuer's initial public offering. The shares are held as follows: 1,382,943 by MPM BioVentures 2014, L.P. ("BV 2014"), 92,239 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 50,164 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 224,924 by MPM Sunstates Fund, L.P. ("MPM SunStates") and 33,609 by MPM Asset Management Investors Sunstates Fund LLC ("AM SunStates"). MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). BV LLC is the manager of AM BV2014. MPM SunStates Fund GP LLC and MPM SunStates GP Managing Member LLC ("SunStates GP") are the direct and indirect general partners of MPM SunStates. SunStates GP is the manager of AM SunStates. Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of BV LLC and Ansbert Gadicke is a member of SunStates GP. The shares are held as follows: 635,058 by BV 2014, 42,356 by BV 2014(B), 23,035 by AM BV2014, 65,708 by MPM SunStates and 9,818 by AM SunStates. Immediately exercisable. The warrants are held as follows: 24,611 by BV 2014, 1,641 by BV 2014(B), 892 by AM BV2014, 13,495 by MPM SunStates and 2,016 by AM SunStates. See Form 3 for MPM SunStates Fund, L.P for additional members of this joint filing /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC, the general partner of MPM BioVentures 2014, L.P 2020-10-01 /s/ Todd Foley 2020-10-01 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC, the general partner of MPM BioVentures 2014 (B), L.P. 2020-10-01 Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the manager of MPM Asset Management Investors BV2014 LLC 2020-10-01 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC 2020-10-01 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC 2020-10-01 /s/ Ansbert Gadicke, member of MPM Asset Management LLC 2020-10-01