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; β-cyclodextrin; ocyclodextrin; hydroxypropyl-β-cyclodextrin; sulfobutylether-β-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.