A stable liposomal formulation for treating cancer. The formulation includes liposomes containing one or more of POPC, DMPC, and DOPC and one or more of the anti-cancer drugs sirolimus, umirolimus, and everolimus encapsulated in the liposomes. Also provided are efficient remote film loading methods for loading the liposomes with the anti-cancer drugs and methods for treating cancer with the liposomal formulations.