Full Or Intensity-Reduced High-Dose Melphalan And Single Or Double Autologous Stem Cell Transplant With Or Without Bortezomib Consolidation In Patients With Newly Diagnosed Multiple Myeloma

Objective A post hoc subgroup analysis of two phase III trials (NCT00416273, NCT00416208) was carried out to investigate the influence of 100/140 and 200 mg/m(2) melphalan as well as single/double autologous stem cell transplantation (ASCT) on progression-free survival (PFS). Additionally, the effect of bortezomib consolidation on PFS was analyzed. Methods Following induction therapy and high-dose melphalan with subsequent ASCT, patients with newly diagnosed multiple myeloma (NDMM) were randomized 1:1 to either four 35-day cycles of bortezomib consolidation (1.6 mg/m(2) IV on days 1, 8, 15, 22) or observation. Results Of the 340 patients included in this analysis, 13.5% received 1 x MEL100/140, 22.9% 2 x MEL100/140, 31.2% 1 x MEL200, and 32.4% 2 x MEL200. With higher cumulative melphalan dose, PFS improved (P = .0085). PFS curves of patients treated with 2 x MEL100/140 and 1 x MEL200 were very similar. The superior dose effect of MEL200 over MEL100/140 was non-existent in the bortezomib consolidation arm but pronounced in the observation arm (P = .0015). Similarly, double ASCT was only beneficial in patients without bortezomib consolidation (P = .0569). Conclusions Full dose melphalan and double transplantation seem advantageous only as long as patients are not receiving bortezomib consolidation afterwards.