Safety, pharmacokinetics, and early bactericidal activity of quabodepistat in combination with delamanid, bedaquiline, or both in adults with pulmonary tuberculosis: a randomised, active-controlled, open-label trial

Quabodepistat (formerly OPC-167832) showed potent activity in preclinical studies and in the first stage of an early bactericidal activity study in adults with smear-positive, drug-susceptible pulmonary tuberculosis. Stage 2 of this study was designed to evaluate the safety, tolerability, pharmacokinetics, and early bactericidal activity of quabodepistat in combination with delamanid, bedaquiline, or both versus rifampicin, isoniazid, ethambutol, and pyrazinamide combination therapy for 14 days. Stage 2 of this open-label, active-controlled, randomised, parallel-group study was conducted at two research sites in South Africa in adults (aged 18–64 years) with drug-susceptible pulmonary tuberculosis. Eligible participants had a BMI of 16–32 kg/m2 and the ability to produce an adequate volume of sputum (≥10 mL overnight) and were excluded if they had drug-resistant tuberculosis or previous treatment for Mycobacterium tuberculosis within the past 3 years. Participants were centrally randomly assigned via interactive web response technology system, with no stratification, into four treatment groups in a ratio of 14:14:14:4 (quabodepistat 30 mg plus delamanid 300 mg, quabodepistat 30 mg plus bedaquiline 400 mg, or quabodepistat 30 mg plus delamanid 300 mg plus bedaquiline 400 mg orally once daily for 14 days, or rifampicin, isoniazid, ethambutol, and pyrazinamide combination therapy [control] according to local standard of care for 20 days). The primary outcomes were safety and tolerability during and after 14 days of treatment in all participants who received any study medication and pharmacokinetics at day 1 and day 14 in participants in the quabodepistat groups with adequate data for deriving pharmacokinetics parameters. The main secondary outcome was bactericidal activity from baseline to day 14 in all eligible participants who were quantitatively culture-positive at baseline. The study was not powered for formal statistical hypothesis testing; therefore, data were summarised by treatment group with descriptive statistics. This study is registered with ClinicalTrials.gov (NCT03678688) and is closed to new participants. 98 participants were screened for entry into stage 2 of the trial between Feb 1, 2021, and Jan 27, 2022, of whom 46 were randomly assigned (14 to each quabodepistat group, 4 to the control group) and 44 received at least one dose of study medication (one patient excluded from the quabodepistat plus delamanid and quabodepistat plus bedaquiline