UPDATED: Exelixis posts promising pivotal thyroid cancer data on cabozantinib

Exelixis ($EXEL) cleared a crucial late-stage hurdle for cabozantinib today, with the biotech reporting the drug's Phase III study for medullary thyroid cancer posted promising results for improving progression-free survival. Investigators say the median PFS in the cabozantinib arm was 11.2 months versus four months in the placebo arm. There was a 72% drop in the risk of disease progression in the drug arm. And that's good enough for Exelixis to head to the FDA with a request to begin a rolling submission for approval of its lead treatment.

Shares of Exelixis, which had surged close to 10% on Friday in anticipation of the announcement, quickly spiked 16% on the news this morning.

The trial win will help build confidence in Exelixis's plans to eventually pursue an approval for prostate cancer, a blockbuster market that is growing increasingly crowded with top-level competitors. And it's an important win for CEO Mike Morrissey, who gambled everything on cabozantinib as he cut back and circled all the biotech's wagons around the cancer program.

"The success of the EXAM trial is an important advance for MTC patients and for Exelixis," said Morrissey. "These data demonstrate cabozantinib's profound anti-tumor activity in an indication that has seen little clinical progress over the past few decades. ...Potential approval of cabozantinib in MTC would be a first step to achieve our goal of improving the lives of cancer patients, and would set a solid foundation on which to build a cabozantinib franchise that includes large indications such as prostate cancer."

Exelixis says it will detail the data at an upcoming conference. In the meantime, it will continue to track the health of the patients in the study, looking to prove cabo can improve overall survival rates by 50%.

"This represents important progress in the treatment of MTC, an indication that has long been underserved and still has a significant unmet medical need," said Dr. Steven Sherman, an investigator and a professor at MD Anderson Cancer Center. "I believe that cabozantinib has great potential to improve the care and outcomes of MTC patients."

- here's the Exelixis release