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Background. The Revised International Staging system (R-ISS) is the standard risk stratification model used for newly diagnosed (ND) multiple myeloma (MM) (Palumbo et al. JCO 2015). R-ISS identifies 3 groups of patients (pts) with different PFS and OS. However, 60% of pts are considered as intermediate-risk (R-ISS II), possibly including pts with different risk of progression/death. Recently, 1q copy number alterations (CNAs), which were not included in the R-ISS, proved to be a poor prognostic factor in NDMM pts. The European Myeloma Network (EMN), under the umbrella of the HARMONY project, collected more than 7000 patient data from European clinical trials. The aim of this analysis is to revise the R-ISS risk stratification model, by analyzing the prognostic value of each single baseline risk feature, including 1q CNAs, to improve prognostication in NDMM pts. Methods. Data from 15 European clinical trials enrolling NDMM pts from 2005 to 2014 were collected through EMN and registered in HARMONY platform. HARMONY is a European public-private partnership focusing on hematologic malignancies with unmet medical needs, including MM. OMOP Common Data Model was used to harmonize data. All pts received an immunomodulatory agent (IMiD) and/or a proteasome inhibitor (PI) upfront. In a multivariate Cox regression analysis adjusted for age, sex and therapy, we evaluated the impact of each risk feature on overall survival (OS) and progression-free survival (PFS). The hazard of death conferred by the most significant variables was used to create an additive risk score. Results. 7077 NDMM pts were registered in the HARMONY platform and included in the analysis. Data were mature with a median follow-up of 75 months; median age was 62 years. The majority of pts were transplant-eligible (65%). 40% of the pts received IMiDs only, 15% PIs only, 46% both drug classes during their first-line treatment. In a multivariate Cox model, ISS (II vs I HR 1.55 p These prognostic variables were simultaneously present in 2227 pts and the most frequent reason of exclusion of the remaining pts was 1q CNAs that was missing in some of the trials. We exploited the OS impact of these risk features in pts with complete data to create an additive scoring system (Table 1). Pts were then stratified into 4 groups: Low [(n=429 (19.3%), score 0)], Low-Intermediate [(n=686 (30.8%), score 0.5-1], Intermediate-High [(n=917 (41.2%), score 1.5-2.5] and High [(n=195 (8.8%), score 3-5]. Each group showed significantly different OS (Figure 1A) and PFS (Figure 1B). Median OS was not reached vs 109.2 vs 68.5 vs 37.9 months and median PFS was 68 vs 45.5 vs 30.2 vs 19.9 months in the above 4 risk groups, respectively. With this new stratification model, R-ISS stage II pts (n=1372) were better distributed into Low-Intermediate (n=517), Intermediate-High (n=811) and High risk (n=44) groups, confirming that this wide group included heterogeneous pts with a different risk of progression and/or death. This new risk stratification maintained its prognostic value in subgroup analysis of transplant-eligible and transplant-ineligible pts and in pts receiving IMiDs, PIs or both. Conclusion. This analysis on a large number of patient data collected thanks to a well-established European collaboration demonstrated that the existing R-ISS stratification model may be improved. This additive scoring system based on the impact of single risk features could be the future risk stratification model for NDMM, so called "R2-ISS". About half of the pts can be classified as Low or Low-Intermediate risk and about half of the pts can be classified as Intermediate-High or High risk, representing an opportunity to design risk-adapted approaches in a meaningful number of pts. Moreover, such additive risk score easily allows the inclusion of new prognostic variables in the future as they continue to emerge. The inclusion of new patient data is ongoing, and validation in an independent cohort is planned. Disclosures D'Agostino: GSK: Membership on an entity's Board of Directors or advisory committees. Waage:Janssen: Consultancy, Honoraria, Speakers Bureau; Takeda: Consultancy; Shire: Honoraria. Zamagni:Sanofi: 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; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Speakers Bureau; 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. Mateos:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: 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; Janssen-Cilag: Consultancy, Honoraria; PharmaMar-Zeltia: Consultancy; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie/Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: 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. Larocca:Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: 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; Amgen: Honoraria; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria. van de Donk:Takeda: Other: Ad Board; Genentech: Other: Ad Board; Bayer: Other: Ad Board; BMS: Other: Ad Board, Research Funding; Amgen: Other: Ad Board, Research Funding; Celgene: Other: Ad Board, Research Funding; Novartis: Other: Ad Board; Janssen: Other: Ad Board, Research Funding. Cairns:Celgene, Amgen, Merck: Research Funding; Celgene: Other: Travel Support. Salwender:Takeda: Honoraria; Bristol-Myers Squibb/Celgene: Honoraria; Janssen-Cilag: Honoraria; Amgen: Honoraria; Oncopeptides: Honoraria; Sanofi: Honoraria; GlaxoSmithKline: Honoraria; AbbVie: Honoraria. Blade Creixenti:Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Dürig:Janssen: Consultancy; AbbVie: Consultancy; Celgene: Consultancy. Bringhen:Karyopharm: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Zweegman:Sanofi: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Cavo:AbbVie: Consultancy, 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, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: 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 accomodations, Speakers Bureau; GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Goldschmidt:Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product:, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product:, Research Funding; Dietmar-Hopp-Foundation: Other: Grants and/or provision of Investigational Medicinal Product:; Molecular Partners: Research Funding; Merck Sharp and Dohme (MSD): Research Funding; Novartis: Honoraria, Research Funding; Johns Hopkins University: Other: Grants and/or provision of Investigational Medicinal Product; Chugai: Honoraria, Other: Grants and/or provision of Investigational Medicinal Product:, Research Funding; Incyte: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product:, Research Funding; University Hospital Heidelberg, Internal Medicine V and National Center for Tumor Diseases (NCT), Heidelberg, Germany: Current Employment; GlaxoSmithKline (GSK): Honoraria; Adaptive Biotechnology: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Mundipharma GmbH: Research Funding; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding. Cook:Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; IQVIA: Research Funding; Sanofi: Consultancy; Amgen: Consultancy; Roche: Consultancy; Karyopharm: Consultancy. San-Miguel:Amgen, BMS, Celgene, Janssen, MSD, Novartis, Takeda, Sanofi, Roche, Abbvie, GlaxoSmithKline and Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees. Boccadoro:Sanofi: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; AbbVie: Honoraria; Mundipharma: Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees. Sonneveld:Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Skyline Dx: Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy. OffLabel Disclosure: The presentation includes discussion of off-label use of a drug or drugs for the treatment of multiple myeloma.

