Antiretroviral therapy is costly and toxic, and resistance to it will eventually develop.  As a result, there have been several attempts to develop alternative treatment strategies. 

One such strategy that underwent extensive human testing was Structured Treatment Interruption.  This was based on the premise that the immune system should recognize and control the virus, which would likely become reactivated once treatment had been stopped after having been suppressed to undetectable levels.  However, the outcome was disastrous – the results of  the SMART study, which compared intermittent therapy (IT)  with continuous therapy (CT), “showed that there was increased risks of AIDS or death, serious AIDS-defining events, and severe complications”.  The study was terminated when it became apparent to the Data and Safety Monitoring Board (DSMB) that twice the number of progression events had occurred in a three-month period.

An Alternative to the Present Long Term Therapy

Obviously, there still remains a clear need for an alternative to the present long term therapy, given the problems associated with compliance to the drugs, viral resistance, costs and the metabolic effects associated with antiviral therapy.  These include cardiovascular disease, lipoatrophy, peripheral neuropathy and accelerated liver disease.  Hence, the need to explore the possibility of HIV Interval Therapy (HIT).  This  differs from intermittent therapy in that an immunomodulatory drug, Immugen’s lead compound, will be used during a treatment interval. The purpose of the study is to determine exactly how long that interval will be. 

Proof-of-Concept Study

A proof-of-concept study of an HIV Interval Therapy program (HIT) will be conducted in rhesus nemestrina monkeys (pig-tailed macaques) infected with SIV under the supervision of Preston Marx, Ph.D., at the Tulane National Primate Center.  The animals will be infected with SIV  and treated with either THC or Immugen's lead compound until the animals are eligible for anti-retroviral therapy (ARV). During the course of ARVs, the animals will be treated with a cannabinoid until viral loads are either undetectable or down to 50 copies or less per ml. Once the ARVs are stopped the slope of viral  recrudescence will be determined. Immugen predicts that the slope will be gradual as compared to a structured treatment interruption scenario, in which the virus almost always spikes or rebounds to pretreatment levels.  It is hoped that the drug will be able to reprogram the immune response and sustain homeostasis, thereby depriving the virus of the very potent stimulatory factors required for its replication and resurgence.  Ultimately this will provide the scientific basis for the cessation of antiviral therapy as well as support HIT among HIV-infected individuals, who are not yet eligible for antiviral therapy, by prolonging the latency of the virus.