UPDATED: Vanda jumps again as FDA panel smiles on sleep-disorder drug

Riding high on a surprisingly positive FDA staff review, Vanda Pharmaceuticals ($VNDA) and its drug for a rare sleep disorder skated to an expected endorsement from a panel of agency advisers, sending the company's shares up another 20% after hours.

The FDA's central nervous system drugs panel resoundingly backed tasimelteon, a drug designed to help blind patients with non-24-hour disorder sleep through the night. Vanda's therapy works safely and effectively to correct circadian rhythms, the committee voted, inducing a second bump for the company's resurgent shares, which nearly doubled Tuesday when the FDA released its fawning review documents.

The drug's enthusiastic reception at the FDA gave more than a few analysts pause, as Vanda and the agency didn't reach an agreement on primary endpoints until the study was already underway. Furthermore, the soft-gloved agency reaction came in stark contrast to the same panel's much harsher take on Sanofi's ($SNY) Lemtrada just the day before.

The FDA is not required to follow its committees' advice, though it often does, and the agency is expected to make a final ruling on Vanda's drug by the end of January.

If approved, tasimelteon would become the only treatment for non-24 on the U.S. market, CEO Mihael Polymeropoulos said, and the drug's orphan status would give Vanda exclusive rights through 2022.

"We are now one step closer toward our goal of providing a treatment option that addresses the physiologic cause of this serious, debilitating orphan condition that impacts a majority of totally blind individuals," Polymeropoulos said in a statement.

Non-24 affects roughly 80,000 U.S. patients, the company said.

- read Vanda's release