Background. Proteasome inhibitor (PI)-based induction/consolidation proved to be effective in newly diagnosed multiple myeloma (NDMM) patients (pts) eligible for melphalan 200 mg/m2 plus autologous stem-cell transplantation (MEL200-ASCT). High response rates have been reported with carfilzomib (K) plus lenalidomide-dexamethasone (KRd) or cyclophosphamide-dexamethasone (KCd). Lenalidomide (R) alone is a standard of care for post-ASCT maintenance; K maintenance showed promising results in phase I/II studies, but no data on KR maintenance vs R are available. Aims. The aims of this analysis were to evaluate the progression-free survival (PFS) of KRd induction-ASCT-KRd consolidation (KRd_ASCT) vs 12 cycles of KRd (KRd12) vs KCd induction-ASCT-KCd consolidation (KCd_ASCT) and the PFS of KR vs R maintenance. Secondary aims were efficacy in different subgroups of pts and safety of the maintenance phase. Methods. NDMM pts ≤65 years were randomized [R1: 1:1:1, stratification International Staging System (ISS) and age] to: KRd_ASCT: 4 28-day cycles with KRd induction (K 20/36 mg/m2 IV days 1,2,8,9,15,16; R 25 mg days 1-21; dexamethasone [d] 20 mg days 1,2,8,9,15,16) followed by MEL200-ASCT and 4 KRd consolidation cycles; KRd12: 12 KRd cycles; KCd_ASCT: 4 28-day induction cycles with KCd (K 20/36 mg/m2 IV days 1,2,8,9,15,16; cyclophosphamide 300 mg/m2 days 1,8,15; d 20 mg days 1,2,8,9,15,16) followed by MEL200-ASCT and 4 KCd consolidation cycles. Thereafter, pts were randomized (R2) to maintenance with KR (K 36 mg/m2 days 1,2,15,16, subsequently amended to 70 mg/m2 days 1,15 for up to 2 years; plus R 10 mg days 1-21 every 28 days until progression) or R alone (10 mg days 1-21 every 28 days until progression). Centralized minimal residual disease (MRD) evaluation (8-color second-generation flow cytometry, sensitivity 10-5) was performed in pts achieving ≥very good partial response before maintenance and every 6 months (m) during maintenance. Data cut-off was June 30, 2020. Results. 474 NDMM pts were randomized (KRd_ASCT, n=158; KRd12, n=157; KCd_ASCT, n=159) and analyzed. Pt characteristics were well balanced. Intention-to-treat (ITT) data of pre-maintenance MRD (KRd_ASCT, 62%; KRd12 56%, KCd_ASCT 43%) and safety of the induction/consolidation phases in the 3 arms were already reported (F. Gay et al. ASH 2018; S. Oliva et al. ASH 2019). After a median follow-up from R1 of 45 m, median PFS was not reached with KRd_ASCT, 57 m with KRd12 and 53 m with KCd_ASCT (KRd_ASCT vs KCd_ASCT: HR 0.53, P During maintenance, a similar proportion of pts experienced ≥1 grade (G)3-4 hematologic adverse events (AEs)/serious AEs (SAEs) in the 2 arms (KR 22% vs R 23%); the most frequent were neutropenia (KR 18% vs R 21%) and thrombocytopenia (KR 3% vs R 3%). Rate of ≥1 G3-4 non-hematologic AEs/SAEs was higher with KR (27%) compared with R (15%), P=0.012; the most frequent were infections (KR 4% vs R 7%); all other events were reported in ≤5% of pts and included: gastrointestinal (KR 5% vs R 2%), cardiac (KR 4% vs R 1%), hypertension (KR 3% vs R 0%), and thrombotic microangiopathy (3% vs 0%). 4 pts developed a second primary malignancy in KR (breast 1 pt; thyroid 1 pt; myelodysplastic syndrome 1 pt; non-melanoma skin cancer 1pt) vs 1 pt in R (acute lymphoblastic leukemia). Dose reductions of R were reported in 23% of KR and 29% of R pts; dose reductions of K were reported in 20% of pts. The rate of discontinuation due to AEs was similar in the 2 arms (KR 10% vs R 9%). Conclusions. Treatment with KRd_ASCT significantly improved PFS compared with both KRd12 and KCd_ASCT. Maintenance with KR also improved PFS vs R. Figure Disclosures Gay: 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; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; 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. Musto:Celgene: Honoraria; Amgen: Honoraria. Galli:BMS: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Takeda: Honoraria. Belotti:Jannsen: 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. 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; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, 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; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Speakers Bureau. 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. De Sabbata:Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: 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. Liberati:VERASTEM: Honoraria, Research Funding; ROCHE: Honoraria, Research Funding; PFIZER: Honoraria, Research Funding; ONCOPEPTIDES AB: Honoraria, Research Funding; TAKEDA: Honoraria, Research Funding; MORPHOSYS: Honoraria, Research Funding; ONCONOVA: Honoraria, Research Funding; ABBVIE: Honoraria, Research Funding; NOVARTIS: Honoraria, Research Funding; KARYOPHARM: Honoraria, Research Funding; INCYTE: Honoraria; JANSSEN: Honoraria; CELGENE: Honoraria; AMGEN: Honoraria; BMS: Honoraria; BEIGENE: Honoraria; ARCHIGEN: Honoraria; BIOPHARMA: Honoraria; FIBROGEN: Honoraria. Offidani:Janssen: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Cavo:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Speakers Bureau; Sanofi: 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, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Karyopharm: Honoraria; Amgen: 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, Other: Travel accomodations, Speakers Bureau. Boccadoro: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; Celgene: Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Research Funding; Amgen: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding. 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).

Background Copy-number alterations of chromosome 1q are frequently found in multiple myeloma (MM) and are associated with poor prognosis. Recently, it has been demonstrated that the number of 1q copies correlates with a high-risk behavior (BA Walker et al, Leukemia 2019, TM Schmidt et al, Blood Cancer J 2019), but no data are available in carfilzomib-treated patients (pts). Here we aim at dissecting the role of Gain1q (3 copies of 1q) vs amplification 1q (Amp1q, ≥4 copies of 1q) in carfilzomib-treated NDMM pts enrolled in the randomized FORTE trial (NCT02203643). Methods Fluorescence in situ hybridization (FISH) in CD138+ purified bone marrow plasma cells (BMPCs) was centralized and performed at baseline. Two hundred BMPC nuclei from each sample were scored. The cut-off level for Gain1q was 10% of nuclei with ≥3 copies of 1q (mean plus 3 standard deviations of 1q alterations in BMPC from 15 healthy donors). The cut-off for Amp1q was 20% of nuclei with ≥4 copies of 1q. In the FORTE trial, transplant-eligible NDMM pts were randomized 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 to receive KR vs R maintenance. Results A total of 474 pts were enrolled. Median follow-up from 1st randomization was 45 months (m). Evaluation of 1q by FISH was missing in 70 pts (15%), while in 4 pts (1%) FISH was present but the number of 1q copies was not evaluable. Among evaluable pts, chromosome 1q was normal in 219 (55%) pts, Gain1q was found in 129 (32%) pts, while Amp1q in 52 (13%). Gain1q- and Amp1q-positive pts were well distributed among treatment arms. Baseline characteristics associated with Amp1q, compared to Gain1q, were LDH >upper limit of normal (P=0.002) and low hemoglobin (P=0.029) and platelets (P=0.044). Best response to therapy was not significantly different in Normal 1q vs Gain1q vs Amp1q groups (≥very good partial response rates: 85% vs 84% vs 77%; stringent complete response rates: 52% vs 50% vs 38%). Best overall minimal residual disease negativity by flow cytometry (sensitivity 10-5) pre-maintenance was also not significantly different (55% vs 55% vs 44%, respectively). In a multivariate analysis adjusted for treatment and Revised International Staging System (R-ISS), the risk of progression/death was