Development of mitoxantrone.

Mitoxantrone (Novantrone; dihydroxyanthracenedione) belongs to a new structural class of antineoplastic agents, the anthracenediones. It was the outcome of a program in synthetic chemistry, at the Medical Research Division of the American Cyanamid Company, which started from a molecule with structural features predicted to favor intercalation with double stranded DNA. The initial lead compound had immunomodulatory effects and was subsequently found also to possess significant activity against transplantable murine tumors. A large series of analogues was synthesized and mitoxantrone was selected for clinical trial on the basis of its potency and excellent antitumor activity in mice. It is a cytotoxic agent that will kill both proliferating and non-proliferating cells. A variety of experiments conducted with both intact cells and cell-free systems have revealed mitoxantrone's ability to bind to single stranded and double stranded RNA and DNA. The drug inhibits cellular RNA and DNA synthesis to about the same extent and causes chromosomal aberrations. In vivo experiments using murine models have demonstrated good activity for mitoxantrone against a variety of transplantable tumors including both leukemias and solid types, in many cases giving putative cures. Surprisingly, it is effective when given up to 30 days before tumor implantation. Combination studies with standard anticancer agents gave evidence of therapeutic synergy in a number of cases. Preclinical studies in several animal models indicate that mitoxantrone does not have the cumulative cardiotoxic liability associated with anthracycline antibiotics such as doxorubicin.