In vitro activity: Q203 is an imidazopyridine amide (IAP) compound that block Mycobacterium tuberculosis growth by targeting the respiratory cytochrome bc1 complex. It has the potential for the treatment of tuberculosis. Q203 inhibited the growth of MDR and XDR M. tuberculosis clinical isolates in culture broth medium in the low nanomolar range and was efficacious in a mouse model of tuberculosis at a dose less than 1 mg per kg body weight, which highlights the potency of Q203. Q203 is active against the reference strain Mycobacterium tuberculosis H37Rv with MIC50s of 2.7 nM in culture broth medium and 0.28 nM inside macrophages. In addition, Q203 displays pharmacokinetic and safety profiles compatible with once-daily dosing. Together, these data indicate that Q203 is a promising new clinical candidate for the treatment of tuberculosis.

Kinase Assay: Q203 is active against the reference strain Mycobacterium tuberculosis H37Rv with MIC50s of 2.7 nM in culture broth medium and 0.28 nM inside macrophages.

Cell Assay:

Mice: Efficacy of Q203 in a mouse model of established tuberculosis is studied. Bacterial loads are enumerated in the lung of infected mice after 14 d and 28 d of treatment. Q203 is used at 0.4, 2 and 10 mg per kg body weight. Bedaquiline and isoniazid (INH) are used as positive controls at 6.5 and 15 mg per kg body weight, respectively. Five mice per group and per time point are used.