Heterotandem bicyclic peptide complex

A heterotandem bicyclic peptide complex comprising:

• (a) a first peptide ligand which binds to Nectin-4 and which has the sequence CiP[1Nal][dD]CiiM[HArg]DWSTP[HyP]WCiii (SEQ ID NO:
• 1);
• conjugated via an N-(acid-PEG3)-N-bis(PEG3-azide) linker to
• (b) two second peptide ligands which bind to CD137 both of which have the sequence Ac-Ci[tBuAla]PE[D-Lys(PYA)]PYCiiFADPY[Nle]Ciii-A (SEQ ID NO:
• 2);
• or a pharmaceutically acceptable salt thereof,
• wherein each of said peptide ligands comprise a polypeptide comprising three reactive cysteine groups (Ci, Cii and Ciii), separated by two loop sequences, and a molecular scaffold which is 1,1′,1″-(1,3,5-triazinane-1,3,5-triyl)triprop-2-en-1-one (TATA) and which forms covalent bonds with the reactive cysteine groups of the polypeptide such that two polypeptide loops are formed on the molecular scaffold;
• wherein Ac represents acetyl, HArg represents homoarginine, HyP represents trans-4-hydroxy-L-proline, 1Nal represents 1-naphthylalanine, tBuAla represents t-butyl-alanine, PYA represents 4-pentynoic acid and Nle represents norleucine.