significantly higher in the presence of Gain1q vs Normal 1q (HR 1.65, 95% CI 1.14-2.37, P=0.007) and the highest in the presence of Amp1q as compared to both Normal 1q (HR 3.04, 95% CI 1.99-4.65, P Median progression-free-survival (PFS) was not reached in the Normal 1q group, while Gain1q (53 m) and especially Amp1q (21.8 m) groups performed very poorly. The presence of Amp1q vs Normal 1q (HR 5.88, 95% CI 3.10-11.17, P Subgroup analysis on the presence/absence of concomitant high-risk features was performed. Gain1q predicted a lower PFS compared to Normal 1q in the presence of concomitant standard-risk features (ISS 1, ISS 2, standard-risk cytogenetics) but not in the presence of high-risk disease (ISS 3, high-risk cytogenetics). On the other hand, the worse prognosis of Amp1q pts was confirmed across all subgroups. A subgroup analysis according to the upfront treatment received was performed. Interestingly, treatment with KRd_ASCT completely abrogated the risk conferred by Gain1q (HR 1.25 vs Normal 1q, 95% CI 0.58-2.7, P=0.565), while Amp1q-positive pts still showed a very poor outcome (median PFS 17 m, HR 6.03 vs Normal 1q, 95% CI 2.78-13.1, P In KCd_ASCT and KRd12-treated pts, the 3 groups performed similarly to the overall population. Conclusion This is a first report on the prognostic role of the number of 1q copies in carfilzomib-treated NDMM pts. Having ≥4 copies of 1q universally predicts a very poor PFS and OS despite the use of a 2nd generation proteasome inhibitor upfront. On the other hand, KRd_ASCT completely abrogated the PFS disadvantage conferred by 3 copies of 1q. RNA sequencing on representative samples of Normal 1q vs Gain1q vs Amp1q is in progress to explore differentially expressed genes in Amp1q pts that could be exploited in future treatment strategies. Figure 1 Disclosures D'Agostino: GSK: Membership on an entity's Board of Directors or advisory committees. Giuliani:Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Participation in congresses, Research Funding; Janssen Pharmaceutical: Membership on an entity's Board of Directors or advisory committees, Other: Clinical study sponsorship; participation in congresses, Research Funding; Millennium Pharmaceutical: Other: Clinical study sponsorship, Research Funding; GSK: Other: Clinical study sponsorship, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Other: Participation in congresses. Tacchetti:Amgen: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Takeda: Honoraria; AbbVie: Honoraria; Oncopeptides: Honoraria; Bristol-Myers Squibb: Honoraria. Musto:Amgen: Honoraria; Celgene: Honoraria. Boccadoro:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; AbbVie: Honoraria; Mundipharma: Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding. Gay:Amgen: 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; Roche: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: 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; 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; Bristol-Myers Squibb: Honoraria, 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).

Background Despite an improvement in treatment response, high-risk multiple myeloma (MM) patients (pts) experience early relapse and short disease-free survival. Together with more validated high-risk features, high levels of circulating plasma cells (high CPC) have been considered a marker of aggressive disease and poor outcome (F. Gay et al, ASH 2019; W.I. Gonsalves et al, Am J Hematol 2020). To date, there are no uniform data on the optimal cut-off predictive of clinical outcome. No prospective data on CPC are available in the setting of novel-drug clinical trials with comprehensive baseline evaluation and minimal residual disease (MRD) assessment. Aims 1) To identify the best cut-off for CPC to predict progression-free survival (PFS); 2) to assess the impact of high CPC levels on the clinical outcome of newly diagnosed (ND)MM pts in the context of concomitant risk features and MRD evaluation. Methods In the multicenter randomized FORTE clinical trial, 474 NDMM pts ≤65 years were randomized (R1) to receive either: carfilzomib-lenalidomide-dexamethasone (KRd) induction-autologous stem-cell transplant-KRd consolidation (KRd_ASCT); KRd for 12 cycles (KRd12); or carfilzomib-cyclophosphamide-dexamethasone (KCd) induction-ASCT-KCd consolidation (KCd_ASCT). Thereafter, pts were randomized (R2) to maintenance treatment with lenalidomide alone (R) or plus carfilzomib (KR). MRD was assessed by 2nd-generation multiparameter flow cytometry (MFC, sensitivity 10-5) in pts who achieved ≥very good partial response before maintenance and then every 6 months. At diagnosis, single-platform FC was used to sort and count CPC. Receiver Operating Characteristic (ROC) analysis was used to define a cut-off based on PFS at 36 months as outcome. Correlations between high CPC and the most important baseline prognostic features (age, International Staging System (ISS), lactate dehydrogenase (LDH), chromosomal abnormalities (CA) by FISH [(del17p, t(4;14), t(14;16), t(11;14), amp1q, del1p, del13], Revised-ISS (R-ISS)) were explored. Hence, we performed a multivariate (MV) analysis to assess the impact of high CPC on the achievement of MRD negativity, on PFS and OS. Finally, we evaluated the impact of baseline CPC and MRD achievement. Results CPC analysis was performed in 401/474 pts at diagnosis; median follow-up was 44.2 months (39.6-47.9) and baseline features were similar to those reported in the overall FORTE population. Median CPC were 0.02% (IQR 0-0.14). The optimal CPC cut-off to predict PFS (ROC analysis) was 0.07% (5 cells/ul, 0.005 x109/l) and was consistent with a cut-off previously identified as a predictor of sustained MRD negativity (MRDsus12; L. Bertamini et al, EHA 2020). High-CPC pts (>0.07%) were 130/401 (32%), while 271/401 (68%) had low CPC (≤0.07%). The proportion of high-CPC pts was comparable among treatment arms. Baseline features significantly associated with high CPC in a MV analysis were: ISS II/III, high LDH, amp1q, t(4;14), t(14;16) and bone marrow plasma cells (>60%). Regarding PFS, in a MV analysis adjusted for R-ISS and R1 treatment, including all the baseline features, high CPC were associated with a lower PFS (HR 2.49, 95% CI 1.76-3.51, P The impact of baseline CPC levels on PFS was consistent in all high-risk subgroups (Fig. 1C), except in those patients who achieved pre-maintenance MRD negativity [(neg); interaction P=0.03]. Low-CPC and MRD-neg pts showed the best outcome with a 3-year PFS of 84%. Low-CPC MRD-positive (pos) and high-CPC MRD-neg pts had similar 3-year PFS (70% vs 68%). High-CPC MRD-pos pts had a dismal outcome (3-year PFS 32%; Fig. 1D). Conclusion High CPC with a cut-off of 0.07% (5 cells/ul, 0.005 x109/l) is a strong and independent high-risk factor, predicting a shorter PFS and OS even in the context of other high-risk features. The achievement of MRD neg independently improved the poor prognosis of high-CPC patients. Figure 1 Disclosures D'Agostino: GSK: Membership on an entity's Board of Directors or advisory committees. Galieni:Janssen: Honoraria; AbbVie: Honoraria; Takeda: Honoraria; Celgene: Honoraria. Molica:Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Tacchetti:Oncopeptides: Honoraria; AbbVie: Honoraria; Takeda: Honoraria; Amgen: Honoraria; Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; Janssen: Honoraria. Musto:Amgen: Honoraria; Celgene: Honoraria. Gay:GSK: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: 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; 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; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Boccadoro:GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; AbbVie: Honoraria; Mundipharma: Research Funding. 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. 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).

