Hemispherx Biopharma to present clinical data on XMRV retrovirus at International Workshop

Hemispherx Biopharma, Inc. (AMEX:HEB) will present new clinical data on the possible inter-relationships of XMRV positivity/chronic fatigue syndrome/Ampligen® responsiveness at the 1^st International Workshop on XMRV being held at the National Institutes of Health in Bethesda, MD, on September 7 and 8, 2010.

CFS is a severe disorder consisting of profound fatigue and a variety of other debilitating symptoms that affects up to 4 million Americans. Recently, DNA was identified from a human gamma retrovirus (XMRV) in 67% of CFS subjects. Evidence also suggested that approximately 50% of the CFS subjects mounted a specific antibody response against XMRV (Science 326, 585-589 (2009)). The objective of this study was to compare demographic parameters and health/performance status of XMRV antibody positive vs. negative CFS subjects enrolled in a Phase III clinical trial evaluating the safety and efficacy of a toll-like receptor 3 agonist, rintatolimod (PolyI:PolyC12U, Ampligen®). The response to Ampligen® with regard to the primary endpoint, treadmill exercise tolerance testing (ETT), in this population was also evaluated.

Two-hundred-eight (208) evaluable subjects, who met the original (1988) and revised (1994) Centers for Disease Control criteria for CFS, participated in this randomized, placebo-controlled, double-blinded, multicenter study. Only severely debilitated patients with a Karnofsky Performance Scale between 40-60 were selected for this study. The primary endpoint was exercise treadmill duration. Subjects received Ampligen® (200-400 mg) or an equivalent volume of placebo (saline) twice weekly by intravenous infusion for 40 weeks. Baseline (or earliest available specimen) serum samples from all 208 subjects were analyzed for antibodies directed against XMRV.

The XMRV antibody positive cohort had a greater relative percentage of subjects showing a >25% increase in ETT with Ampligen® treatment compared to placebo than the XMRV antibody negative cohort. The results also suggest that the XMRV antibody negative subjects with CFS have a lower activity level and a reduced ability to complete normal daily activities at baseline. If validated as a relevant basis for targeting the XMRV positive CFS patient sub-population, the observed response advantage of the XMRV may translate into needing a smaller sample size for future research using a placebo-controlled parallel design to obtain 80% power>