Commentary on Abstracts #1398 and #1400

Few advances in the treatment of multiple myeloma have been made in recent years, and this disease remains incurable. The observation that about 20% of plasma cells from myeloma patients express CD20 has led to some interest in studying monoclonal antibodies in this disorder. Treon et al (abstract #1398) reported the preliminary results of their phase II trial with rituximab in previously treated multiple myeloma patients. Among nine patients evaluable for response at the time of the report, there was one PR in a patient with mostly CD20-positive bone marrow plasma cells.

Hussein and coworkers (abstract #1400) presented the interim results of an ongoing phase II trial with 28 patients accrued. Patients were treated with four weekly injections of rituximab, repeated every 6 months for six cycles. They also received MP (melphalan and prednisone). Following treatment with antibody alone, there were only 2 major responses and 2 minor responses in 25 evaluable patients. Only 20% of patients had CD20-positive plasma cells prior to treatment, and this correlated with response. Following initiation of MP, 13 patients had a major response, and 3 experienced a minor response.