296AbstractMONOMETHYLVALINE COMPOUNDS CAPABLE OF CONJUGATION TO LIGANDSAuristatin peptides, including MeVal-Val-Dil-Dap-Norephedrine (MMAE) and MeVal Val-Dil-Dap-Phe (MMAF), were prepared and attached to Ligands through various linkers, including maleimidocaproyl-val-cit-PAB. The resulting ligand drug conjugateswere active in vitro and in vivo. (Figure 1)