TB-CAPT kicks off the first of three trials

The TB-CAPT XDR Trial team. From the left: Widaad Zemanay, Heibrecht Fielies (joining via video call) Parveen Brown, and Minkie Gumede.  

The TB-CAPT consortium has successfully kicked off the first of three trials included in the TB-CAPT project. The TB-CAPT XDR trial, led by Helen Cox and Chad Centner of the University of Cape Town (UCT) in South Africa, will evaluate the use of a new cartridge on GeneXpert, an automated tuberculosis (TB) molecular test. This rapid test can identify resistance to key drugs used in the treatment of drug-resistant TB.

TB-CAPT will evaluate the impact of novel TB diagnostic interventions on patient outcomes in two clinical trials and the accuracy of a new TB diagnostic for drug-resistant TB in a feasibility study. The three trials will be conducted in Tanzania, Mozambique, and South Africa. The first one, the TB-CAPT XDR trial, began in late May and is implemented jointly by UCT and the University of Witwatersrand (Wits), Johannesburg, South Africa.

Turning the tide on drug resistant TB

Drug resistant TB (DR-TB) is a growing problem worldwide. Annually, about half a million people fall ill with TB that is resistant to the most important TB drug, rifampicin, around the world. Containing drug-resistant TB through providing effective diagnosis and treatment is critical if we want to turn the tide on the disease.

Today, only 57 percent of drug resistant TB patients are successfully treated. Rapid diagnostics and reliable information about what type of TB treatment a patient with drug resistant TB should receive allows the best possible treatment to be started as soon as possible and improves their chance of cure.

The TB-CAPT XDR trial will evaluate the new Xpert MTB/XDR cartridge on GeneXpert, an automated TB molecular diagnostic testing machine that was endorsed by WHO for testing of rifampicin resistance in TB endemic countries in 2010. This new cartridge test cuts the time it takes to get a result from weeks to hours.

There is currently only limited data available for how accurate this test is. The TB-CAPT XDR trial aims to add to existing data and provide insights into how reliable the test is and how this new cartridge could be successfully introduced in TB labs in South Africa and other high burden TB countries. 

Streamlined data analysis process to ensure the maximum impact of the study

The XDR trial will evaluate samples from 753 patients with rifampicin-resistant TB in laboratories in Cape Town and Gqeberha (formerly Port Elizabeth). Both laboratories are part of the South African National Health Laboratory Service and collaborate with public TB clinics across the country. The goal is to wrap up the sample collection and begin data analysis towards the end of 2021 or early next year.

Many high burden TB countries, including South Africa, have seen a dramatic drop-off in TB testing during the past year, caused by the COVID-19 pandemic. The TB-CAPT XDR trial team is carefully monitoring the development of TB testing in South Africa and its potential impact on the trial. However, luckily, it currently looks like there will be enough available samples for the TB-CAPT XDR trial team to analyse.  

Once the TB-CAPT XDR trial team have reached their target sample size, they will begin data analysis. Continuous data validation will be carried out during the enrolment phase to help speed up the analysis process. Helen Cox explains:

“If the study results are positive, we want to get the data in the hands of policymakers as fast as possible to ensure that the new Xpert MTB/XDR test can be included in the global TB diagnostics portfolio without unnecessary delays.”