Provided is a cytotoxic agent comprising liposomes wherein said liposomes enclose a solution comprising at least one direct alpha emitting radionuclide selected from 211At, 212Bi, 213Bi, 223Ra, 224Ra, 225Ac and 227Th, or the indirect alpha-emitter 212Pb, and at least one other therapeutic agent, wherein said therapeutic agent is a chemotherapeutic agent. The compositions can be used in medicaments for treating hyperplastic or neoplastic diseases.