Efficacy of Long-Term Treatment with Low-Dose Thalidomide for Patients with Relapsed/Refractory Multiple Myeloma

Introduction: We report the results of a prospective study of long-tern treatment with single-agent thalidomide in patients who had responded in a preceding trial of the use of thalidomide for relapsed/refractory myeloma. Patients and Methods: Nineteen patients were enrolled: 11 patients (57.9%) treated at a dosage of 100 mg/day; 2 patients (10.5%) at a dosage of 200 mg/day; 2 patients (10.5%) at a dosage of 300 mg/day; and 4 patients (21.1%) at a dosage of 400 mg/day. The median follow-up from the start of the preceding study was 3.0 years. At the time of entry to this study, 5 patients (26.3%) had partial response (PR), another 5 patients (26.3%) had a minimal response (MR), and the remaining 9 patients (47.4%) had shown no change (NC). Results: The cumulative MR rate was 78.9% (at the 32nd week) and the cumulative PR rate was 47.4% (at the 112th week). The median progression-free survival was 104 weeks and the median time to next treatment was 144 weeks. No patients experienced grade 4 or greater hematologic toxicity or grade 3 or greater non-hematologic toxicity. Conclusion: Long-term thalidomide maintenance therapy induced an increase in response rate, suppressed the progression to active myeloma without severe adverse events, and contributed to long survival with good activities of daily living.