Early preclinical development of Mycobacterium tuberculosis amino acid biosynthesis pathway inhibitor DRILS-1398 as a potential anti-TB drug

The search for new anti-tubercular agents is vital for the fight against Mycobacterium tuberculosis, particularly given the rise of drug-resistant strains. DRILS-1398, a pyrazolo[4,3-d]pyrimidine derivative, was discovered as a potent inhibitor of M.tb chorismate mutase (M.tb-CM) with an IC₅₀ = 3.0 ± 0.2 μM (n = 3) and IC₉₀ = 10 μM. The compound demonstrated efficacy against multi-drug resistant M.tb strains (MIC = 4 μg/mL, ∼10.0 μM) and effective inhibition of intracellular M.tb in THP-1 macrophages. With favorable pharmacokinetics, moderate stability in vitro, and a promising safety profile, DRILS-1398 showed no toxicity at doses up to 500 mg/kg b.w./day when dosed orally daily once for 7 consecutive days in mice. Both DRILS-1398 and its formulation DRILS-1398(F) were successful in clearing M.tb infection from the lungs and spleen in murine models. These findings suggest DRILS-1398 as a promising lead candidate for developing a first-in-class anti-tubercular drug.