The present invention is directed to novel lyophilized pharmaceutical preparations comprising a cytotoxic dipeptides such as melphalan flufenamide and one or more excipient(s) selected from the group comprising a polysorbate; a polyethylene glycol; ²-cyclodextrin; ±-cyclodextrin; hydroxypropyl- ²-cyclodextrin; sulfobutylether-²-cyclodextrin; lactose; benzyl alcohol; disodium succinate; propylene glycol; Cremophor EL; Dimethyl sulfoxide; D-mannitol; Trehalose; Sucrose and an amino acid. This preparation may be further formulated and is useful in cancer therapy.