The Foundation for Innovative New Diagnostics (FIND) and Cepheid, Sunnyvale, Calif, are launching the new Xpert MTB/XDR test, which enables expanded drug-resistance tuberculosis (TB) profiling in less than 90 minutes. Xpert MTB/XDR can be used to empower clinicians to quickly prescribe treatment regimens for extensively drug-resistant TB (XDR-TB). Able to detect TB that is resistant to multiple first- and second-line TB drugs, the rapid molecular test could help fill a critical gap that is currently jeopardizing global TB elimination targets. By contrast, Cepheid says current methods for identifying drug-resistance profiles for XDR-TB are very complex to perform, can take up to 16 weeks to deliver results, and as a result are often completely unavailable to patients.1 XDR-TB is the most complicated form of TB, with the worst outcomes. Mortality has been reported as high as 41% in some cohorts.2 “By providing test results in just a few hours, the Xpert MTB/XDR test will save lives,” says Catharina Boehme, CEO of FIND. Xpert MTB/XDR leverages Cepheid’s new 10-color technology, which enables the detection of multiple mutations across several genes, from a single sample. Xpert MTB/XDR can detect resistance to isoniazid, ethionamide, fluoroquinolones, amikacin, kanamycin ,and capreomycin. Access to testing that can reliably identify resistance toward isoniazid as well as to fluoroquinolones and amikacin will help enable clinicians to quickly select the most appropriate MDR-TB treatment for each individual patient.7 The test runs on Cepheid GeneXpert systems equipped with 10-color multiplexing modules. GeneXpert 10-color modules are capable of processing the already widely used Xpert MTB/RIF and Xpert MTB/RIF Ultra tests for diagnosis of TB and rifampicin resistance. “This test is the first to leverage 10-color homogeneous detection within the GeneXpert system,” says David H Persing, MD, executive vice president and chief medical and technology officer at Cepheid. “In partnership with David Alland, MD, MSc, and his team at Rutgers University as well as FIND, we have demonstrated the ability to detect a wide array of TB drug resistance mutations directly from clinical specimens with a high level of accuracy comparable with standard testing.” A study conducted by Cepheid showed promising results for the detection of mutations associated with first- and second-line drug resistance, while preliminary data from independent analytical and clinical evaluation studies conducted by FIND indicate that the test’s sensitivity (ability to correctly identify drug-resistance) and specificity (ability to correctly identify drug-susceptibility) is comparable with current standard tests (culture-based phenotypic drug-susceptibility testing) and sequencing, and that the test meets the performance characteristics defined by the high-priority target product profiles for new TB diagnostics.6 Data from the FIND evaluations will form part of the dossier now being prepared for the World Health Organization (WHO) review at the end of this year. If the test is recommended for use by WHO, countries could include it in their national policies and accelerate its scale up—particularly in high-burden TB countries such as India and China. FIND is now working with Cepheid and WHO to support the rollout of the test. The test is CE-IVD marked and is not available  in the United States. For more information, visit Cepheid. References

  1. World Health Organization. Drug-resistant TB: XDR-TB FAQ. May 2020
  2. World Health Organization. Global tuberculosis report 2019. accessed May 2020
  3. FIND press release, 11 October 2017. accessed May 2020
  4. TB Alliance. FDA approves new treatment for highly drug-resistant forms of tuberculosis. accessed May 20202020)
  5. World Health Organization. Consolidated guidelines on drug-resistant tuberculosis treatment. accessed May 2020
  6. WHO. High-priority target product profiles for new tuberculosis diagnostics: report of a consensus meeting. accessed May 2020
  7. World Health Organization. Consolidated guidelines on drug-resistant tuberculosis treatment. accessed May 2020