Calistoga Pharmaceuticals, Inc., announced interim results from the ongoing Phase 1 trial evaluating CAL-101, a PI3K inhibitor, showing promising clinical responses in patients with relapsed or refractory chronic lymphocytic leukemia (CLL). At this interim assessment, 29 percent of CLL patients treated in the cohort expansion dose levels had partial responses observed after 28 days of therapy (1 cycle) and 94 percent have achieved evidence of biologic activity with a greater than 50 percent decrease in lymphadenopathy (shrinkage of lymph node tumors). Five out of six partial responders continue treatment with CAL-101, with the longest response greater than 224 days. All patients had prior rituximab and fludarabine therapy and nearly half of the patients had prior alemtuzamab therapy. Half of the patients were refractory to their last therapy prior to entering the study.