X0306 4 2018-02-20 0 0001412067 Cascadian Therapeutics, Inc. CASC 0001237289 SANDELL SCOTT D 1954 GREENSPRING DRIVE SUITE 600 TIMONIUM MD 21093 0 0 1 0 Common Stock 2018-02-20 4 C 0 1818000 3.30 A 10882574 I See Note 1 Series E Preferred Stock 3.30 2018-02-20 4 C 0 1818000 0.00 D Common Stock 1818000 0 I See Note 1 The Reporting Person is a manager of NEA 15 GP, LLC, ("NEA 15 GP") which is the sole general partner of NEA Partners 15, L.P. ("NEA Partners 15"). NEA Partners 15 is the sole general partner of New Enterprise Associates 15, L. P. ("NEA 15"). NEA 15 is the sole member of Growth Equity Opportunities Fund IV, LLC ("GEO IV"), which is the direct beneficial owner of the shares. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the shares held by GEO IV in which the Reporting Person has no pecuniary interest. Each share of the Series E Preferred Stock is convertible into shares of the Issuer's Common Stock (subject to adjustment as provided in the related certificate of designation of preferences) at any time at the option of the holder, and has no expiration date, provided that the holder will be prohibited from converting Series E Preferred Stock into shares of the Issuer's Common Stock if, as a result of such conversion, the holder, together with its affiliates, would own more than 19.99% of the total number of shares of the Issuer's Common Stock then issued and outstanding, which percentage may be changed at the holders' election to any other number less than or equal to 19.99% upon 61 days' notice to the Issuer. /s/ Sasha Keough, attorney-in-fact 2018-02-22