Vaccine trial has promise

Prevents active TB in HIV-negative patients

IN A major advance for tuberculosis (TB) vaccine development, a candidate TB vaccine can prevent active pulmonary TB in HIV-negative adults, a phase II study has found.

Primary analysis recently published in the New England Journal of Medicine shows positive results in clinical trials in tuberculosis endemic regions.

The South African Tuberculosis Vaccine Initiative (Satvi) and the Wellcome Centre for Infectious Diseases Research in Africa tuberculosis research groups, based in the Institute of Infectious Disease & Molecular Medicine at UCT, are two of 11 sites in Kenya, South Africa and Zambia where the study is conducted.

The study is sponsored by the global health-care company GSK, conducted in partnership with Aeras, a non-profit organisation dedicated to developing vaccines against tuberculosis.

The primary results of the ongoing phase IIb clinical trial testing the candidate tuberculosis vaccine M72/ AS01E1 show an overall vaccine efficacy of 54%, with varied response rates observed in different demographic subgroups. The candidate vaccine had an acceptable safety profile.

TB is the leading cause of death through infectious disease worldwide and a significant public health threat with 1.6 million attributed deaths in 2016 globally.

In South Africa, the estimated incidence is 781 per 100000 of the population. The World Health Organisation estimates that a quarter of the global population has latent TB, with increasing prevalence of multidrug-resistant strains. Currently, there is no available TB vaccine with proven, consistent efficacy in adult populations.

“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,” said Satvi director Professor Mark Hatherill.

The trial involves 3573 HIV-negative adults. For this analysis, participants who received two doses of either M72/AS01E or a placebo 30 days apart have been followed for at least two years to detect evidence of pulmonary tuberculosis disease.

Ten participants who received the vaccine developed active pulmonary tuberculosis compared to 22 participants in the placebo group.

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.

Associate Professor Thomas Scriba said the team was thrilled a new generation TB vaccine candidate could prevent progression to active TB.