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The role of salvage high-dose chemotherapy and autologous stem cell transplantation (sHDCT/ASCT) for relapsed and/or refractory multiple myeloma (RRMM) in the era of continuous novel agent treatment has not been defined. This randomized, open-label, phase III, multicenter trial randomized patients with 1st-3rd relapse of multiple myeloma (MM) to a transplant arm (n = 139) consisting of 3 Rd (lenalidomide 25 mg, day 1-21; dexamethasone 40 mg, day 1, 8, 15, and 22; 4-week cycles) reinduction cycles, sHDCT (melphalan 200 mg/m 2 ), ASCT, and lenalidomide maintenance (10 mg/day) or to a control arm (n = 138) of continuous Rd. Median PFS was 20.7 months in the transplant and 18.8 months in the control arm (HR 0.87; 95% CI 0.65-1.16; p = 0.34). Median OS was not reached in the transplant and 62.7 months in the control arm (HR 0.81; 95% CI 0.52-1.28; p = 0.37). Forty-one patients (29%) did not receive the assigned sHDCT/ASCT mainly due to early disease progression, adverse events, and withdrawal of consent. Multivariate landmark analyses from the time of sHDCT showed superior PFS and OS (p = 0.0087/0.0057) in patients who received sHDCT/ASCT. Incorporation of sHDCT/ASCT into relapse treatment with Rd was feasible in 71% of patients and did not significantly prolong PFS and OS on ITT analysis while patients who received sHDCT/ASCT may have benefitted.

Objective: Analysis of the efficiency and toxicity of cyclophosphamide-based stem cell mobilization in patients with relapsed multiple myeloma (RMM)., Methods: Peripheral blood stem cells (PBSCs) were mobilized with high dose cyclophosphamide (2 g/m 2 daily on days 1 and 2) and G-CSF plus pre-emptive/rescue plerixafor in RMM patients (first to third relapse) treated within the ReLApsE trial of the German-Speaking Myeloma Multicenter Group (GMMG)., Results: Mobilization was initiated with high-dose cyclophosphamide (HD-CY) and G-CSF in 30 patients. Fifteen patients received additional pre-emptive/rescue administration of plerixafor. Stem cell collection was successful (≥2×10 6 CD34+ cells per kg bw) in 77% (23/30 patients). Patients with prior high-dose melphalan collected a significantly lower median total number of PBSCs than patients without prior high-dose melphalan (3.3×10 6 vs 17×10 6 CD34+ cells/kg bw). Toxicity of HD-CY was frequent with 12 serious adverse events (SAE) in 37% of patients (11/30 patients). Infections accounted for the majority of SAE reports. In two patients, SAEs were lethal (septic shock)., Conclusions: These data proof feasibility of PBSC collection at relapse but emphasize the importance of collection and storage of additional PBSC transplants during first-line treatment when mobilization is more efficient and less toxic., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)