A peptide ligand specific for MT1 -MMP comprising a polypeptide comprising two diaminopropionic acid (Dap) or N-alkyldiaminopropionic acid (N-AlkDap) residues, and a third residue selected from cysteine, Dap or N-AlkDap, separated by at least two loop sequences, and a molecular scaffold, the peptide being linked to the scaffold by covalent alkylamino linkages with the Dap or N-AlkDap residues of the polypeptide and by covalent thioether linkages with the cysteine when the third residue is cysteine, such that two polypeptide loops are formed on the molecular scaffold, wherein the peptide ligand comprises an amino acid sequence of formula (II): -A1-X1-U/O2-X3-X<；su b>；4-G5-A2-E6-D7<；/sub >；-F8-Y9-X10-X11-A<；su b>；3- (SEQ ID NO: 1) (II) or a pharmaceutically acceptable salt thereof； wherein: A1, A2, and A3 are independently cysteine, L-2,3-diaminopropionic acid (Dap), N-beta-alkyl-L-2,3- diaminopropionic acid (N-AlkDap), or N-beta-haloalkyl-L-2,3-diaminopropionic acid (N- HAlkDap), provided that at least one of A1, A2, and A3 is Dap, N-AlkDap or N-HAlkDap； X represents any amino acid residue； U represents a polar, uncharged amino acid residue selected from N, C, Q, M, S and T； and O represents a non-polar aliphatic amino acid residue selected from G, A, I, L, P and V.Un ligando de péptido específico para MT1-MMP que comprende un polipéptido que comprende dos residuos de ácido diaminopropiónico (Dap) o acido N-alquildiaminopropiónico (N-AlkDap), y un tercer residuo seleccionado de cisteína, Dap o N-AlkDap, separados por al menos dos secuencias de bucle, y un andamiaje molecular, el péptido se liga al andamiaje por ligaciones de alquilamino covalentes con los residuos de Dap o N-AlkDap del polipéptido y por ligaciones de tioéter covalentes con la cisteína cuando el tercer residuo es cisteína, tal que dos bucles de polipéptido se forman en el andamiaje molecular, en donde el ligando de péptido comprende una secuencia de aminoácidos de la fórmula (II): -A1-X1-U
