Immunogenicity and safety of the meningococcal B recombinant (4CMenB) vaccine in allogeneic hematopoietic cell transplantation recipients.

Objectives: Despite a high risk of invasive meningococcal (Men) disease, there is no published data on any MenB vaccine after hematopoietic cell transplantation (HCT). We investigated the immunogenicity and safety of the 4CMenB recombinant vaccine (Bexsero) in adult HCT recipients.

Methods: Patients were eligible from 6 months post-HCT to receive 2 4CMenB doses at 2-month intervals. Sera were collected at baseline, 1 month after the second dose, and 12 months after enrolment. The serum bactericidal activity (SBA) using human complement (hSBA) was assessed against fHbp, NadA, PorAP1.4, and NHBA antigens. The vaccine response was defined by one criterion for one vaccine antigen: (1) in patients with a hSBA titer <4 at baseline: a titer ≥4; (2) in patients with a hSBA titer ≥4 at baseline: at least a 4 time increase.

Results: Forty (40) patients were included at a median of 2.14 (0.57-13.03) years posttransplant. At baseline, most patients (32/40, 80%) had hSBA titers <4 for all vaccine antigens. After 2 vaccine doses, the proportion of patients with a titer ≥4 was significantly increased for fHbp (23/40, 57.5%), NadA (25/40, 62.5%), and PorA (31/40, 77.5%) but not for NHBA for which only 6 of 40 (15%) patients responded. Of patients, 36 out of 0 (90%) were responders to ≥1 antigen. However, 9 months later, only 23 out of 37 (62.2%) patients were still seroprotected. No severe adverse event was observed.

Discussion: The response rate of 90% for ≥1 vaccine antigen and our safety data supports the 4CMenB vaccination of HCT recipients from 6 months after transplant with 2 doses.