Clonal Plasma Cells in Autograft Predict Inferior Post-AHSCT Survival in MM

The presence and degree of clonal plasma cells in autografts for patients with multiple myeloma (MM) who are undergoing autologous hematopoietic stem cell transplantation (AHSCT) were “highly predictive of inferior” survival outcomes, according to a recent study.

Oren Pasvolsky, MD, of the University of Texas MD Anderson Cancer Center, the Rabin Medical Center, and Tel Aviv University, and colleagues conducted the study because most patients with MM who undergo AHSCT “eventually relapse, perhaps due to the presence of clonal plasma cells in the autograft.”

They conducted a retrospective analysis to evaluate the impact of clonal plasma cells in the autograft in patients with high-risk chromosomal abnormalities who received AHSCT between 2008 and 2018.

Dr. Pasvolsky and colleagues used next-generation flow cytometry to determine if autografts contained clonal plasma cells. They found that 75 patients (18%) had clonal plasma cells present in the autograft and 341 (82%) did not have clonal plasma cells in their autograft.

Patients with clonal plasma cells in the autograft had a measurable residual disease (MRD)-negative complete remission (CR) rate of 11% after transplant. Patients without clonal plasma cells in the autograft had a significantly higher MRD-negative CR rate of 42% (P<.001).

The median progression-free survival (PFS) was 12.8 months in patients who had clonal plasma cells in the autograft, significantly shorter than the median PFS of 32.1 months in those who did not have them (P<.001). Patients with clonal plasma cells in the autograft had a median overall survival (OS) of 36.4 months, significantly shorter than the median OS of 81.2 months in patients who did not have them (P<.001).

In the subset of patients who had an MRD-negative very good partial response or better before AHSCT, patients with clonal plasma cells in the autograft also had “inferior” PFS (hazard ratio [HR], 4.21, P=.006) and OS (HR, 7.04, P=.002) compared with those who did not have clonal plasma cells in the autograft.

Furthermore, the degree of clonal plasma cell positivity in the autograft was independently predictive of worse PFS (HR, 1.50, P=.001) and OS (HR, 1.37, P=.001) in a multivariate analysis.

“In conclusion, both the presence and degree of [clonal plasma cells] in the autograft were highly predictive of inferior PFS and OS,” Dr. Pasvolsky and colleagues wrote.

Reference

Pasvolsky O, Milton DR, Rauf M, et al. Impact of clonal plasma cells in autografts on outcomes in high-risk multiple myeloma patients. Blood Cancer J. 2023;13(1):68. doi:10.1038/s41408-023-00842-6