Other Termination. Regeneron may terminate this Agreement with respect to a given Collaboration Program or Licensed Product effective # upon ​ days’ written notice to CytomX in the event that Regeneron in good faith believes it is not advisable for Regeneron to continue to Develop or Commercialize any Licensed Products in such Collaboration Program, or # immediately upon written notice to CytomX in the event that CytomX or any of its Sublicensees or Affiliates, or any Person acting on CytomX’s behalf, initiates or asserts any Regeneron Patent Challenge and fails to initiate rescission of such Regeneron Patent Challenge within ​ Business Days after such written notice and thereafter fails to rescind such Regeneron Patent Challenge within ​ days after such written notice. In the event any Sublicensee (or any Person acting on its behalf) of CytomX initiates or asserts any Regeneron Patent Challenge in any forum, CytomX shall, upon written request by Regeneron, immediately terminate the applicable sublicense agreement with such Sublicensee.

CytomX will have the right to terminate this Agreement immediately upon written notice to Regeneron if Regeneron or any of its Sublicensees or Affiliates initiates or asserts any CytomX Patent Challenge and fails to initiate rescission of such CytomX Patent Challenge

within ​ Business Days after such written notice and thereafter fails to rescind such CytomX Patent Challenge within ​ days after such written notice. In the event any Sublicensee (or any Person acting on its behalf) of Regeneron initiates or asserts any CytomX Patent Challenge in any forum, Regeneron shall, upon written request by CytomX, immediately terminate the applicable sublicense agreement with such Sublicensee.

Discretionary Termination. Regeneron, in its sole discretion, may terminate this Agreement in its entirety effective as of any time after the ​ of the Effective Date upon delivery of at least ​ days’ prior written notice to CytomX.