Gilead Announces Interim Phase 2 Results for GS-9973 in Previously Treated Chronic Lymphocytic Leukemia

NEW ORLEANS--(BUSINESS WIRE)--

Gilead Sciences, Inc. GILD today announced interim results from a single-arm, open-label Phase 2 study evaluating GS-9973, an investigational oral inhibitor of spleen tyrosine kinase (Syk), for the treatment of patients with relapsed or refractory hematologic malignancies. The data show that among patients with chronic lymphocytic leukemia (CLL) who received at least eight weeks of GS-9973 monotherapy, 97 percent (n=28/29) experienced a reduction in lymph node size. Detailed results will be presented today during a poster session at the 55th Annual Meeting of the American Society of Hematology (ASH) in New Orleans (Abstract #1634).

“Most patients with CLL eventually develop resistance to currently available therapies,” said Jeff Sharman, MD, Willamette Valley Cancer Institute and Research Center – River Bend. “This underscores the importance of identifying new treatments for patients with CLL. The B cell receptor signaling pathway is a novel area of focus for investigational therapies in CLL. GS-9973 targets the Syk protein, which initiates most signaling from the B cell receptor. Response rates observed in this interim analysis support that GS-9973 has promising clinical activity in CLL to be further explored and developed.”

Of the 29 CLL patients included in the efficacy analysis, 20 (69 percent) achieved greater than 50 percent tumor shrinkage, including four of seven patients with a chromosome 17p deletion and/or a mutation in the TP53 gene, genetic abnormalities that have been linked to poor prognosis.

The safety of GS-9973 was also assessed in a population of 78 patients with CLL or non-Hodgkin's lymphoma (NHL) who had received at least four weeks of therapy. At the time of the data cut-off, 50 patients (64 percent) were continuing with GS-9973 treatment, with a median exposure of 10 weeks (range: 1-24 weeks).

Among the 78 patients in the safety analysis, five (six percent) reported Grade ≥3 fatigue. Reversible Grade ≥3 transaminase elevations (a measure of liver function) were reported in nine patients (12 percent). Eleven patients (14 percent) discontinued treatment due to adverse events. Four patients died during the study, three from progressive disease and one from septic shock.

About the Study

This Phase 2, open-label, single-arm safety and efficacy study is evaluating GS-9973 (800 mg twice daily) in patients with relapsed or refractory CLL or NHL, including indolent NHL (iNHL), diffuse large B-cell lymphoma and mantle cell lymphoma. The median age of the patients included in the safety analysis presented today was 72 years. These patients had received a median of two prior treatment regimens before study entry. The primary endpoint of the study is progression-free survival. Patients are allowed to continue daily dosing as long as they benefit from therapy. At the time of the data cut-off, it was too early to quantitate drug activity in the NHL population. The study is ongoing.

About GS-9973

GS-9973 is an investigational, targeted, reversible oral inhibitor of spleen tyrosine kinase (Syk), a protein that is critical for the activation, proliferation and survival of B lymphocytes. Combination therapy with GS-9973 and idelalisib, Gilead's investigational, targeted, oral inhibitor of PI3K delta, is also being evaluated in a Phase 2 trial of patients with relapsed or refractory CLL, iNHL and other lymphoid and hematological malignancies.

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

About Chronic Lymphocytic Leukemia

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.

About Gilead Sciences

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, California, Gilead has operations in North and South America, Europe and Asia Pacific.

Forward-Looking Statement

This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks, uncertainties and other factors, including the possibility of unfavorable results from clinical trials involving GS-9973, including in combination with idelalisib or other agents. Gilead may also experience challenges in enrolling patients in clinical studies, requiring those studies to be modified or delayed. Further, Gilead may make a strategic decision to discontinue development of GS-9973 if, for example, Gilead believes commercialization will be difficult relative to other opportunities in its pipeline. As a result, GS-9973 may never be successfully commercialized. These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. The reader is cautioned not to rely on these forward-looking statements. These and other risks are described in detail in Gilead's Quarterly Report on Form 10-Q for the quarter ended September 30, 2013, as filed with the U.S. Securities and Exchange Commission. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation to update any such forward-looking statements.

For more information on Gilead Sciences, please visit the company's website at www.gilead.com, follow Gilead on Twitter (@GileadSciences) or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000