Topotecan, a cytotoxic DNA topoisomerase-I inhibitor that crosses the blood-brain barrier, inhibits the replication of JC virus (the virus that causes PML) in vitro, at concentrations that are not toxic to human cells. Topotecan also inhibits the replication of HIV-1 and the function of Tat (which upregulates the replication of JC virus).
Patients are randomized to be treated immediately with topotecan or to have treatment delayed for 8 weeks. The dosing schedule for patients receiving immediate or delayed treatment is topotecan as a continuous 21-day intravenous infusion every 28 days. All patients must have received optimal, stable antiretroviral therapy for 3 weeks prior to entry and preferably will continue that therapy during the study.
