Upfront stem cell transplantation for newly diagnosed multiple myeloma with del(17p) and t(4;14): a study from the CMWP-EBMT.

We analyzed newly diagnosed multiple myeloma patients with del(17p) and/or t(4;14) undergoing either upfront single autologous (auto), tandem autologous (auto-auto) or tandem autologous/reduced-intensity allogeneic (auto-allo) stem cell transplantation. 623 patients underwent either auto (n = 446), auto-auto (n = 105), or auto-allo (n = 72) between 2000 and 2015. 46% of patients had t(4;14), 45% had del(17p) while 9% were reported having both abnormalities. Five-year overall survival (OS) was 51% (95% confidence interval [CI], 45-58%) for single auto, 60% (95% CI, 49-72%) for auto-auto, and 67% (95% CI, 53-80%) for auto-allo (p = 0.187). Five-year progression-free survival (PFS) was 17% (95% CI, 12-22%), 33% (95% CI, 22-43%), and 34% (95% CI, 21-38%; p = 0.048). Five-year relapse rate was 82, 63, and 56%, while non-relapse mortality was 1, 4, and 10%. In multivariable analysis, in t(4;14) with single auto as reference, auto-auto (hazard ratio [HR], 0.44; p = 0.007) and auto-allo (HR, 0.45; p = 0.018) were associated with better PFS. In terms of t(4;14) and OS, auto-auto appeared to improve outcome compared with single auto (HR, 0.49; p = 0.096). In del(17p), outcome in PFS was similar between single auto and auto-auto, while auto-allo appeared to improve PFS (HR, 0.65; p = 0.097). No significant difference in OS was identified between the groups in patients with del(17p).