Predictors of unsustained measurable residual disease negativity in patients with multiple myeloma.

ABSTRACT: The prognostic impact of achieving and in particular maintaining measurable residual disease (MRD) negativity in multiple myeloma is now established; therefore, identifying among MRD-negative patients the ones at higher risk of losing MRD negativity is of importance. We analyzed predictors of unsustained MRD negativity in patients enrolled in the FORTE trial (NCT02203643). MRD was performed by multiparameter flow cytometry (sensitivity of 10-5) at premaintenance and every 6 months thereafter. The cumulative incidence (CI) of MRD resurgence and/or progression was analyzed in MRD-negative patients. A total of 306 of 474 (65%) MRD-negative patients were analyzed. After a median follow-up of 50.4 months from MRD negativity, 185 of 306 (60%) patients were still MRD negative and progression free, 118 (39%) lost their MRD-negative status, and 3 patients (1%) died without progression. Amp1q vs normal (4-year CI, 63% vs 34), ≥2 concomitant high-risk cytogenetic abnormalities vs 0 (4-year CI, 59% vs 33%), circulating tumor cells at baseline (high vs low at 4-year CI, 62% vs 32%), and time-to-reach MRD negativity postconsolidation vs preconsolidation (4-year CI, 46% vs 35%) were associated with a higher risk of unsustained MRD negativity in a multivariate Fine-Gray model. During the first 2 years of maintenance, patients receiving carfilzomib-lenalidomide vs lenalidomide alone had a lower risk of unsustained MRD negativity (4-year CI, 20% vs 33%).

Prospective evaluation of minimal residual disease in the phase II FORTE trial: a head-to-head comparison between multiparameter flow cytometry and next-generation sequencing.

Background: Limited data are available on the concordance between multiparameter flow cytometry (MFC) and next-generation sequencing (NGS) for minimal residual disease (MRD) detection in a large trial for multiple myeloma (MM) patients. Methods: MRD was explored in the FORTE trial for transplant-eligible MM patients randomised to three carfilzomib-based induction-intensification-consolidation treatments and carfilzomib-lenalidomide (KR) vs R maintenance. MRD was assessed by 8-colour 2nd-generation flow cytometry in patients with ≥very good partial response before maintenance. NGS was performed in case of suspected complete response (CR) in a correlative subanalysis. Biological/prognostic concordance between MFC and NGS, conversion to MRD negativity during maintenance, and 1-year/2-year sustained MRD negativity were explored. Findings: Between September 28, 2015 and December 22, 2021, 2020 samples were available for MFC and 728 for the simultaneous MFC/NGS correlation in the "suspected CR population". Median follow-up was 62 months. Biological agreement was 87% at the 10-5 and 83% at the 10-6 cut-offs. A remarkable prognostic concordance was observed: hazard ratios in MFC-MRD and NGS-MRD-negative vs -positive patients were 0.29 and 0.27 for progression-free survival (PFS) and 0.35 and 0.31 for overall survival, respectively (p < 0.05). During maintenance, 4-year PFS was 91% and 97% in 1-year sustained MFC-MRD-negative and NGS-MRD-negative patients (10-5), respectively, and 99% and 97% in 2-year sustained MFC-MRD-negative and NGS-MRD-negative patients, regardless of treatment received. The conversion rate from pre-maintenance MRD positivity to negativity during maintenance was significantly higher with KR vs R both by MFC (46% vs 30%, p = 0.046) and NGS (56% vs 30%, p = 0.046). Interpretation: The significant biological/clinical concordance between MFC and NGS at the same sensitivity suggests their possible use in the evaluation of one of the currently strongest predictors of outcome. Funding: Amgen, Celgene/Bristol Myers Squibb, Multiple Myeloma Research Foundation.