definiens: means ( a ) the JAK2 Inhibitor Compound known as INCB018424 ( the chemicalstructure of which has previously been disclosed to [COMPANY] in a letter dated November 23, 2009 ) ; ( b ) the back - up JAK2Inhibitor Compounds set forth on Schedule 1.60 ( the chemical structures of which have previously been disclosed to Novartisin a letter dated November 20, 2009 ) ( each a ) ; ( c ) any Potential JAK LicensedCompound to the extent deemed a JAK Licensed Compound pursuant to Section 4.5 ; ( d ) all salts, prodrugs, esters, metabolites, solvates, stereoisomers and polymorphs of the foregoing ; and ( e ) all derivatives of the foregoing containing oneor more atoms substituted with a radio isotope ( including without limitation derivatives containing deuterium )