Polyethylene glycol-liposomal doxorubicin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in the management of AIDS-related Kaposi's sarcoma

Abstract

Doxorubicin is an antineoplastic drug which has in vitro and in vivo activity against a number of malignancies including Kaposi's sarcoma. Incorporation of doxorubicin into polyethylene glycol-coated (pegylated) liposomes alters the pharmacokinetics of the drug. Liposomal doxorubicin has a smaller volume of distribution and slower plasma clearance than standard free doxorubicin. The liposomal formulation achieves higher concentrations in the highly vascularised lesions of Kaposi's sarcoma than in normal tissue. Liposomal doxorubicin monotherapy in patients with AIDS-related Kaposi's sarcoma produced overall response rates (complete plus partial) of 43 and 59% in large comparative studies and 67 to 100% in noncomparative studies which included > or = 20 patients. In comparative studies, liposomal doxorubicin was significantly more effective than the combination of standard doxorubicin, bleomycin and vincristine (overall response rates of 43 and 25%, respectively) and bleomycin and vincristine (BV) [overall response rates of 59 and 23%, respectively]. In addition, overall response rates to the liposomal drug were higher in both treatment arms of 2 smaller comparative studies which compared liposomal doxorubicin with BV, but significant between-treatment differences were not detected. Patient numbers in these 2 studies, however, may have been too small to detect significant differences. Liposomal doxorubicin is generally well tolerated. Myelosuppression is the most common dose-limiting adverse effect in patients with AIDS and Kaposi's sarcoma. Neutropenia occurs most often; anaemia and thrombocytopenia occur less frequently, as do nausea and vomiting and stomatitis. Palmar-plantar erythrodysaesthesia occurs in some patients, most commonly after 6 to 8 weeks of chemotherapy. Although symptoms may occasionally be severe, the syndrome usually does not require dosage reduction or treatment delay. Limited data suggest that the incidence of cardiotoxicity may be lower after liposomal doxorubicin than after equivalent doses of standard doxorubicin. Overall, liposomal doxorubicin appears to be one of the most active single agents available for treating patients with AIDS-related Kaposi's sarcoma. The therapeutic potential of liposomal doxorubicin administered in combination with other active agents to patients with Kaposi's sarcoma is, as yet, unknown. However, administered alone, the drug seems to be more effective than the best available combination chemotherapy regimens.