Immunogenicity and Safety of an Adjuvanted Herpes Zoster Subunit Vaccine in Older Adults Previously Vaccinated with a Live-Attenuated Herpes Zoster Vaccine: A Phase III, Group-Matched, Clinical Trial

BACKGROUND: Herpes zoster (HZ), caused by reactivation of varicella-zoster virus (VZV), typically manifests as a dermatomal rash and can lead to postherpetic neuralgia (PHN). HZ and PHN risk increase with age. Efficacy against HZ induced by a live-attenuated zoster vaccine (ZVL; Merck) declines following vaccination (21% in years 5–12 post-vaccination). To ensure protection, revaccination can be considered. Therefore, we assessed immunogenicity and safety of HZ/su, a non-live candidate vaccine containing VZV glycoprotein E (gE) subunit and AS01(B) adjuvant system (GSK), in adults previously vaccinated with ZVL ≥5 years before, (HZ-PreVac) compared with adults not vaccinated with ZVL (HZ-NonVac). METHODS: In this phase III, group-matched, open, multicenter study (NCT02581410), 2 parallel groups of adults ≥65 years of age (YOA) received 2 HZ/su doses 2 months apart. A co-primary objective was to compare humoral immune responses 1 month post-dose 2 (M3) in the 2 groups (non-inferiority criterion: upper limit [UL] of the 95% confidence interval [CI] for HZ-NonVac/HZ-PreVac adjusted anti-gE antibody geometric mean concentration [GMC] ratio <1.5). Humoral and cellular immune responses were evaluated at various time points. Solicited and unsolicited adverse events (AEs) were recorded for 7 and 30 days post each dose, respectively. Serious AEs (SAEs), HZ cases and potential immune-mediated diseases (pIMDs) will be recorded until study end. Here, we present data up to M3, as the study is still ongoing. RESULTS: 430 participants were vaccinated. M3 humoral immune responses in HZ-PreVac were non-inferior to those in HZ-NonVac and the co-primary objective was met as the UL of the 95% CI of the adjusted GMC ratio was 1.17 (Table 1). In addition, there were no apparent differences in CD4[2+] T-cell frequencies between groups (Figure 1). No clinically meaningful differences between frequencies of solicited AEs, unsolicited AEs or SAEs in the 2 groups were observed (Table 2). No SAEs considered vaccine-related by investigators, no suspected HZ cases and no pIMDs were reported up to M3. CONCLUSION: HZ/su vaccination in adults ≥65 YOA who previously received ZVL stimulates strong immune responses and does not raise safety concerns. FUNDING: GlaxoSmithKline Biologicals SA DISCLOSURES: K. Grupping, GSK group of companies: Employee, Salary; L. Campora, GSK group of companies: Employee, Salary; M. Douha, GSK group of companies: Employee, Salary; T. C. Heineman, GSK group of companies: Consultant and Shareholder, Consulting fee; N. P. Klein, GSK group of companies: Investigator, Grant recipient sanofi pasteur: Investigator, Grant recipient; Merck & Co: Investigator, Grant recipient; MedImmune: Investigator, Grant recipient; Protein Science: Investigator, Grant recipient; Pfizer: Investigator, Grant recipient; H. Lal, Pfizer: Employee and Shareholder, Salary and Stock as part of compensation; GSK group of companies: Employee at the time of study and Shareholder, Salary and Stock as part of compensation; J. Peterson, GSK group of companies: Investigator, Principal investigator fees; L. Oostvogels, GSK group of companies: Employee and Shareholder, Salary and Shares