(ChemotherapyAdvisor) – Carfilzomib is effective and well tolerated in multiple myeloma patients that have failed to respond to 5 or more lines of therapy, according to a team of US-based researchers. This conclusion is based on a study entitled “A phase 2 study of single-agent carfilzomib (PX-171-003-A1) in patients with relapsed and refractory multiple myeloma,” which was published online in Blood on July 25.

Using an open-label, single-arm design, eligible patients received single-agent carfilzomib (20mg/m2, iv, 2X/week for 3 of 4 weeks in Cycle 1, then 27mg/m2 for ≤12 cycles) until they reached the primary end point—overall response rate (ORR; ≥partial response). “Secondary end points included clinical benefit response rate (≥minimal response), duration of response (DOR), progression-free survival, overall survival (OS), and safety,” the investigators wrote.

Of the 266 patients evaluable for safety and 257 evaluable for efficacy, 95% were refractory to their last therapy and 80% were refractory or intolerant to both bortezomib and lenalidomide. Prior to enrollment in this study, the patient population had already received a median of 5 prior lines of therapy, including bortezomib, lenalidomide, and thalidomide.

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The following results were reported. Treatment with carfilzomib yielded an ORR of 23.7%, median DOR of 7.8 months, and median OS of 15.6 months. In terms of tolerability, adverse events (AEs) were manageable without cumulative toxicities, with the most common AEs being fatigue (49%), anemia (46%), nausea (45%), and thrombocytopenia (39%). However, 33 patients (12.4%) withdrew from the study due to an AE.

The investigators concluded: “Durable responses and an acceptable tolerability profile in this heavily-pretreated population demonstrate the potential of carfilzomib to offer meaningful clinical benefit.”