Background: 18F-FDG-PET/CT is currently the standard technique to define imaging-minimal residual disease (MRD) in multiple myeloma (MM) patients. A joint analysis of 2 prospective randomized trials in newly diagnosed transplant-eligible MM (NDTEMM) patients applied for the first time the Deauville Scores (DS) to focal lesions (FS) and bone marrow uptake (BMS) showing the liver background (DS < 4) as the best cut-off to define PET/CT negativity after therapy and complete metabolic response (CMR) (Zamagni et al, ASH 2018). Validation of this new standardized criteria in an independent prospective series of NDTEMM patients is highly required. Imaging-PET/CT MRD also showed to be complementary to Multiparameter Flow Cytometry (MFC) in predicting patient's outcomes (Moreau P, JCO 2017). In this analysis, we aimed at confirming the applicability and validity of DS criteria to define PET/CT CMR and showing their impact on patient's outcomes in the multicenter phase II randomized FORTE trial for NDTEMM patients. We also looked at the complementarity with BM techniques, especially MFC. Methods: NDTEMM patients ≤ 65 years were randomized to receive carfilzomib, lenalidomide, dexamethasone (KRD) induction - autologous stem cell transplantation (ASCT) intensification-KRd consolidation (arm A); KRd12 (arm B) and carfilzomib, cyclophosphamide, dexamethasone (KCd) induction-ASCT intensification-KCd consolidation (arm C). Thereafter, patients were randomized to maintenance with lenalidomide alone or plus carfilzomib. PET/CT scans were performed locally at baseline (B) and prior to the start of maintenance (PM). DS were applied both in the BM and FLs, as previously described (Zamagni E, EHA 2020). CMR was defined as DS < 4 both in the FLs and BM. MRD evaluation was performed by 8-color second-generation flow cytometry (sensitivity 10-5) in patients who achieved at least VGPR before maintenance (Gay F, ASCO 2019). The impact of each parameter on outcomes was evaluated by landmark analyses at PM. A multivariable Cox regression analysis was adopted to identify independent predictors for PFS and OS. Results: 182 out of the 474 global patients enrolled in the trial had a pre- and post-treatment PET/CT evaluation available and were included in this analysis. Patients' baseline characteristics were: median age 57 years, ISS and R-ISS stage III 18% and 10%, respectively, high-risk cytogenetics (t(4;14) ± del(17p) ± t(14;16), detected by FISH) 26%, reflecting baseline clinical features of the entire FORTE population. At B, 93% of patients had FLs, with a median maximum standardized uptake value (SUVmax) of 5.7 [IQR: 4.1-8.1], 7% presented extra-medullary lesions and nearly all patients had increased BM uptake, with a median SUVmax of 3.4 [IQR: 2.8-4.3]. FS and BMS ≥ 4 were present in 87% and 57% of patients, respectively. At PM, PET/CT negativity according to DS < 4, was present in 80% in the FLs and 85% in the BM, respectively. 63% showed CMR. 92% and 61% of patients achieved ≥ VGPR and CR as best response, respectively, while 73% of them achieved MFC MRD negativity. The achievement of a best CR significantly correlated with BMS < 4 at PM (P= 0.003). In univariate analysis, at Landmark time PM, FS Conclusion: In conclusion, the present analysis confirms the applicability and validity of DS criteria to define PET/CT CMR in an independent prospective series of NDTEMM patients. CMR significantly and independently correlated in uni- and multivariable analysis with patient's outcomes in terms of PFS and OS and was complementary to the MFC MRD negativity. Figure Disclosures Zamagni: Takeda: Honoraria, Other: Travel, Accommodations, Expenses, Speakers Bureau; Celgene Corporation: 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; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, 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. Gay:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: 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; Celgene: 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; Janssen: 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. Galli:Takeda: Honoraria; Janssen: Honoraria; Celgene: Honoraria; BMS: 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. Rivolti:Celgene: Membership on an entity's Board of Directors or advisory committees. Tacchetti:Bristol-Myers Squibb: Honoraria; AbbVie: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Oncopeptides: Honoraria; Janssen: Honoraria; Amgen: Honoraria. Fanti:Bayer, Astellas, GE Healthcare, ANMI, Janssen: Membership on an entity's Board of Directors or advisory committees; Bayer, Astellas, GE Healthcare, Sanofi, AAA: Honoraria. Boccadoro:Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria; Mundipharma: Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Amgen: Honoraria, Research Funding. Cavo:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: 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; BMS: 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, Other: Travel accomodations, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel accomodations, Speakers Bureau; GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria. Musto:Amgen: Honoraria; Celgene: Honoraria. Oliva:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; 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; Celgene: Honoraria.

Background. Infections represent a major cause of toxicity in newly diagnosed multiple myeloma (NDMM) patients, and their incidence is higher during the first 4 months of therapy (Dumontet, Leukemia 2018). The use of prophylactic levofloxacin for the first 3 months of therapy demonstrated to reduce rates of infections (Dryson, Lancet Hematol 2019). However, factors predicting the risk of infections in patients treated with novel agents and the need for antimicrobial prophylaxis for all vs selected patients remain under debate. We investigated the incidence of severe infections and associated baseline risk-factors in NDMM patients. Methods. Data from Italian patients enrolled in clinical trials and receiving carfilzomib-based (IST-CAR-506, IST-CAR-561), bortezomib-based (EMN02) and lenalidomide-based (EMN01, RV-MM-PI-0752, RV-MM-EMN-441) treatment were pooled together and analyzed. The primary aim of the analysis was to evaluate the incidence of severe infections, defined as any grade (G) 3-5 event or G2 if involving the lung/lower respiratory tract (CTCAE version 4.0). The rate of early severe infections (i.e. infections occurring during the first 4 months of treatment) was also analyzed. Secondary goals were to identify baseline factors associated with an increased risk of early severe infections and to evaluate the impact of early severe infections on treatment outcome. Results. A total of 1892 patients were included in the analysis. Median age was 65 years, 970 (51%) patients were transplant eligible (TE) and 922 (49%) transplant ineligible (NTE). Overall, 1059 (56%) patients received IMiD-based induction therapy and 833 (44%) a PI-based induction therapy. Median follow-up was 68 months. We recorded 898 infections of any grade, of which 436 (49%) were considered severe. Most frequent severe infections included lung/lower respiratory tract infection (50%), febrile neutropenia (23%) and sepsis/septic shock (10%). Overall, severe infections occurred when myeloma response to treatment was ≤PR in 62% of cases, VGPR in 29% and sCR/CR in 9%. 