Immunogenicity of Inactivated Varicella Zoster Vaccine in Autologous Hematopoietic Stem Cell Transplant Recipients and Patients With Solid or Hematologic Cancer

Background. In phase 3 trials, inactivated varicella zoster virus (VZV) vaccine (ZV(IN)) was well tolerated and efficacious against herpes zoster (HZ) in autologous hematopoietic stem cell transplant (auto-HSCT) recipients and patients with solid tumor malignancies receiving chemotherapy (STMc) but did not reduce HZ incidence in patients with hematologic malignancies (hMs). Here, we describe ZV(IN) immunogenicity from these studies. Methods. Patients were randomized to ZV(IN )or placebo (4 doses). Immunogenicity was assessed by glycoprotein enzyme-linked immunosorbent assay (gpELISA) and VZV interferon (IFN)-gamma enzyme-linked immunospot (ELISPOT) assay in patients receiving all 4 doses without developing HZ at the time of blood sampling. Results. Estimated geometric mean fold rise ratios (ZV(IN)/placebo) by gpELISA and IFN-gamma ELISPOT similar to 28 days post-dose 4 were 2.02 (95% confidence interval [CI], 1.53-2.67) and 5.41 (95% CI, 3.60-8.12) in auto-HSCT recipients; 1.88 (95% CI, 1.79-1.98) and 2.10 (95% CI, 1.69-2.62) in patients with STMc; and not assessed and 2.35 (95% CI, 1.81-3.05) in patients with HM. Conclusions. ZV(IN) immunogenicity was directionally consistent with clinical efficacy in auto-HSCT recipients and patients with STMc even though HZ protection and VZV immunity were not statistically correlated. Despite a lack of clinical efficacy in patients with HM, ZV(IN) immunogenicity was observed in this population. Immunological results did not predict vaccine efficacy in these 3 populations.