PRO-542 shows efficacy in trial

Polly Clayden, HIV i-Base

A report in the July issue of the Journal of Infected Diseases of a phase 1 study of PRO 542 – a recombinant antibody-like fusion protein that binds to and neutralises HIV-1 isolates, showed significant viral load reduction, good tolerability and no dose limiting toxicities, in HIV-infected adults.

Subjects were treated with a single intravenous infusion of PRO 542 at doses of 0.2-10 mg/kg. The drug was well tolerated, and the AUC and peak serum concentrations increased linearly with the dose, as did reduction in HIV-1 RNA. No patient developed antibodies to PRO 542.

Sustained antiviral effect may be achieved with dosing of PRO 542. This novel agent deserves further investigation.


Single dose safety, pharmacology, and antiviral activity of the human immunodeficiency virus (HIV) type 1 entry inhibitor PRO 542 in HIV-infected adults. Jacobson et al. J of Infect Dis 2000 Jul; 182(1):326-9

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