ATLANTA, Dec. 11, 2012 /PRNewswire/ -- Pharmacyclics, Inc. (NASDAQ: PCYC) today announced follow-up findings from an ongoing, open-label, Phase 2, single-agent study suggesting that in patients with relapsed or refractory mantle cell lymphoma (MCL), both those who were bortezomib-naive and bortezomib-exposed, the investigational oral agent ibrutinib (PCI-32765) resulted in high and durable responses and was generally well tolerated. In the study, 111 patients received ibrutinib and 110 were evaluable for efficacy. The median follow-up time was 9.2 months, with a range of time to response to treatment of 1.4 to 16.4 months.
The results were presented by lead investigator Michael L. Wang, M.D., associate professor in the Department of Lymphoma and Myeloma at The University of Texas MD Anderson Cancer Center, at the 54th Annual Meeting of the American Society of Hematology (ASH) in Atlanta, Ga. The study showed an overall response rate (ORR) of 68 percent, including a complete response (CR) of 22 percent and a partial response (PR) of 46 percent with a median progression free survival (PFS) estimated at 13.9 months. Results were similar between the bortezomib-naive and bortezomib-exposed patients.
Long-term follow up of the initial 51 patients enrolled in this study that were presented last year at ASH shows there was an incremental improvement in the response rate over time. The ORR increased for this patient subset from 69 percent in 2011 to an ORR of 75 percent in 2012, with the CR increasing from 16 percent to 39 percent over the same period.
"Now with a larger number of patients studied, we see the overall response rate remains durable and the safety profile continues to appear manageable," said Dr. Wang. "In addition, what is particularly encouraging is that with longer follow-up there is an incremental increase in the number of patients who achieve complete response."