X0306 4 2017-11-16 1 0001576263 Mirati Therapeutics, Inc. MRTX 0001263508 BAKER BROS. ADVISORS LP 860 WASHINGTON STREET 3RD FLOOR NEW YORK NY 10014 0 0 0 1 Former 10% Owner 0001580575 Baker Bros. Advisors (GP) LLC 860 WASHINGTON STREET 3RD FLOOR NEW YORK NY 10014 0 0 0 1 Former 10% Owner 0001087940 BAKER FELIX 860 WASHINGTON STREET 3RD FLOOR NEW YORK NY 10014 0 0 0 1 Former 10% Owner 0001087939 BAKER JULIAN 860 WASHINGTON STREET, 3RD FLOOR NEW YORK NY 10014 0 0 0 1 Former 10% Owner Common Stock Warrants (right to buy) 0.001 2017-11-16 4 P 0 304392 12.999 A 2017-11-20 Common Stock 304392 304392 I See Footnotes Common Stock Warrants (right to buy) 0.001 2017-11-16 4 P 0 1618684 12.999 A 2017-11-20 Common Stock 1618684 1618684 I See Footnotes On November 16, 2017, 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 14159, L.P. the "Funds") purchased 304,392 and 1,618,684 warrants to purchase the common stock of the Issuer, respectively, for $12.999 per warrant, pursuant to an underwritten public offering. After giving effect to the transaction reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's warrants reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667. After giving effect to the transaction reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's warrants reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences. Baker Bros. Advisors LP (the "Adviser") serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose. The warrants have no expiration date. By: Baker Bros. Advisors LP, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing 2017-11-20 By: Baker Bros. Advisors (GP) LLC, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing 2017-11-20 /s/ Felix J. Baker 2017-11-20 /s/ Julian C. Baker 2017-11-20