A 3-month clofazimine-rifapentine-containing regimen for drug-susceptible tuberculosis versus standard of care (Clo-Fast): a randomised, open-label, phase 2c clinical trial.

backgroundBased on results from preclinical and clinical studies, a five-drug combination of isoniazid, rifapentine, pyrazinamide, ethambutol, and clofazimine was identified with treatment shortening potential for drug-susceptible tuberculosis; the Clo-Fast trial aimed to determine the efficacy and safety of this regimen. We compared 3 months of isoniazid, rifapentine, pyrazinamide, ethambutol, and clofazimine, administered with a clofazimine loading dose, to the standard 6 month regimen of isoniazid, rifampicin, pyrazinamide, and ethambutol in drug-susceptible tuberculosis.

methodsClo-Fast was a phase 2c open-label trial recruiting participants at six sites in five countries. Participants aged 18 years or older with pulmonary tuberculosis who were sputum smear positive for acid-fast bacilli or molecular tuberculosis assay positive (with Mycobacterium tuberculosis with sensitivity to rifampicin and isoniazid) were eligible for enrolment. Individuals with HIV infection with a CD4

findings104 participants were randomly assigned to group 1 (n=58), group 2 (n=31), and group 3 (n=15). 82 (79%) were male and 74 (71%) had radiographically advanced disease; 30 (29%) were people with HIV. The trial was stopped early for lack of clinical efficacy. For the primary efficacy outcome, 49 (89%) of 55 group 1 participants and 28 (90%) of 31 group 2 participants had stable sputum culture conversion by week 12 (adjusted hazard ratio 1·21 [90% CI 0·82-1·79]; p=0·2089). Adverse events grade 3 or worse occurred in 26 (45%) of 58 group 1 participants and five (16%) of 31 group 2 participants (difference 30%, 90% CI 14-45; p=0·002). The cumulative probability of a week 65 unfavourable outcome was 52% (95% CI 37-69) in group 1 versus 27% (14-50) in group 2 (p=0·049).

interpretationAlthough the trial was stopped early, we found that a 3-month regimen containing clofazimine and rifapentine had 12-week culture conversion rates that did not differ statistically from the standard of care. The regimen was associated with an unacceptably high proportion of participants with unfavourable composite clinical outcomes and grade 3 or worse adverse events.

fundingUS National Institutes of Health Advancing Clinical Therapeutics Globally for HIV/AIDS and Other Infections (ACTG) and the National Institute of Allergy and Infectious Diseases.