Early testing of measurable residual disease (MRD) in bone marrow after chimeric antigen receptor (CAR) T-cell infusion in patients with multiple myeloma (MM) could potentially provide prognostic information, according to a recent study.
The study was led by Radhika Bansal, MBBS; Mizba Baksh, MBBS; Jeremy Larsen, MD; Shaji K. Kumar, MD; and Yi Lin, MD, PhD, all affiliated with the Mayo Clinic.
They conducted the research because bone marrow assessment of MRD is “prognostic for survival” in MM, but bone marrow remains hypocellular at month one after CAR-T infusion.
“Thus, the value of MRD negative status at this timepoint is unclear,” the study’s authors wrote.
The researchers evaluated the impact of bone marrow MRD status at month one in patients with MM who received CAR-T therapy at the Mayo Clinic between August 2016 and June 2021.
In the 60 patients evaluated, 78% (47/60) had MRD-negative bone marrow at month one after CAR-T. Of those 47 patients, 85% also showed a decrease to a less-than-normal level of involved and uninvolved free light chain (FLC). Patients who achieved a complete response (CR) or stringent CR had higher rates of MRD-negative bone marrow at month one. Those patients also had higher rates of decrease to a less-than-normal level of involved and uninvolved FLC.
“An early MRD assessment at month one can potentially predict for risk of relapse and be used for risk-adapted monitoring,” the researchers wrote.
Nearly half (40%) of patients with MRD-negative bone marrow at month one had sustained MRD. At month one, 38% of patients with MRD-negative bone marrow samples were hypocellular. A recovery to “normal cellularity” occurred in 50%, with a median time to normalization of 12 months, according to the researchers. The rate of conversion from MRD-positive status to MRD-negative status was 5%.
Patients with MRD-negative bone marrow had longer progression-free survival (PFS) “irrespective” of bone marrow cellularity, compared with patients who had MRD-positive bone marrow at month one (PFS, 17.5 vs 2.9 months; P<.0001).
“[MRD-negative bone marrow at month one] and FLC below normal were associated with prolonged survival,” the study’s authors concluded. “Our data support the continued evaluation of [bone marrow] early post-CAR-T infusion as a prognostic tool.”
Bansal R, Baksh M, Larsen JT, et al. Prognostic value of early bone marrow MRD status in CAR-T therapy for myeloma. Blood Cancer J. 2023;13(1):47. doi:10.1038/s41408-023-00820-y