US researchers may have come a step closer to finding a possible cure for AIDS: using radioimmunotherapy, they were able to destroy HIV-infected cells in blood samples of patients who had been treated with a highly active antiretroviral therapy (HAART). The research results were presented at the Annual Meeting of the Radiological Society of North America (RSNA) in Chicago.
The highly active antiretroviral therapy inhibits replication, and thereby reduces the viral burden and improves the prognosis for the patients. However, HAART is unable to destroy potential reservoirs of latent infected cells in the body. And this is precisely the issue addressed by researchers from the Albert Einstein College of Medicine in New York. They administered radioimmunotherapy to blood samples from 15 patients who had previously received HAART. To do this, they paired the monoclonal antibody mAb2556, which targets the surface protein gp41 of HIV cells, with the radionuclide Bismuth-213.
The results were unequivocal: RIT killed the HIV-infected lymphocytes previously treated with HAART. During this process, the HIV infection was reduced to such an extent that it was no longer detectable in the blood samples. “The elimination of HIV-infected cells with RIT was profound and specific”, said first author Ekaterina Dadachova. “The radionuclide we used delivered radiation only to HIV-infected cells without damaging nearby cells.”
Furthermore, the researchers discovered another property of the radio-labeled monoclonal antibody. In trials using an in vitro human blood brain barrier model, mAb2556 crossed the barrier without damaging it and killed the HIV-infected cells. “Antiretroviral treatment only partially penetrates the blood brain barrier, which means that even if a patient is free of HIV systemically, the virus is still able to rage on in the brain and cause problems”, explained Dadachova. “Our study showed that RIT is also able to kill HIV-infected cells in the central nervous system”.