Will new latest treatments for TB help us recover from the setback global fight to end TB has faced due to Covid-19?
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The impact of the COVID-19 pandemic on TB diagnosis and mortality in 2020 has been frightening, to say the least. Recently released WHO data shows that 1.4 million fewer people got TB care in 2020 as compared to 2019 - a 21% decrease. Also over 0.5 million people died from TB in 2020 due to lack of diagnosis. Latest data by Stop TB Partnership shows that in 9 countries (Bangladesh, India, Indonesia, Myanmar, Pakistan, Philippines, South Africa, Tajikistan, and Ukraine) together account for 60% of the global TB burden, TB diagnosis and treatment enrolment in 2020 declined by 1 million - a drastic reduction of 23%. Globally, in 2020 there was an estimated drop of at least 1 million in TB-treatment enrolment, pushing the TB response to 2008 levels in terms of people diagnosed and treated.
A
modelling
analysis done in May 2020 found that even short COVID-19-related lockdowns
can generate long-lasting setbacks in TB control, due to disruption in routine
TB care services. A 3-month lockdown followed by 10 months to restore to normal
could lead to an additional 6.3 million cases of TB and an additional 1.4
million TB deaths between 2020 and 2025 globally. In India the disruptions are
expected to cause an additional 1.19 million TB cases and 361,000 TB deaths
over the next 5 years.
Shorter and all oral regimen for XDR and MDR-TB
At CROI
2021, Dr Pauline Howell of the University of the Witwatersrand, South
Africa, presented a new analysis based on two years of the Nix-TB study, in
which approximately 90% of the patients with highly drug-resistant TB who were
treated with a 6-month, all-oral regimen of pretomanid, bedaquiline and
linezolid (BPaL) remained free of their disease. Pretomanid, which is used in
this regimen, is a new chemical entity developed by TB Alliance.
Nix-TB is an open-label, single-group study that had 65% participants with
XDR-TB and 35% patients with unresponsive MDR-TB. At 6 months after the
completion of therapy, 90% of the enrolled patients were found to have had a
favourable outcome - 89% of those with XDR-TB and 92% of those with MDR-TB.
The study thus shows that XDR-TB and complicated MDR-TB can be treated with a
26-week-long, all-oral, 3-drug regimen with a 90% success rate, which is similar
to that obtained with the standard of care in the treatment for drug-sensitive
TB. Currently used regimens have had a success cure rate of only 34% for XDR-TB
and 55% for MDR-TB cases. Moreover, they routinely last for two years or longer
and are very costly.
In her presentation at CROI, Dr Howell shared that, "Results of this
simplified, shortened, and all-oral regimen for highly drug-resistant TB show
sustained high efficacy through a 2-year follow-up from end of treatment. A
follow-on trial ZeNix
that investigates the optimal dose and duration of linezolid in the BPaL regimen,
has recently completed enrolment. The objective of this study is to evaluate if
the efficacy of the BPaL drug regimen can be maintained, while reducing
toxicity and increasing tolerability through a shorter linezolid duration of 2
months and/or its smaller dose of 600 mg (as compared to the current 1200-mg
dosage). We look forward to the primary endpoint 6 months into post-treatment
results."
Meanwhile, WHO has recommended the BPaL regimen under operational research conditions and it has also been authorised by the European Medicines Agency.
In an exclusive interview given to CNS (Citizen News Service), Dr Howell said, "TB Alliance is studying this regimen in multiple countries. Operational research is now underway in at least five countries with many more expected to join this year. Physicians in USA are prescribing the regimen under routine practice conditions. The regimen was approved in India by the Drug Controller General of India (DCGI) last year. The ZeNix trial is taking place in Russia, Georgia, Moldova and South Africa, evaluating different doses and durations of the drug linezolid as part of this regimen. They have also partnered with MSF to evaluate BPaL-based regimens for all people with DR-TB (at least rifampicin-resistant TB), and not just highly drug-resistant strains."
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