Background: Multiple myeloma disproportionately affects the elderly and is currently an incurable malignancy. New therapies for myeloma, particularly oral therapies, are urgently needed.
To determine if thalidomide with or without other agents, improves response rate (≥ 50% reduction in monoclonal protein), survival, and/or progression in patients with previously untreated myeloma. To determine the frequency and significance of major adverse events associated with thalidomide in this setting.
Methods: A literature search of Medline (1966–June 2006), Embase (1980–June 2006), the Cochrane Library, abstracts from the annual meetings of the American Society of Hematology (1999–2005) and the American Society of Oncology (1999–2006) was completed with a pre-specified search strategy. No language restrictions were applied. Randomized controlled trials of induction thalidomide (any dose, any duration) for adults with previously untreated multiple myeloma were included. Trials of exclusively maintenance therapy were excluded. Two reviewers independently extracted data. The methodological quality of selected trials was assessed and summarized. Weighted data was expressed as relative risk, risk difference, number needed to treat (NNT), and number needed to harm (NNH). A random-effects model was used.
Results: Six eligible studies involving almost two thousand patients (N=1875) were identified and meta-analyzed. Two studies were published and four were reported in abstract form only. Five studies reported overall response rate (ORR); the four largest trials reported statistically significant improvements in ORR with the addition of thalidomide to standard therapy. The weighted relative risk of responding to a thalidomide-containing regimen versus control was 1.50 (95% CI 1.21 to 1.86). The NNT to achieve one additional response with thalidomide was 4 (95% CI 2.9 to 8.3). Two trials reported improvements in EFS/PFS. One trial reported an improvement in OS. The risk of VTE, peripheral neuropathy, and constipation was consistently elevated with thalidomide such that for every 50 patients treated with a thalidomide-containing-regimen, one could expect 12 to 13 additional patients to respond, 4 additional patients to develop VTE (NNH 12.5; 95% CI 8.3 to 20), 2 additional patients to develop peripheral neuropathy (NNH 25; 95% CI 16.7 to 50), and 4 additional patients to develop constipation (NNH14; 95% CI 10 to 25). In our analyses, prophylactic anticoagulation appeared to decrease, but not abolish, the risk of VTE with thalidomide.
Conclusions: Thalidomide improves response rate and possibly progression free and overall survival in patients with previously untreated myeloma. It also increases the incidence of VTE, neuropathy, constipation and other adverse events. Further studies are required to confirm the survival advantage seen in one study, and to determine the optimum strategy for VTE prophylaxis.