Author: Jean-Claude Muller, 穆卓Executive Editor at BtoBioInnovation email@example.com
SPECIAL REPORT #36
A Step closer to a Tuberculosis Vaccine
A team of scientists have reported, in the October 29, 2019 issue of the New England Journal of Medicine, that M72/AS01E, an investigational tuberculosis vaccine had an overall efficacy, at month 36, of 49.7% in a group of 3575 patients. The result of this large phase IIb study, performed in active pulmonary tuberculosis disease centers in Kenya, South Africa and Zambia, falls just short of the 54% efficacy rate recorded in the primary study published in September 2018. Although a 50% efficacy rate is hardly ideal – the measles vaccine, by contrast, is 98% protective- this new vaccine has the potential of saving millions of lives.
Mycobacterium tuberculosis infects about 10.4 million people every year and 1.7 million die of it. In addition, nearly a quarter of the world’s population has latent tuberculosis infection This means they carry the bacteria in an inactive form and do not transmit the disease to others. People with latent tuberculosis have a 5 to 10% risk to develop the disease in their lifetime. Most common medications used to treat tuberculosis include four major antibiotics: Isoniazid, Rifampin, Ethambutol and Pyrazinamide. Although highly active, these drugs have induced the emergence of multi-drug resistant tuberculosis (MDR-TB) which constitutes a major health threat. Eight countries account for almost two thirds of global tuberculosis cases: India (27%), China (9%), Indonesia (8%), the Philippines (6%), Pakistan (4%), Nigeria (4%) Bangladesh (4%) and South Africa (3%). India alone records nearly three million new cases annually, with 400,000 deaths and more than 100,000 subjects are multi-drug resistant according to World Health Organisation (WHO). The WHO aims to reduce the number of tuberculosis cases by 90% and the number of deaths by 95% between 2015 and 2035.
Tuberculosis is a contagious bacterial infection (Mycobacterium tuberculosis) spread through inhaling tiny droplets from the coughs or sneezes of an infected person. It mainly affects the lungs, but it can affect any part of the body including the nervous system. The most common symptoms of the disease are a persistent cough for more than three weeks, unexplained weight loss, fever and night sweats. Bacille Calmette-Guerin (BCG), which was introduced back in 1921, is the only current vaccine for the protection of tuberculosis of babies and young children in countries where the disease is common.
M72/AS01E, the candidate vaccine, represents an effort by GSK of more than 20 years and has been developed and supported by IAVI, a non-profit organisation and the Bill and Melinda Gates Foundation. The vaccine uses the same adjuvant AS01 as the one of GSK’s shingles vaccines Shingrix, along with a M72 recombinant fusion protein derived from two Mycobacterium tuberculosis antigens (MtB32A and MtB39A).
Dr. Thomas Breuer, Chief Medical Officer of GSK Vaccines said: “These results demonstrate that for the first time in almost a century, the global community potentially has a new tool to help provide protection against TB. I want to thank our scientists for their dedicated effort and scientific innovation in developing this impactful vaccine candidate in partnership with IAVI and other key organisations.”
David Lewinsohn, a UK tuberculosis expert said the potential of the vaccine was a “real game changer”. “What is really remarkable is that the vaccine was effective in adults who were already infected with Mycobacterium tuberculosis, that is the causative agent of tuberculosis” he said.
It is very likely that the vaccine will need to be tested in additional populations (India, China, Indonesia, Russia,…) in possibly bigger trials before getting approved. Researchers say, proving that such a vaccine works, requires studies that are much larger than ones required for viral diseases such as measles. Best estimates now consider the vaccine could reach people with greatest needs by 2028 at the earliest.
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