Exelixis soars after drugmaker details results from study of potential skin cancer treatment

Shares of Exelixis jumped Monday before markets opened and after the drugmaker said its treatment for a deadly form of skin cancer fared better than another drug in a late-stage clinical study.

The company said a combination of its drug, cobimetinib, and another treatment, vemurafenib, generated a statistically significant increase in progression-free survival of nearly 10 months compared with slightly more than 6 months for patients taking just vemurafenib. The potential treatment was tested in patients with an advanced form of melanoma that has a certain genetic mutation.

Progression-free survival measures the time from the start of treatment until a patient's cancer begins advancing again or the patient dies.

Exelixis is partnering with Swiss drugmaker Roche Holding AG's Genentech to develop the drug. Roche has already asked European regulators to approve the treatment, while Genentech plans to submit an application to the U.S. Food and Drug Administration later this year.

Shares of Exelixis Inc., based in South San Francisco, California, climbed more than 18 percent, or 29 cents, to $1.85 shortly before markets opened Monday.

The stock had traded above $4 as recently as last month, but the price sank earlier in early September after Exelixis said another potential treatment for an advanced form of prostate cancer fell short in late-stage research. The company said it would cut its workforce by about 70 percent, or 160 employees, because of those results.