Impact of Minimal Residual Disease (MRD) By Multiparameter Flow Cytometry (MFC) and Next-Generation Sequencing (NGS) on Outcome: Results of Newly Diagnosed Transplant-Eligible Multiple Myeloma (MM) Patients Enrolled in the Forte Trial
Authors: Oliva Stefania , Genuardi Elisa , Petrucci Maria Teresa , D'Agostino Mattia , Auclair Daniel , Spadano Antonio , Jacob Allison P. , Cea Michele , De Rosa Luca , Gozzetti Alessandro , Ruggeri Marina , Capra Andrea , Gilestro Milena , Pescosta Norbert , Palmas Angelo D. , Siniscalchi Agostina , Kirsch Ilan R. , Corradini Paolo , Musto Pellegrino , Boccadoro Mario , Zamagni Elena , Gay Francesca 
Published: February 2021

Background. In multiple myeloma (MM), the role of minimal residual disease (MRD) by multiparameter flow cytometry (MFC) and next-generation sequencing (NGS) is well established (H. Avet-Loiseau et al. IMW 2019, S. Oliva et al. EHA 2020).
Aims. The aims of this analysis were the evaluation of (1) the rate of conversion from MRD-positivity (MRD-pos) to MRD-negativity (MRD-neg) with MFC and NGS during maintenance and (2) the impact on progression-free survival (PFS) and overall survival (OS) of MRD-neg with both techniques in different subgroups including different treatment arms.
Methods. Newly diagnosed (ND)MM patients (pts) aged ≤65 years were randomized (R1) to receive carfilzomib (K)-lenalidomide (R)-dexamethasone (d) induction followed by autologous stem-cell transplantation (ASCT) and KRd consolidation (KRd_ASCT), 12 KRd cycles (KRd12), or K-cyclophosphamide(C)-d induction followed by ASCT and KCd consolidation (KCd_ASCT). After consolidation, pts were further randomized (R2) to KR vs R maintenance. MRD was assessed every 6 months (m) by 8-color second-generation flow cytometry (sensitivity 10-5) in pts with ≥very good partial response (VGPR). In pts achieving at least a complete response (≥CR), MRD was also assessed by NGS at the same time points (Adaptive Biotechnologies, Seattle, US-WA; sensitivity 10-5-10-6). Logistic regression analysis adjusted for International Staging System (ISS) stage (I vs II/III) and R1 was performed to evaluate the conversion rate from MRD-pos to MRD-neg during maintenance (KR vs R). PFS and OS of MRD-neg vs MRD-pos in the intention-to-treat (ITT) population were evaluated. For these analyses, MFC-pos pts included those who were positive by MRD plus those &lt;VGPR, whereas NGS-pos pts included those who were MRD-pos plus &lt;CR (excluding CR pts not evaluable by NGS). 1-year sustained MRD-neg by MFC and NGS was evaluated in pts with at least 2 samples available at least 1 year apart.
Results. Rates of MRD-neg by MFC and NGS before maintenance in the 3 induction/consolidation arms have been previously presented (S. Oliva et al. EHA 2020). At R2, 65% of randomized pts were MRD-neg by MFC (equally distributed in the 2 arms); 39% (48/123) of MRD-pos pts turned MRD-neg after a median of 7.6 m (IQR 6.5-12): 46% (29/63) in KR vs 32% (19/60) in R (OR 2.27; P=0.04) arms. At R2, 72% of pts evaluable for CR were MRD-neg by NGS (equally distributed in the 2 arms); 33% of MRD-pos pts (15/45) became MRD-neg at 10-5: 39% (9/23) in KR vs 27% (6/22) in R arms (=NS).
In the ITT analysis, after a median follow-up of 45 m from R1, pts who were MRD-neg before maintenance by both techniques showed a superimposable prolonged PFS and OS vs pts who were MRD-pos: 3-year PFS was 80% vs 52% (HR 0.36, 95% CI 0.26-0.49 P&lt;0.001) in MFC-neg vs MFC-pos pts and 83% vs 55% (HR 0.34, 95% CI 0.22-0.52, P&lt;0.001) in NGS-neg vs NGS-pos pts (Fig. 1A); 3-year OS was 96% vs 79% (HR 0.24, 95% CI 0.14-0.42 P&lt;0.001) in MFC-neg vs MFC-pos pts and 97% vs 82% in NGS-neg vs NGS-pos pts (HR 0.30, 95% CI 0.15-0.61, P&lt;0.001). The favorable impact of MRD-neg on PFS was confirmed in all subgroups, in particular in the high-risk setting. PFS in 1-year sustained MRD-neg was superimposable between MFC and NGS (4-year PFS 88% by MFC and 94% by NGS at 10-5).
The impact of pre-maintenance MRD negativity by MFC on PFS was explored in different treatment arms: 3-year PFS was longer in KRd_ASCT vs KRd12 and in KRd_ASCT vs KCd_ASCT arms; MRD-pos pts showed a similar PFS in the 3 arms. The same trend was shown by NGS MRD negativity: 3-year PFS was longer in KRd_ASCT vs KRd12 and in KRd_ASCT vs KCd_ASCT arms. A longer PFS was observed in pre-maintenance MRD-neg pts who were randomized to KR vs R both by MFC (HR 0.51, P=0.02) and NGS (HR 0.38, P=0.03); similar features were observed in MRD-pos pts (Fig. 1B).
Conclusions. KR maintenance induced a high rate of conversion from MRD-pos to MRD-neg both by MFC and NGS. The outcomes of pts who were MRD-neg by MFC and NGS at 10-5 were similar, as well as those of pts with 1-year sustained MRD-neg both by MFC and NGS. These clinical findings confirmed a high degree of concordance between these two techniques. MRD-neg pts receiving KRD_ASCT showed a longer PFS (88% at 3 years) than pts receiving KRd12 and KCd_ASCT. KR vs R significantly prolonged PFS even in pts who were MRD-neg before maintenance.
Figure 1

Disclosures
Oliva: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees. Petrucci:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. D'Agostino:GSK: Membership on an entity's Board of Directors or advisory committees. Jacob:Adaptive Biotechnologies: Current Employment, Current equity holder in publicly-traded company. Gozzetti:Amgen: Honoraria; Takeda: Honoraria; Janssen: Honoraria, Research Funding. Kirsch:Adaptive Biotechnologies: Current Employment. Corradini:KiowaKirin: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Other: Travel and accommodations paid by for; F. Hoffman-La Roche Ltd: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Other; BMS: Other; Amgen: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Celgene: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Daiichi Sankyo: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Incyte: Consultancy; Janssen: Consultancy, Honoraria; Kite: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Other: Travel and accommodations paid by for. Musto:Amgen: Honoraria; Celgene: Honoraria. Boccadoro:Sanofi: Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Research Funding; AbbVie: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Zamagni:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Speakers Bureau; Takeda: Honoraria, Other: Travel, Accommodations, Expenses, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Speakers Bureau; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Gay:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees.

OffLabel Disclosure:
The presentation includes discussion of off-label use of a drug or drugs for the treatment of multiple myeloma (including carfilzomib, cyclophosphamide, lenalidomide and dexamethasone).