PHILADELPHIA, March 24, 2014 (GLOBE NEWSWIRE) -- Hemispherx Biopharma, Inc. (NYSE MKT:HEB) participated in the 11th Biennial International Research and Clinical Conference held in San Francisco, California, USA, on March 20-23, 2014. The title of the presentation was " Differential Exercise Responses to Rintatolimod [Ampligen®] Exhibited by Patients with Severe Chronic Fatigue Syndrome (CFS)". This Phase III prospective, double-blind, randomized, placebo-controlled trial was conducted at twelve centers by leading researchers in fatigue and post-exertional fatigue. The data on the experimental immunotherapeutic included a re-examination post-hoc of the primary and secondary endpoints as a function of dichotomization of patient responses. Dichotomization of improvement in exercise performance from baseline at the ≥25% and ≥50% levels were analyzed on the Intent-to-Treat (ITT) Population. For the ITT population a significantly greater percentage of rintatolimod patients (39%) vs. placebo patients (23%) improved ET (exercise tolerance) duration by ≥25% (p=0.013) while 26% compared to 14% of rintatolimod vs. placebo patients, respectively, improved ET duration by ≥50% (p=0.028). A frequency distribution analysis of ≥25% improvement, <25% change and ≥25% worsening in ET from baseline at 40 weeks for the baseline >9 minutes cohort showed net improvement to be 18.3% for the rintatolimod cohort vs. 4.6% deterioration for placebo (p=0.015). A continuous responder analysis using 5% increments from ≥25% to ≥50% provided a robust clinical enhancement in ET effect in the rintatolimod cohort for the ITT population, as well as, for a subset of patients with baseline ET duration >9 minutes as compared to placebo. The Karnofsky Performance Score (KPS) and Vitality (SF-36 subscale) quality of life secondary endpoints demonstrated similar clinically significant improvements for the rintatolimod cohort as a function of the same ET dichotomization. Rintatolimod was generally well-tolerated in this CFS/ME population. Rintatolimod (Ampligen®), an experimental immunotherapeutic, produced significant enhancement in ET and quality of life indicators in a subset of patients with CFS/ME. Rintatolimod also reduced deterioration in ET compared to placebo in patients who fail to improve physically.