Twice-weekly carfilzomib is approved at 27 and 56 mg/m2 to treat relapsed multiple myeloma patients. In the phase III study ARROW, once-weekly 70 mg/m 2 carfilzomib prolonged the median progression-free survival of relapsed multiple myeloma patients in comparison with twice-weekly 27 mg/m2 carfilzomib, without adding significant toxicity. Data were pooled from two phase I/II studies of newly diagnosed multiple myeloma patients who received nine induction cycles of carfilzomib (either 70 mg/m2 once-weekly or 36 mg/m2 twice-weekly), cyclophosphamide and dexamethasone, followed by carfilzomib maintenance. Overall, 121 transplant-ineligible patients with newly diagnosed multiple myeloma were analyzed (once-weekly, n=63; twice-weekly, n=58). We found no significant difference in median progression-free survival [35.7 months (95%CI: 23.7-not reached, NR) vs. 35.5 months (95%CI: 24.3-NR); HR: 1.39; P=0.26] and 3-year overall survival [70% [95%CI: 59%-84%) vs. 72% (95%CI: 60%-85%); HR: 1.27; P=0.5] between once-weekly and twice-weekly carfilzomib. From the start of maintenance, 3-year progression-free survival [47% (95%CI: 33%-68%) vs. 51% (95%CI: 38%-70%); HR: 1.04; P=0.92] and overall survival [72% (95%CI: 58%-89%) vs. 73% (95%CI: 59%-90%); HR: 0.82; P=0.71] were similar in the once- versus twice-weekly carfilzomib. The rate of grade 3-5 hematologic (24% vs. 30%; P=0.82) and non-hematologic (38% vs. 41%; P=0.83) adverse events was similar in the two groups. Once-weekly 70 mg/m2 carfilzomib as induction and maintenance therapy for newly diagnosed multiple myeloma patients was as safe and effective as twice-weekly 36 mg/m2 carfilzomib and provided a more convenient schedule. The trials are registered at clinicaltrials.gov identifiers: 01857115 (IST-CAR-561) and 01346787 (IST-CAR-506).
