Gilead Sciences, Inc. (Nasdaq: 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.