PHILADELPHIA ( TheStreet) --Three years after being rejected by U.S. Food and Drug Administration, Hemispherx Biopharma ( HEB) is back seeking regulatory approval for Ampligen, its controversial therapy for chronic fatigue syndrome. Everyone loves a comeback story with a happy ending, but Hemispherx's second attempt won't turn out any happier than the first. FDA is likely to reject Ampligen again because Hemispherx ignored the agency's demand to run a new clinical trial in chronic fatigue syndrome. Instead, Hemipsherx has spent the past three years doing essentially nothing but re-analyzing data from the old Ampligen phase III trial completed in 2004. FDA reviewed the original study already, deeming it "lacking credible evidence of efficacy of Ampligen." It would be highly unusual -- unprecedented, even -- for FDA to reverse itself and find a retrospective rehash of old Ampligen data more compelling this time around. FDA has been facing political pressure to speed new drugs to market, particularly for diseases like chronic fatigue syndrome with no current treatments. But this hardly means FDA is going to throw out its drug-review rulebook. FDA has scheduled an advisory panel for Dec. 20 to review Hemispherx's Ampligen resubmission. The agency is expected to issue a final approval decision on or before Feb. 2, 2013. Ampligen's long odds haven't deterred speculators from bidding up Hemispherx's stock price, just like they did in 2009. At Wednesday's close of 90 cents, Hemispherx shares are up more than 220% since July 11 when the company announced plans to resubmit Ampligen for FDA approval. For those that don't remember, the phase III study enrolled 234 patients with chronic fatigue syndrome, randomized to treatment with Ampligen or a placebo. The study's primary endpoint was improvement in treadmill exercise tolerance at week 40. Hemispherx announced positive results from the Ampligen study in May 2004, claiming that Ampligen patients demonstrated a 17.4% improvement in treadmill exercise tolerance compared to a 4.3% improvement for placebo patients -- a net difference of 13.1%. The result was statistically significant with a p value of 0.047. However, in May 2006, results from this same study were presented at a medical meeting showing a 12.9% difference in treadmill exercise performance between Ampligen and placebo that was not statistically significant.