Tuberculosis vaccine can prevent active disease

A new candidate vaccine for tuberculosis (TB) can halve the risk of patients developing the disease, finds a new clinical trial involving a Crick researcher.

The research, published in the New England Journal of Medicine, studied HIV-negative adults with ‘latent’ TB to see if the M72/AS01E vaccine could prevent them from progressing to active disease.

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis (MTB), but not everyone who is infected by the bacterium develops the disease. Latent TB is when is when the immune system keeps the infection under control, so the patient has no symptoms and don’t spread the disease. However, if they progress to ‘active’ pulmonary TB, the lung infection causes persistent cough, weight loss, fever and breathing difficulties, and can be fatal.

The clinical trial involved 3,573 HIV-negative adults in Kenya, South Africa and Zambia with TB. This analysis looked at 1623 participants who were given the trial vaccine and 1660 who were given a placebo. Two years on, people given the vaccine were half as likely to develop active TB as those given the placebo; ten participants in the vaccine group developed active pulmonary TB compared to 22 in the placebo group.

Professor Robert J Wilkinson, Crick group leader and Director of the Wellcome Centre for Infectious Diseases Research in (CIDRI-Africa), said: “We are pleased to have had a large part in the conduct and analysis of this study. The results are intriguing and, overall, highly encouraging. A major task now will be to analyse samples collected from the trial to look for clues how we might do even better. Our previous experience and the combination of Crick and the Wellcome Centre in Cape Town uniquely positions us to play a significant role in this effort, at the same time as contributing to the development of scientific careers in Africa.”

The study was conducted over 11 locations in Kenya, South Africa and Zambia, including the South African Tuberculosis Vaccine Initiative (SATVI) and CIDRI-Africa at the University of Cape Town. The study is sponsored by global healthcare company GSK and conducted in partnership with Aeras, a non-profit organization dedicated to developing TB vaccines.

“These results are a major advance for TB vaccine development, showing for the first time that a protein subunit vaccine can prevent progression to active TB disease in people who are already infected with latent TB at the time of vaccination,” says Professor Mark Hatherill, Director of SATVI.

“We are thrilled that a new generation TB vaccine candidate can prevent progression to active TB disease. This study lays the foundation for the next step, which is to determine what this protective immune response looks like so that we can improve TB vaccines even further,” said Associate Professor Thomas Scriba, Deputy Director of SATVI.

The study is still ongoing and a final analysis including all efficacy, safety, reactogenicity and immunogenicity data will be performed in 2019 after all participants have completed three years of follow up.