Dynavax is giving up work on its combination vaccine for tetanus, diphtheria and acellular pertussis (Tdap) after mulling phase 1 data for the shot.
The biotech had been evaluating the persistence of pertussis immunogenicity for the asset, dubbed Tdap-1018, in an extension study of patients who had already received a booster dose of the shot as part of a phase 1 trial. The vaccine uses Dynavax’s CpG 1018 adjuvant.
Data were due to be read out this quarter, but the company explained in its third-quarter earnings release Nov. 7 that it had decided to discontinue the program based on the results.
“The program showed improved immunogenicity driven by CpG 1018, however, we do not believe the data support sufficient differentiation to be successful commercially,” Dynavax CEO Ryan Spencer said. “This decision aligns with our commitment to prudent management of resources aimed at generating long-term value.”
Tdap vaccines are already available in the U.S. in the form of Sanofi’s Adacel and GSK’s Boostrix. While the shots are more expensive than traditional tetanus and diphtheria (Td) vaccines, Tdap shots have increased in popularity, while sales of Td shots have waned.
Dynavax markets Hepislav-B, a hepatitis B vaccine that saw year-over-year revenues rise 27% to $79.3 million in the third quarter of 2024. The biotech is eyeing a 60% share of a hepatitis B adult vaccine market that it expects to reach $900 million by 2030.
The company’s plans for a four-dose Heplisav regimen in patients on hemodialysis were knocked back by the FDA earlier this year, and it has since been agreed that an observational retrospective cohort study will be used to strengthen the filing.
With Tdap-1018 gone, the company’s remaining clinical pipeline consists of a shingles vaccine in a phase 1/2 trial and a plague vaccine in a phase 2 study funded by the U.S. Department of Defense.
"We are confident that the continued top-line growth of HEPLISAV-B sets the foundation for durable, long-term value creation,” Spencer said in the Nov. 7 release. “We will continue to execute on our strategic growth pillars focused on maximizing the HEPLISAV-B opportunity, delivering on our clinical pipeline, and pursuing external opportunities to drive sustainable value for our shareholders.”