Background: Twice a week carfilzomib at 27 mg/m 2 is approved for treatment of relapsed or refractory multiple myeloma. Phase 1/2 CHAMPION-1, the first study exploring once-weekly carfilzomib dosing, established the maximum tolerated dose at 70 mg/m 2 in combination with dexamethasone. We aimed to compare progression-free survival in patients with relapsed and refractory multiple myeloma given once weekly carfilzomib or twice weekly carfilzomib. Methods: In this prespecified interim analysis of the randomised, open-label, phase 3 A.R.R.O.W. trial, we recruited patients (aged 18 years and older) with relapsed and refractory multiple myeloma previously treated with two or three treatments, including a proteasome inhibitor and immunomodulatory agent, from hospital, clinic, oncology or medical centres. Key eligibility criteria were refractory to most recent therapy (including bortezomib or ixazomib) with measurable disease, and Eastern Cooperative Oncology Group Performance Status of 0 or 1. Patients were randomly assigned (1:1) to receive carfilzomib once a week (70 mg/m 2 ) or twice a week (27 mg/m 2 ). The randomisation sequence was generated using a validated randomisation software and implemented using an interactive response technology system that assigned patients to treatment sequentially based on the randomisation sequence as patients were enrolled at participating clinical sites. Patients were stratified by International Staging System stage at study entry or baseline, whether or not they were refractory to bortezomib treatment, and age (block size of 4). The once weekly group received carfilzomib (30 min intravenous infusion) on days 1, 8, and 15 of all cycles (20 mg/m 2 day 1 [cycle 1]; 70 mg/m 2 thereafter). The twice weekly group received carfilzomib (10 min intravenous infusion) on days 1, 2, 8, 9, 15, and 16 (20 mg/m 2 days 1 and 2 during cycle 1; 27 mg/m 2 thereafter). All patients received dexamethasone (40 mg on days 1, 8, 15 [all cycles] and 22 [cycles 1–9 only]). Treatment continued until disease progression or unacceptable toxic effects. The primary objective was to compare progression-free survival between groups in the intention-to-treat population. Safety analysis was done in all randomly assigned patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, number NCT02412878, and is no longer enrolling patients. Findings: Between September, 2015, and August, 2016, 578 patients were recruited from 118 sites. 478 patients were randomly assigned and included in the efficacy analyses (240 to receive once weekly carfilzomib; 238 to receive twice weekly carfilzomib). Median progression-free survival was higher in the once weekly group than the twice weekly group (11·2 months [95% CI 8·6–13·0] vs 7·6 months [5·8–9·2]; hazard ratio [HR] 0·69, 95% CI 0·54–0·83; p=0·0029). The incidence of grade 3 or worse adverse events was higher in the once weekly group than the twice weekly group (68% [n=161] vs 62% [n=145]); the most common events were anaemia, pneumonia, and thrombocytopenia (42 [18%] vs 42 [18%], 24 [10%] vs 16 [7%], and 17 [7%] vs 16 [7%], respectively for once weekly carfilzomib vs twice weekly carfilzomib). A lower proportion of patients had grade 3 or worse cardiac failure in the once weekly group (7 [3%]) than in the twice weekly group (10 [4%]). Treatment-related deaths occurred in five (2%) of 238 patients in the once weekly group (sepsis [n=1], death [n=1], acute lung injury [n=1], acute respiratory distress syndrome [n=1], and tumour lysis syndrome [n=1]) and in two (1%) of 235 patients in the twice weekly group (plasma cell myeloma [n=1] and congestive heart failure [n=1]). There were 58 deaths in the once weekly group and 68 deaths in the twice weekly group at the time of data cutoff. Interpretation: Once weekly carfilzomib at 70 mg/m 2 significantly prolonged progression-free survival versus the twice weekly schedule. Overall safety was comparable between the groups. Once weekly carfilzomib appears safe and more effective with a convenient dosing regimen versus the twice weekly schedule for the treatment of patients with relapsed and refractory multiple myeloma. Funding: Amgen, Inc.
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