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‘Cabo’ on Time for Exelixis, Fares Well; Wider Label Next?

By Randy Osborne

Staff Writer

As expected, Exelixis Inc. won the FDA’s nod for cabozantinib, a therapy for medullary thyroid cancer (MTC) – a less common form of the disease, originating in parafollicular C cells – but bigger revenue potential lies ahead, if the compound passes muster in metastatic prostate cancer, where Phase III trials are under way.

U.S. regulators gave approval late Thursday to Cometriq, or “cabo,” as many know it, which inhibits tumor growth, metastasis and angiogenesis by targeting MET, VEGFR2 and RET. The only other approved therapy for MTC is Caprelsa (vandetanib), cleared in April 2011, which hits VEGFR, EGFR and the RET tyrosine kinase. London-based AstraZeneca plc has sold about $19 million worth of Caprelsa this year.

Exelixis submitted the new drug application (NDA) in late May, and many investors saw favorable writing on the wall recently when the FDA removed the drug from November’s agenda for the meeting of the Oncologic Drugs Advisory Committee.

The NDA filing hinged on results from the Phase III EXAM trial in advanced MTC, conducted under a special protocol assessment plan with the FDA, with progression-free survival (PFS) as the primary endpoint. In October 2011, Exelixis said top-line data showed cabo improved median PFS by 7.2 months. (See BioWorld Today, Oct. 25, 2011.)

The pivotal Phase III trial for cabo in much larger market of metastatic castration-resistant prostate cancer (mCRPC) is called COMET-1, with a primary endpoint of overall survival in mCRPC patients in those who show disease progression after treatment with docetaxel and Zytiga (abiraterone acetate, Johnson & Johnson) and/or MDV3100 (enzalutamide, Medivation Inc.).