The use of thalidomide as maintenance therapy following stem cell transplant or conventional chemotherapy is under investigation in several studies. The same high level of activity that makes it so effective in relapsed/refractory myeloma may provoke therapy-limiting toxicities when used for maintenance. A study by Tosi et al (2005) looked at toxicity in 40 patients on long-term (>12 months) salvage therapy with thalidomide alone or in combination with dexamethasone. Serious Grade 3 neurotoxicity was observed in 27.5% of patients, requiring termination of therapy despite a positive response. Another 32.5% displayed Grade 2 neurotoxicity and 15% experienced Grade 1 symptoms.

In an effort to reduce the significant effects, a small study by Bibas et al (2004) evaluated the safety and tolerability of low-dose thalidomide therapy. Intermittent low-dose thalidomide in combination with dexamethasone and zoledronic acid was evaluated as maintenance therapy in 30 patients with refractory/relapsing disease. Nineteen patients (63%) achieved a response (>50% reduction in M protein). None of the patients given low-dose therapy developed peripheral neuropathy, a common and debilitating side effect of thalidomide therapy.

Another recent study (Stewart et al, 2004) assessed tolerability of a maintenance regimen of prednisone 50 mg with thalidomide 200 mg or 400 mg given for 1 year post stem cell transplant. Of the 67 patients enrolled, 88% reduced their initial dose of thalidomide and 72% reduced their prednisone dose within 2 years of starting maintenance therapy. The investigators concluded that only the 200 mg dose of thalidomide is tolerable as a maintenance therapy for multiple myeloma.

Results of recent trials of thalidomide usage as maintenance therapy are summarized below.