Prednimustine in refractory non-Hodgkin's lymphoma: a phase II study of the Northern California Oncology Group.

Fifty-six patients with advanced non-Hodgkin's lymphoma (NHL) were entered into a phase II study of prednimustine, an ester of chlorambucil and prednisolone. All patients were refractory to extensive prior combination chemotherapy. Therapy with prednimustine, 100 mg/m2/day orally, was given for three consecutive days every 2 weeks. The overall response rate in 43 evaluable patients was 30% (13/43), with 9% (4/43) achieving complete response (CR) and 21% (9/43) achieving partial response (PR). In the favorable histology subgroup (23 patients), the response rate was 39% (9/23), with 4% (1/23) achieving CR and 35% (8/23) achieving PR. In the unfavorable histology subgroup (20 patients), responses were seen in 20% (4/20) with 15% (3/20) achieving CR, all in heavily pretreated diffuse histiocytic lymphoma. Toxicity of this regimen was mild, with leukopenia below 3,000/mm3 in 22% and thrombocytopenia below 90,000/mm3 in 16% of patients. A positive correlation was observed between response and hematologic toxicity, indicating the potential for a dose-escalation schedule in future trials. These data confirm activity of prednimustine in NHL refractory to standard treatment. In view of its relatively mild toxicity, we conclude that prednimustine is an appropriate agent to test in combination chemotherapy regimens in this group of lymphomas.