An increasing number of patients are developing multidrug-resistant (MDR) virus, as determined by genotypic antiretroviral resistance testing (GART), due to treatment failure to suppress viral replication after several rounds of combination antiretroviral therapy. The best therapeutic strategy for these patients is uncertain. Two strategies currently being used are (1) STI followed by a new antiretroviral regimen and (2) immediate initiation of a new antiretroviral regimen.

Patients are screened for the presence of MDR virus and a plasma HIV RNA level greater than 10,000 [AS PER AMENDMENT 07/03/01: greater than 5,000] copies/ml. Eligible patients attend a baseline visit [AS PER AMENDMENT 07/03/01: and a subsequent randomization visit] where the qualifying GART results are provided. Patients who consent to participate have phenotypic antiretroviral resistance testing (PART) done on a specimen from the same blood draw that was used for the GART evaluation. After PART results are available, patients are randomized [AS PER AMENDMENT 07/03/01: If the predicted sensitivities are not available for some or all drugs included in the PART, the patient may still be randomized.] to either a 4-month STI followed by a new antiretroviral regimen or an immediate new antiretroviral regimen. The antiretroviral regimens chosen are based on the patients' history and both GART and PART results. [AS PER AMENDMENT 07/03/01: Additional GART and PART may be requested after at least 4 months of antiretroviral treatment.] Patients have the follow-up data collection done at Months 1-8 and every 4 months thereafter. Changes in antiretroviral therapy, Grade 4 adverse experiences, progression of disease, and deaths are reported as they occur. Patients are seen for clinical management as often as deemed necessary. All patients are followed to a common closing date estimated to be 24 months after the last patient is randomized. Some patients may participate in a Point Mutation Substudy [AS PER AMENDMENT 07/03/01: Plasma Point Mutation Substudy and PBMC Point Mutation Substudy].