Carfilzomib Weekly Plus Melphalan and Prednisone in Newly Diagnosed Elderly Multiple Myeloma (IFM 2012-03)

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.