Ivax Corporation reported that it is developing, in collaboration with the Laboratory of Molecular Biology of the National Cancer Institute, a recombinant immunotoxin designed to treat HIV infection by selectively destroying HIV infected cells. This immunotoxin is engineered to selectively kill HIV-infected cells by targeting an HIV envelope glycoprotein only found on the surface of HIV infected cells.

Currently, HIV infected people are treated with combinations of drugs referred to as "highly active antiretroviral treatment" or "HAART" which produce a dramatic reduction in viral load, elevation of CD4 blood cell counts, and improvement in clinical status and survival. The long-term effectiveness of HAART is, however, severely limited by the persistence of reservoirs of infected cells which appear to be the source of the rapid increase of viral load upon cessation of HAART therapy. As a result, HAART treatment must be continued, despite serious side effects.

In animals with established HIV-1 infection, the targeted immunotoxin significantly increased the anti-HIV activity of HAART. In a model of acute HIV infection, animals treated with low dose HAART and the targeted immunotoxin demonstrated strong suppression of viral load during and after cessation of HAART. In contrast, animals treated with HAART alone had viral suppression during HAART but a prompt increase in viral load after HAART.

Dr. Phillip Frost, chairman and CEO of Ivax commented, "The HIV envelope targeted immunotoxin is designed to reduce the dependence of HIV infected persons on HAART and to prevent establishment of HIV infection after HIV exposure. Ivax is developing this new drug in the hope that it will make a vital contribution to the global effort to prevent and control HIV infection."