654 (35%) patients reported at least 1 infection of any grade and 377 (20%) patients at least one severe infection. Early infections (first 4 months) occurred in 243 patients (13%) and early severe infections in 129 patients (6.8%). Overall, 21 patients (1.1%) died due to infection, of whom 6 during the first 4 months. In a multivariate analysis (Table), main factors associated with increased risk of early severe infections were ISS stage 3 (OR 2.14, 95% CI 1.32-3.48), presence of del17p by FISH (OR 1.80, 95% CI 1.1-2.96), intermediate fit status (OR 1.88 95% CI 1.1-3.21) and frail status (OR 2.12, 95% CI 1.08-4.18) according to IMWG frailty score (Palumbo, Blood 2015). No difference in risk of early severe infections was observed according to induction treatment with PI vs IMiD (OR 1.10, 95%CI 0.68-1.78). In a time-dependent Cox regression analysis adjusted for potential confounders (age, RISS stage and performance status), the risk of disease progression/death was significantly higher in patients who had an early severe infection compared to patients without early severe infection (median PFS 21.3 months vs 31.3 months, HR 1.32, 95% CI 1.07-1.63, p Conclusions. We found that 34% of patients experiencing severe infections had the event during the first 4 months of therapy. Patients with aggressive disease and elderly frail patients are at higher risk of early severe infections, hampering treatment adherence and efficacy, and eventually affecting PFS and OS. Identifying patients more susceptible to severe infections through easily available parameters could pave the way for the evaluation of risk-adapted antimicrobial prophylaxis in clinical trials. Table 1 Disclosures D'Agostino: GSK: Membership on an entity's Board of Directors or advisory committees. Offidani:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Petrucci:BMS: 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; 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; 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; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Liberati:JANSSEN: Honoraria; AMGEN: Honoraria; CELGENE: Honoraria; ROCHE: Honoraria, Research Funding; PFIZER: Honoraria, Research Funding; ONCOPEPTIDES AB: Honoraria, Research Funding; TAKEDA: Honoraria, Research Funding; MORPHOSYS: Honoraria, Research Funding; ONCONOVA: Honoraria, Research Funding; ABBVIE: Honoraria, Research Funding; NOVARTIS: Honoraria, Research Funding; KARYOPHARM: Honoraria, Research Funding; BMS: Honoraria; BEIGENE: Honoraria; ARCHIGEN: Honoraria; BIOPHARMA: Honoraria; FIBROGEN: Honoraria; INCYTE: Honoraria; VERASTEM: Honoraria, Research Funding. Benevolo:Amgen: Honoraria; Celgene: Honoraria; Novartis: Honoraria. Gaidano:Sunesys: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astrazeneca: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Galli:Takeda: Honoraria; Janssen: Honoraria; Celgene: Honoraria; BMS: Honoraria. Corradini:Janssen: Consultancy, Honoraria; Incyte: Consultancy; Gilead: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Daiichi Sankyo: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Amgen: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Sanofi: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Other; BMS: Other; KiowaKirin: Consultancy, Honoraria; Kite: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Other: Travel and accommodations paid by for; F. Hoffman-La Roche Ltd: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Other: Travel and accommodations paid by for. Conticello:Amgen, Takeda, Janssen: Honoraria. Cavo:Novartis: 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, Other: Travel accomodations, 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; GlaxoSmithKline: Honoraria, Speakers Bureau; Karyopharm: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; 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 accomodations, Speakers Bureau. Sonneveld:Skyline Dx: Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding. Boccadoro:Mundipharma: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria. Bringhen:Bristol-Myers Squibb: Honoraria; Takeda: Consultancy; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, 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. OffLabel Disclosure: The presentation includes discussion of off-label use of a drug or drugs for the treatment of multiple myeloma (including carfilzomib, cyclophosphamide, dexamethasone, bortezomib, melphalan, prednisone and lenalidomide).

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 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 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).

Introduction Multiple Myeloma (MM) is characterized by hyperdiploidy (HD) or immunoglobulin gene (IgH) rearrangements as initiating events. Clonal heterogeneity is a hallmark of its biology as highlighted by Next Generation Sequencing. In this context, data on the impact of peculiar mutations, copy number aberrations (CNAs), and chromosomal rearrangements (CRs) at the transcriptomic level are still scanty. In this study, we aimed to dissect the transcriptional deregulation promoted by the most recurrent genomic drivers. Based on this geno-trascriptomic link, we also aimed to identify biomarkers that could suggest personalized treatments. Methods We analyzed 517 newly diagnosed patients from the IA12 release of the CoMMpass study, focusing on mutations in MM driver genes, structural variants, copy number segments and raw transcript counts. RNAseq data was processed with the VOOM/LIMMA pipeline. To perform an in-silico drug sensitivity screen, we anchored cell lines to patients samples using the Celligner algorithm and interrogated the DepMap dataset. Results We first analyzed the global impact of genetic aberrations on the transcriptome. Chr(1q)amp/gain, followed by IgH translocations and HD showed the highest number of deregulated transcripts. Individual mutations had much less impact, with the exception of NRAS and chr(13q) genes (DIS3, TGDS, RB1). Next, we investigated differential influence between hotspots (HS) vs nonHS mutations within driver genes. KRAS and NRAS, showed little changes between nonHS and wild type (WT), as the transcriptome was mostly impacted by HS mutations. IRF4 K123 showed a specific transcriptional profile, while nonHS mutations still carried functional relevance although on different genes. For BRAF, the kinase dead D594 mutation surprisingly impacted the most in comparison to V600 and WT cases. Next, we explored the effect of bi-allelic genetic events with known prognostic impact. TP53 double-hits were associated with an upregulation of PHF19, a MM poor prognostic marker, and downregulation of SLAMF7, a new immunotherapy target. CYLD and TRAF3 double-hits correlated with NF-κB pathway activation, and the former showed a significant BCL2 upregulation. Bi-allelic events on chr13 exhibited gene-specific consequences: DIS3 inactivation deregulated mostly lncRNAs, while TGDS impacted on genes involved in cell-cycle regulation. Regarding chromosomal gains, only chr(1q)amp (> 3 copies) showed a gene dosage effect with upregulation of the potential therapeutic targets MCL1 and SLAMF7. Given that the BCL2 axis was perturbated by several genetic alterations, we systematically compared the expression levels of BCL2, NOXA, MCL1 and BCL2L1 in CYLD inactivated, t(11;14) and chr(1q)amp patients. BCL2 levels were higher in the CYLD group, which parallels with the overexpression of the anti-apoptotic gene BCL2L1. NOXA, which promotes MCL1 degradation, was significantly upregulated in t(11;14). Chr(1q)amp patients showed a concomitant MCL1 overexpression and NOXA downregulation. To correlate these results to drug sensitivity, we performed an in-silico screen. We first selected MM and lymphoma cell lines from the DepMap dataset based on a gene expression profile that was most similar to the MM samples, then analyzed candidate drugs. The SKMM2 MM cell line, harboring t(11;14), del(CYLD) e NOXAamp was highly sensitive to Venetoclax. The same was true for the lymphoma ones RI1 and OCI-LY3, both harboring NOXAamp, but negative for t(11;14). On the contrary, the U266 and MOLP8 both with t(11;14) carrying a MCL1amp due to a chr(1q)amp were fully resistant. Of note, these latter resulted sensitive to the pan-BCL2 axis inhibitor Sabutoclax. Conclusions Our study suggests a link between the genomic architecture and transcriptome in MM, where CNAs and CRs had a stronger impact on expression than gene mutations. However, given that not all mutations are identical, HS ones need further testing as they may represent a future treatment target. Moreover, the mutational status is crucial since, while mono-allelic events are often of little transcriptional value, compound heterozygosity carries a huge influence on transcriptomic which provides biological basis for the observed prognostic impact of "double-hit" MM. Finally, we suggest that a comprehensive profiling of the BCL2 pathway may identify biomarkers of sensitivity to BCL2 inhibitors in addition to the t(11;14). Disclosures D'Agostino: GSK: Membership on an entity's Board of Directors or advisory committees. Corradini:Celgene: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Sanofi: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Incyte: Consultancy; Daiichi Sankyo: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Other; BMS: Other; F. Hoffman-La Roche Ltd: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Novartis: Consultancy, Honoraria, Other: Travel and accommodations paid by for; Servier: Consultancy, Honoraria; Kite: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Other: Travel and accommodations paid by for; KiowaKirin: Consultancy, Honoraria. Bolli:Celgene: Honoraria; Janssen: Honoraria.

