A compound comprising a photosensitizer covalently coupled to a protein selected from the group consisting of antibodies or their derivatives or fragments thereof, synthetic peptides such as scFv, mimotopes which bind CD antigens, cytokine receptors, interleukin receptors, hormone receptors, growth factor receptors, more particularly tyrosine kinase growth factor receptor of the ErbB family, wherein the photosensitizer is coupled to the binding protein via O6-alkylguanine-DNA alkyltransferase (hAGTm), a modified human DNA repair protein.
