X0306 4 2018-01-30 0 0001693664 ARMO BioSciences, Inc. ARMO 0001055951 ORBIMED ADVISORS LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 1 0 1 0 0001502240 OrbiMed Capital GP IV LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 1 0 1 0 0001615374 OrbiMed Capital GP V LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 1 0 1 0 Common Stock 2018-01-30 4 C 0 3709356 A 3709356 I By OrbiMed Private Investments IV, LP Common Stock 2018-01-30 4 C 0 409547 A 409547 I By OrbiMed Private Investments V, LP Series A Convertible Preferred Stock 2018-01-30 4 C 0 1783704 0.00 D Common Stock 1783704 0 I By OrbiMed Private Investments IV, LP Series B Convertible Preferred Stock 2018-01-30 4 C 0 1226156 0.00 D Common Stock 1226156 0 I By OrbiMed Private Investments IV, LP Series C Convertible Preferred Stock 2018-01-30 4 C 0 415869 0.00 D Common Stock 415869 0 I By OrbiMed Private Investments IV, LP Series C-1 Convertible Preferred Stock 2018-01-30 4 C 0 283627 0.00 D Common Stock 283627 0 I By OrbiMed Private Investments IV, LP Series B-1 Convertible Preferred Stock 2018-01-30 4 C 0 332271 0.00 D Common Stock 332271 0 I By OrbiMed Private Investments V, LP Series C Convertible Preferred Stock 2018-01-30 4 C 0 45961 0.00 D Common Stock 45961 0 I By OrbiMed Private Investments V, LP Series C-1 Convertible Preferred Stock 2018-01-30 4 C 0 31315 0.00 D Common Stock 31315 0 I By OrbiMed Private Investments V, LP The total represents shares received upon conversion of shares of Series A, B, C and C-1 Convertible Preferred Stock. The total represents shares received upon conversion of shares of Series B-1, C and C-1 Convertible Preferred Stock. Each share of Series A Convertible Preferred Stock, Series B Convertible Preferred Stock, Series B-1 Convertible Preferred Stock, Series C Convertible Preferred Stock and Series C-1 Convertible Preferred Stock automatically converted into one share of Issuer's Common Stock for no additional consideration immediately prior to the completion of the Issuer's initial public offering. The Convertible Preferred Stock had no expiration date. These Shares are held of record by OrbiMed Private Investments IV, LP ("OPI IV"). OrbiMed Capital GP IV LLC ("GP IV") is the general partner of OPI IV, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the managing member of GP IV. By virtue of such relationships, GP IV and Advisors may be deemed to have voting and investment power over the securities held by OPI IV and as a result may be deemed to have beneficial ownership over such securities. These Shares are held of record by OrbiMed Private Investments V, LP ("OPI V"). OrbiMed Capital GP V LLC ("GP V") is the general partner of OPI V, and Advisors is the managing member of GP V. By virtue of such relationships, GP V and Advisors may be deemed to have voting and investment power over the securities held by OPI V and as a result may be deemed to have beneficial ownership over such securities. Each of GP IV, GP V and Advisors disclaim beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. The Reporting Persons have designated a representative, currently Carl L. Gordon, a member of Advisors, to serve on the Issuer's board of directors. This report on Form 4 shall not be deemed an admission that any of the reporting persons is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose. /s/ Carl Gordon 2018-01-30