Standard Versus Double Dose Dolutegravir in Patients With HIV-associated Tuberculosis

Dolutegravir is being rolled out to replace efavirenz in first-line antiretroviral therapy (ART) in low-middle income countries (LMICs) because it is more effective, better tolerated, and has a considerably higher genetic barrier to resistance. Tuberculosis is the commonest cause of HIV-related morbidity and mortality in LMICs. Rifampicin, which is a key component of anti-tuberculosis therapy, induces genes that are important in the metabolism and transport of dolutegravir. The resulting drug-drug interaction between dolutegravir and rifampicin significantly reduces dolutegravir exposure, which can be overcome by increasing the dose of dolutegravir to 50 mg 12 hourly. The additional dose of dolutegravir will be difficult to implement in high burden settings. Furthermore, the additional dolutegravir tablet increases pill burden and costs. If standard dose dolutegravir is shown to be effective in patients with tuberculosis this would sweep away one of the major barriers to its implementation in LMICs. There are three lines of evidence to support studying standard dose dolutegravir in patients with HIV-associated tuberculosis. First, there are compelling pharmacokinetic and pharmacodynamic data supporting the therapeutic efficacy of lower dolutegravir exposure. Second, the investigators have conducted a drug-drug interaction study of dolutegravir dosed at 50 mg or 100 mg once daily in healthy volunteers with rifampicin. Although, as expected, concomitant rifampicin significantly reduced dolutegravir exposure at both doses, all dolutegravir trough concentrations on rifampicin were above the protein-adjusted 90% inhibitory concentration (PA IC90). Third, exposure to the first-generation integrase inhibitor raltegravir is also significantly reduced with concomitant rifampicin. A phase 2 study in patients with HIV-associated tuberculosis showed that virologic outcomes were similar with standard and double dose raltegravir. It is plausible that findings could be similar with dolutegravir. The hypothesis is that virologic outcomes with standard dose dolutegravir-based ART will be acceptable in patients on rifampicin-based anti-tuberculosis therapy. If the proportion of participants who achieve virological suppression on standard dose dolutegravir is acceptable, this would pave the way for a phase 3 trial of dolutegravir 50 mg daily versus an appropriate standard of care regimen, like efavirenz-based ART, in patients with HIV-associated tuberculosis.