Pharmacyclics, Inc. (Nasdaq: PCYC) today announced results from a Phase II trial of the investigational oral agent ibrutinib which demonstrated rapid and sustained disease control as a monotherapy in untreated, relapsed and refractory chronic lymphocytic leukemia (CLL) patients, irrespective of characteristics that predict poor outcomes to chemoimmunotherapy.
This study was discussed at today's American Association for Cancer Research (AACR) annual meeting in Washington, DC together in addition to 8 other presentations covering advances in clinical and pre-clinical research with ibrutinib. The Phase II study, which was sponsored by the National Heart, Lung and Blood Institute, included an analysis of two CLL patient cohorts.
The results of the study were presented by lead investigator Adrian Wiestner , M.D., PhD, Hematology Branch, NHLBI, National Institutes of Health. "Ibrutinib was highly efficacious as a single agent in patients with untreated, relapsed and unresponsive CLL, irrespective of their del 17p status," Dr. Wiestner said. "Responses in this study appear to be durable, and results indicate the drug is effective against the disease in lymph nodes, spleen and bone marrow. This is important because existing therapies often fail to effectively eliminate cancer cells in these tissue sites. Targeted therapy for CLL is becoming a reality, and this new approach may greatly improve the lives of patients with this disease."
The study also evaluated in vivo effects of ibrutinib using blood and tissue samples collected before and during treatment. Ibrutinib demonstrated rapid and sustained disease control in blood, lymph nodes, spleen and bone marrow. After 6 months, 95 percent of patients experienced a reduction in lymph node size and all showed reduction in spleen enlargement, with a median reduction of 55 percent. In 26 patients, for whom a bone marrow biopsy was done, tumor infiltration decreased by 82 percent.
The Progression Free Survival probability for these patients at 12 months was estimated to be 94 percent. Most adverse events were mild and manageable and included diarrhea, fatigue and rash, severe events occurred in less than 13 percent of patients.
"We are very pleased with the continued research that is being demonstrated at AACR across 9 different presentations. These advances show the potential breadth of the ibrutinib program and provide further opportunities for us to pursue. We are grateful for the continued support of our collaborators, investigators, patients and shareholders," said Bob Duggan , CEO and chairman of the board.
Ibrutinib has been designated as a FDA Breakthrough Therapy in CLL patients with deletion 17p, based on data from completed Phase I/II clinical studies, where ibrutinib as a monotherapy was used to treat patients with this disease. Ibrutinib has the potential to improve the outcome in this serious and life-threatening disease, and may provide a substantial improvement over existing therapies for this indication.