Allogeneic Stem Cell Transplant Shows Minimal OS, PFS Benefits in MM

Most patients with multiple myeloma (MM) did not significantly benefit from treatment with allogeneic stem cell transplant (allo-SCT) in a study presented as an abstract at the 64th American Society of Hematology Annual Meeting and Exposition in New Orleans, Louisiana.

Although allo-SCT is increasingly used to treat MM and other hematological conditions, there have been mixed efficacy results in the context of MM. Some patients with treatment-resistant disease experience remission following allo-SCT, whereas others have adverse reactions due to opportunistic infections and graft-vs-host effects. Despite its increased use in this patient population in recent years, there are no clear guidelines surrounding allo-SCT treatment in MM.

The retrospective study included 89 patients who were diagnosed with MM and had received allo-SCT following an autologous stem cell transplant (ASCT) at Mayo Clinic in Rochester, Minnesota, between 2000 and 2022. The median age was 51.3 years. The main outcomes of interest included overall survival (OS) and progression-free survival (PFS) after allo-SCT.

There were 2 reported indications for allo-SCT in the cohort: relapsed or progressive disease (91%) and high risk in remission (9%). Information on risk stratifica- tion, according to International Myeloma Working Group criteria, was available for 94% of patients. Among those patients, 63% were considered to be standard risk and 32% were high risk. Overall, 55% of patients underwent myeloablative allo-SCT, whereas 45% underwent nonmyeloablative allo-SCT.

The median follow-up time was 11.5 years, the median OS was 1.7 years, and the median PFS was 0.8 years. OS was 46%, 26%, and 16% at 2, 4, and 8 years, respectively. In this population, OS was not significantly impacted by age, sex, race, allo-SCT indication, or myeloablative regimen. Patients who were considered high risk at diagnosis had an OS of 32% at 2 years, 18% at 4 years, and 7.1% at 8 years, whereas standard-risk patients had an OS of 52% at 2 years, 27% at 4 years, and 20% at 8 years. However, the findings regarding OS in the 2 risk stratification groups were not statistically significant.

At 2, 4, and 8 years of follow-up, PFS was 27%, 16%, and 7.9% overall, with no significant variations due to age, race, allo-SCT indication, risk group, or conditioning regimen. Sex was nearly clinically significant, with male patients showing slightly higher PFS at 2, 4, and 8 years.

The findings suggest that allo-SCT may not significantly benefit most patients with MM. Less than 20% of patients in the study cohort experienced long-term survival after treatment with allo-SCT following ASCT, and most patients had experienced disease progression or death by 2 years post treatment. Newer alternatives, such as chimeric antigen receptor T-cell therapy or bispecific T-cell engager therapy, may be feasible alternatives to allo-SCT in this population, the authors noted.

Reference
Schmidt WM, Buadi FK, Hayman SR, et al. Outcomes of allogeneic stem cell transplant for multiple myeloma. Presented at: 64th American Society of Hematology Annual Meeting and Exposition, December 10-13, 2022; New Orleans, LA: Abstract 3196. Accessed December 17, 2022. https://ash.confex.com/ash/2022/webprogram/Paper156078.html