MRD dynamics predicts progression and reveals a vulnerable state for immunotherapy interception in multiple myeloma

The clinical significance of one or two measurable residual disease (MRD) assessments is established in multiple myeloma (MM). However, how to stratify patients according to ≥3 MRD assessments remains unknown. The traits of MRD resistance and if treatment of persistent MRD vs relapse could improve outcomes also remains unknown. MRD dynamics were computed using next-generation flow cytometry and Connector in 539 newly-diagnosed MM patients with ≥3 assessments in the GEM2012MENOS65/GEM2014MAIN and GEM2017FIT trials. Molecular and immune profiling were performed in matched diagnostic and MRD samples. The survival impact of treating persistent MRD vs relapse was investigated with anti-BCMA CAR T cells in MIcγ1huCRBN mice. Computed MRD dynamics based on 3,610 MRD assessments identified five subgroups with different survival. Patients with late-sustained MRD response had excellent outcomes, similar to those with early-sustained MRD response. Patients with volatile results and those with primarily and resurgent MRD resistance had dismal survival. MRD dynamics outperformed transplant-eligibility and the R-ISS. These results were validated in 249 MM patients treated in routine practice. Multiomics characterization of MRD dynamics in patients and mouse models of MRD resistance revealed genomic evolution, transcriptional adaption and a pro-inflammatory tumor-immune microenvironment. Increasing clonality and exhaustion of endogenous T cells throughout disease progression urged investigating if MRD interception with anti-BCMA CAR-T cells could improve outcomes. Infusion at MRD resistance prolonged mouse survival compared to identical treatment at relapse. Altogether, MRD dynamics is the strongest predictor of progression and may help tailoring treatment to prevent additional tumor and immune alterations prior to relapse.