Dynavax’s lofty ambition to snatch Shingrix’s crown got off to a promising start after the biopharma’s investigational shingles vaccine held its own against GSK’s mainstay in the first part of a phase 1/2 study.
The trial evaluated various formulations and dosing regimens of the recombinant subunit vaccine, dubbed Z-1018, against Shingrix in healthy adults aged 50 to 69 years old. The formulation Dynavax has decided to move into the second part of the trial was shown to achieve a 100% humoral vaccine response rate—which measures antibody production—at one month after the second vaccine dose, compared to 96.9% for the Shingrix cohort.
When it came to responses for gE-specific CD4+ T cells, this Z-1018 group showed a cellular immune response rate of 89.7% compared to 93.5% for the Shingrix group, Dynavax said in an Aug. 21 release.
Dynavax’s vaccine was well tolerated, according to the release, with investigators seeing “low rates of grade 2 and 3 solicited local and systemic post-injection reactions (PIRs) in all dose, formulation, and dosing regimen arms.”
For the formulation Dynavax will take forward, 12.5% of patients reported grade 2 or 3 PIRs, and 27.5% reported grade 2 or 3 systemic PIRs. The rates for the Shingrix cohort were higher, at 52.6% and 63.2%, respectively.
“These positive data mark an important inflection point for our novel shingles vaccine program as we strive to develop a product with a potential best-in-class profile with the aim to disrupt the multi-billion-dollar shingles vaccine market, which is currently dominated by one product,” Dynavax CEO Ryan Spencer said in the release.
“We met our goal for this study, as the results show immune responses comparable to Shingrix, along with a favorable tolerability profile, and provide the basis for selecting the dose and regimen to advance into further development,” Spencer added. “Based on these findings, plans are underway to initiate part 2 of the phase 1/2 trial in the 70 and older population, an opportunity to further de-risk this program ahead of phase 3 development.”
Shingrix was approved by the FDA in 2017, and GSK racked up 850 million pounds sterling ($1.1 billion) in sales of the vaccine in the second quarter of 2025 alone.
Despite Shingrix’s seemingly unassailable position, Dynavax’s chief medical officer Robert Janssen, M.D., explained that the company is betting that Z-1018’s immune and tolerability data could offer a path to carving out a slice of the market.
“We are very encouraged by the magnitude and consistency of the immune responses observed, particularly the robust CD4⁺ T cell activity for Z-1018 compared to Shingrix,” Janssen said. “A vaccine that provides a strong immune response alongside favorable tolerability, compared to the current standard of care, could provide an important new option for protection against this debilitating disease.”
Z-1018 consists of a Dynavax-manufactured glycoprotein E (gE) antigen along with the biopharma’s CpG 1018 adjuvant. CpG 1018 is already used in Dynavax’s approved hepatitis B vaccine HEPLISAV-B as well as in various COVID vaccines.
Based on the results of the study to date, the company has settled on taking a 100-mcg dose of gE antigen with an eight-week dosing interval into the next part of the study, due to start later this year. That study will be another head-to-head against Shingrix, studying the vaccines in patients aged 70 years and older.