Electrochemical Assay to Monitor Anti-TB Antibiotics

ABSTRACT: Tuberculosis (TB) is one of the top ten causes of death globally and is the second most powerful single infectious agent behind HIV/AIDS. While the incidence of TB continues to decrease every year, there has been a significant rise in drug resistant TB (DR-TB), with 10% of the cases developing into extensively drug resistant TB (XDR TB). The therapeutic outcome of these drug resistant TB forms are unexpectedly poor due to toxicity of second line antibiotics and low efficacy of therapeutic regimes due to lack of blood monitoring. Despite tremendous evidence that concentrations matter enormously and they are highly variable, therapeutic drug monitoring in TB has been perceived as a luxury, rather than a necessity. Additionally, blood levels of antibiotics can only be measured using sophisticated instruments in highly specialized laboratories, increasing the cost and turnaround times and making the monitoring essentially impossible in the global clinical field. Currently there is no rapid and cost-effective method capable of monitoring anti-TB antibiotics in blood. A recent landmark clinical study showed that a three-drug NIX-TB regimen (Linezolid, Pretomanid and Bedaquiline) has great potential, remarkably curing ~90% of patients with XDR-TB after only six months of treatment. However, many patients experienced side effects due to high dose linezolid and patients often require therapeutic drug level monitoring. This remains a major gap in TB care since this testing currently takes one week even in high resource settings and is unavailable in most high TB incidence countries. A rapid and simple electrochemical test to quantify the levels of anti-tuberculous antibiotics in blood meets a critical need within TB care. Giner aims to demonstrate the feasibility of an electrochemical assay for the three antibiotics used in NIX-TB regimen in human serum samples with low (lt100 μl) sample requirements and a sample-to-result time of lt10 minutes. Quantification will be demonstrated at a broad relevant clinical range of 0.05 μg/mL to 100 μg/mL. The Aims of the Phase I feasibility program are: 1) Development of an electrochemical assay for each drug in NIX-TB regimen (Linezolid, Pretomanid and Bedaquiline); 2) Validation of sensitivity, specificity, and simultaneous measurement capability; and 3) Evaluation of assay performance in human blood serum and benchmarking against the gold standard analytical method.