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PRO 542: phase 1 study, drug administered by IV infusion
Reported by Jules Levin
  At Retrovirus researchers from Progenics reported on a phase 1 study, open-label study of single doses of this drug administered by IV infusion to 12 HIV-infected treatment-naive and treatment-experienced individuals.
Pro 542 inhibitis HIV-1 attachment. It is a type of entry inhibitor that inhibits the attachment phase of entry. The drug has potent anti-HIV in vitro activity with activity against R5, X4, and R5X4 viruses. It has been found to be synergistic with T-20 in vitro.
7 patients with viral load=5000 copies/ml received a single infusion of 25 mg/kg of Pro 542, and 5 patients with >100,000 copies/ml received a single infusion of 25 mg/kg. Patients were either on no ART or on stable therapy.
Overall, the mean maximal change in viral load was about -0.25 log copies/ml. Bu day 3 after infusion viral load increased to mean of -0.1 log copies/ml. In patients with advanced HIV and drug-sensitive virus, viral load reduction was about -0.5 log, and reduction was sustained for 4-6 weeks. Viral susceptibility was not dependent on baseline viral load or on CD4 count. No resistance developed. The viral phenotype changed in 2 patients from R5X4 to R5. The authors concluded that Pro 542 demonstrates modest anti-HIV activity in some patients, and it may be useful in salvage therapy. More frequent dosing schedules (once or twice monthly, 3x weekly) are currently being assessed.
Abst. 561. Olsen et al. Retrovirus Conference 2003, Feb 10-14, Boston, MA.