Bortezomib after dose-reduced allogeneic stem cell transplantation for multiple myeloma to enhance or maintain remission status

Objective. We investigated the effect of at least two cycles of bortezomib (1.3 mg/m(2) intravenously, days 1, 4, 8, and 11) after dose-reduced allogeneic stem cell transplantation (SCT) on toxicity, CD3(+) cells, graft-versus-host disease (GvHD), and response in patients with multiple myeloma. Methods. Eighteen patients with multiple myeloma without progressive disease were included. The proteasome inhibitor was given at median of 8 months after allografting to enhance or maintain remission status. Results. Fourteen patients (78%) completed the proposed two cycles. Four patients had to discontinue therapy due to neurotoxicity (n = 3) or gastrointestinal toxicity (n = 1). Severe grade III/IV toxicity was seen for thrombocytopenia (50%), leukopenia (17%), or neuropathy (17%), which was more often seen in patients treated concomitantly with cyclosporine (P = 0.06). The median circulating CD3(+) cells decreased during treatment from 550 mu L to 438 mu L (p = 0.03), resulting in herpes zoster infection in three patients (17%). In three patients, a mild aggravation of existing acute or chronic GvHD of the skin, and in one patient de novo skin grade I acute GvHD was noted. In patients with measurable disease, complete remission, partial remission, and minor response was seen in 3 (30%), 5 (50%), and 2 (20%) patients, respective. Conclusion. Bortezomib after allogeneic SCT is effective but further studies are needed to balance the efficacy with potential hazards such as infectious complications, aggravation of GvHD, and neurotoxicity. (c) 2006 International Society for Experimental Hematology. Publishedby Elsevier Inc.