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First late-stage trial vaccine doses begin in South Africa for tuberculosis

The first dosing in a late-stage trial to evaluate an investigational drug for tuberculosis (TB) has started in South Africa, which has one of the highest burdens in the world.

 HQ Team

March 20, 2024: The first dosing in a late-stage trial to evaluate an investigational drug for tuberculosis (TB) has started in South Africa, which has one of the highest burdens in the world.

The Bill & Melinda Gates Medical Research Institute will carry out further probes into whether the adjuvanted subunit vaccine M72/AS01E protects adolescents and adults from progressing from latent TB with active pulmonary TB, and is well tolerated.

The results will help control the respiratory disease that killed 1.3 million people in 2022, primarily in low- and middle-income countries. 

With more than 10 million newly diagnosed cases each year, many in impoverished people in their prime working years, tuberculosis also has profound socioeconomic impacts in low-resource countries.

While TB is one of the world’s deadliest infectious diseases — and the leading cause of death amongst people living with HIV — the only available TB vaccine, BCG, dates back to 1921. 

Inadequate protection for adults

It protects babies and young children against severe forms of TB, but it offers inadequate protection for adolescents and adults against the pulmonary form of the disease, which is primarily responsible for the transmission of the TB bacterium.

Alemnew Dagnew, MD, MsC, MPH, of Gates MRI, and the lead developer, said that if he and his colleagues can replicate the findings from the phase 2b trial, the M72/AS01E vaccine could “reinvigorate” the global fight against TB, which took a significant hit during the Covid-19 pandemic.

“If the vaccine is efficacious, it will have a huge impact on the control of tuberculosis globally,” Dagnew was quoted as saying by the Center for Infectious Disease Research and Policy, a centre within the University of Minnesota that focuses on addressing public health preparedness and emerging infectious disease response.

The investigators aim to enrol up to 20,000 participants, including people living with HIV, at 60 trial sites in South Africa and six other countries—Zambia, Malawi, Mozambique, Kenya, Indonesia, and Vietnam. 

Participants will receive either the investigational M72/AS01E vaccine or a placebo in what is known as a double-blind trial, meaning neither the trial participant nor the clinical investigators will know who receives the vaccine or placebo. It’s expected to take at least five years to complete the trial.

50% protection

In a phase 2b trial in 2019, the vaccine showed roughly 50% protection against progression to active pulmonary TB in adults with latent TB. 

A 2022 report from the World Health Organization estimated that a vaccine that was at least 50% effective in reducing TB disease in adults and adolescents could prevent up to 76 million cases and 8.5 million deaths over 25 years.

It could avert more than $41 billion in TB-related household costs.

“While it is a long journey to results, the start of this trial in South Africa brings us a critical step closer to having an effective vaccine to protect those most at risk of TB,” Alex Pym, PhD, Director of Infectious Diseases at Wellcome, said in a Gates MRI statement.

Gates MRI is conducting the trial with funding from the Bill & Melinda Gates Foundation and the Wellcome Trust. GSK will provide the adjuvant post-licensure if the trial is successful.

One of 17 candidates

M72/AS01E is one of 17 TB vaccine candidates in clinical development. 

In January 2023, WHO Director-General Tedros Adahanom Ghebreyesus, PhD, announced the formation of a TB Vaccine Accelerator to speed the licensing and use of TB vaccines, comparing the program to WHO’s efforts to boost development, production, and equitable access to COVID-19 vaccines, treatments, and tests.

At a meeting held during the World Economic Forum in Davos, Switzerland, to announce the program, Tedros said many TB vaccines had been languishing for years because TB hasn’t been in the spotlight.

“What’s now needed is renewed commitment…and action, with a sense of urgency,” Tedros said. “If it was done for COVID, there’s no reason it cannot be done for this.”

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