Updated Phase 1 Data for Exelixis' XL184 Demonstrate Pharmacodynamic and Clinical Anti-Tumo...( -Encouraging signs of anti-tumor ...),Health

-Encouraging signs of anti-tumor activity observed in patients with

medullary thyroid cancer-

SAN FRANCISCO, Oct. 23 /PRNewswire-FirstCall/ -- Exelixis, Inc. (Nasdaq: EXEL) today reported encouraging data from an ongoing phase 1 trial of XL184, a potent inhibitor of MET, RET, and VEGFR kinases, in patients with advanced solid tumors or lymphoma. Anti-tumor activity has been observed in a variety of cancers at doses that are not associated with significant toxicity. Consistent with the anti-VEGFR activity of XL184, preliminary pharmacodynamic analyses show reductions in several biomarkers of angiogenesis. Data were presented today in a poster session (Abstract #A152) at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics, which is being held October 22-26, 2007 in San Francisco.

There were 33 patients available for safety, pharmacokinetic, and tumor response analyses as of the June 22, 2007 cutoff; further data were also provided for six additional patients after the cutoff. Of seven patients with medullary thyroid cancer (MTC), three have had partial responses (2 confirmed and 1 unconfirmed). Six of the seven patients had tumor shrinkage and one had non-measurable disease. All seven assessable patients with MTC experienced a rapid decrease in plasma levels of calcitonin, a marker frequently elevated in medullary thyroid cancer, and six of the seven patients had a decrease in the tumor marker carcinoembryonic antigen (CEA). All seven MTC patients are still on study. In addition, one patient with a neuroendocrine tumor has an unconfirmed partial response. In total, 15 patients with various solid malignancies or lymphoma have had stable disease
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