-Preliminary data show encouraging early signs of activity in solid tumors-

Exelixis, Inc. (Nasdaq: EXEL) today reported encouraging data from an ongoing Phase 1 dose-escalation trial of XL228 in patients with advanced malignancies. XL228 is a small molecule inhibitor of insulin-like growth factor type 1 receptor (IGF1R), SRC, Aurora kinases, and fibroblast growth factor receptor types 1, 2, and 3 (FGFR1-3), which are associated with cancer cell proliferation, survival, and metastasis. The compound also inhibits BCR-ABL, including the T315I mutant form which is resistant to currently approved inhibitors. David Smith, MD, Professor of Medicine at the University of Michigan, an investigator on the Phase 1 trial, will present the data in an oral session (Abstract #3512) beginning at 4:15 p.m. local time on Saturday, May 30, 2009, at the American Society of Clinical Oncology Annual Meeting, which is being held May 29-June 2 in Orlando.

“The data from this ongoing Phase 1 study are encouraging with respect to both clinical and pharmacodynamic activity and safety,” said Michael M. Morrissey, Ph.D., president of research and development at Exelixis. “A confirmed partial response in a patient with NSCLC and an additional 30% of patients remaining on study for 12 or more weeks suggest that XL228 may provide clinical benefit to cancer patients with no other options. Additionally, the clinical pharmacodynamic data are consistent with preclinical results indicating that XL228 effectively inhibits multiple targets that play key roles in various malignancies.”

The dose-escalation trial evaluated eight dose levels of XL228 (ranging from 0.45-8.0 mg/kg) administered once or twice weekly. Of 40 evaluable patients, 1 patient with non-small cell lung cancer, whose cancer had progressed after 5 prior treatment regimens, had a confirmed partial response and was on study for 48 weeks. Twelve additional patients (30%) were on study for 12 or more weeks, including 2 patients (1 with small cell lung cancer and 1 with colorectal cancer) on study for more than 12 months, and 3 patients (1 with pancreatic cancer, 1 with leiomyosarcoma, and 1 with colorectal cancer) on study for more than 6 months. Most of these patients had received multiple prior treatment regimens.

Adverse events have generally been of Grade 1 or 2 severity and manageable. Three serious drug-related adverse events have been reported: 1 patient with Grade 3 vomiting, 1 patient with Grade 2 hypotension and bradycardia, and 1 patient with Grade 3 diarrhea.