Pharmacyclics, Inc. (PCYC) on Monday announced results from a Phase II trial of the investigational oral agent ibrutinib which showed rapid and sustained disease control as a monotherapy in untreated, relapsed and refractory chronic lymphocytic leukemia patients, irrespective of characteristics that predict poor outcomes to chemoimmunotherapy.
The study included an analysis of two CLL patient cohorts: the elderly, above 65 years of age, and the high risk genetic group with a deletion of chromosome 17p. Many elderly patients with CLL are unable to tolerate aggressive therapies. Patients with deletion of chromosome 17p typically are poor responders to chemoimmunotherapy and have limited treatment options with no standard of care defined. Of all CLL patients enrolled in the trial, 72% had been characterized as Rai stage 3-4, indicating an advance stage, high risk patient population.
The study also evaluated in vivo effects of ibrutinib using blood and tissue samples collected before and during treatment. Ibrutinib showed rapid and sustained disease control in blood, lymph nodes, spleen and bone marrow. After 6 months, 95% of patients experienced a reduction in lymph node size and all showed reduction in spleen enlargement, with a median reduction of 55%. In 26 patients, for whom a bone marrow biopsy was done, tumor infiltration decreased by 82%.
The progression free survival probability for those patients at 12 months was estimated to be 94%. Most adverse events were mild and manageable and included diarrhea, fatigue and rash, severe events occurred in less than 13% of patients.
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