Pharmacyclics Announces Updated Results for BTK Inhibitor PCI-32765 for the Treatment of Relapsed or Refractory Chronic Lymphocytic Leukemia

Pharmacyclics, Inc

announced today updated results of a Phase Ib/II trial of the selective, irreversible Bruton's tyrosine kinase (BTK) inhibitor, PCI-32765, for the treatment of patients with relapsed or refractory chronic lymphocytic leukemia (

)/small lymphocytic lymphoma. The longer-term follow-up results of a previously reported multicenter Phase Ib/II trial (Byrd, ASCO 2011) presented today at the ASH Annual Meeting in San Diego, CA by Dr. Susan O'Brien, Professor of Medicine in the Department of Leukemia of the University of Texas MD Anderson Cancer Center, continue to demonstrate PCI-32765 as a highly active treatment in patients with relapsed or refractory CLL. The trial included a total of 61 patients with relapsed or refractory CLL/SLL enrolled at two dose levels, 420 mg (n=27) or 840 mg (n=34). Oral PCI-32765 was administered daily until disease progression. Data was available from a landmark analysis of 12 months. With a median follow-up of 12.6 months in the 420mg cohort and 9.3 months in the 840mg cohort, the overall response rate (ORR), including PR and CR, for the 420mg dose level was 67% and for the 840 mg dose 68%, as measured by the 2008 International Workshop on Chronic Lymphocytic Leukemia criteria. The responses have been independent of high-risk clinical or genetic features. The estimated 12 month PFS for the pooled cohorts was 86%. The safety profile of PCI-32765 was particularly notable for minimal off target toxicities. The most common treatment related adverse events reported in the trial were Grade 1 (mild) or 2 (moderate) diarrhea, cough, fatigue, and upper respiratory infections, and only 2 patients have discontinued study treatment due to adverse events. Overall, these data support Phase III evaluation of PCI-32765 as a single agent in relapsed or refractory CLL/SLL.