Exhibit 31.3

CERTIFICATION

I, Charles M. Baum, certify that:

1. I have reviewed this Amendment No. 1 to the Quarterly Report on Form 10-Q/A of Mirati Therapeutics, Inc.; and

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report.

Date: August 20, 2018	/s/ Charles M. Baum
	Charles M. Baum
	President and Chief Executive Officer
	(Principal Executive Officer)