Up-front fludarabine impairs stem cell harvest in multiple myeloma: report from an interim analysis of the NMSG 13/03 randomized placebo controlled phase II trial

The impact of chemotherapy resistant B cells in multiple myeloma (MM) needs to be evaluated by in vivo targeted therapy. Here we report the conclusions from a phase II randomized, placebo controlled trial adding fludarabine to the induction with cyclophosphamide-dexamethasone. Based on an interim toxicity and safety analysis, the trial was stopped following inclusion of 34 of a planned 80 patients due to a reduced number of patients (4/17) actually harvested in the experimental arm compared to the control arm (11/17; p<0.05). In conclusion, the scheduled fludarabine dosage in 2 cycles combined with alkylating therapy impairs stem cell mobilization and standard therapy in young MM patients and should not be administrated up-front.