Bortezomib with or without dexamethasone in relapsed multiple myeloma following allogeneic hematopoietic cell transplantation.

We retrospectively evaluated the efficacy of bortezomib in 23 patients with multiple myeloma who had relapsed after allografting. Bortezomib was given as single agent to 9 patients (39%) and in combination with steroids in the other 14 (61%). Major toxicities were thrombocytopenia (10/23, 43%) and peripheral neuropathy (12/23, 52%). The overall response rate was 61% (14/23), including 22% (5/23) immunofixation-negative complete remissions. No significant differences in toxicity and response rates were seen between patients treated with bortezomib plus steroids and bortezomib alone. After a median follow-up of 6 months, progression free survival was 6 months. Twenty-one patients are alive, two and five in continuous very good partial and complete remissions, respectively.