TB vaccine developers express disappointment, pride

The developers of the MVA85A tuberculosis vaccine expressed disappointment on Monday that the vaccine did not confer added protection in infants in a recent Phase IIb clinical study and pride in completing the study.

In the study, published in The Lancet on Monday, a single dose of MVA85A was found not sufficient in conferring statistically significant protection against TB disease or infection in infants previously vaccinated at birth with Bacille Calmette-Guerin. The vaccine candidate also did not provide statistically significant protection from infection with Mycobacterium tuberculosis, the bacterium that causes TB.

The funding for the trial was provided by Aeras, a non-profit biotech, the Wellcome Trust and the Oxford-Emergent Tuberculosis Consortium. Scientists at Oxford University originally developed and investigated the vaccine.

"Although the results of this first efficacy trial of a new TB vaccine are not what we had hoped for, further analysis of the data should reveal a great deal about how the body's immune system protects against TB and what is necessary to develop an effective vaccine," Helen McShane, the developer of the vaccine from Oxford University, said. "The results from this study should let us know far more about the type and level of immune response required, and that will boost future efforts to develop an effective TB vaccine by Oxford and other researchers throughout the world."

MVA85A is the first novel, preventive TB vaccine candidate since the BCG vaccine to complete a Phase IIb efficacy and safety study. The BCG vaccine was developed more than 90 years ago.

"Completion of the study has been a significant achievement by the MVA85A development partners and demonstrates the advantages of collaboration through a public-private partnership model to address global public health challenges," Jacqui Shea, the general manager of OETC, said. "While MVA85A has not met its efficacy goal, this study should enable the TB vaccine community to better understand the immune response against TB and help to design future efficacy studies."

According to the World Health Organization, BCG is currently used with approximately 100 million newborns globally each year. The vaccine is able to prevent severe TB forms in some children, though its widespread use in infants has not controlled a global epidemic of TB.

"Vaccine development is an incredibly difficult undertaking, and the scientific community has only become fully engaged in the development of TB vaccines in the last decade," Tom Evans, Aeras' interim CEO, said. "Because of the urgency to control the global TB epidemic, and despite these trial results, we remain steadfast in our belief that an improved TB vaccine will be developed and represents the best hope for eliminating the disease. The valuable scientific understanding gained from this trial will provide crucial information for the robust global portfolio of more than a dozen other TB vaccines undergoing clinical testing, a number that was unimaginable a decade ago."

MVA85A is currently also being investigated as part of a Phase IIb efficacy study in people living with HIV in South Africa and Senegal, a Phase IIa study in infants born to HIV positive mothers in South Africa and Phase I studies in the United Kingdom.