Prospective Study on the Vaccine Response to Meningococcal B Vaccine After Allogeneic Stem Cell Transplantation

Overview

Allogeneic hematopoietic stem cell transplant (HSCT) recipients are at risk of various bacterial infections, especially due to a progressive decrease of specific antibodies. Around 90% of HSCT recipients have unprotective titers of specific antibodies to serogroups A and C meningogocci (Parkkali 2001; Mahler 2012). Some small studies suggest that the response to meningococcal A and C vaccines is close to 100% after 3 doses given 18 months after transplant. Although the response to 2 doses of 4CMenB is over 75% in other immunocompromised patients (Feavers, 2017), studies with 4CMenB are lacking after HSCT. Nevertheless, as serogroup B caused 74% of IMD in Europe between 2004-2014 (Whittaker, 2017), the meningococcal B vaccination is recommended by the more recent guidelines from 6 months after transplant. There are, however, no data on the safety and efficacy of this vaccine after hematopoietic stem cell allograft (HSCT). The objective of this study is to assess the response to 2 doses of a multicomponent meningococcal B vaccine (4CMenB) given at 2 months interval in adult allogeneic HSCT recipients transplanted at least 6 months ago. The response will be assessed 1 month and 10 months after the second dose of vaccine by measuring bactericidal antibodies against NadA, fHbp, NHBA and PorAP1 vaccinal antigens according to methods previously reported (Caron Lancet Infect Dis 2011). The response rate will be correlated to pre- and post-transplant factors. The hypothesis of this study is that 80% of the patients should have protective titers one month after the 2nd dose.

Monocentric study. Forty patients are expected. Primary objective: Response rate one month after 2 doses of vaccine Secondary objectives: safety, rate of protection before vaccination, comparison of the antibody titers at one month vs. at 10 months after the vaccine program. Relationship between pre and post-transplant factors.