The present invention concerns a new medical treatment involving the combination of two active entities, as well as pharmaceutical compositions comprising the two active entities. Specifically, the invention provides a pharmaceutical composition comprising a stable lipid assembly comprising as a first active entity an apoptosis-affecting lipid which does not self-aggregate in a polar environment to form liposomes and a lipopolymer. The pharmaceutical composition further comprises, as the second active entity, a cytotoxic amphipathic weak base drug carried by the lipid assembly or by a different liposome. According to one embodiment, the apoptotic-affecting lipid is a pro-apoptotic lipid. A preferred pro-apoptotic lipid is ceramide, preferably C6-ceramide. The cytotoxic amphipathic weak base drug is preferably doxorubicin or a biologically active, anthracyline-based doxorubicin analog thereof.