8. The Adjuvanted Recombinant Zoster Vaccine (RZV) Confers Long-term Protection Against Herpes Zoster: Interim Results of an Extension Study (ZOSTER-049) of Two Clinical Trials (ZOE-50 and ZOE-70)
Authors: Boutry Céline , Hastie Andrew , Shi Meng , Diez-Domingo Javier , Tinoco Juan Carlos , Yu Chong-Jen , Pirrotta Paola , Kalema George , Schuind Anne 
Published: January 2021

Abstract

Background
Two large-scale phase 3 clinical trials (ZOE-50 [NCT01165177] and ZOE-70 [NCT01165229]) demonstrated that, in adults ≥ 50 years of age followed over a mean period of 3.1 and 3.7 years respectively, the adjuvanted recombinant zoster vaccine (RZV) was efficacious against herpes zoster (HZ), highly immunogenic and had a clinically acceptable safety profile. In this extension study (ZOSTER-049 [NCT02723773]), RZV-induced immunogenicity persistence and long-term vaccine efficacy (VE) against HZ were evaluated; we report interim results after at least 2 years of follow-up (starting and ending ≈5.1 and 7.1 years, respectively, after initial vaccination during the parent studies).

Methods
The study design is detailed in Figure 1. Primary objective: VE against HZ over the ZOSTER-049 study. Secondary objectives: VE against HZ from 1 month post-dose 2 in ZOE-50/-70 until the end of observation for year (Y)2 of ZOSTER-049, persistence of vaccine-induced humoral immunogenicity (HI) in terms of anti-gE antibody concentrations (by ELISA) and cell-mediated immune (CMI) response in terms of frequency of gE-specific CD4+ T-cells (by intracellular cytokine staining).
Figure 1. Study design of the extension study in relation to the parent studies. ZOSTER-049 study procedures, timing, endpoints and cohorts

Results
Of the 7,413 participants enrolled in ZOSTER-049, 7,277 were included in the VE analysis (Figure 2) and 6,972 reached Y2 of this study. The overall VE against HZ during at least 2 years of follow-up in ZOSTER-049 was 84.0% (95% confidence interval [CI]: 75.9–89.8%). From 1 month post-dose 2 in the ZOE-50/-70 studies until the end of observation for Y2 of ZOSTER-049, the overall VE was 90.9% (95% CI: 88.2–93.2%). Anti-gE antibody concentrations persisted ≈6 times above pre-vaccination levels up to Y8 after vaccination (Figure 3A) and the frequency of gE-specific CD4[2+] T-cells remained above baseline from Y6 to Y8 after vaccination (i.e. until the end of observation for Y2 of ZOSTER-049) (Figure 3B).
Figure 2. Demographic characteristics of participants included in the ZOSTER-049 study, for the analysis of vaccine efficacy against herpes zoster (mTVC)

Figure 3. Long-term persistence of humoral immunogenicity (HI) and cell-mediated immune (CMI) responses up to year 8 post-vaccination dose 2 administered in the ZOE-50/-70 studies

Conclusion
RZV demonstrated high VE against HZ until the end of the observation period for this Y2 interim analysis. The HI and CMI responses remained stable and high until the end of observation (i.e. 7.1 years after initial vaccination).
Funding: GlaxoSmithKline Biologicals SA
Acknowledgements: LA Truta/S Hulsmans (Modis c/o GSK) provided writing/editorial support

Disclosures
Céline Boutry, PhD, Aixial (Consultant) Andrew Hastie, MD, GSK group of companies (Employee) Meng Shi, MS, GSK group of companies (Employee) Javier Diez-Domingo, MD, GSK group of companies (Board Member, Scientific Research Study Investigator, Advisor or Review Panel member)MSD (Board Member, Scientific Research Study Investigator, Advisor or Review Panel member) Paola Pirrotta, PharmD, GSK group of companies (Employee) George Kalema, PhD, GSK group of companies/Keyrus Biopharma (Consultant) Anne Schuind, MD, GSK (Employee, Other Financial or Material Support, own GSK stock options or restricted shares as part of renumeration)