Researchers at Panacos Pharmaceuticals, working with scientists at the National Institutes of Health and the George Washington University Medical Center, have discovered a new compound that in lab tests appears to inhibit HIV at a cycle of viral development previously untargeted by existing antiretroviral drugs. The compound, called PA-457, interferes with the assembly of the coat surrounding newly formed copies of the virus during the viral maturation process, one of the final steps in the HIV infection and replication cycle. An incomplete outer coat leaves replicated copies of the virus unable to infect other immune system cells. According to a study of the compound, published in the October 20 online edition of The Proceedings of the National Academy of Sciences, the compound appears effective even against strains of HIV that have developed resistance to other anti-HIV medications. PA-457 is currently in preclinical development. Officials at Panacos plan to file an Investigational New Drug application with the Food and Drug Administration later this year. Should the drug proceed through clinical trials and receive FDA approval, it would be the first approved drug in a new "maturation inhibitor" class of anti-HIV medications.
"The most pressing need in HIV treatment today is for new therapies that are effective against drug-resistant strains of the virus," said Carl Wild, chief science officer for Panacos. "Our work demonstrates that, unlike currently approved antiretroviral drugs, PA-457 interferes with the assembly of the capsid shell surrounding the virus's nucleic acid core. Consistent with this observation, PA-457 potently inhibits virus strains resistant to approved HIV drugs. These findings suggest that PA-457 may one day provide a new treatment option for the increasing number of patients infected by drug-resistant strains of HIV."