Randomized phase II study of weekly carfilzomib 70 mg/m(2) and dexamethasone with or without cyclophosphamide in relapsed and/or refractory multiple myeloma patients

In this randomized phase II study (GEM-KyCyDex, clinicaltrials gov. Identifier: NCT03336073), the combination of weekly carfilzomib 70 mg/m2, cyclophosphamide and dexamethasone (KCd) was compared to carfilzomib and dexamethasone (Kd) in relapsed/refractory multiple myeloma (RRMM) after 1-3 prior lines (PL). One hundred and ninety-seven patients were included and randomized 1:1 to receive KCd (97 patients) or Kd (100 patients) in 28-day cycles until progressive disease or unacceptable toxicity occurred. Patient median age was 70 years, and the median number of PL was one (range, 1-3). More than 90% of patients had previously been exposed to proteasome inhibitors, approximetely 70% to immunomodulators, and approximetely 50% were refractory to their last line (mainly lenalidomide) in both groups. After a median follow-up of 37 months, median progression-free survival (PFS) was 19.1 and 16.6 months in KCd and Kd, respectively (P=0.577). Of note, in the post hoc analysis of the lenalidomide-refractory population, the addition of cyclophosphamide to Kd resulted in a significant benefit in terms of PFS: 18.4 versus 11.3 months (hazard ratio =1.7, 95% confidence interval: 1.1-2.7; P=0.043). The overall response rate and the percentage of patients who achieved complete response was around 70% and 20% in both groups. The addition of cyclophosphamide to Kd did not result in any safety signal, except for severe infections (7% vs. 2%). In conclusion, the combination of cyclophosphamide with Kd 70 mg/m2 weekly does not improve outcomes as compared with Kd alone in RRMM after 1-3 PL, but a significant benefit in PFS was observed with the triplet combination in the lenalidomide-refractory population. The administration of weekly carfilzomib 70 mg/m2 was safe and convenient, and, overall, the toxicity was manageable in both arms.Acknowledgments: The authors would like to thank to Roberto Maldonado for his help with data management and Philip Mason for language revision of the manuscript. Funding: The PETHEMA Foundation sponsored the trial. The manufacturer of carfilzomib (Amgen) supplied the drugs free of charge and financially supported the trial, but was not involved in the analysis, interpretation, or decision to publish the trial. Additionally, this study was supported by the International Myeloma Society