Exelixis shares rise as late-stage study begins

The stock rose 28 cents, or 4.6 percent, to close at $6.43 Monday. Shares have traded between $4.64 and $12.29 over the last 52 weeks.

Early Monday, the company said XL184 moved into a Phase III clinical trial following discussions with the Food and Drug Administration. It is being studied as a potential treatment for medullary thyroid cancer, which accounts for about 5 percent of all thyroid cancers, according to the American Cancer Society.

There are currently no FDA-approved therapies specifically for medullary thyroid cancer; common treatments include surgery, radiation, and chemotherapy.

"We are thrilled that the pivotal trial for XL184 is now open for enrollment, and we look forward to rapid accrual of patients with medullary thyroid cancer," said Michael M. Morrissey, president of research and development at Exelixis, in a statement.

The study will compare XL184 with placebo and involve 315 patients. The main goal of the clinical trial is progression-free survival, or how long a patient survives without the cancer progressing. Secondary goals will include overall survival rates and tumor response rates.

The drug candidate is also in separate early-to-midstage studies as a lung cancer therapy and for a common type of brain tumor called glioblastoma multiforme.