Final results from the phase Ib/II study (PX-171-006) of carfilzomib, lenalidomide, and low-dose dexamethasone (CRd) in patients with relapsed or progressive multiple myeloma.

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8529 Background: Carfilzomib (CFZ) is approved in the US as single-agent treatment for patients with multiple myeloma (MM) who have progressed after bortezomib (BTZ) and an IMiD and are refractory to last line of treatment. We previously reported interim data from PX-171-006 (NCT00603447), a Ph 1b/2 study of CRd in relapsed or progressive MM (Wang et al. ASCO 2011). Herein we report final results. Methods: Patients (1–3 prior treatments) received CRd in 28-day (D) cycles—CFZ IV on D1, 2, 8, 9, 15, 16, lenalidomide (LEN) PO D1–21, and dexamethasone (dex) wkly. In phase 1, CFZ (15–27 mg/m2) and LEN (10–25 mg) doses were escalated to determine the maximum tolerated dose (MTD) with a maximum planned dose (MPD) of CFZ 20 mg/m2 D1, 2 of Cycle 1 and 27 mg/m2 thereafter, LEN 25 mg/d, and dex 40 mg/wk, followed by phase 2 expansion at MTD/MPD. Endpoints included IMWG overall response rate (ORR), duration of response (DOR), progression-free survival (PFS), and safety. Results: A total of 84 patients were enrolled since June 2008. Overall, prior treatment included BTZ (77%/18% refractory) and LEN (70%/35% refractory); 20% had high-risk cytogenetics/FISH. MTD was not reached in Ph 1, supporting expansion at the MPD (n=52, 23% BTZ refractory and 42% LEN refractory). As of Nov 2012 (median follow-up 24.4 mo): ORR was 69% overall and 76.9% at MPD with very good partial response in 36.9% and 38.5% and stringent complete response in 3.6% and 3.8%, respectively; median DOR was 18.8 (95% CI 9.7–41.5) and 22.1 mo (95% CI 9.5–NE) respectively; median PFS was 11.8 (95% CI 7.6–20.7) and 15.4 mo (95% CI 7.9–NE), respectively. Seven responders at MPD pursued other therapy and were censored for PFS.A median of 8.5 (range 1−46) CFZ cycles were started; 4% required CFZ dose reductions; 15% discontinued CFZ due to adverse events (AEs). Grade 3/4 AEs were generally consistent with earlier studies in advanced MM that used similar doses of single-agent CFZ; grade 3/4 peripheral neuropathy was 1%. Conclusions: CRd was well tolerated, providing robust and durable responses in this pt population where 35% were LEN refractory. This combination is being further evaluated in several ongoing phase 2/3 trials. Clinical trial information: NCT00603447.