Affinivax and Astellas’ pneumococcal vaccine candidate ASP3772 has been granted a breakthrough therapy designation by the US Food and Drug Administration (FDA), the companies announced earlier this week.

At the same time, Affinivax and Astellas revealed results from the Phase II trial of ASP3772 – a novel vaccine candidate designed to provide B-cell and T-cell immune protection against Streptococcus pneumoniae.

The vaccine contains 24 pneumococcal polysaccharides as well as two conserved pneumococcal proteins.

In the Phase II trial, the primary objective was to evaluate the safety, tolerability and reactogenicity of ASP3772 compared to Pfizer’s Prevnar13.

The secondary objective was to evaluate the immunogenicity of ASP3772 compared to Prevnar13 or Pneumovax.

In the trial ASP3772 was found to be well tolerated, with mild and self-limited injection site and systemic reactions similar to those seen in the Prevnar13 group.

At the three dose levels studied, ASP3772 exhibiting an antibody response to each of the 24 polysaccharides and to the conserved pneumococcal proteins.

In comparison to Prevnar13 alone, ASP3772 also demonstrated a similar or better IgG and OPA immune response to the 13 share serotypes.

In particular, ASP3772 demonstrated a statistically higher immune response to serotype 3 at all dose levels, as well as a higher immune response to serotypes 5 and 19F at the highest doses tested.

On top of that, when compared to Prevnar13 plus Pneumovax23, ASP3772 demonstrated a similar or better IgG and OPA immune response to the 13 shared serotypes with Prevnar13.

ASP3772 also demonstrated a similar – and in most cases statistically higher – immune response for all remaining 11 serotypes.

“Extending the coverage to 24 Streptococcus pneumoniae strains, we believe that ASP3772 has the potential to offer broader protection than any pneumococcal vaccine currently on the market or in clinical testing today, and we look forward to continuing to advance this important vaccine candidate through clinical trials in both adults and infants,” said Steven B. Brugger, chief executive officer of Affinivax.