Rifampin-Based Tuberculosis Treatment Versus Rifabutin-Based Tuberculosis Treatment in Persons With HIV

Rifampin (RIF), the cornerstone of TB treatment, has very problematic drug-drug interactions with PIs. The use of relatively high doses of ritonavir appear necessary to overcome this interaction, but it is unclear whether the co-treatment regimen of RIF-based TB treatment and double-dose PI-based ART will be safe and tolerable for patients with HIV-related TB and effective in treating both HIV and TB. The study proposed to determine if, for HIV-1-infected participants with active TB who require PI-based ART, a standard-dose lopinavir/ritonavir (LPV/r) regimen, with or without raltegravir (RAL), coupled with rifabutin (RBT)-based TB treatment is superior to a double-dose LPV/r regimen coupled with RIF-based TB treatment.

At study entry, participants were randomized (1:1:1) to receive standard-dose LPV/r-based HIV treatment plus RBT-based TB treatment (Arm A), double-dose LPV/r-based HIV treatment plus RIF-based TB treatment (Arm B), or standard-dose LPV/r-based HIV treatment plus RAL plus RBT-based TB treatment (Arm C).

Accrual was planned to take place in two accrual periods. Accrual period 1 would enroll 60 participants who would undergo an initial dose-finding period before continuing regular study follow-up. Once the review of the dose-finding pharmacokinetic (PK) and safety data from accrual period 1 participants was completed, accrual period 2 was planned to open to accrual.

Study duration was 72 weeks. Visits occurred at weeks 2, 4, 8, 12, 16, 20, 24, 32, 40, 48, and 72. The key evaluations included physical examination, clinical assessments, TB evaluations including chest x-ray, acid-fast bacilli (AFB) smear, mycobacterial culture, and drug susceptibility testing, CD4 cell count, HIV viral load, hematology, chemistry, and pregnancy testing in women of reproductive potential. Sputum, serum, and urine were stored for use in future analyses. An intensive PK visit occurred at day 12. PK blood draws in participants in Arms A and C were at RBT pre-dose and at 2, 4, 5, 6, and 24 hours RBT post-dose. PK blood draws in participants in Arm B were at LPV/r pre-dose and at 2, 4, 5, and 6 hours LPV/r post-dose.

The target sample size was 471 participants, but the study was terminated after 71 participants due to feasibility concerns. The 71 participants were followed for the planned 72 weeks. Because of the limited sample size, formal statistical comparisons were not undertaken as originally planned.