definiens: shall mean any challenge to the validity or enforceability of any patents or patent application s owned in whole or in part by Tufts by : ( a ) filing a declaratory judgment action in which a ny such patents or patent applications is alleged to be invalid or unenforceable ; ( b ) filing a request for re - examination of any of such patents or patent applications pursuant to 35 U.S.C . § 302 and/or § 311, or provoking or becoming party to an interference with an applicati on for any such patents or patent applications pursuant to 35 U.S.C. § 135 ; or ( c ) fil ing or commencing any post grant review, inter partes review, third party observation, derivation, oppos ition, cancellation, nullity or similar proceedings against any of such patents or patent applications . ” ( f)The fourth paragraph of Article VI of the Licens e Agreement is hereby deleted in its entirety and the following is hereby inserted in lieu thereof : “ Notwithstanding the foregoing, Tufts shall have th e right at any time after [ * * * ] to convert the License hereunder to non - exclusive if Licensee, its Subsidiaries or its sublicensees have not by the time of such conversion met each of the following milestones by the applicable date : Milestone Due By [ * * * ] [ * * * ] [ * * * ] [ * * * ] ( g ) The Novartis Amendment is hereby terminated and of no further force and effect