A phase IIb trials of the first new vaccine against tuberculosis (TB) in decades has ended in disappointment, although the researchers behind the effort say the study will help guide the development of other candidates.
The MVA85A vaccine was found to be safe and well-tolerated but failed to show efficacy in preventing TB when given as a booster shot to the current Bacille Calmette-Guerin (BCG) vaccine, which was introduced in 1921.
TB kills 1.4 million people annually, despite the widespread use of the BCG vaccine, which is unable to prevent pulmonary TB despite preventing some forms of the disease in infants.
The study enrolled 2,794 healthy infants aged four to six months who were randomised to receive either MVA85A or placebo and followed up over an average of two years. At the end of the study there were 32 cases of TB in the vaccine group, compared to 39 in the control group, and the difference was not statistically significant.
Earlier trials in adults had suggested that the vaccine would generate higher levels of immune response.
“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,” commented the vaccine’s developer Prof. Helen McShane of the University of Oxford in the UK.
The trial was sponsored by non-profit vaccines company Aeras, the Wellcome Trust and the Oxford-Emergent Tuberculosis Consortium (OETC), a joint venture between the University of Oxford and Emergent BioSolutions.
MVA85A is also being investigated in a phase IIb efficacy study in people living with HIV in Senegal and South Africa, a phase IIa study in infants born to HIV positive mothers in South Africa, as well as early-stage trials in the UK.
Meanwhile, there are several other TB vaccines in the pipeline, including one based on an adjuvant and antigen combination developed at GlaxoSmithKline which Aeras is helping advance into phase II trials in Kenya, India and South Africa.