Background. The outcome of multiple myeloma (MM) patients is heterogeneous. In 2015, analyzing 4445 newly diagnosed MM (NDMM) patients enrolled into 11 clinical trials after a median follow-up of 46 months, a risk stratification algorithm named Revised-ISS (R-ISS) was developed combining International Staging System (ISS), chromosomal abnormalities (CA) detected by interphase fluorescent in situ hybridization and serum lactate dehydrogenase (LDH) (Palumbo et al., JCO 2015). Here we report a mature follow-up of 5584 patients enrolled in 14 clinical trials, providing an updated report on the R-ISS prognostic role and highlighting potential improvements. Methods. Data from different European cooperative groups were collected through the European Myeloma Network (EMN) and registered in a big data platform developed by HARMONY, which is a European public-private partnership focusing on hematologic malignancies with unmet medical needs and providing a legal-ethical framework for international data sharing and analysis. The primary end point of this analysis was overall survival (OS) according to R-ISS. All NDMM patients received immunomodulatory agents (IMiDs) or proteasome inhibitors (PIs) as part of their upfront treatment. Results. 5584 NDMM patients with a median age of 65 years were analyzed after a median follow-up of 74 months. 35% of evaluable patients had ISS I disease, 40% ISS II and 25% ISS III. LDH was ≤ the upper limit of normal (ULN) in 87% of evaluable patients, >ULN in 13%. To define high-risk CA, we performed a multivariate Cox model for OS individually evaluating del(17p), t(4;14) and t(14;16) positivity. Del(17p) (HR 1.78, p Overall, 3674 patients (66%) had complete ISS, CA and LDH data and were thus eligible for R-ISS analysis. Baseline characteristics and OS of patients with complete vs incomplete data (median OS 80.6 vs 80.2 months, p=0.95) were similar, excluding a selection bias. R-ISS I was calculated as ISS I, no high-risk CA [del(17p) and/or t(4;14)] and normal LDH; R-ISS III was calculated as ISS III and high-risk CA or high LDH; R-ISS II included all the other possible combinations. 962 (26.2%) patients had R-ISS I disease, 2334 (63.5%) R-ISS II and 378 (10.3%) R-ISS III. Median OS was 158.6 months for R-ISS I, 71.1 months for R-ISS II and 36.6 months for R-ISS III patients (Figure 1). 5-year OS rates were 80%, 56% and 34%, while 10-year OS rates were 60%, 33% and 13% for R-ISS I, II and III respectively. In a multivariate Cox model, R-ISS II vs I (HR 2.20, 95% CI 1.94-2.5), R-ISS III vs I (HR 4.58, 95% CI 3.88-5.4), male sex (HR 1.20 vs female sex, 95% CI 1.09-1.31) and age >65 years (HR 1.62 vs ≤65 years, 95% CI 1.47-1.78) significantly increased the risk of death (p The prognostic role of R-ISS was confirmed by subgroup analyses on: transplant-eligible patients [2161, 58.8%; both receiving (1611, 43.8%) or not receiving (550, 15.0%) transplant]; transplant-ineligible patients (1513, 41.2%); and patients receiving PIs (874, 23.8%), IMiDs (1669, 45.4%) or both (1131, 30.8%). We next tested whether additional factors can impact OS in a multivariate Cox model including R-ISS, age and sex. NDMM patients with an IgA monoclonal component showed a worse OS compared to non-IgA patients (HR 1.21, p1 or Karnofsky Conclusion. We confirmed the prognostic role of R-ISS within the largest cohort of NDMM patients analyzed so far. Moreover, we detected other independent OS predictors that can help us to further refine the current prognostic method. The addition of new datasets is planned; the improvement of the current R-ISS may foster a worldwide collaboration. Disclosures Lahuerta: Takeda, Amgen, Celgene and Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bertsch:Celgene: Other: travel support; Sanofi: Other: travel support. Zamagni:Celgene Corporation: Honoraria, Other: Advisory board, Speakers Bureau; Janssen: Honoraria, Other: Advisory board, Speakers Bureau; Amgen: Honoraria, Other: Advisory board, Speakers Bureau; BMS: Honoraria, Other: Advisory Board, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Sanofi: Honoraria, Other: Advisory Board, Speakers Bureau. Bullinger:Seattle Genetics: Honoraria; Janssen: Honoraria; Hexal: Honoraria; Gilead: Honoraria; Celgene: Honoraria; Daiichi Sankyo: Honoraria; Bristol-Myers Squibb: Honoraria; Bayer: Other: Financing of scientific research; Astellas: Honoraria; Amgen: Honoraria; Abbvie: Honoraria; Sanofi: Honoraria; Pfizer: Honoraria; Novartis: Honoraria; Menarini: Honoraria; Jazz Pharmaceuticals: Honoraria. Larocca:Amgen: Honoraria; 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; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Mateos:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmamar: Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria; EDO: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Celgene: 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. Van De Donk:Roche: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; AMGEN: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding. Salwender:Janssen Cilag: Consultancy, Honoraria, Other: Travel grants; Celgene: Honoraria, Other: Travel grants; AMGEN: Honoraria, Other: Travel grants; Sanofi: Honoraria, Other: Travel grants; Bristol-Myers Squibb: Honoraria, Other: Travel grants; Takeda: Honoraria, Other: Travel grants; Oncopeptides: Honoraria, Other: Travel Grants. Bladé:Jansen, Celgene, Takeda, Amgen and Oncopeptides: Honoraria. Tacchetti:Janssen: Honoraria; BMS: Honoraria; Oncopeptides: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau. Zweegman:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Goldschmidt:Chugai: Honoraria, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Adaptive Biotechnology: Membership on an entity's Board of Directors or advisory committees; MSD: Research Funding; Dietmar-Hopp-Foundation: Other: Grants and/or provision of Investigational Medicinal Product; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Molecular Partners: Research Funding; Novartis: Honoraria, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; ArtTempi: Honoraria; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Research Funding; John Hopkins University: Other: Grants and/or provision of Investigational Medicinal Product. Cavo: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; 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; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel accommodations, Speakers Bureau. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria. Sonneveld:SkylineDx: Research Funding; Takeda: Honoraria, Research Funding; Karyopharm: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; BMS: Honoraria; Amgen: Honoraria, Research Funding. Boccadoro:Sanofi: 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; Celgene: Honoraria, Research Funding. OffLabel Disclosure: This presentation includes discussion of off-label use of a drug or drugs for the treatment of multiple myeloma.

