Abstract: Background: The role of maintenance lenalidomide in myeloma, following autologous stem cell transplantation (ASCT) or not, is well established. However, 29% of patients discontinue the treatment with a median duration of less than 2 years with an increased rate of secondary primary malignancies (SPM). Pomalidomide could provide alternative maintenance therapy. Methods: This was a single arm phase II study of pomalidomide/dex (PD) maintenance therapy for MM patients (pts) in first relapse after treatment in the IFM 2009 trial. At first relapse, 100 pts received pomalidomide/cyclophosphamide/dex (PCD) for 4 cycles, after which half underwent ASCT (if no first line transplant) followed by 2 cycles of PCD consolidation (Arm A), or 5 cycles of PCD (if previously transplanted) (Arm B). All pts then received maintenance therapy consisting of 28-day cycles of pomalidomide 4 mg daily on days 1-21 and dex 20 mg once a week until progression (Blood 2018). The primary objective was to establish the safety and efficacy of PD as maintenance therapy. Results: A total of 75 pts were enrolled in the maintenance phase from January 2015 to November 2017 (Table 1) and the database was locked on 07/07/2021. The median age was 60 (range 39-70); 67% (50/75) were male. 53 pts had ISS stage I, 10 stage II and 3 stage III disease (9 missing). Infectious prophylaxis was antiviral in 94%, sulfamethoxazole/trimethoprim in 76%, penicillin in 69% and fluoroquinolone in 38%. A granulocyte colony stimulating factor was administered in 15 (20%) pts and immunoglobulins in 13 (17%). One quarter had thromboprophylaxis. The median follow-up was 73 months (95% CI: 68-75). Among the 75 pts, 63 (84%) left the study, 34 (54%) due to progressive disease, 19 (30%) due to AE/SAE, 7 (11%) on investigator (PI) discretion and 3 (5%) after consent withdrawal. 12 (16%) remained on therapy in July 2021.The median duration of maintenance was 23.7 months (IQR: 14.5-44). Pts received a median of 26 cycles (range 1-80) and 17 (23%) had 50 or more cycles. The reasons for pomalidomide discontinuation were progression or death in 54%, AE/SAE in 30%, PI decisions in 11% and patient decisions in 5%. 56 (75%) pts required a reduction in the dose of pomalidomide due to AE/SAE in 50%, omission in 19%, resumption of treatment in 11%, PI decisions in 16% and patient decisions in 2.7%. The reasons for dex discontinuation were progression or death in 30%, AE/SAE in 43%, PI decisions in 22% and patient decisions in 3%. 57 (76%) pts required a reduction in the dose of dex due to AE/SAE in 54%, omission in 3.4%, resumption of treatment in 0.3%, PI decisions in 38.7% and patient decisions in 3.1%. 31 SAE were reported in 22 pts: 13 (42%) infections, 5 tumors, 1 case of thrombosis, 1 diabetic ketoacidosis and 12 others. Grade 3/4 hematologic AE included neutropenia (51%), lymphopenia (35%), anemia and thrombocytopenia (0%). G3/4 drug-related non-hematologic AE ( & gt;5%) comprised 13% infections (5% pneumonia). G1/2 AE included 69% infections (49% bronchitis), 49.3% gastrointestinal disorders (20% diarrhea, 20% constipation), 48% fatigue, 31% skin disorders, 25% muscle spasms, 24% insomnia and 14.7% eye disorders (6.7% cataracts, 4% dry eyes). Concerning peripheral neuropathy, one patient had G3/4 and 45% G1/2. Eight pts developed SPM: 4 basocellular carcinoma, 1 epidermoid carcinoma, 1 melanoma, 1 colon carcinoma and 1 non small cell bronchial carcinoma. We observed an improvement in the response from the initiation of treatment: PR: 32.4 to 17.4%, VGPR: 56.8 to 49.3%, CR: 9.5 to 28%, sCR: 0 to 5.3% (at initiation to best response, respectively). A total of 33.4% of pts improved their response. The median PFS was 33.2 months (95% CI: 25.6-53.3). 41 pts died and the median OS was not reached (95% CI: 70.7-NR). All deaths were related to myeloma progression except 2 due to pulmonary infection, 1 lung carcinoma and 1 colorectal cancer. Conclusions: In the first relapse PCD trial, 75% initiated maintenance therapy. Long term administration of pomalidomide/dexamethasone as maintenance therapy is feasible. Thirty percent stopped pomalidomide because of SAE/AE, mostly related to hematologic AE, but this could be managed with dose reductions. There was generally G1/2 neuropathy, rare SPM and no other unexpected toxicity. One third of the pts improved their depth of response. The combination is safe, feasible and well tolerated and experience to date supports its further exploration with monoclonal antibodies. Figure 1 Figure 1. Disclosures