New data demonstrated that antibodies induced by Novartis Vaccines investigational, four component, Meningococcal Serogroup B Vaccine (4CMenB) killed the majority of a collection of geographically and genetically diverse meningococcal serogroup B (MenB) strains. The strain coverage research findings were recently published in the Proceedings of the National Academy of Sciences.
To define the potential coverage of 4CMenB against circulating MenB strains, the research investigators examined the characteristics of a collection of 124 MenB strains using pooled sera from immunized adults, and 57 strains using pooled sera from immunized infants The strains were selected to represent a wide range of variability of antigens but were not intended to represent any specific regional epidemiologic sample of MenB strains. The data demonstrated that 85 per cent of the tested strains were killed by pooled sera of adults vaccinated with 4CMenB, as measured by serum bactericidal assay (SBA). SBA is an established and validated correlate of protection. Additionally, the vaccine performed well in infants; even though infant immune systems are still maturing, 74 per cent of strains were killed using pooled sera from infants vaccinated with 4CMenB. Infants are most at risk of MenB disease and their protection presents the greatest unmet need.
In addition to the vaccine coverage results, a subsequent analysis of a new predictive model, "Meningococcal Antigen Typing System" (MATS), against the tested MenB strains, supported the potential benefits of a multi-component vaccine. When MATS detected that three vaccine antigens were sufficiently present on any MenB strain, 100 per cent of the time these strains were killed by pooled sera from immunized adults. In addition, when one or two antigens were detected to be sufficiently present on any MenB strain, 85 and 94 per cent of the time, respectively, they were killed.
"These important findings support our innovative approach using multiple novel components in a single vaccine to provide broad coverage against the deadly and unpredictable MenB disease," said Andrin Oswald, Head of Novartis Vaccines and Diagnostics Division. "Novartis is committed to developing a MenB vaccine that protects all age groups who are at highest risk of contracting often deadly MenB disease, especially infants and young children]".
MATS is a new, simple and reproducible assay that correlates with SBA to overcome the challenge of traditional SBA testing on large collections of strains. The immense diversity and number of circulating MenB strains around the world and the limited infant serum volume derived from clinical trials makes traditional testing difficult and cannot be made a routine procedure. Novartis Vaccines, in collaboration with Novartis Diagnostics, developed MATS as a scientific model to predict whether MenB strains are potentially covered by the vaccine.
The MATS method allows simple and rapid prediction of potential vaccine coverage in different geographic regions and monitoring of strain evolution. Its results alone are not intended to demonstrate, and do not imply, clinical effectiveness.
"The MATS model is a milestone in meningococcal serogroup B vaccine development," said Joel Ward MD, Professor of Pediatrics at the Center for Vaccine Research, School of Medicine, University of California Los Angeles. "Given the geographic diversity of MenB and the potential for mutation, it was previously considered impossible to evaluate immune responses to the many circulating strains that can cause deadly disease. MATS has the potential to be used for vaccines against meningococcal diseases and for vaccines against other bacteria as well."
Novartis is providing the MATS assay platform to national and regional reference laboratories around the world. These institutions are analyzing their local or regional circulating strains to predict the potential coverage of 4CMenB in their territories. National coverage data on more than 1,500 MenB strains are expected to be available by the middle of 2011.
The research included 124 meningococcal serogroup B strains that were obtained from meningococcal reference laboratories in the UK, France, Germany, Italy, Norway, New Zealand, Australia and the US. Healthy human adult volunteers were immunized with 4CMenB and sera were collected and pooled. A prioritized subset of 57 strains was analyzed with serum from infants immunized at 2, 4, 6 and 12 months of age. Since less serum was available from infants, fewer strains were tested in this age group.
MATS accurately predicted the percentage of epidemiologically diverse, disease-causing MenB strains that 4CMenB would cover (or kill in SBA) in adults and infants by evaluating their antigen detection level and cross-protective immune response. To establish the MATS method, results were compared with killing of MenB, determined by SBA in human complement (hSBA), the most direct and established approach to measure vaccine's protective immune response, using pooled sera from adults and infants vaccinated with 4CMenB.
The Novartis 4CMenB vaccine was developed using a pioneering approach known as "reverse vaccinology." In contrast to conventional methods of developing vaccines, reverse vaccinology decodes the genetic makeup (genome sequence) of MenB and selects those proteins that are most likely to be protective vaccine candidates. 4CMenB targets multiple components and is designed to provide an optimal immune response against the majority of MenB strains, while at the same time addressing the constantly changing nature of the bacteria.
4CMenB is the only candidate MenB vaccine currently in phase III testing. Comprehensive data from more than 7,500 infant and adolescent/adult subjects is expected to be the basis for the planned filing in the EU by year end.