The Centers for Disease Control and Prevention estimates that more than 1.2 million people are currently living with HIV in the United States and the number of new cases of HIV infection in the United States is expected to remain constant at approximately 50,000 cases per year.
Current Treatments for HIV: In 1996, a combination of oral medications known as anti-retroviral therapy (ART) was introduced to treat patients with HIV. Since then, the introduction of new drug classes of ART and combination drug treatment strategies have enhanced treatment for HIV.
ART in HIV-infected patients can decrease levels of HIV in the blood to below the limits of detection, increase life expectancy and improve quality of life. However, there continues to be an unmet need for HIV therapies for the following reasons:
- ART can have significant side effects. The most recent U.S. guidelines on ART contain a number of tables of adverse effects of combination regimens and how to manage them. Some combinations present potentially life-threatening complications and other complications that are chronic, cumulative and overlapping, and sometimes irreversible.
- ART requires life-long daily treatment. The risks of long-term daily administration of ART remain unknown but are potentially significant. In addition, the requirement for life-long daily treatment has made strict adherence to the treatment regime difficult. Poor compliance has led to the development of drug-resistant HIV variants that are ineffectively controlled by the available armamentarium of ART.
ART cannot eradicate the virus and, therefore, does not cure HIV-infected patients. For example, up to 20% of patients receiving ART fail to achieve normal CD4+ T-cell counts, resulting in a continued weakened immune system. In addition, certain patients are not able to achieve effective control of the virus using current treatment regimens. ART cannot eradicate the virus because the virus persists in latently infected cells. These cells, which constitute the HIV latent reservoir, do not express HIV antigens and are therefore invisible to the immune system. Instead, these cells serve as the source for virus replication and viral rebound in the absence of ART. Following discontinuation of treatment with ART, HIV viral levels return to levels observed prior to treatment with ART within 12 weeks of treatment interruption.