Osteolytic bone disease has a significant impact on both quality of life and overall survival of patients with multiple myeloma (MM). Given that bone and immune cells share the same microenvironment and interact with each other via cytokines, signaling molecules and regulatory proteins in the bone marrow (Tsukasaki M et al., Nat Rev Immunol 2019), we sought to elucidate the effect of osteoclasts (OCs) on the immune microenvironment. Specifically, T cells significantly suppress differentiation of OCs through signaling crosstalk between RANKL and IFN-γ (Takayanagi H et al., Nature 2000). However, little is known regarding the effect of OCs on the immune system. Here we investigated the effect of OCs on immune cells, especially on T cells. Dysregulation of several checkpoint molecules has been shown in MM (Kwon M et al., J Immunol 2017). We, therefore, assessed the expression of various immune checkpoint receptors, such as PD-1, TIGIT, OX40 and CD137 on T cells in co-culture with or without autologous OCs by multi-color flow cytometry. OC co-culture significantly increased co-inhibitory checkpoint (PD-1 and TIGIT) through direct contact, while decreasing co-stimulatory checkpoint (OX40 and CD137) in CD3+ T cells. Expression of the checkpoint ligand, PD-L1 was significantly increased on MM cells in the presence of both T cells and OCs compared to the presence of T cells alone. Conversely, OCs in the absence of T cells did not induce significant increase of PD-L1 on MM cells. According to previous literature, PD-L1 expression on MM cells is induced in part by IFN-γ (Liu J et al., Blood 2007). Interestingly, our data demonstrated that OCs activated IFN-γ producing T cells in co-culture conditions. Furthermore, we observed that T cell and OC-mediated upregulation of PD-L1 on MM cells was partially reversed by using IFN-γ neutralizing antibody. This implies that OCs indirectly induce PD-L1 upregulation on MM cells by enhancing IFN-γ secretion from T cells. In addition, we found that naïve CD4+ T cells have a higher propensity to differentiate into Th17 lineage in the presence of Th17 differentiation cytokines when co-cultured with OCs. Moreover, we observed an increased expansion of Th17 cells in co-culture with OCs. Those Th17 cells also showed a similar pattern of dysregulation of immune checkpoint axes. Our study demonstrates that OCs positively regulate co-inhibitory checkpoint molecules and negatively regulate co-stimulatory molecules on T cells. These findings indicate that OCs play an important role in inhibiting T cell-mediated antitumor immunity. Targeting OCs may help restore impaired immune surveillance in MM in addition to their critical role in preventing lytic bone lesions in MM. These data may support the role of antiresorptives in immune surveillance with indirect anti-tumor effects. Disclosures No relevant conflicts of interest to declare.

Introduction : Cytogenetic abnormalities by fluorescence in situ hybridization (FISH) are clinically relevant prognostic factors in MM. Data in transplant ineligible patients treated with bortezomib or lenalidomide in first-line therapy for high-risk (HiR) patients is limited. Careful analysis of cytogenetic subgroups in trials comparing different treatments remains an important goal. This sub-analysis evaluates the impact of cytogenetics on outcomes in transplant-ineligible patients with newly diagnosed MM (NDMM) treated with bortezomib-based induction (BORT) or lenalidomide-based (LEN) treatment. Methods : In the GIMEMA-MM-03-05-trial, patients were randomized to bortezomib-melphalan-prednisone-thalidomide for 9 cycles followed by maintenance with bortezomib-thalidomide (VMPT-VT) vs VMP for 9 cycles, without maintenance. In the EMN01-trial, patients were randomized to melphalan-prednisone-lenalidomide (MPR) or cyclophosphamide-prednisone-lenalidomide (CPR) or lenalidomide plus low-dose dexamethasone (Rd) for 9 cycles, followed by maintenance with lenalidomide alone or plus prednisone continuously. Results of these studies have previously been reported (Palumbo A et al JCO 2010 and 2014; Magarotto V et al Blood 2016 127(9)). Cytogenetics were assessed using FISH. Patients were categorized into cytogenetic risk groups according to International Myeloma Working Group criteria. HiR cytogenetics included del(17p), t(4;14), and t(14;16); all other patients were categorized as standard risk (StR). Subgroup analyses were performed to determine the consistency of treatment effects of BOR vs LEN in the different subgroups using interaction terms between treatment and FISH, ISS, age, sex, Karnofsky PS and LDH. The different effect of BORT vs LEN in cytogenetic subgroups was confirmed by one sensitivity analysis where the follow-up of the BORT study was reduced to make the follow-up times similar; and by another sensitivity analysis with multiple imputation method for missing cytogenetic value. Results : 902 of 1165 patients from the intent-to-treat population had available cytogenetic profiles, with 243 (27%) patients in the HiR group and 659 (73%) in the StR group. In the BORT vs LEN groups, median age was 71 vs 73 years (p In the subgroup analysis, a significant difference was found in the cytogenetic subgroup with a superior advantage of BORT versus LEN in HiR group, whereas no significant difference was found between BORT and LEN in the other subgroups analyzed (ISS, age, sex, Karnofsky PS and LDH) (interaction-p=0.01) (Fig. 1 B). BORT treatment resulted in a reduced risk of death or progression compared with LEN in patients with HiR. In HiR patients, median PFS was 30.8 with BORT compared with 14.8 months with LEN (HR: 0.54; 95% CI: 0.41-0.72); in StR, median PFS was 29.1 with BORT compared with 22.1 months with LEN (HR: 0.87; 95%; CI: 0.72-1.05) (Fig. 1 A). Considering the standard of care VMP and Rd, in the HiR group (n=95) VMP resulted in a 48% reduced risk of death or progression compared with Rd (HR: 0.53; 95% CI: 0.34-0.83), whereas no significant difference in PFS was found in the StR group (n=273) (HR: 1.00; 95% CI: 0.75-1.33), interaction-p=0.02. BORT treatment resulted in a reduced risk of death in patients with HiR cytogenetics: median OS was 62.4 months with BORT compared with 43.2 months with LEN (HR: 0.68; 95% CI: 0.47-0.96); in StR, median OS was 78.1 months with BORT and was not reached with LEN (HR: 1.06; 95% CI: 0.82-1.36), interaction-p=0.04 (Fig. 1 A). In patients with del(17p) (n=131) median PFS was 18.0 vs 12.9 months for BORT vs LEN (HR: 0.71; 95% CI: 0.49-1.04), interaction-p=0.73. In patients with t(4;14) (n=118) median PFS was 31.5 vs 15.2 months for BORT vs LEN (HR: 0.41; 95% CI: 0.27-0.62) interaction-p=0.002. In patients with t(14;16) (n=31) median PFS was 36.2 vs 9.8 months for BORT vs LEN treated patients (HR: 0.34; 95% CI: 0.16-0.76), interaction-p=0.045. Conclusions : BORT treatment resulted in a PFS and OS benefit vs LEN in patients with HiR cytogenetics. Treatment with VMP led to a significant reduction of the risk of death or progression vs Rd in HiR patients. These results support VMP induction as a standard treatment option for patients with NDMM who are ineligible for transplant with HiR cytogenetics. Disclosures Larocca: Celgene: Honoraria; Janssen: Honoraria; Bristol-Myers Squibb: Honoraria; Amgen: Honoraria. Offidani: 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. Musto: Janssen: Honoraria; Celgene: Honoraria. Patriarca: MSD Italia: Honoraria; Janssen: Honoraria. Corradini: Gilead: Honoraria; Amgen: Honoraria; Janssen: Honoraria; Roche: Honoraria; Celgene: Honoraria; Sanofi: Honoraria; Takeda: Honoraria; Novartis: Honoraria. Bosi: Amgen: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees. Petrucci: Celgene: Honoraria; Janssen: Honoraria; Bristol-Myers Squibb: Honoraria; Takeda: Honoraria; Amgen: Honoraria. Boccadoro: Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Mundipharma: Research Funding; AbbVie: Honoraria.

