Gilead’s Idelalisib significantly reduces rate of disease progression or death in Phase 3 CLL study

FOSTER CITY, Calif.—Gilead Sciences, Inc. today announced that the company’s Phase III study (Study 116) evaluating idelalisib in combination with rituximab in previously-treated chronic lymphocytic leukemia (CLL) patients who were not fit for chemotherapy was stopped early based on a pre-specified interim analysis performed by an external Data Monitoring Committee (DMC) showing a highly statistically significant effect on the primary endpoint of progression-free survival (PFS). Detailed results from the study will be presented at the 2013 American Society of Hematology meeting in New Orleans on Dec. 10.

Idelalisib is an investigational, highly selective oral inhibitor of phosphoinositide 3-kinase (PI3K) delta. PI3K delta signaling is critical for the activation, proliferation, survival and trafficking of B lymphocytes and is hyperactive in many B-cell malignancies. Idelalisib is being developed both as a single agent and in combination with approved and investigational therapies.

CLL is a slow-growing cancer in which the bone marrow overproduces white blood cells, leaving less room in the blood and bone marrow for other types of blood cells. It is the most common leukemia in adults in the United States, occurring typically in older individuals, and it can lead to life-threatening complications, including serious infections and anemia. In 2013, there were an estimated 16,000 new CLL diagnoses in the United States and 4,500 deaths related to this cancer.

“Patients with relapsed CLL have limited treatment options and are often not able to tolerate chemotherapy,” said Dr. Richard R. Furman, Richard A. Stratton Assistant Professor of Clinical Medicine in the Division of Hematology/Oncology at Weill Cornell Medical Center / New York Presbyterian Hospital. “Based upon the results of this study demonstrating significant improvements in progression-free and overall survival, idelalisib represents an important addition to the armamentarium for patients living with this life-threatening disease.”

Thes study data in CLL support Gilead’s plans for regulatory filings for idelalisib in the United States and European Union. On Sept. 11, Gilead submitted a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for idelalisib for the treatment of refractory indolent non-Hodgkin’s lymphoma (iNHL). Following Gilead’s NDA submission for iNHL, FDA granted idelalisib a Breakthrough Therapy designation for CLL in relapsed patients based on results from Study 116. Gilead is now engaging in a dialogue with the FDA regarding a regulatory filing in CLL. Gilead filed for approval in iNHL and CLL with the European Medicines Agency (EMA) on October 28, 2013.

Study 116 was a randomized, double-blind, placebo-controlled, Phase III study evaluating the efficacy and safety of idelalisib in combination with rituximab. The study enrolled 220 adult patients at approximately 70 study sites in the United States and Europe. Eligible patients had previously treated recurrent CLL, with measurable lymphadenopathy that had progressed within 24 months since completion of prior therapy. The patients required treatment (based on IWCLL criteria) but were not fit to receive cytotoxic therapy. Patients were randomized to receive eight infusions of rituximab over 24 weeks plus either idelalisib (150 mg) or placebo taken orally twice daily continuously until disease progression or unacceptable toxicity. Patients from Study 116 randomized to idelalisib will continue receiving idelalisib and patients in the control arm (placebo plus rituximab) were eligible to receive open-label idelalisib therapy in an extension study.

In addition to Study 116, the development program in CLL includes two ongoing Phase III studies of idelalisib in previously treated patients. Gilead’s clinical development program for idelalisib in iNHL includes a Phase II study in highly refractory patients (Study 101-09) and two Phase III studies of idelalisib in previously treated patients. Combination therapy with idelalisib and GS-9973, Gilead’s novel spleen tyrosine kinase (Syk) inhibitor, also is being evaluated in a Phase II trial of patients with relapsed or refractory CLL, iNHL and other lymphoid malignancies.

Additional information about clinical studies of idelalisib and Gilead’s other investigational cancer agents can be found at www.clinicaltrials.gov. Idelalisib and GS-9973 are investigational products and their safety and efficacy have not been established.

Gilead Sciences is a biopharmaceutical company that discovers, develops and commercializes innovative therapeutics in areas of unmet medical need. The company’s mission is to advance the care of patients suffering from life-threatening diseases worldwide. Headquartered in Foster City, Calif., Gilead has operations in North and South America, Europe and Asia Pacific.