HYDERABAD, INDIA – The world is one major step closer to a vaccine against tuberculosis, researchers said here, with results from a clinical trial of an investigational candidate showing 50% efficacy in preventing latent TB infection from progressing to active TB disease that was sustained three years after the start of the study.
“We have never before seen these results among adults who already have latent TB,” said Dr. Ann Ginsberg of IAVI, which along with GlaxoSmithKline developed the M72/AS01E candidate. “This has the potential to avert tens of millions of new cases and save millions of lives globally.”
During the phase 2b clinical trial, which enrolled 3575 participants with latent TB infection across 11 sites in South Africa, Kenya and Zambia, 39 participants were confirmed to have pulmonary TB infection, Ginsberg said. Of those, 26 were in the group receiving a placebo vaccine, while 13 were in the group receiving the candidate vaccine.
Researchers found high concentrations of antibodies were produced after the first of two vaccine doses were administered to participants, and high levels were sustained throughout the three-year follow up period, Dr. Olivier Van Der Meeren of GlaxoSmithKline said. This immune system reaction is significant, Dr. Van Der Meeren said, as “one major difficulty in TB is we don’t know how the immune system protects against TB.”
While the study could not determine a correlation between elevated antibodies and protection from progression to active disease exists, he said, further research could answer that question.
Researchers created a “biobank” of blood samples from 99% of participants which “provides an opportunity to look at whether there are markers in the blood of people who were protected compared to people who were not protected,” Dr. Ginsberg said.
“The search for correlative protection is the holy grail in vaccine research,” Dr. Van Der Meeren said. “Hopefully the biobank will help in correlating results,” he added.
Identifying blood markers that would correlate with protection would be extraordinarily helpful in developing more TB vaccines, Dr. Ginsberg said. Having a robust portfolio of vaccine candidates is important, she said, as one vaccine is unlikely to prevent infection or disease in all populations.
The World Health Organization is working to facilitate next steps, a representative from the multilateral agency said, including organizing a clinical trial design workshop with partners, developers and countries and making plans to support member states in adopting and implementing immunization programs if and when the vaccine goes to market.
GlaxoSmithKline is in discussions with external partners to move the candidate forward, Dr. Van Der Meeren said. Among other considerations, he added, “we need to partner with others to see how much vaccine needs to be manufactured and where it needs to be deployed.”
Any TB vaccine that comes to market “should be affordable and available everywhere it is needed”multidrug-resistant TB survivor Diptendu Bhattacharya, who also spoke at the presentation of vaccine data, said.
His concern was based on experience. Bhattacharya, who had to stop his doctoral studies in biotechnology after being diagnosed with multidrug-resistant tuberculosis, recounted the challenges he faced during his treatment: finding affordable drugs to effectively treat the disease in the Indian market.