Garderet: Amgen: Consultancy; Sanofi: Consultancy; Takeda: Consultancy; Celgene: Consultancy; Janssen: Consultancy. Roussel: Amgen: Consultancy; BMS: Honoraria; GSK: Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy. Leleu: Novartis: Honoraria; Mundipharma: Honoraria; Merck: Honoraria; Karyopharm Therapeutics: Honoraria; Janssen-Cilag: Honoraria; Gilead Sciences: Honoraria; Celgene: Honoraria; Carsgen Therapeutics Ltd: Honoraria; Bristol-Myers Squibb: Honoraria; Amgen: Honoraria; AbbVie: Honoraria; Oncopeptides: Honoraria; Pierre Fabre: Honoraria; Roche: Honoraria; Sanofi: Honoraria; Takeda: Honoraria, Other: Non-financial support. Karlin: Takeda: Honoraria, Other: member of advisory board; Amgen: Honoraria, Other: travel support and advisory board ; Sanofi: Honoraria; Abbvie: Honoraria; oncopeptide: Honoraria; GSK: Honoraria, Other: member of advisory board; Janssen: Honoraria, Other: member of advisory board, travel support; Celgene-BMS: Honoraria, Other: member of advisory board. Perrot: Abbvie: Honoraria; BMS 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; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Honoraria, Research Funding; GSK: 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. Moreau: Abbvie: Honoraria; Oncopeptides: Honoraria; Celgene BMS: Honoraria; Amgen: Honoraria; Sanofi: Honoraria; Janssen: Honoraria. Macro: abbvie: Honoraria; sanofi: Honoraria; celgene bms: Honoraria; takeda: Honoraria; janssen: Honoraria. Jourdan: Novartis: Consultancy; Abbvie: Consultancy; bms/celgene: Consultancy. Jaccard: Pfizer: Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria. Mohty: Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Sanofi: Honoraria, Research Funding; Gilead: Honoraria; Janssen: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Takeda: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; Adaptive Biotechnologies: Honoraria. Hulin: Celgene/BMS: Honoraria; Janssen: Honoraria; Sanofi: Honoraria; Takeda: Honoraria; abbvie: Honoraria. OffLabel Disclosure: pomalidomide as maintenance treatment

Abstract: Background. Peripheral blood stem cell (PBSC) collection prior to high dose chemotherapy for autologous transplantation (ASCT) is a standard of care, and an attractive alternative to the use of bone marrow cells, for transplantation in Multiple Myeloma (MM). The optimal methodology for mobilizing PBSC has yet to be defined, both G-CSF and GM-CSF can be used; although, the stimulatory effect may be more pronounced when given after high dose cyclophosphamide (usually administered at a dose of 1.5 to 6g/m2 IV for one to two days) and use of Plerixafor, a CXCR4 antagonist (Mozobil®). The latter 2 options are preferred, overall, in France. Indeed, it was shown that the most recent combined bortezomib and IMids-based induction regimens used prior to ASCT in MM upfront yielded poorly or required multiple days of collection with steady state method. Because of the intense competition for hospital resources and the staff required to evaluate and manage patients preparing for stem cell mobilization and transplantation, it is reasonable to attempt to quantify the total impact of stem cell mobilization on available staff resources and cost to the hospital, especially when newer therapies, i.e. plerixafor is available and may be more suitable for some of these patients. We aimed at better evaluate the burden of stem cell mobilization on the hospital of the 2 techniques of mobilization, either high dose endoxan (n=57) versus plerixafor (n=55); this study will not, however, evaluate the suitability or advisability of one therapy versus another. Method and Results . This is a retrospective observational cohort database analysis of 112 consecutive patients with MM treated upfront with ASCT between 2009 and 2013 and that had been mobilized with either high dose endoxan or plerixafor from 15 IFM centers. We planned to determine the cost versus benefit of either technique taking in consideration a number of key markers that influence the mobilization process. A cost-consequences analysis of the different regimens of mobilization will be performed. Cost will be quantified using "microcosting" approach. Only direct medical costs are included in this economic analysis. Hospital resources will be calculated using two different approaches: per diem hospitalization costs (excluding direct medical costs) versus French public diagnosis-related group (DRG). The point of view of the French Public Health System is adopted for this study. Monetary values for 2012 euros