Mitoxantrone inhibits PKC in a competitive manner with respect to histone H1, and its K _i value is 6.3 μM and in a non-competitive manner with respect to phosphatidylserine and ATP. Treatment of B-CLL cells for 48 h with mitoxantrone (0.5 μg/mL) induces a decrease in cell viability. Mitoxantrone induces DNA fragmentation and the proteolytic cleavage of poly(ADP-ribose) polymerase (PARP), demonstrating that the cytotoxic effect of mitoxantrone is due to induction of apoptosis. Mitoxantrone shows cytotoxicity to human breast carcinoma cell lines MDA-MB-231 and MCF-7 with IC ₅₀ values of 18 and 196 nM, respectively.

Mitoxantrone given IP at the optimal dose (1.6 mg/kg/day; as a free base) produces a statistically significant number of 60-day survivors (curative effect) in mice with IP implanted L1210 leukemia. In SC implanted Lewis lung carcinoma, mitoxantrone and ADM administered IV also shows effective antitumor activities and produces a 60% and a 45% ILS, respectively..