Rabies vaccine(Sanofi)

A new generation, serum-free, antibiotic-free, purified Vero rabies vaccine (PVRV-NG; Sanofi) has been developed based on the same Pitman-Moore viral strain used for the currently licensed purified Vero cell rabies vaccine (PVRV; Verorab®, Sanofi) and human diploid cell vaccine (HDCV; Imovax® Rabies, Sanofi). PVRV-NG has demonstrated a satisfactory safety profile and induces robust immune responses, with non-inferiority demonstrated versus PVRV when given as a three-dose pre-exposure prophylaxis (PrEP) regimen in healthy children and adults. Here, we evaluated the safety and immunogenic non-inferiority of PVRV-NG compared to HDCV when administered as simulated post-exposure prophylaxis (PEP), with concomitant administration of human rabies immunoglobulin (HRIG), in healthy adults in the USA. Participants were vaccinated according to the 5-dose Essen intramuscular regimen (4-week, 1-injection site regimen, with a single dose given on days 0, 3, 7, 14 and 28) for PEP, with concomitant HRIG administered on day 0. Rabies virus neutralising antibodies (RVNA) were evaluated on days 0, 14, 28 and 42. Non-inferiority of PVRV-NG compared with HDCV was shown if the lower limit of the 95 % confidence interval (CI) for the difference in seroconversion rates (RVNA titers ≥ 0.5 IU/mL on day 14) between PVRV-NG and HDCV was above the non-inferiority margin of -5 %. Safety was evaluated after each vaccination and monitored throughout the study. The difference in seroconversion rate between the PVRV-NG and HDCV groups was -2.8 % (95 % CI, -8.08 to 4.20), indicating that non-inferiority was not demonstrated. The seroconversion rate was < 99 % in both study groups on day 14. There were no major safety concerns identified, and PVRV-NG demonstrated a similar safety profile to HDCV.

A serum-free, highly purified rabies vaccine produced in Vero cells is under development. The initial formulation, PVRV-NG, was evaluated in five Phase II studies and subsequently reformulated (PVRV-NG2). This multicenter, observer-blinded Phase II study investigated the safety and immune response of three different doses (antigen content) of PVRV-NG2 versus a licensed human diploid cell rabies vaccine (HDCV; Imovax rabies®). Healthy adults (N = 320) were randomized to receive PVRV-NG2 (low, medium, or high dose), PVRV-NG, or HDCV (2:2:2:1:1 ratio), according to a five-dose Essen simulated post-exposure regimen (Days [D] 0, 3, 7, 14, and 28). All participants received human rabies immunoglobulin intramuscularly on D0. Immunogenicity was assessed at D0, 14, 28, 42, and 6 months after the final injection using the rapid fluorescent focus inhibition test. Seroconversion rates were calculated as the percentage of participants achieving rabies virus neutralizing antibody titers ≥0.5 IU/mL. All analyses were descriptive. At each timepoint, geometric mean titers (GMTs) increased with antigen content (measured using an enzyme-linked immunosorbent assay). High-dose PVRV-NG2 GMTs were the highest at all timepoints, medium-dose PVRV-NG2 GMTs were similar to those with HDCV, and low-dose PVRV-NG2 GMTs were similar to PVRV-NG. The safety profile of PVRV-NG2 was comparable to PVRV-NG; however, fewer injection site reactions were reported with PVRV-NG2 or PVRV-NG (range 36.7-47.5%) than with HDCV (61.5%). This study demonstrated a dose-effect of antigen content at all timepoints. As post-exposure prophylaxis, the safety and immunogenicity profiles of the high-dose PVRV-NG2 group compared favorably with HDCV. Clinicaltrials.gov number: NCT03145766.