Lasting clinical remission may occur in 11% to 25% of patients with multiple myeloma who undergo allogeneic hematopoietic stem cell transplant (alloHSCT) regardless of which reduced-intensity conditioning (RIC) regimen is used, according to results from a study published in Biology of Blood and Marrow Transplantation. However, relapsed disease before transplant and high-risk cytogenetics were associated with worse progression-free survival (PFS) and overall survival (OS).

AlloHSCT is a potentially curative treatment for multiple myeloma, and RIC can reduce nonrelapse mortality. Here, researchers assessed whether any of the 3 possible RIC regimens resulted in superior clinical outcomes.

In this retrospective comparative study, 73 patients with multiple myeloma underwent alloHSCT after having received busulfan with fludarabine (BuFlu), fludarabine with 100 mg/m2 melphalan (FM100), or fludarabine with 140 mg/m2 melphalan (FM140) as the RIC regimen.

Nonrelapse mortality at 3 years was 21% (3 patients) in the BuFlu group, 28% (5 patients) in the FM100 group, and 24% (6 patients) in the FM140 group. The most common cause of nonrelapse mortality was graft-versus-host disease.

PFS at 3 years was 16% (hazard ratio [HR] 1.2; 95% confidence interval [CI], 0.6-2.1) in patients receiving BuFlu, 26% (HR 0.6; 95% CI, 0.3-1.2) in patients receiving FM100, and 11% (ref) in patients receiving FM140. OS at 3 years was 39% (HR 1.1; 95% CI, 0.5-2.2) in BuFlu-treated patients, 43% (HR 0.7; 95% CI 0.3-1.4) in FM100-treated patients, and 32% (ref) in FM140-treated patients.

Relapsed disease prior to alloHSCT independently predicted inferior OS (HR 2.6; P =.004), as did high-risk cytogenetics (HR 2.1; P =.02). RIC regimen did not predict PFS or OS.

The authors concluded that the 3 RIC regimens “demonstrated similar outcomes and toxicity when used as conditioning regimens for multiple myeloma.” In addition, “patients with complete remission at transplantation and those with standard-risk cytogenetics had the best long-term outcomes regardless of the preparative treatment used.”

Reference

1. Maymani H, Lin P, Saliba RM, et al. Comparison of outcomes of allogeneic hematopoietic cell transplantation for multiple myeloma using three different conditioning regimens [published online January 10, 2019]. Biol Blood Marrow Transplant. doi: 10.1016/j.bbmt.2019.01.009