A study involving 30 cancer centers in the United States and Canada yielded durable responses to and an acceptable tolerability profile for carfilzomib (Kyprolis), which was approved last month by the FDA for the treatment of advanced multiple myeloma. The results of this trial were published online ahead of print by the journal Blood a few days later.

In the open-label, single-arm, phase 2b study, a team led by David S. Siegel, MD, PhD, chief of multiple myeloma at the John Theurer Cancer Center at Hackensack University Medical Center in Hackensack, New Jersey, evaluated this next-generation, selective proteasome inhibitor for the treatment of relapsed and refractory multiple myeloma. Carfilzomib 20 mg/m2 was administered intravenously twice weekly for 3 of 4 weeks, and then in doses of 27 mg/m2 for up to 12 cycles.

The 266 evaluable patients had received at least two prior therapies, including bortezomib, lenalidomide, and thalidomide. Most patients (95%) had not responded to their last therapy, and 80% were refractory to or intolerant of both bortezomib and lenalidomide.

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With carfilzomib, overall response rate was 23.7%, with a median duration of response of 7.8 months and a median overall survival of 15.6 months. Adverse events were manageable without cumulative toxicities; common adverse events were fatigue (49%), anemia (46%), nausea (45%), and thrombocytopenia (39%). A total of 33 patients (12.4%) experienced peripheral neuropathy, primarily grades 1 and 2, and the same number of patients withdrew from the study due to an adverse event.

The researchers concluded that durable responses and the acceptable tolerability profile in this heavily pretreated population demonstrated the potential of carfilzomib to offer meaningful clinical benefit, particularly given the limited number of treatment options available to persons with advanced-stage multiple myeloma and the diminished prospects for retreatment once a therapy has been used.