MOUNTAIN VIEW, Calif. ( TheStreet) -- Obese patients treated with Vivus' ( VVUS) obesity drug Qnexa for two years lost approximately 10% with fewer side effects than from a previously reported one-year clinical trial, the company announced Monday. Vivus shares rose 13% to $6.96 in mid-day trading on the hope that the longer-term Qnexa data would be sufficient to ease concerns raised by an U.S. advisory panel in July. That panel voted against recommending the drug's approval mainly because of safety concerns tied to pregnancy risk, psychiatric and cardiovascular side effects. The U.S. Food and Drug Administration is set to make its Qnexa approval decision on on Oct. 28, which gives Vivus scant time to share the new data with the agency. "The two-year Qnexa data look about as good as one could expect, with weight loss maintained and a side effect profile that seems better," said Dr. Tim Garvey, a professor at the University of Alabama and an investigator who enrolled patients in both the one year- and two-year Qnexa studies. Vivus declined to comment further about the two-year Qnexa data, citing a quiet period tied to the ongoing FDA review process. Patients who enrolled in the two-year study of Qnexa known as "Sequel" previously completed a one-year study of the drug and were asked to continue taking one of two doses of Qnexa or a placebo for another 52 weeks. Patients who stuck with the Qnexa study for two years tend to be those who respond best to the drug or who are not as bothered by possible side effects. Patients treated with the high dose of Qnexa lost an average of 26 pounds, or 11.4% of their body weight, after two years. A mid-dose of Qnexa resulted in patients losing an average of 10.4% of their body weight. Placebo patients lost 2.5% of their body weight. "The weight loss effect of Qnexa was maintained over two years, which is better than what we saw with lorcaserin, where patients seem to return to their baseline weight during the second year," said Garvey. Lorcaserin is a competing weight-loss drug from Arena Pharmaceuticals ( ARNA). Treatment with Qnexa was associated with a reduction in weight-related co-morbid conditions such as high blood pressure or diabetes. Eighty-three percent of Qnexa patient completed the study compared to 86% of placebo patients, while patient dropout due to adverse events were about 4% for Qnexa patients and 2.6% for the placebo group, Vivus said.