A drug designed to combat seizures in children with severe epilepsy has been approved by an outside panel of advisors to the FDA, a major milestone on the way to full approval.

Epidiolex would be the first drug derived from cannabis on the U.S. market.

The panel of 13 advisors concluded that the benefit-risk profile of Epidiolex is favorable for the treatment of seizures. Earlier this week, FDA staff indicated support for the drug in light of the results of clinical trials.

Shares of U.K.-based GW Pharmaceuticals, which makes Epidiolex, were up more than 1 percent following the news.

The medicine's active ingredient cannabidiol is derived from the cannabis plant. Epidiolex does not contain THC and does not give patients any psychoactive effects. The FDA has already approved synthetic cannabinoids to alleviate the side effects of treatments such as chemotherapy.

Industry watchers expect the eventual approval of Epidiolex will encourage further research and investment into cannabis-based drugs.

The FDA is expected to issue a final decision on June 27.

— Reuters contributed to this report.