Following a recommendation by an independent Data Monitoring Committee (DMC), Gilead Sciences, Inc. (Nasdaq:GILD) today announced that its Phase 3 study (Study 116) evaluating idelalisib in previously-treated chronic lymphocytic leukemia (CLL) patients who are not fit for chemotherapy will be stopped early. This DMC recommendation is based on a predefined interim analysis showing highly statistically significant efficacy for the primary endpoint of progression-free survival in patients receiving idelalisib plus rituximab compared to those receiving rituximab alone. The safety profile of idelalisib was acceptable and consistent with prior experience in combination with rituximab in previously treated CLL. Gilead has informed the U.S. Food and Drug Administration (FDA) of the plan to end the study and will engage in a dialogue with the FDA regarding a regulatory filing in CLL. Data from Study 116 will be submitted for presentation at an upcoming scientific conference. “Given the significant unmet medical need in CLL, particularly in this population of patients who are not fit for chemotherapy, we are pleased that idelalisib has shown a clinically meaningful benefit for patients,” said Norbert W. Bischofberger, PhD, Gilead’s Executive Vice President, Research and Development and Chief Scientific Officer. “This is the first Phase 3 study to report positive results for a new class of targeted therapies that inhibit B-cell receptor signaling as a major component of their mechanism of action, an important area of focus in the development of chemotherapy-free regimens in CLL and other B-cell malignancies. We extend thanks to the investigative sites and to the other research collaborators participating in this study, as well as to the patients who volunteered, and we look forward to sharing these data with the hematology community.” Patients from Study 116 randomized to idelalisib will continue receiving idelalisib and patients in the control arm (placebo plus rituximab) will become eligible to receive open-label idelalisib therapy in an extension study. Gilead is also planning an expanded access program (EAP) for patients with recurrent CLL who are not fit for chemotherapy and require treatment.