Minimal Residual Disease Evaluation By Multiparameter Flow Cytometry and Next Generation Sequencing in the Forte Trial for Newly Diagnosed Multiple Myeloma Patients
Authors: Oliva Stefania , Genuardi Elisa , Belotti Angelo , Frascione Pio Manlio Mirko , Galli Monica , Capra Andrea , Offidani Massimo , Vozella Federico , Zambello Renato , Auclair Daniel , Siniscalchi Agostina , Yesil Jennifer , Annibali Ombretta , Kirsch Ilan M. , Caltagirone Simona , Jacob Allison P. , Ballanti Stelvio , Palmas Angelo D. , Ledda Antonio , Corradini Paolo , Omedé Paola , Cavo Michele , Musto Pellegrino , Boccadoro Mario , Gay Francesca 
Published: November 2019

Background: The role of Minimal residual disease (MRD) as surrogate for survival in Multiple Myeloma (MM) patients is well established. Therefore, new response criteria recommend including Multiparameter Flow cytometry (MFC) and next generation Sequencing (NGS) MRD negativity (minimum sensitivity of 1 in 105 nucleated cell) to deeply characterize complete remission (CR) [Kumar SK, Lancet Oncol 2016]. Here we analyzed and compared MRD data from the FORTE trial both by MFC and NGS techniques.
Methods: Newly diagnosed MM patients ≤65 years were randomized to receive carfilzomib, lenalidomide, dexamethasone (KRd) induction - autologous stem cell transplantation (ASCT) intensification - KRd consolidation (KRd_ASCT); KRd12 and carfilzomib, cyclophosphamide, dexamethasone (KCd) induction - ASCT intensification - KCd consolidation (KCd_ASCT). Thereafter, patients were randomized to maintenance therapy with lenalidomide alone or lenalidomide plus carfilzomib. MRD evaluation was performed by 8-color second generation flow cytometry (sensitivity 10-5) in patients who achieved at least a very good partial response (VGPR) before maintenance. In a subgroup of these ≥ VGPR patients, next generation flow (NGF; sensitivity 10-5 - 10-6) was performed. Moreover, in patients achieving ≥ CR, MRD pre-maintenance was also assessed by NGS (Adaptive Biotechnologies, Seattle, WA; sensitivity 10-5 - 10-6). Therefore, only patients achieving ≥ CR have both MFC and NGS evaluations, and we focused on this ≥ CR population to compare MRD results with the 2 techniques. Spearman's rank correlation coefficient was used to measure the concordance between MFC and NGS. Fisher or Pearson's Chi-squared tests were adopted, where appropriate, to evaluate the statistical significance, at the level of 0.05.
Results: ≥ CR pre-maintenance was achieved in 233 patients enrolled in the trial; at data cut-off, MFC and NGS data were available for 176/233 (76%) patients who were included in this analysis (62 received KRd_ASCT, 65 KRd12 and 49 KCd_ASCT). Median age of this ≥ CR population is 57 years (IQR 52-62), 14% have International Staging System (ISS) III stage and 26% high risk cytogenetics by FISH features [either del(17p) or t(4;14) or t(14;16)] reflecting baseline clinical features of the entire FORTE population. 139/176 (79%) ≥ CR patients were MFC negative at a cut-off of at least 10-5. Rate of MRD negative MFC among ≥ CR negative in the 3 arms were: 53/62 (85%) in KRd_ASCT, 51/65 (78%) in KRd12 and 35/49 (71%) in KCd_ASCT, reflecting the higher rate of MCF MRD negativity pre-maintenance reported by ITT in the overall population in the 2 KRD arms [Gay F, ASH 2018]. NGS negativity at a cut-off of at least 10-5 was detected in 87/176 (49%) of ≥ CR patients. Rate of MRD negative NGS at least 10-5 among ≥ CR negative in the 3 arms were: 35/62 (56%) in KRd_ASCT, 31/65 (48%) in KRd12 and 21/49 (43%) in KCd_ASCT. NGS negativity at a cut-off 10-6 was detected in 34/123 (28%) of ≥ CR patients (for 53/176 CR patients 10-6 sensitivity was not reached). Rate of MRD negative NGS at least 10-6 among ≥ CR negative in the 3 arms were:14/41 (34%) in KRd_ASCT, 10/44 (23%) in KRd12 and 10/38 (26%) in KCd_ASCT.
Thereafter, we have analyzed the concordance between MRD results by the two techniques. Overall (samples at 10-5 and 10-6 sensitivity), Spearman's coefficient is 0.63 (p < 0.001); discordances between the two methods have been observed in 54/176 paired samples (30%). In particular, 53 samples (30%) are NGS positive but MFC negative, of which 34/53 (64%) have reached 10-6 sensitivity by NGS. Only 1 MFC positive sample is NGS negative. In a subgroup of patients evaluable both by NGS and NGF (26 paired samples, sensitivity 10-6), Spearman' s coefficient is 0.83 (p < 0.001), although a higher sample size is needed to confirm these preliminary concordant results.
Conclusion: In patients who achieved ≥ CR, rate of at least 10-5 MRD MCF negativity was 79% and rate of at least 10-5 NGS negativity was 49%. Assessment both by MFC and NGS showed a good concordance, particularly if the same sensitivity is reached. Longer follow up is needed to assess the impact of MFC in comparison with NGS on patients' outcomes, particularly to evaluate if 10-6 NGS or NGF sensitivity may provide further clinical information, possibly identifying patients with very long survival or potentially cured.

Disclosures
Oliva: Celgene: Honoraria; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Belotti:Janssen: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Galli:Bristol-Myers Squibb: Honoraria; Takeda: Honoraria; Leadiant (Sigma-Tau): Honoraria; Janssen: Honoraria; Celgene: Honoraria. Offidani: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; Amgen: Honoraria, 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; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Vozella:Amgen: Honoraria; Celgene: Honoraria. Zambello:Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Kirsch:Adaptive Biotechnologies: Employment. Jacob:Adaptive Biotechnologies: Employment, Other: shareholder. Ballanti:Amgen: Honoraria; Bristol-Myers Squibb: Honoraria; Janssen: Honoraria; Celgene: Honoraria. Corradini:Roche: Honoraria; Sanofi: Honoraria; KiowaKirin: Honoraria; Kite: Honoraria; Novartis: Honoraria, Other: Travel Costs; BMS: Other: Travel Costs; Servier: Honoraria; Takeda: Honoraria, Other: Travel Costs; Gilead: Honoraria, Other: Travel Costs; AbbVie: Consultancy, Honoraria, Other: Travel Costs; Amgen: Honoraria; Celgene: Honoraria, Other: Travel Costs; Daiichi Sankyo: Honoraria; Jazz Pharmaceutics: Honoraria; Janssen: Honoraria, Other: Travel Costs. Omedé:Janssen: Membership on an entity's Board of Directors or advisory committees. Cavo:takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau; bms: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; novartis: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Musto:Amgen: Honoraria; Celgene: Honoraria. Boccadoro:Sanofi: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; AbbVie: Honoraria; Mundipharma: Research Funding. Gay:AbbVie: 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; Celgene: 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; 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; 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; Takeda: Honoraria, 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; Amgen: Honoraria, 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.

OffLabel Disclosure:
The presentation includes discussion of off-label use of a drug or drugs for the treatment of multiple myeloma.