What happened

Exelixis (NASDAQ:EXEL) is up 24% at 12:21 p.m. EDT after announcing that the phase 3 Celestial trial met its primary endpoint of helping liver cancer patients taking Cabometyx live longer than those taking placebo.

Separately, the biotech also said the Food and Drug Administration accepted its marketing application to expand Cabometyx's label to first-line kidney cancer and gave the application a priority review with a goal of completing the review by Feb. 15, 2018. That's good progress, but widely expected, so most of today's jump is due to the Celestial result.

A female doctor talking to a male patient in a hospital bed.

Image source: Getty Images.

So what

This was an interim look at the Celestial data, so Exelixis just noted that the trial was stopped early for the positive results, but didn't release any actual data, which is typical for this type of situation. Interim looks at data often have higher thresholds for success than the final readouts, so there's a good chance that the data will look pretty good, but investors will have to wait for a medical conference where Exelixis will present the data to find out.

The trial was set up assuming patients receiving placebo would live 8.2 months and the trial would likely be successful if patients taking Cabometyx lived at least 10.8 months. Hopefully Cabometyx was able to extend patients' lives by more than just 2.6 months compared to placebo, but even if that was all the drug managed to help, these patients have failed other treatments so Cabometyx will still be prescribed since it's better than nothing.

Now what

Exelixis is shooting for submitting its marketing application to the FDA to get approved to treat liver cancer in the first quarter of 2018. Assuming the agency gives the application a priority review, Cabometyx could get approved before the end of next year.

Sales in liver cancer could come even earlier since Cabometyx is already on the market as a second-line kidney cancer treatment. Some doctors will prescribe the drug off-label before the approval, but probably not until after Exelixis releases the full data set and insurers start covering the drug for liver cancer.

Brian Orelli has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Exelixis. The Motley Fool has a disclosure policy.