Re-evaluating the Duration in Children of TB Treatment

Current tuberculosis (TB) treatment is effective (works well), but it takes a long time to cure TB. This study will evaluate if TB treatment with a higher dose of rifampicin, one of the TB medicines, and shorter TB treatment duration is as effective and safe as the standard, TB treatment (with the usual rifampicin dose and usual duration). This study hopes to find a better shorter treatment that works as well as the current treatment (standard of care). This could benefit children worldwide who are getting TB treatment. Children 3 months to less than 10 years of age who have drug-susceptible TB (can be successfully treated with standard TB medicines) are eligible for this study.

Inclusion Criteria: * 3 months to less than 10 years of age * Body weight greater than or equal to 3 kilograms (kg) and less than 45 kg at study entry * Confirmed or clinically diagnosed intrathoracic (pulmonary) and/or some forms of extrathoracic (extrapulmonary) drug-susceptible TB: * Confirmed intrathoracic (pulmonary) TB, based on chest radiograph and/or symptoms consistent with TB, and/or some forms of extrathoracic TB, with all of the following as determined by the site investigator: * Microbiological confirmation of M. tuberculosis from any clinical specimen by either culture or molecular methods * At least rifampicin-susceptibility demonstrated by genotypic (molecular) or phenotypic methods * Documented clinical decision to treat for drug-susceptible TB * Clinically diagnosed intrathoracic (pulmonary) TB, based on chest radiograph and/or symptoms consistent with TB, and/or some forms of extrathoracic TB, with all of the following as determined by the site investigator: * Documented clinical decision to treat for drug-susceptible TB * HIV positive or negative * For participants living with HIV, they must be on a dolutegravir-based antiretroviral therapy regimen at the time of study entry Exclusion Criteria: * Received routine treatment for TB disease for greater than 5 days at the time of enrollment * Exposure to a case of intrathoracic TB in the 12 months prior to enrollment with known or suspected resistance to any of the drugs in the treatment regimens OR confirmed resistance on molecular or phenotypic drug-susceptibility testing to any drugs in the treatment regimens * Has greater than or equal to grade 3 results of any of the following during screening: creatinine, serum ALT, AST, total bilirubin * Has hemoglobin less than 7.5 g/dL during screening * Has TB meningitis, osteoarticular TB, or miliary TB as determined by the site investigator * Severe renal, pulmonary, cardiac, gastrointestinal, neurologic or any other condition that in the judgement of the investigator would make participation in the study unsafe, complicate interpretation of study outcome data, or otherwise interfere with achieving study objectives * Use of any prohibited drug within 3 days of enrollment * Severe acute malnutrition defined as weight-for-height/length z-score or BMI-for-age z-score less than -3 * Hypersensitivity to any of the study drugs (rifampicin, isoniazid, pyrazinamide or ethambutol) * For Main Trial (Step 2) participants, previously enrolled in the Lead-in PK Study (Step 1)