SUNNYVALE, Calif., June 20, 2013 /PRNewswire/ -- Pharmacyclics, Inc. (the "Company") (Nasdaq: PCYC) today announced results of a study evaluating ibrutinib, an investigational oral Bruton's tyrosine kinase (BTK) inhibitor in patients with Waldenstrom's Macroglobulinemia (WM). Pharmacyclics is jointly developing ibrutinib with Janssen Research & Development, LLC. The data were presented today at the International Conference on Malignant Lymphoma (ICML), taking place in Lugano, Switzerland.
A Phase II study examining the efficacy and tolerability of ibrutinib in patients with relapsed/refractory WM was led by Dr. Steven Treon at the Bing Center for Waldenstrom's Research in Boston, MA. In WM the malignant B-cells produce large amounts of a normal antibody called immunoglobulin M (IgM). Antibodies such as IgM help the body to fight infection; however, in WM excess IgM causes the blood to thicken and causes many of the symptoms of the disease. ,
Thirty five relapsed/refractory WM patients who received a median of 2 prior therapies were evaluated. Key findings presented at ICML include:
- The best overall response rate was 83% (11.4% very good partial response; 54.3% partial response; 17.1% minor response)
- After six treatment cycles (a cycle = 4 weeks of treatment) bone marrow disease burden decreased from 70% down to 40% (p=0.0004)
- Levels of IgM reduced from 3,190 mg/dL at baseline to 1,232 mg/dL (6 cycles best response; p=5.1x10 -9)
- Red blood cell production improved with levels of hematocrit increasing from 30.8% to 39.7% (6 cycles best response; p=1.1x10 -11)
- The safety profile observed in patients with WM was similar to the established safety profile in other B-cell malignancies. Grade 3 and higher adverse events associated with the treatment of ibrutinib were infrequent with thrombocytopenia and neutropenia seen in 8.6%, and single cases of stomatitis and atrial fibrillation. None of these events led to ibrutinib discontinuation.
- As of June 3, 2013, 91.4% of patients remain on the study with a minimum of 6 cycles of follow up. The study was extended by an additional 28 patients to further evaluate the safety and efficacy of ibrutinib in WM and a total of 63 patients are now enrolled.
"These data suggest that ibrutinib was a highly active and well-tolerated treatment for Waldenstrom's patients in this study, and provide further evidence of the role of BTK in tumor growth," noted Steven Treon, M.D., Ph.D, Director of the Bing Center for Waldenstrom's Research and an attending physician at Dana-Farber Cancer Institute and Brigham and Women's Hospital, in Boston, MA. "Despite the relatively small patient population, there are currently no approved treatments specifically for Waldenstrom's, so the need for novel therapies such as ibrutinib should not be under-estimated."About IbrutinibIbrutinib is an investigational agent designed to specifically target and selectively inhibit an enzyme called Bruton's tyrosine kinase (BTK). BTK is a key mediator of at least three critical B-cell pro-survival mechanisms occurring in parallel – regulation of apoptosis, adhesion, and cell migration and homing. Through these multiple signals, BTK regulation helps to direct malignant B-cells to lymphoid tissues, thus allowing access to a micro environment necessary for survival. The effectiveness of ibrutinib alone or in combination with other treatments is being studied in several B-cell malignancies, including chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle cell lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, Waldenstrom's macroglobulinemia and multiple myeloma. To date six Phase III trials have been initiated with ibrutinib and a total of 31 trials are currently registered on www.clinicaltrials.gov. Janssen Biotech, Inc. and Pharmacyclics entered a collaboration and license agreement in December 2011 to co-develop and co-commercialize ibrutinib. About WMSlow-growing and rare, with an incidence in the U.S. and Europe of approximately 3-5 cases a year per million people,  WM belongs to a family of cancers classified as non-Hodgkin lymphoma (NHL). WM originates from B-cells, a type of white blood cell (lymphocyte) that develops in the bone marrow. Approximately 70 percent of WM cases are diagnosed in those over the age of 65,  and the median overall survival is 5-11 years. , About PharmacyclicsPharmacyclics ® is a clinical-stage biopharmaceutical company focused on developing and commercializing innovative small-molecule drugs for the treatment of cancer and immune mediated diseases. Our mission and goal is to build a viable biopharmaceutical company that designs, develops and commercializes novel therapies intended to improve quality of life, increase duration of life and resolve serious unmet medical healthcare needs; and to identify promising product candidates based on scientific development and administrational expertise, develop our products in a rapid, cost-efficient manner and pursue commercialization and/or development partners when and where appropriate. Presently, Pharmacyclics has three product candidates in clinical development and several preclinical molecules in lead optimization. The Company is committed to high standards of ethics, scientific rigor, and operational efficiency as it moves each of these programs to viable commercialization.