THE INVENTION RELATES TO A TARGETING AGENT, TO WHICH AT LEAST ONE CRYPTOPHYCIN IS ATTACHED, OF THE FORMULA (I), WHERE: R1 IS A HALOGEN ATOM AND R2 IS AN OH GROUP, AN ACYL GROUP DERIVED FROM AN AMINO ACID AA OR A (C1-C4) ALKANOYLOXY GROUP； OR ELSE R1 AND R2 TOGETHER FORM AN EPOXY UNIT； AA DENOTES A NATURAL OR ARTIFICIAL AMINO ACID； R3 IS A (C1-C6) ALKYL GROUP； R4 AND R5 ARE BOTH H OR TOGETHER FORM A CH=CH DOUBLE BOND BETWEEN C13 AND C14； R6 AND R7 ARE INDEPENDENTLY FROM ONE ANOTHER, H OR A (C1-C6) ALKYL GROUP； R8 AND R9 ARE INDEPENDENTLY FROM ONE ANOTHER, H OR A (C1-C6) ALKYL GROUP； R11 IS AT LEAST ONE SUBSTITUENT OF THE PHENYL CORE SELECTED FROM AMONG: H, AN OH GROUP, (C1-C4) ALKOXY, A HALOGEN ATOM OR A NH2, NH(C1-C6) ALKYL, OR N(C1-C6) ALKYL GROUP； R11 IS AT LEAST ONE SUBSTITUENT OF THE PHENYL CORE SELECTED FROM AMONG H OR A (C1-C4) ALKYL GROUP； THE TARGETING AGENT AND THE CRYPTOPHYCIN DERIVATIVE BEING COVALENTLY BONDED, THE BOND BEING LOCATED AT THE ORTHO (O), META (M), OR PARA (P) POSITION OF THE PHENYL CORE CONTAINING THE CR1 UNIT.
