A phase 3 randomized, double-blind, comparator-controlled study to evaluate safety, tolerability and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine, in allogeneic hematopoietic cell transplant recipients (PNEU-STEM).

BACKGROUND: Individuals who receive allogeneic hematopoietic cell transplant (allo-HCT) are immunocompromised and at high risk for pneumococcal infections, especially in the months following transplant. This study evaluated the safety and immunogenicity of V114 (VAXNEUVANCE™), a 15-valent pneumococcal conjugate vaccine (PCV), when given to allo-HCT recipients.

METHODS: Participants received 3 doses of V114 or PCV13 in one-month intervals starting 3-6 months after allo-HCT. Twelve months after HCT, participants received either PNEUMOVAXTM 23 or a fourth dose of PCV (if they experienced chronic graft versus host disease). Safety was evaluated as the proportion of participants with adverse events (AEs). Immunogenicity was evaluated by measuring serotype-specific immunoglobulin G (IgG) geometric mean concentrations (GMCs) and opsonophagocytic activity (OPA) geometric mean titers (GMTs) for all V114 serotypes in each vaccination group.

RESULTS: A total of 274 participants were enrolled and vaccinated in the study. The proportions of participants with AEs and serious AEs were generally comparable between intervention groups, and the majority of AEs in both groups were of short duration and mild-to-moderate intensity. For both IgG GMCs and OPA GMTs, V114 was generally comparable to PCV13 for the 13 shared serotypes, and higher for serotypes 22F and 33F at Day 90.

CONCLUSIONS: V114 was well tolerated in allo-HCT recipients with a generally comparable safety profile to PCV13. V114 induced comparable immune responses to PCV13 for the 13 shared serotypes, and higher for V114 serotypes 22F and 33F. Study results support use of V114 in allo-HCT recipients.