definiens: means any action, suit, proceeding or claim by CytomX or itsSublicensees or Aﬃliates challenging the validity, patentability, scope, priority, construction, inventorship, enforceability orAstellas ’s or its Aﬃliate ’s or licensor ’s ownership of any [COMPANY] Patent or any Collaboration Patent owned by [COMPANY], asapplicable, in any forum, in each case, with respect to a Product under this Agreement, but excludes any assertion byCytomX or its Sublicensees or Aﬃliates relating to validity, patentability, scope, priority, construction, non - infringement, inventorship, ownership or enforceability as a defense in any legal proceeding, administrative proceeding or arbitrationbrought by [COMPANY] or its Aﬃliates or licensors asserting infringement against CytomX or its Sublicensees or Aﬃliates withrespect to the relevant Product under this Agreement