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NEW 'THETA SWITCH' DRUG MAY INCREASE LONG-TERM SURVIVAL IN HIV DISEASE

PALM SPRINGS, Calif., March 8 /PRNewswire/ -- HemispheRx Biopharma (Nasdaq: HEMXU) reported today at the University of California's Fourth Annual "Frontiers of HIV Therapy" conference new laboratory and clinical evaluations of the "Theta Switch" theory as an important immunological mechanism of long-term survival in HIV-infected individuals.

In a paper delivered at the conference today, HemispheRx reported that its nucleic acid compound, Ampligen, in conjunction with AZT switched a significant percentage of HIV-infected clinical trial subjects from an unresponsive Theta status to a responsive one. Results of research conducted by the U.S. military suggest that HIV-infected subjects' median survival advantage may shift from 34 months to 69 months, apparently as a direct result of Theta switching. AZT alone was not found to significantly improve Theta Switch responsiveness.

The Theta Switch theory, a novel immune mechanism recently advanced by National Institutes of Health (NIH) scientists Clerici and Shearer, may explain how long-term survival in HIV disease differs vastly from individual to individual. The Theta Switch causes a cascade of immune cells to "track" or channel down pathways of either mounting cellular defenses or secretory (antibody) defenses. In HIV disease, the cellular defenses may be the more vital in predicting the quality of life and survival duration.

According to the theory, the immuno competent cells can either proceed down the unresponsive path of antibody secretion (a so-called Type 2 Theta response) or the responsive path of cell mediated immune activity (a Type 1 Theta response, also called a DTH or a positive skin test response). A Type 2 response has been typically associated with HIV disease progression (leading ultimately to death) whereas a Type 1 response has been historically associated with a "survival advantage", especially in the recent longitudinal studies of HIV-infected military personnel evaluated by the Military Consortium for Applied Retroviral Research and the Veterans Administration Study Group.

Previously, researchers had no drug products or experimental tools which unequivocally directed the immune system down the desirable Theta 1 path. Indeed, the immunological path selected in any single HIV infected individual appeared to be largely dictated by apparently random events occurring during the course of the disease. However, researchers at HEM showed that its patented nucleic acid ("NA") products could drive the immune reaction in the apparently correct direction by selectively controlling the "Theta Switch". This was demonstrated in vivo by the ability of certain NAs to throw the Switch correctly and to elicit the production of a specific biological "cocktail" of cytokines, including interferon, interleukin ("IL") 2 and IL-12, which are the mediators or the biochemical workhorses of the Theta 1 Switch.

The in vivo results were then compared with clinical results collected from approximately 70 HIV-infected subjects (CD4 cells 200- 600) who were evaluated over an extended time (approximately 2,000 observational weeks) with respect to potential recovery of the Theta 1 response (measured by the skin test) using a specific NA product named Ampligen in conjunction with AZT, an antiviral compound. The DTH antigens used in the HEM clinical studies were similar to those recently reported in the military research. The clinical studies suggest that drug intervention converts a significant percentage of anergic (non-Theta 1/DTH responders) to a fuller or more complete Theta 1 response pattern. Results of the Military research (Birx et al., Journal of AIDS, Vol. 6, 1993) suggests that the median survival advantage may shift from 34 months to 69 months, apparently as a direct result of shifting this immunological response pattern to the cellular defense pattern.

HEM now plans to evaluate this immunological based regimen in conjunction with the newer classes of protease-based antiviral drugs which alone can reduce the HIV viral concentration in blood by 99% for several months. However, recent reports suggest that, thereafter, resistant HIV strains may emerge from these purely antiviral regimens. By scheduling the immunological and antiviral therapies in specific sequences, the researchers plan to evaluate whether the elicitation of the Theta 1 Switch Response at the proper time will ameliorate the emergence of resistant HIV strains and thereby further prolong the benefit periods in HIV disease.
 -0- 3/8/96


/CONTACT: Dr. William A. Carter, CEO of HemispheRx BioPharma, 215-988-0080/

(HEMXU)

CO: HemispheRx Biopharma ST: Pennsylvania, California IN: MTC HEA SU:

DW -- NYF016 -- 1545 03/08/96 11:00 EST
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Date:Mar 8, 1996
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