Carfilzomib Weekly-Melphalan-Prednisone In Untreated Elderly Multiple Myeloma Ifm2012-03

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.