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Phase II Data on Rebeccamycin Analogue in Hepatobiliary Tumors Presented at ASCO

SOUTH SAN FRANCISCO, Calif., June 2 /PRNewswire-FirstCall/ -- Exelixis, Inc. announces that safety and activity data presented at the 2003 annual meeting of the American Society of Clinical Oncology (ASCO) from a Phase 2 trial in 33 patients with bile duct tumors (gall bladder tumors and cholangiocarcinomas) treated with the DEAE- rebeccamycin analogue (XL119), showed encouraging results relative to overall survival and progression free survival (alive without progressive disease, i.e., patients with partial response or stable disease). The safety profile was manageable and was consistent with that previously observed in Phase 1 and 2 studies.

Data from the Phase 2 study were presented in a poster entitled, Multicenter phase II and pharmacokinetic study of rebeccamycin analogue (RA) in advanced biliary cancers, by principal investigator Afshin Dowlati, M.D., of Case Western Reserve University and University Hospitals of Cleveland. The Phase 2 study was sponsored by the U.S. National Cancer Institute (NCI). Exelixis and the NCI are collaborating on the development of the DEAE-rebeccamycin analogue under a Clinical Trials Agreement (CTA).

The Phase 2 trial was conducted in previously untreated patients with advanced biliary cancers, measurable disease and normal liver function. Patients were treated with a dose of 165 milligrams per meter squared per day for five days, every three weeks. Key findings of the study were as follows.

-- Of 33 patients, the median survival was 265 days (approximately 8.8 months). -- Of 30 evaluable patients (excluding three patients who were not on study long enough for evaluation), in patients with progressive disease (treated for four or fewer cycles) the median disease progression free survival was 49 days (less than two months) and the median survival was 149 days (approximately five months). -- In patients without progressive disease (partial response or stable disease, treated for more than four cycles), median disease progression free survival was 154 days (approximately five months; p=0.0004 compared to progressive disease patients) and the median survival was approximately 11 months (p=0.008 compared to progressive disease patients).

"We believe that results of the Phase 2 trial of the DEAE-rebeccamycin analogue in patients with hepatobiliary tumors are suggestive of enhanced clinical benefit, with data showing an overall survival rate of close to nine months," said Dr. Dowlati. "In a disease for which there is no approved standard of care, these results are highly encouraging. We believe that that the DEAE-rebeccamycin analogue deserves further study in larger patient population in a well-controlled, randomized trial in order to fully explore its therapeutic potential."

In terms of disease stabilization and safety profile, of 30 evaluable patients, half had clinical courses suggestive of clinical benefit with the following observed: improved performance status, decrease in tumor marker (CA 19.9) or tumor shrinkage (radiologic partial responses or stable disease). As previously observed, the most prevalent side effect was myelosuppression, primarily neutropenia, which was reversible when dosing was reduced or delayed.

A poster entitled, Randomized phase II trial of 2 different administration schedules of rebeccamycin analogue (RA) as 2nd line therapy in patients (pts) with advanced non-small cell lung cancer (NSCLC), was also presented at ASCO, by Dr. Dowlati.

Exelixis has exclusive worldwide rights to XL119, the DEAE-rebeccamycin analogue, which it received as part of a broad cancer research collaboration established with Bristol-Myers Squibb in July 2001. Ongoing Phase 2 trials in a broad range of tumors are being conducted by the NCI under the CTA. Pending the outcome of current discussions with the U.S. Food & Drug Administration, Exelixis intends to initiate a Phase 3 in collaboration with the NCI of the DEAE-rebeccamycin analogue in patients with bile duct tumors, anticipated to begin later in 2003 or early 2004. Exelixis market research estimates that the annual incidence of bile duct tumors is approximately 7,500-10,000 cases in the U.S. and in Europe, and a comparable number in Japan and other Asian countries.

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