Introduction: High throughput techniques, such as massively parallel sequencing, are becoming an attractive approach to characterize multiple myeloma (MM) genomic profiles. However, the clinical relevance and contribution to risk assessment of such approaches need to be established. The Multiple Myeloma Research Foundation (MMRF)CoMMpass trial (NCT01454297) has collected data from 1000 newly-diagnosed MM patients enrolled worldwide and observed through an expected follow-up of up to eight-years. Comprehensive analysis of somatic mutations detected in purified MM cells could reveal disease features with prognostic value, which may not have been detected using traditional approaches. Materials and methods: We analyzed data from the interim analysis 8 cohort. CD138+ purified MM specimens from bone marrow aspirates and mononuclear cells from peripheral blood were collected at diagnosis. Whole exome libraries from both tumor and constitutional DNA samples were created. Somatic single nucleotide variants (SNV) were identified using three different variant callers (Seurat,Strelka andMutect), only nonsynonymous SNV calls made from at least two callers were included in the analysis. Patients were analyzed on an intention-to-treat basis. We evaluated the impact on progression free survival (PFS) of recurrently mutated genes (with at least a nonsynonymous SNV in more than 10 patients) in a Cox model adjusted for international staging system (ISS) and cytogenetic profile (high risk, standard risk and missing). An additive score related to mutated genes was calculated on the basis the level of each coefficient estimated using a Cox Model with backward selection based on theAkaikeInformation Criterion (AIC). Results: 517 patients with baseline somatic mutation data were included in the analysis. Median age at diagnosis was 64 years (range 27-93). All patients received novel agents as first line treatment; 236 (45.6%) received autologous stem cell transplantation (ASCT). Each patient showed a median number of 55 nonsynonymous somatic SNV (range 8-1970) in a median number of 47 genes (range 5-1741). Excluding immunoglobulin genes, the most recurrent mutated genes were KRAS (25%), NRAS (19.5%), TTN (12.1%), MUC16 (9.1%) and DIS3 (9.1%). Based on the results of a multivariable Cox model corrected for ISS and cytogeneticprofile, we created a scoring system determined by the mutational status of 9 genes identified in a nonbiased manner (Table 1). Three groups were identified: group I (score 0-2, 17%); group II (score=3, 51%), and group III (score >3, 32%). After a median follow-up of 371 days, the 18-month PFS rate was 93% for group I, 85% for group II, and 67% for group III. In a Cox model adjusted for ISS and cytogeneticprofile, the hazard ratio was 2.34 (p=0.112) for group II versus group I, and 5.96 (p Conclusion: The use of a prognostic model based on the mutational status of 9 recurrently mutated genes could improve risk assessment of newly-diagnosed MM patients. To our knowledge, this is the largest study correlating nonsynonymous somatic SNV with MM patients' outcome. Longer follow-up and validation in independent cohorts are needed to confirm our findings. Disclosures Larocca: Amgen, Celgene, BMS, Janssen-Cilag: Honoraria. Gay:Amgen: Honoraria; Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Membership on an entity's Board of Directors or advisory committees. Palumbo:Janssen Cilag: Honoraria; Takeda: Employment, Honoraria.

BACKGROUND: Suicide gene therapy applied to haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is one of the widest clinical applications of gene therapy. By the infusion of donor lymphocytes transduced to express the Herpes Simplex Virus Thymidine Kinase (TK) suicide gene, patients achieve a rapid immune reconstitution and substantial protection against tumor recurrence. TK-cells are promptly eliminated in case of graft versus host disease (GvHD), with complete resolution of the adverse reaction. In previous studies, we showed that TK-cell infusions are necessary and sufficient to promote the generation of a fast, polyclonal and full competent T cell repertoire. In the present work we characterize the immunological profile of a cohort of long-term survivors after suicide gene therapy and we studied the long-term fate of TK-cells to shed light on memory T cell dynamics after transplantation. RESULTS: We studied 9 adult patients who underwent haplo-HSCT and infusion of purified suicide-gene modified donor T cells (median dose: 1.9x107 cells/kg, range:0.9x106-39.5x106) for high-risk hematologic malignancies between 1995 and 2010 (TK patients). At a median follow-up of 7,4 years (range 3.2-12.3), all patients are in complete remission. Two out of 9 patients (22%) experienced GvHD in the early phase post immune reconstitution; in all cases, ganciclovir (GCV) administration proved effective in abrogating the adverse reaction. No symptoms or complications related to GvHD were observed during the long-term follow up, and none of the patient is receiving immunosuppressive drugs. A complete recovery of NK cells, B lymphocytes and αβ or γδ T cells was observed. The CD8+ and CD4+ T cell compartment of TK patients were characterized by level of naïve and memory cell comparable to age and sex matched healthy controls. The quantification of CD4+ CD31+ CD62L+ CD45RA+ CD95- recent thymic emigrants and measure of single joint T-cell receptor excision circles demonstrated that the normalization of the T cell compartment was supported by a completely recovered thymic output. TK-cells were detected in all patients (100%), at low levels (median=4cells/uL). Ex vivo selection of pure TK-cells after polyclonal stimulation and LNGFR-purification confirmed the presence of functional transduced cells, thus directly demonstrating the ability of memory T cells to persist for years. Of notice TK-cells could be retrieved also in patients successfully treated with GCV for GvHD, thus confirming the selective action of GCV only on proliferating TK-cells. Accordingly, GCV sensitivity was preserved in long-term persisting TK-cells, independently from their differentiation phenotype. TK-cells circulating in patients displayed a memory phenotype comprising effector memory (TEM), central memory (TCM) and stem memory (TSCM) T cells and exhibited a low level of Ki-67 positivity, thus suggesting the maintenance of a pool of gene modified memory cells through homeostatic proliferation. The number of TK-cells circulating at the longest follow-up did not correlate with the number of infused cells, nor patients or donors’ age, but instead with the peak of TK-cells observed within the first months after infusion, suggesting that antigen recognition is dominant in driving in vivo expansion and persistence of memory T cells. We evaluated whether the phenotype of infused TK-cells was able to affect the long-term fate of gene-modified memory T cells. We observed that the number of infused TSCM cells positively correlated with early TK-cell expansion and with their long-term persistence, suggesting that TSCMmight play a privileged role in the generation of a long-lasting immunological memory. CONCLUSION: These data show that a complete and physiological donor-derived immune system is restored in adult surviving long-term after suicide gene therapy. After infusion, gene modified cells persist for up to 12 years in treated patients. This setting can be exploited to investigate the requirements at the basis of the generation of a long-lasting immunological memory in vivo. Further studies on TK-cell TCR repertoire and vector integrations are currently being performed to elucidate the in vivo dynamics of infused memory T cells. Disclosures Lambiase: MolMed S.p.A: Employment. Traversari:MolMed S.p.A: Employment. Bordignon:MolMed S.p.A: Chairman and CEO Other. Bonini:MolMed S.p.A: Consultancy.