Exelixis Drug Slows Progress of a Deadly Brain Cancer

Exelixis Inc. and Bristol-Myers Squibb Co.’s experimental drug delayed the spread of an aggressive brain cancer, a study found.

The researchers found that patients who hadn’t previously been treated with an antiangiogenic therapy -- a drug designed to stem the growth of new cancer-feeding blood vessels -- went 16 weeks before their cancer worsened while taking the drug, known as XL184, Exelixis said today in a statement. Patients who had received prior treatment lived 7.9 weeks without their disease spreading, the South San Francisco-based company said.

Glioblastoma is the most common, deadliest type of brain tumor, according to the Mayo Clinic website. Overall, 82 percent of glioblastoma patients in the study showed some tumor shrinkage in at least one brain scan after taking XL184. The results will be presented next month at the annual meeting of the American Society of Clinical Oncology.

The data show “robust clinical activity which we believe compares favorably with current treatment options,” said Michael Morrissey, Exelixis’s president of research and development, in the statement.

The study treated 59 patients with a lower dosage of the drug than had been tested previously. It showed that among those who had not received prior therapy, 11 out of 37 got some benefit from taking XL184. The lower dose was better tolerated by patients while showing a comparable response, Exelixis said in its statement.

Multiple Pathways

XL184 targets multiple pathways involved in tumor growth to keep cancer from spreading. Like Roche Holding AG’s Avastin, which reached sales of $5.7 billion last year, XL184 seeks to block a protein called VEGF, involved in the formation of cancer-supporting blood vessels.

Exelixis’s drug also targets a novel pathway known as MET, short for mesenchymal epithelial transition growth factor. Overexpression of that receptor on cancer cells has been linked to higher spreading and proliferation of cancer cells.

Glioblastoma “remains the largest near-term opportunity for XL184, although improving upon Avastin remains a hurdle,” Joel Sendek, an analyst at Lazard Capital Markets, wrote in a May 12 note to investors.

The cancer society released 4,500 abstracts of studies today in advance of its conference in Chicago beginning June 4.

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