prices will be used for all components. Median (range) age was 59.5 (24-72), sex ratio was 1.5, ISS 3 was 26% in either group, all patients were collected to allow the number of graft requested by the hematologist of reference. The median CD34 collected was 8.9 (4-30) for HD cyclophosphamide and 5.8 (2-15) for plerixafor. All data will be updated at ASH 2016 including cost comparison. Conclusion. Because of the intense competition for hospital resources and the staff required to evaluate and manage patients preparing for stem cell mobilization and transplantation, it is reasonable to attempt to quantify the total impact of stem cell mobilization on available staff resources and cost to the hospital, especially when newer therapies, i.e. plerixafor is available and may be more suitable for some of these patients. Disclosures Macro: Janssen: Consultancy, Honoraria; Bristol: Consultancy; Celgen: Consultancy, Honoraria; Novartis: Honoraria; sanofi: Consultancy; Amgen: Consultancy, Honoraria. Hulin:celgene: Honoraria; janssen: Honoraria; takeda: Honoraria. Attal:sanofi: Consultancy; celgene: Consultancy, Research Funding; janssen: Consultancy, Research Funding; amgen: Consultancy, Research Funding. Moreau:Novartis: Honoraria; Bristol-Myers Squibb: Honoraria; Takeda: Honoraria; Amgen: Honoraria; Janssen: Honoraria, Speakers Bureau; Celgene: Honoraria. Leleu:TEVA: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; LeoPharma: Honoraria; Pierre Fabre: Honoraria; Amgen: Honoraria; Bristol-Myers Squibb: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Janssen: Honoraria.

Abstract: Background Induction therapy followed by autologous stem cell transplantation (ASCT) is the standard of care for patients with symptomatic multiple myeloma less than 66 years old. The quality of response to the induction treatment is an important prognostic factor and is predictive of progression free survival (PFS) following ASCT. The triplet combinations bortezomib-thalidomide-dexamethasone (VTD) and bortezomib-cyclophosphamide-dexamethasone (VCD) have demonstrated high response rates in prospective phase 2 and phase 3 clinical trials, they are 2 of the most commonly used induction regimens prior to ASCT, and are both recommended in the International guidelines. To date, no comparative data from prospective randomized trials of the safety and efficacy of VTD vs VCD are available. This provided the rationale for the phase 3 investigation of VTD vs VCD prior to ASCT in patients with de novo MM in this randomized multicenter study (NCT01564537). Methods Patients with de novo symptomatic MM less than 66 years old were prospectively randomized to receive either 4 cycles of VTD (arm A) or 4 cycles of VCD (arm B) followed by ASCT. The VTD regimen consisted of four 21-day cycles of bortezomib 1.3 mg/m²/d, subcutaneously (SC) D1, 4, 8 and 11, Dexamethasone 40 mg/d, PO D1 to 4, D9 to 12 and Thalidomide 100 mg/d, PO D1 to D21. The VCD regimen consisted of four 21-day cycles of bortezomib 1.3 mg/m²/d, SC D1, 4, 8 and 11, Dexamethasone 40 mg/d, PO D1 to 4, D9 to 12 and Cyclophosphamide 500 mg/m²/d, PO D1, 8, 15. Patients were stratified according to ISS (1-2 versus 3) and cytogenetics (high-risk defined by 17p deletion and t(4;14) versus other).The primary endpoint was very good partial response (VGPR) rate following 4 cycles. Response was assessed in a central lab according to the IMWG criteria. Assuming a VGPR rate of 60% in the VTD arm versus 45% in the VCD arm (15% difference), the possibility to detect a statistically significant difference required the enrolment of 340 patients overall (170 per arm). Adverse events were graded using the NCI CTCAE catalogue, version 4.0. Results From 11/2013 to 02/2015, 358 patients were enrolled into the study. 18 were screening failures, and 170 were randomized each to arm A (VTD) and arm B (VCD). The median age was 60 years (range, 26-65), 62% of the patients were male, and overall, the patient characteristics were well-balanced across the 2 arms of the study. The median number of induction cycles administered in both arms was 4 (1-4). On an intent-to-treat basis, the overall response rate ( 〉 partial response [PR]) was 92.3% in arm A, including a 10.7% complete response (CR) rate and a VGPR rate of 66.7%, while in arm B the overall response rate was 84%, with a 9.5% CR and a 56.2% VGPR rate. VGPR and PR rates were significantly higher in the VTD arm with p-values of 0.04 and 0.02, respectively. Seven patients died during induction therapy (2%), 3 in arm A from infections (2) and pulmonary embolism (1), and 4 in arm B from progression to extramedullary myeloma (2) and infections (2). Grades 3 / 4 peripheral neuropathy occurred in 4% and 2.2% in Arm A and B, respectively. Grade 3/4 neutropenia was seen in 11.9% vs 22.5% in Arm A and B, respectively. Conclusion This trial is the first prospective randomized comparison of 4 cycles of VTD versus 4 cycles of VCD administered as induction therapy prior to ASCT. VTD was shown to be significantly superior to VCD in terms of VGPR and PR rates. Neuropathy rates low in both arms, while neutropenia was more frequent with VCD. Disclosures Moreau: Millennium: 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; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hulin:Celgene Corporation: Honoraria; Janssen: Honoraria; Bristol Myers Squibb: Honoraria; Amgen: Honoraria. MACRO:celgene: Membership on an entity's Board of Directors or advisory committees; jansen: Membership on an entity's Board of Directors or advisory committees; millenium: Membership on an entity's Board of Directors or advisory committees. Garderet:Bristol-Myers Squibb: Consultancy. Stoppa:Celgene: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Janssen: Consultancy, Honoraria. Facon:Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millenium: Membership on an entity's Board of Directors or advisory committees; Onyx: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Pierre Fabre: Membership on an entity's Board of Directors or advisory committees. Laribi:Hospira SAS: Research Funding. Avet-Loiseau:jansen: Membership on an entity's Board of Directors or advisory committees; onyx: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; millenium: Membership on an entity's Board of Directors or advisory committees; millenium: Membership on an entity's Board of Directors or advisory committees; celgene: Membership on an entity's Board of Directors or advisory committees; jansen: Membership on an entity's Board of Directors or advisory committees; onyx: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Attal:jansen: Honoraria; celgene: Membership on an entity's Board of Directors or advisory committees.

Abstract: In myeloma patients, trisomy 3 improved time to progression and trisomies 3 and/or 5 improved overall survival. In contrast, trisomy 21 significantly worsened overall survival.

Abstract: 8016 Background: MAIA, an ongoing phase 3 trial of transplant-ineligible patients (pts) with NDMM, demonstrated significant improvement in progression-free survival with D-Rd vs Rd alone. Assessment of pt-reported outcomes alongside efficacy endpoints provides pt perspective on their quality of survival and overall value of HRQoL while on treatments (tx). Methods: The EORTC QLQ-C30 and EQ-5D-5L questionnaires were completed by pts using an electronic device at baseline and every 3 mo during tx; interim results are presented for first 12 mo. Tx effects were assessed using repeated measures, mixed effects models and thresholds for clinically meaningful benefit were based on established criterion from the literature. Results: Compliance rates were high and comparable at baseline ( 〉 90%) and through month 12 ( 〉 80%) for both groups (D-Rd [n = 368]; Rd [n = 369] ). Improvement in Global Health Status (GHS) occurred in both groups; however, for D-Rd, significantly greater improvement was observed at cycle 3 (LS mean change; D-Rd: 4.5 [95% CI: 2.4, 6.6], Rd: 1.5 [95% CI: -0.7, 3.7] ; [p = 0.0454]) and increasing improvement occurred across all time points. Significant improvement and clinically meaningful benefit in HRQoL for D-Rd was also observed in EQ-5D-5L Visual Analog Scale (VAS) scores (LS mean change; D-Rd: 10.1 [95% CI: 8.1, 12.1] , Rd: 4.9 [95% CI: 2.8, 7.0]; [p = 0.0002] ). The VAS median time to worsening was 10 mo longer for D-Rd. Of note, meaningful differences were observed between the tx groups in two subscale scores, pain symptoms and cognitive functioning. Statistically significant less pain was reported early with D-Rd (LS mean change at cycle 3; D-Rd: -17.9 [95% CI: -20.7, -15.0], Rd: -11.0 [95% CI: -14.0, -8.1] ; [p = 0.0007]); clinically meaningful reduction in pain symptoms was sustained with D-Rd. There was a decline in cognitive functioning at cycle 12 in both tx arms, with no statistically significant differences between groups. Conclusions: Faster and sustained improvement in HRQoL was observed in pts treated with D-Rd vs Rd with similar findings reflected across pain subscale. Clinical trial information: NCT02252172.

