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.

Inclusion Criteria

Patients may be eligible for this study if they:

• Are HIV-positive.
• Have PML, including symptoms of PML.
• Are able to complete the study.
• Agree to have a catheter inserted in a vein.
• Have taken at least 3 weeks of a stable anti-HIV drug combination (unless they are unable to take anti-HIV drugs).
• Are at least 18 years old.
• Agree to use effective methods of birth control.

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have a history of certain central nervous system (CNS) diseases.
• Have a history of certain psychiatric disorders, such as bipolar disorder or schizophrenia.
• Have syphilis that has not been treated.
• Have certain severe medical problems, including AIDS-related opportunistic infections (such as PCP) that require treatment.
• Have received chemotherapy in the past 30 days.
• Have ever received chemotherapy for PML.
• Are pregnant or breast-feeding.
• Are taking certain medications, including any other investigational drugs.