Affinivax, Inc. and Astellas Pharma Inc. announced results from the Phase 2 clinical trial of ASP3772, a novel vaccine candidate targeting Streptococcus pneumoniae. Developed using Affinivaxs proprietary MAPS (Multiple Antigen-Presenting System) platform technology, ASP3772 is designed to offer both B-cell (antibody) and T-cell immune protection against Streptococcus pneumoniae. ASP3772 includes 24 pneumococcal polysaccharides, as well as two conserved pneumococcal proteins. The results from the Phase 2 clinical trial demonstrated that ASP3772 was well tolerated. ASP3772 also exhibited an antibody response to each of the 24 polysaccharides, as well as an additional antibody response to the conserved pneumococcal proteins. The Phase 2 data for ASP3772 were delivered in an oral presentation at the 31stEuropean Congress of Clinical Microbiology & Infectious Diseases (ECCMID), taking place online from 9-12 July 2021. The U.S. Food and Drug Administration (FDA) has also granted Breakthrough Therapy designation for ASP3772 for the prevention of pneumonia and invasive disease caused by Streptococcus pneumoniae serotypes included in ASP3772 in adults aged 50 years and older. The FDA decision is informed by the results of the Phase 2 data. The FDAs Breakthrough Therapy process is designed to expedite the development and review of drugs that are intended to treat a serious or life-threatening condition. Designation is based upon preliminary clinical evidence indicating that the drug may demonstrate substantial improvement over available therapies on one or more clinically significant endpoints.
The Phase 2 clinical trial1 of ASP3772 was conducted in 503 adults 65 to 85 years of age, and 293 adults received ASP3772, 97 adults received Prevnar13 and 113 adults (who were previously vaccinated with Prevnar13) received Pneumovax23. The primary objective was to evaluate safety/tolerability and reactogenicity of ASP3772 compared to Prevnar13. The secondary objective was to evaluate the immunogenicity of ASP3772, versus Prevnar13 or Pneumovax23. A summary of the results is below: ASP3772 was observed to be well tolerated with mild and self-limited injection site and systemic reactions, similar to those seen in the Prevnar13 group. Frequently reported local reactions were tenderness and pain, occurring within the first 2-3 days with no clear difference across ASP3772 and Prevnar13 cohorts. Neither serious vaccine-related adverse events, nor clinically relevant abnormalities (vital signs, ECGs, laboratory parameters), were observed. No serious adverse events or medically attended adverse events related to immunization and no potentially immune mediated adverse events were observed in subjects through the 180-day safety assessment period post-immunization. At the three dose levels studied, ASP3772 induced a robust immune response to all 24 pneumococcal serotypes in the MAPS vaccine, as measured by both immunoglobulin G (IgG) and opsonophagocytic activity (OPA). When compared to Prevnar13 alone, ASP3772 demonstrated a similar or better IgG and OPA immune response to the 13 shared serotypes included in both ASP3772 and Prevnar13. Of note, ASP3772 demonstrated a statistically higher immune response to serotype 3 at all ASP3772 dose levels, as well as a statistically higher immune response to serotypes 5 and 19F at the highest ASP3772 dose tested. ASP3772 also demonstrated a statistically higher immune responses for all remaining 11 serotypes that are not included in Prevnar13. When compared to Prevnar13 plus Pneumovax23, ASP3772 demonstrated a similar or better IgG and OPA immune response to the 13 shared serotypes with Prevnar13. Of note, ASP3772 demonstrated a statistically higher immune responses for serotypes 3, 4, 5, 6A, 7F, 9V, and 18C at the highest dose tested. ASP3772 also demonstrated a similar, and in most cases statistically higher, immune response for all remaining 11 serotypes. ASP3772 also demonstrated an increase in antibodies (more than 2-fold, as measured by geometric mean fold rise in IgG) response to the conserved proteins included in the MAPS vaccine design .