Genotype-stratified adjunctive dexamethasone for tuberculous meningitis in HIV-negative adults: a randomized controlled phase 3 trial

# Genotype-stratified adjunctive dexamethasone for tuberculous meningitis in HIV-negative adults: a randomized controlled phase 3 trial *Published: 2026 Mar* Adjunctive corticosteroids such as dexamethasone are recommended in tuberculous meningitis treatment, despite modest and heterogeneous survival benefit. Leukotriene A4 hydrolase (LTA4H) genotypes associate with distinct intracerebral inflammatory phenotypes and may determine corticosteroid response in tuberculous meningitis, with benefit observed in hyperinflammatory TT genotype but uncertain benefit in lower inflammation CC and CT genotypes. Here, in a phase 3, placebo-controlled trial of human immunodeficiency virus-negative Vietnamese adults with tuberculous meningitis, we randomized 613 LTA4H CC- and CT-genotype participants to 6-8 weeks of dexamethasone or placebo, aiming to show noninferiority of placebo (hazard ratio margin of 0.75) or its superiority. Given the significant survival benefit of dexamethasone previously seen in LTA4H TT-genotype individuals, TT-genotype participants all received open-label dexamethasone and were not randomized. A total of 89 TT-genotype participants received open-label dexamethasone. In CC- and CT-genotype participants, the primary endpoint of all-cause death or new neurological event over 12 months from randomization occurred in 108/305 (35.4%) given dexamethasone and 110/308 (35.7%) given placebo (hazard ratio of 0.99, 96% confidence interval (adjusted for multiple testing) 0.748-1.31). The number of observed primary endpoints (n = 218) exceeded the prespecified number (n = 184) used to calculate the trial's sample size and power. Placebo noninferiority was not established in the CC and CT population or in individual genotype subpopulations. Benefit or heterogeneity of effect was not observed by any prespecified subgroup. In TT-genotype participants, the primary endpoint occurred in 28/89 (31.5%) participants, similar to CC and CT participants. Outcomes were not significantly better in TT-genotype participants versus CC- or CT-genotype participants. In CC- and CT-genotype participants, serious adverse events occurred in 161/305 (52.8%) dexamethasone-treated participants and 160/308 (51.9%) placebo-treated participants. In conclusion, neither noninferiority nor superiority of placebo was established in human immunodeficiency virus-negative LTA4H CC- and CT-genotype adults with tuberculous meningitis, and dexamethasone was safe. The modest and heterogeneous benefit of dexamethasone indicates that greater understanding of tuberculous meningitis pathophysiology is needed, alongside better targeted, more effective anti-inflammatory agents than corticosteroids (ClinicalTrials.gov NCT03100786 ). DOI: 10.1038/s41591-025-04138-z