PANACOS BEGINS STUDY OF MATURATION INHIBITOR

Panacos Pharmaceuticals has initiated a Phase I clinical trial of PA-1050040, an investigational maturation inhibitor for the treatment of HIV. This study is designed to evaluate the safety and pharmacokinetic properties of PA-040 in humans after a single dose.

Maturation inhibition is a new target discovered by Panacos scientists and their academic collaborators. The company's first-in-class HIV maturation inhibitor, bevirimat (PA-457), has shown significant anti-HIV activity in HIV patients and is in Phase IIb clinical testing. This second-generation maturation inhibitor program is designed to develop chemical analogs of bevirimat with distinct pharmacological properties, including the potential to have activity against HIV strains resistant to bevirimat -- in case resistant strains appear in the future.

In vitro studies with PA-040 have shown that the compound has a lower level of binding to human serum proteins than bevirimat, which may result in greater levels of free drug in patients dosed with the compound, and thus the potential to have activity against HIV strains that exhibit partial bevirimat resistance. Furthermore, PA-040 retains wild-type activity against one of two bevirimat-resistant HIV isolates that represent the most frequently mutated amino acids found by in vitro resistance-selection experiments performed to date.