CytomX Therapeutics (CTMX) SC 13G/A CytomX Therapeutics / PERCEPTIVE ADVISORS ownership change

EXHIBIT 1

AGREEMENT

The persons below hereby agree that the Schedule 13G to which this agreement is attached as an exhibit, as well as all future amendments to such Schedule 13G, shall be filed on behalf of each of them. This agreement is intended to satisfy the requirements of Rule 13d-1(k)(1)(iii) under the Securities Exchange Act of 1934.

Date: February 16, 2021

PERCEPTIVE ADVISORS LLC
By:	/s/ Joseph Edelman
	Name: Joseph Edelman
	Title:   Managing Member

/s/ Joseph Edelman

JOSEPH EDELMAN

PERCEPTIVE LIFE SCIENCES MASTER FUND, LTD.
By: Perceptive Advisors LLC
By:	/s/ Joseph Edelman
	Name: Joseph Edelman
	Title:   Managing Member