Long-term results of thalidomide in refractory and relapsed multiple myeloma with emphasis on response duration

OBJECTIVE: Thalidomide administered as a single agent produces a response rate of about 40% in patients with refractory or relapsed multiple myeloma (MM). The aim of our study was to determine the quality and duration of such responses. PATIENTS AND METHODS: Forty-two consecutive patients with refractory (20) or relapsed (22) MM were given thalidomide as a single agent at our institution. Most of them (70%) had previously received two or more lines of therapy, and 38% had undergone autologous stem cell transplantation. RESULTS: Eighteen patients (43%) responded to thalidomide 11 minimal responses (MR) and seven partial responses (PR)] according to the European Marrow Transplant Registry (EBMT) criteria. The median time to response was 3 months and the median duration of therapy in responding patients was 9 months. Treatment was discontinued because of toxicity in 10 responding patients. The toxicity mainly led to peripheral neuropathy and fatigue. At the time of this analysis, all responding patients had progressed except one who remains in continued stable PR. The median time to progression was 15.6 months (range 1.3 to 70+), with a trend towards a longer duration for patients who achieved PR vs. MR (21.2 vs. 11.2 months, P = 0.11). The median duration of response was 12.4 months (range: 0.3-67+) (17.2 months for PR vs. 9.7 months for MR, P = 0.11). CONCLUSION: These results show that the effect of thalidomide in refractory/relapsed MM can be sustained, particularly in patients who achieve a greater degree of response, and support the finding that this drug can be used for maintenance therapy.