Thalidomide in the management of multiple myeloma

Abstract

A phase II trial of thalidomide in refractory multiple myeloma was initiated using a dose schedule that escalated from 200 mg/d to 800 mg/d. More than two thirds of patients had cytogenetic abnormalities and more than half had received at least two cycles of high-dose therapy. A paraprotein reduction of at least 25% was noted in 37% of patients and 14% had either a complete remission (CR) or a near CR. No treatmentrelated mortality was observed. With a median follow-up of almost 2 years, the 2-year event-free survival (EFS) and overall survival (OS) estimates were 15% and 60%, respectively. A reduction of paraprotein levels by greater than 50% was associated with a significant reduction in bone marrow plasmacytosis and β 2-microglobulin levels (β2M), and greater recovery of hemoglobin and IgM levels compared to patients whose paraprotein was reduced by a lesser degree. Responses occurred more frequently among patients with a lower plasma cell labeling index (PCLI) and normal cytogenetics. Comparing response and survival by thalidomide dose for low- and high-risk groups revealed a thalidomide dose-response effect in the high-risk group of patients. The virtual absence of myelosuppressive toxicity, except in heavily pretreated patients with compromised bone marrow function, suggests that thalidomide is an ideal agent to be used in combination with cytotoxic agents and dexamethasone. Several trials are currently underway at the Arkansas Myeloma and Transplantation Research Center to determine the clinical benefit of adding thalidomide to post-transplant salvage therapy and in the upfront management of patients.