GW Pharmaceuticals PLC shares soared 9% in premarket trade Tuesday, after Oppenheimer upgraded the stock to outperform from perform, after the company reported better-than-expected earnings along with positive results in a late-stage trial of its Epidiolex treatment. Epidilolex is the first cannabis-based drug to win approval from the U.S. Food and Drug Administration as a treatment for severe forms of childhood epilepsy. The drug is now being tested as a treatment for patients with seizures associated with tuberous sclerosis complex, or TSC. "While we await detailed data that may be shared at a medical conference, we update our probability of approval of the sNDA for TSC to 87% from 41% (filing expected in 4Q), and move to an Outperform rating and a price target of $234 (vs. $162)," Oppenheimer analyst Esther Rajavelu wrote in a note to clients. "We also like management's efforts to broaden the pipeline with open label studies of CBDV for autism spectrum disorder and Rett syndrome which may contribute to a diversified portfolio." Stifel analysts led by Paul Matteis raised their stock price target to $227 from $191 and said dinner with GW management after the earnings report "reaffirms our view that the Epidiolex launch to date, considering all of the variables that have led the product to beat consensus, is going about as well as one could've hoped." Matteis is also expecting the drug to be approved for TSC in 2019. The analyst raised his revenue forecast for Epidiolex for the second quarter to $49 million from $26 million. GW Pharma shares have gained 85% in the last 12 months, while the S&P 500 has gained 10%.