About two years ago, Astellas licensed a novel pneumococcal vaccine technology from Affinivax with eyes on Pfizer’s Prevnar 13. Now, the pair has officially entered human testing.

The first patient has been dosed with the investigational vaccine, dubbed ASP3772, in a phase 1/2 study that aims to evaluate the vaccine’s safety, tolerability and immunogenicity, Affinivax said on Wednesday. And the study is already designed as a head-to-head against Pfizer’s blockbuster shot.

The study will enroll 618 adult patients in two stages. In stage one, investigators will evaluate three different dose levels of ASP3772 in comparison with Prevnar 13 in adults younger than 65. The second stage will focus on elderly patients above 65 years of age who are considered most vulnerable to S. pneumoniae infections. In this stage, Merck & Co.’s Pneumovax 23 will also serve as a comparator for the other serotypes not included in Prevnar 13.

Unlike conventional conjugate vaccines like Prevnar that use proteins to carry polysaccharides, ASP3772 leverages Affinivax’s Multiple Antigen Presenting System (MAPS), which allows the protein antigen itself to induce an immune response as well, thereby boosting its protection.

"We believe that MAPS, in contrast to traditional vaccines, offers a unique way to present the key epitopes of the desired antigens (polysaccharides and/or proteins) to induce a robust and broad immune response," Richard Malley, M.D., Affinivax’s scientific founder, said in a statement. "We now look forward to confirming this in clinical trials."

In addition to a potential better efficacy, the MAPS vaccine platform could also cover more strains than currently available, Affinivax CEO Steve Brugger has told FierceVaccines. It could also stop the bacteria from colonizing the nose and throat before triggering illness in people with weakened immune systems, and it can be cheaper to produce, he said.

Through an exclusive deal formed in February 2017, Astellas obtained worldwide rights to commercialize the pneumococcal vaccine and will lead and fully fund the development program. 

Launched in 2014 with the MAPS technology licensed from Boston Children’s Hospital, Affinivax has so far been running without the typical biotech venture capital injections. Instead, it has found investors in nonprofit organizations such as the Bill & Melinda Gates Foundation and PATH, and through collaborations with ClearPath Development Company and Astellas.

Pneumococcal vaccines are indeed an attractive field. For 2018, the Pfizer vaccine king raked in $5.80 billion in global sales. But competition is brewing. Merck recently started phase 3 testing on its 15-valent conjugate candidate, V114, and nabbed FDA "breakthrough" designation in pediatric use. Pfizer has also entered phase 3 with its Prevnar 13 follow-up, PF-06482077, which covers 20 serotypes of pneumococcus, and got the same FDA label in adults.

Besides pneumococcal, Cambridge, Massachusetts-based Affinivax is also applying the MAPS system to developing vaccines against healthcare-associated infections. Pfizer just suffered a setback there, having capped development of an S. aureus vaccine after a phase 2b study showed no promise.

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