The Individualized M(X) Drug-resistant TB Treatment Strategy Study A Strategy to Improve Treatment Outcomes in Patients With Drug-resistant TB

When drug resistance is detected by molecular methods such as the Xpert MTB/RIF assay, second-line Multi Drug-Resistant (MDR) Tuberculosis treatment is started in the complete absence of detailed resistance information. The diagnosis of Multi Drug-Resistant Tuberculosis is confirmed only on availability of Line Probe Assay (LPA)/Drug Susceptibility Testing (DST) results. Extremely Drug-Resistant (XDR) Tuberculosis is diagnosed by in vitro phenotypic resistance to Rifampicin, Isoniazid, fluoroquinolones and injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin). Existing culture based Drug Susceptibility Testing provides results after 6-8 weeks. This duration may be further increased by other existing laboratory challenges, such as culture contamination.

Furthermore, initial regimens are often not optimal and sometimes completely ineffective as there is a lack of Drug Susceptibility Testing to support them. More importantly, even optimal regimens are changed due to patient intolerance of the drug's side effects.

Whole Genome Sequencing (WGS) has the advantage of determining the complete Deoxyribonucleic acid (DNA) sequence of an organism's genome at a single time point. Using this technology, genotypic mutations conferring resistance to anti-tuberculosis drugs can be identified. This information will assist in identifying not only potential resistant drugs, but also susceptible drugs and thus enable a more accurate and appropriate choice of regimen. In addition, drugs that will not add value to the treatment outcome, but will increase rates of adverse drug reactions, can be eliminated earlier, improving drug-resistant TB treatment outcomes.

In this proposal, we aim to use Mycobacterium Tuberculosis (MTB) whole genome sequencing prior to the selection of a drug-resistant tuberculosis treatment regimen and thus provide an individualized treatment strategy for drug-resistant tuberculosis. By adopting this method, we hope to improve culture negative survival rates at 6 months post treatment initiation .

This study will include 448 adult patients (age ≥ 18 years) that meet inclusion criteria. Patients referred by provincial satellite facilities with microbiological confirmation of drug-resistant tuberculosis (e.g. Xpert MTB/RIF assay / Line Probe Assay) to King DinuZulu Hospital (KDH) will be recruited. Patients randomized to the control arm will receive standard of care (SOC) treatment. Patients randomized to the intervention arm will be given an individualized treatment regimen based on whole genome sequencing conducted on Mycobacteria Growth Indicator Tube (MGIT) positive sputum samples collected at the screening visit.