Abstract: To evaluate the effects of daratumumab, lenalidomide, and dexamethasone (D-Rd) versus lenalidomide and dexamethasone (Rd) on patient-reported outcomes (PROs) in the phase III MAIA study. PATIENTS AND METHODS PROs were assessed on the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30-item and the EuroQol 5-dimensional descriptive system at baseline and every 3 months during treatment. By mixed-effects model, changes from baseline are presented as least squares means with 95% CIs. RESULTS A total of 737 transplant-ineligible (TIE) patients with newly diagnosed multiple myeloma were randomly assigned to D-Rd (n = 368) or Rd (n = 369). Compliance with PRO assessments was high at baseline ( 〉 90%) through month 12 ( 〉 78%) for both groups. European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30-item global health status scores improved from baseline in both groups and were consistently greater with D-Rd at all time points. A global health status benefit was achieved with D-Rd, regardless of age ( 〈 75 and ≥ 75 years), baseline Eastern Cooperative Oncology Group (ECOG) performance status score, or depth of response. D-Rd treatment resulted in significantly greater reduction in pain scores as early as cycle 3 ( P = .0007 v Rd); the magnitude of change was sustained through cycle 12. Reductions in pain with D-Rd were clinically meaningful in patients regardless of age, ECOG status, or depth of response. Similarly, PRO improvements were observed with D-Rd and Rd on the EuroQol 5-dimensional descriptive system visual analog scale score. CONCLUSION D-Rd compared with Rd was associated with faster and sustained clinically meaningful improvements in PROs, including pain, in transplant-ineligible patients with newly diagnosed multiple myeloma regardless of age, baseline ECOG status, or depth of treatment response.

Abstract: 8004 Background: Melphalan-prednisone-bortezomib (MPV) is a standard of care upfront for newly diagnosed elderly myeloma (eNDMM). Despite significant improvements on MPV’s safety profile, toxicity issues remain. Carfilzomib (K) is a novel generation proteasome inhibitor with a different safety profile from Bortezomib. Carmysap phase I/II study (twice a week Carfilzomib+MP) demonstrated K at 36mg/m² safe and active in eNDMM. We thought to study the K weekly-MP combination in eNDMM. Methods: IFM2012-03 is a multicenter phase I/II study in eNDMM (65 and older) aimed to determine the maximum tolerated dose (MTD) of K weekly. 4 cohorts of 6 patients each were recruited at K 36, 45, 56 and 70 mg/m 2 on days 1, 8, 15, 22 IV of 35-days cycles, with oral Melphalan and Prednisone from days 1 to 4 at usual doses. Patients received a 9-cycles induction followed by a K monotherapy maintenance at 36 mg/m 2 IV every 2 weeks for 1 year. 3 dose-limiting toxicities (DLTs) defined MTD at the lower N-1 dose. Results: 24 patients were included at K 36, 45, 56 and 70 mg/m². One DLT occurred at 36 mg/m² (grade 4 lymphopenia), one at 45 mg/m² (tumor lysis syndrome with grade 4 renal insufficiency), two at 56 mg/m² (grade 3 cardiac insufficiency and grade 3 febrile neutropenia) and two at 70 mg/m² (grade 3 nausea/vomiting and grade 3 hepatic cytolysis). One patient died from cardiac dysfunction considered related to K at 56 mg/m². 3 patients stopped therapy and 3 others required dose reduction of K. Following DSMB’s request a second 6-patients cohort was recruited at 70 mg/m², with increased attention around hyperhydration and monitoring HTA. We observed no DLT and no grade 3/4 adverse event in this cohort. Median age was 75 years, 56% patients were R-ISS 2 or 3. For the whole cohort (N=30), the overall response rate was 87% including 67% very good partial responses and 44% complete responses. Conclusions: The MTD of weekly K in the KMP combination is 70 mg/m² upfront for eNDMM, but it seems reasonable to recommend 56mg/m² after 75 years-old for safety reasons. KMP offers high response rates and possibly greater CR rate. However, since the CLARION study (VMP vs KMP) will not allow KMP’s approval in eNDMM in Europe, IFM decided to stop IFM2012-03 after phase I without performing phase II. Clinical trial information: NCT02302495.

