Patients are enrolled sequentially into the next available dosage cohort. Each cohort receives a single dose of tucaresol, is observed for 2 weeks, and then receives 3 alternate-day doses of drug and careful safety monitoring, including 4 weeks follow-up after the final dose. Dose cohorts receive drug sequentially, the lowest-dose cohort receiving the drug first. Dose escalation may not proceed to the next higher-dose cohort until all patients from the prior lower-dose cohort have completed the 4-week follow-up after the multiple dosing, adverse events are within the described bounds, and the FDA has reviewed the safety information from the treated cohort and approved the dose escalation. The drug is administered 4 times within the 8 weeks of the study period. Weekly visits are required. Patients receive financial compensation.