Minimal Residual Disease Status Predicts Progression-Free Survival in Newly Diagnosed Multiple Myeloma (NDMM) Patients Treated with Carfilzomib, Lenalidomide, and Low-Dose Dexamethasone (KRd)
Authors: Jasielec Jagoda , Dytfeld Dominik , Griffith Kent A. , McDonnell Kathryn , Lebovic Daniel , Kandarpa Malathi , Anderson Tara , Mietzel Melissa , Faham Malek , Lee Liana , Levy Joan , Alonge Mattina , Rosebeck Shaun , Kaminski Mark , Jakubowiak Andrzej 
Published: October 2019

Abstract
Background: NDMM patients (pts) treated with KRd in a phase 1/2 trial (NCT01029054) demonstrated high rates of complete response (CR, 64%) and stringent complete response (sCR, 55%) that correlated with excellent estimated 3-year progression-free survival (PFS; 79%) and overall survival (OS; 96%) (Jakubowiak et al, Blood, 2012; Jasielec et al, Blood 2013; 122(21):3220). Furthermore, there was a trend towards superior outcomes in patients with multiparameter flow cytometry (MFC) MRD-negative disease with an estimated 3 year PFS of 84% and OS of 100%, suggesting the importance of MRD analysis in predicting relapse. In this post hoc, retrospective analysis, we present an updated evaluation of PFS based on minimal residual disease (MRD) status.
Methods: Pts received 28-day cycles of carfilzomib (CFZ) 20–36 mg/m2 intravenously (days [d]1, 2, 8, 9, 15, 16), lenalidomide (LEN) 25 mg orally (PO; d1–21), and dexamethasone 40/20 mg PO weekly (cycles 1–4/5–8). For cycles 8–24, KRd was given with a modified CFZ schedule (d1, 2, 15, 16), and single-agent LEN was administered after cycle 24. Pts had the option to receive stem cell transplantation after cycle 4. MRD assessment at the time of complete response (CR) was performed using 10-color MFC and next-generation sequencing (NGS) analysis. Fresh bone marrow aspirate (BMA) was used for MFC analysis as previously reported, while archived BMA slides were used for NGS analysis. The LymphoSIGHT™ NGS method employed universal primer sets to assess clonal rearrangements at the immunoglobulin loci (IGH-VDJ, IGH-DJ and IGK) in diagnostic BMA slides. Myeloma clonotypes were identified in the diagnostic BMA sample of each patient based on high-frequency within the B-cell repertoire. The level of the myeloma clonotype was then quantified in BMA slides obtained at the time of CR.
Results: Twenty-two pts with CR/sCR were evaluated for MRD by both MFC and NGS methods with a median follow-up of 40 months. Limited input DNA was obtained from BMA slides (range 2,189 to 1,870,960 cell equivalents). Concordance analysis in 21 patients with both MFC and NGS MRD data revealed 11 patients that were MRD-negative by both MFC and NGS, while 2 patients were concordantly MRD-positive. NGS demonstrated greater sensitivity compared to MFC, as 8 patients were MRD-positive by NGS but MRD-negative by MFC. Three of these 8 patients relapsed. We evaluated the correlation between MRD status by NGS and PFS. Six MRD samples had less than 40,000 input cell equivalents and were removed from the progression-free survival analysis due to insufficient sample amount. MRD negativity by NGS in KRd patients at the time of CR was associated with longer progression-free survival (median not reached vs 46 months, p = 0.055) (Figure 1).
Conclusions: Our results suggest that achievement of MRD-negative disease by NGS in CR patients is associated with superior PFS. The NGS method appears more sensitive than MFC at detecting residual disease. Finally, MRD assessment by NGS in BMA slides is feasible although may not be the optimal method due to limited input DNA amount. MRD assessment by NGS will be performed on the remainder of the KRd cohort and results will be presented.
Figure 1. Kaplan-Meier analysis of progression-free survival for 6 MRD negative (<10-6) and 10 MRD positive (>10-6) patients. Figure 1. Kaplan-Meier analysis of progression-free survival for 6 MRD negative (<10-6) and 10 MRD positive (>10-6) patients.

Disclosures
Faham: Sequenta, Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Lee:Sequenta, Inc.: Employment, Equity Ownership. Jakubowiak:Bristol Myers-Squib: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; SkylineDx: Honoraria, Membership on an entity's Board of Directors or advisory committees.