Abstract: Background. New standards with increasing efficacy that are also characterized with improving the quality of life are needed for elderly myeloma patients. Although MPT and MPV regimens are remarkable in terms of efficacy, quality of life while on treatment with these 2 regimens remain an issue. The Carmysap twice weekly carfilzomib-based phase 2 study has demonstrated that Carfilzomib at the MTD of 36mg/m² might challenge bortezomib in the VMP standard. However, it has become routine practice to use bortezomib on a weekly schedule, with maintained efficacy and an improved safety profile. We sought to demonstrate that Carfilzomib Weekly plus Melphalan and Prednisone will prove strongly efficacious with acceptable safety profile and quality of life to newly diagnosed elderly multiple myeloma (eNDMM). Methods . IFM2012-03 (also called carmysap weekly) is a phase 1/2 multicenter open label single arm study to determine MTD during the phase 1 part and VGPR+CR rate during the phase 2 part of the study. The inclusion/exclusion criteria of interest were eNDMM (65 and older), with symptomatic and measurable disease, with absolute neutrophils ≥1 G/L, untransfused platelet count ≥75 G/L, hemoglobine ≥8.5 g/dL and clairance creatinine ≥ 30ml/min. We report herein the phase 1 part of the study which last cohort was completed at ASH abstract deadline. For the phase 1 part of the study, each cohort was 6 patients based, and started at 36mg/m² of carfilzomib on days 1, 8, 15, 22 using IV, 30 minutes infusion, route followed by a 13-day rest period per 35-days cycles, melphalan given at 0.25mg/kg/j and oral prednisone 60mg/m², both on days 1 to 4. The subsequent cohorts' doses for carfilzomib were 45, then 56 and finally 70mg/m². 9 cycles were planned as induction followed by a maintenance phase of weekly carfilzomib monotherapy given at 36mg/m² weekly for one year. The MTD was determined when ˃2 DLTs were observed. DLTs were considered during cycle 1 if any hematologic toxicity of grade 4 intensity or preventing administration of 2 or more of the 4 carfilzomib doses of the first treatment cycle, grade ≥3 febrile neutropenia, grade ≥3 gastrointestinal toxicities, any other grade ≥3 nonhematologic toxicity considered related to CMP by the principal investigator, grade ≥ 3 peripheral neuropathy persisting for more than 3 weeks after discontinuation of study drugs. Results. 26 NDMM patients recruited, 24 treated in the study, 6 per cohort at 36 mg/m² carfilzomib +MP, then 45 then 56, and finally at 70mg/m² which cohort cycle 1 is up and running. The median age was 74 with 10 patients older than 75 and sex ratio M/F 65. There was a DLT at 36 mg/m² carfilzomib (grade 4 lymphopenia), one at 45 (lysis syndrome complicated with grade 4 renal insufficiency, two at 56 (cardiac insufficiency grade 3 and febrile neutropenia grade 3). At ASH deadline, all patients from cohort 36 of carfilzomib have completed induction and maintenance up to cycle 6, 5/6 of cohort 45 have completed induction and started the maintenance phase, 5/6 of cohort 56 have completed cycle 6 of induction and pursue within the induction phase, and finally all patients from cohort 70 of carfilzomib are undergoing cycle 1. There are 22 SAE reported for a total of 171 cycles administered of carfilzomib +MP. So far, 3 patients (out of 24) have stopped treatment, including the 2 patients with DLTs, lysis syndrome and cardiac failure, and one patient that presented with pulmonary hypertension later in the disease course on cycle 5 of the 56mg/m² carfilzomib +MP cohort. And, an extra 3 patients have had Carfilzomib dose reduction, 2 patients at 36 from 45 and one at 45 from 56, for neutropenia grade 4, thrombocytopenia grade 4, and Dyspnea grade 3, respectively. Conclusion. The MTD of weekly carfilzomib in the combination to Melphalan and Prednisone could be determined at 70mg/m² in elderly NDMM, demonstrating the good safety profile of carfilzomib in this regimen and fragile population. The complete dataset of the entire study will be updated at ASH with response rate, survival and safety profile. Disclosures Leleu: Chugai: Honoraria; LeoPharma: Honoraria; Pierre Fabre: Honoraria; BMS: Honoraria; Novartis: Honoraria; TEVA: Honoraria; Amgen: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Janssen: Honoraria. Karlin:Janssen: Honoraria; BMS: Honoraria; Amgen: Honoraria; Sandoz: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria. Fitoussi:Sandoz: Membership on an entity's Board of Directors or advisory committees. Moreau:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: 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-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees.