SUNNYVALE, Calif., Aug. 29, 2013 /PRNewswire/ -- Pharmacyclics, Inc. (Nasdaq: PCYC) today announced that the U.S. Food and Drug Administration (FDA) has accepted for filing its New Drug Application (NDA) for the investigational oral Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, for two B-cell malignancy indications: previously treated mantle cell lymphoma (MCL) and previously treated chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). On June 28, 2013 Pharmacyclics submitted a New Drug Application (NDA) under section 505(b) of the Food, Drug & Cosmetic Act for ibrutinib. On Aug 27, 2013 the FDA notified Pharmacyclics that they have completed their filing review and determined that the application is sufficiently complete to permit a substantive review. The FDA's acceptance of the NDA triggers a $75 million milestone payment to Pharmacyclics under its Collaboration Agreement with Janssen Biotech Inc. "We are very excited to have received the official FDA acceptance of our first NDA filing for ibrutinib," said Dr. Urte Gayko, Senior Vice President of Global Regulatory Affairs, Pharmacyclics. "We look forward to continuing to work with the FDA as they complete their review of the ibrutinib application which includes the new Breakthrough Therapy Designation process." About CLL / SLL CLL, a B-cell malignancy, is a slow-growing blood cancer of the white blood cells (lymphocytes), most commonly from B-cells. CLL is the second most common adult leukemia. Approximately 16,000 patients in the US are diagnosed each year with CLL. The prevalence of CLL is approximately 113,000 in the U.S. CLL is a chronic disease that predominantly occurs in the elderly with a five-year survival of approximately 82 percent. 1 Patients commonly receive multiple lines of treatment over the course of their disease. When cancer cells are located mostly in the lymph nodes, the disease is called SLL. CLL and SLL are considered to be different manifestations of the same underlying disease; they share similarities in signs and symptoms, genetic features, disease progression and treatment. About Mantle Cell Lymphoma MCL is a B-cell malignancy, an aggressive type of B-cell non-Hodgkin lymphoma (NHL) that usually occurs in older adults. 2 The disease typically begins in the lymph nodes, but can spread to other tissues, such as bone marrow, liver, and spleen 3. Patients typically survive an average of five years. 4 In the U.S., there are approximately 2,500 new cases of MCL each year and a prevalence of approximately 10,000 (Decision Resources 2012). About Ibrutinib Ibrutinib is an investigational agent designed to provide potent and sustained inhibition of 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.