A randomized, controlled clinical trial to evaluate the immunogenicity of a PreS/S hepatitis B vaccine Sci-B-Vac™, as compared to Engerix BA®, among vaccine na⟨ve and vaccine non-responder dialysis patients

Dialysis patients have a suboptimal response to hepatitis B (HBV) vaccination. This study aimed to compare the immunogenicity of two vaccines: the third-generation Sci-B-Vac (TM) vs. the second-generation Engerix B-A (R). The cohort included two groups of dialysis patients: na < ve and previously vaccinated non-responders. Primary endpoints were antibody titers ae10 IU/L at 3 and 7 month post-vaccination. Secondary objectives were seroprotection rates in vaccine-na < ve patients and in previously vaccinated non-responders. Eighty-six patients were assigned to vaccine (Sci-B-Vac (TM) or Engerix B-A (R)) using computer-generated randomization, stratified by age, gender, diabetes, and previous HBV vaccination. Sci-B-Vac (TM) was administered in three doses, 10 mu g, at 0, 1, and 6 months in na < ve patients; or 20 mu g in previously vaccinated non-responders. Engerix B-A (R) included four doses, 40 mu g at 0, 1, 2, and 6 months. Each group had 43 patients. Seroconversion was 69.8% with Engerix B-A (R) vs. 73.2% with Sci-B-Vac (TM). Antibody titers at 7 months were higher with Sci-B-Vac (TM) (266.4 +/- 383.9, median 53.4) than with Engerix(A (R)) (193.2 +/- 328.9, median 19). However, these differences were not significant, perhaps due to a suboptimal sample size. This study suggests comparable immunogenicity for both vaccines. Thus, we cannot reject the null hypothesis that there is no difference in seroconversion by vaccine type. It is noteworthy that na < ve patients were vaccinated with a standard dose of Sci-B-Vac (TM), while Engerix B-A (R) was administered at a double dose. Similarly, although mean antibody titer levels in the Sci-B-Vac (TM) group were higher than in the Engerix(A)(R) group, this difference did not reach significance. Consequently, a future clinical trial should recruit a larger cohort of patients, using a standard double-dose protocol in both groups.