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.
