Retrovirus antibody positive CFS patients show response to Ampligen®, an experimental therapeutic, relative to XMRV negative group.
Hemispherx Biopharma, Inc. [presented] new clinical data(1) on the possible inter-relationships of XMRV positivity/chronic fatigue syndrome/Ampligen® responsiveness at the 1st International Workshop on XMRV 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 [33.7% of the 208 subjects, according to the report abstract] had a greater relative percentage of subjects showing a greater than 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 [66.3% of the 208] 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 (Alpha=0.05): 216 XMRV antibody positive subjects vs. 330 XMRV antibody negative subjects.
Additional studies to further evaluate XMRV in this CFS population are currently underway….
1. See Abstract P_14, “Comparison of demographic parameters and health/performance status of XMRV antibody positive vs. negative CFS subjects in a phase III trial.” Reviews in Antiviral Therapy & Infectious Diseases, Vol 8; 2010, page 30. By Strayer D, Stouch B, Mikovits J, Carter W. Hemispherx Biopharma, Philadalphia, PA; Whittemore Peterson Institute, Reno, NV, USA.
Sources: Excerpts from Hemispherx Biopharma (www.hemispherx.net) press release, Wed, Sep 8, 2010; presentation abstract cited above.
Note: Because Ampligen’s maker is a publicly traded entity, its caveat statement regarding any press release includes warnings that any press release statements other than historical information should be considered ‘forward-looking’ and “represent the company’s judgment as of the date of the release.” They “do not imply that any study product will ever be approved commercially for the studied or other treatment indications."