Review of amsacrine, an investigational antineoplastic agent

The pharmacology, chemistry, pharmacokinetics, clinical studies, and adverse effects of amsacrine, an investigational antineoplastic agent, are reviewed. Amsacrine's mechanism of action is not clearly understood, although the drug is known to inhibit DNA synthesis. As an investigational NCI "Group C" agent, amsacrine is available to physicians for the treatment of adult patients with refractory acute nonlymphocytic leukemia (ANLL) under an established protocol. Following intravenous administration, amsacrine has a biphasic plasma clearance. It is extensively metabolized by the liver to inactive compounds that are excreted in the bile. Phase I studies indicated that amsacrine was potentially effective in patients with solid tumors and acute leukemias. Patients with solid tumors could tolerate much lower doses of amsacrine than leukemia patients because of dose-limiting bone-marrow suppression in the former. In Phase II studies, amsacrine appeared effective in treating the acute leukemias, with response rates of 31% and 23% for acute lymphocytic leukemia and ANLL, respectively. Patients with other types of cancers have not responded to amsacrine therapy. Frequently occurring adverse effects of amsacrine include leukopenia and thrombocytopenia in patients with solid tumors; nausea, vomiting, and diarrhea; mucositis in patients receiving higher doses (leukemia patients); alopecia; hepatotoxicity; and phlebitis. The clinical usefulness of amsacrine appears limited to treatment of the acute leukemias. Studies of combination therapies that include amsacrine are currently underway and should further define the therapeutic role of amsacrine.