Abstract 1957 Poster Session II, Sunday, 5/2 (poster 172)

Children with nephrotic syndrome are at increased risk of complicated or disseminated varicella when receiving immunosuppressive doses of steroids or alkylating agents. To evaluate the safety and immunogenicity of live, attenuated varicella vaccine in children with nephrotic syndrome, we initiated a multi-center trial of VARIVAX® in children & adolescents aged 1-19 yrs, who had initial presentation or relapse of nephrotic syndrome within 12 months of study entry. Patients (pts) were excluded if they were currently receiving >2mg/kg/alternate day (qod) steroids (max 40mg qod); daily steroids, cyclosporin or tacrolimus in the previous month; or cytotoxic agents in the last 3 months. The study goal was to evaluate the safety, tolerability and antibody (Ab) response to a 2-dose regimen of VARIVAX®. An acceptable level of seroprotection was defined as a varicella Ab level ≥ 5gpELISA units as this is associated with a very low rate of breakthrough varicella in healthy children. Ab response was measured 6 weeks after each dose. Pts with a varicella Ab level <5 gpELISA units after dose 2 were offered a 3rd dose of vaccine. To date, 20 seronegative pts, 58% male, mean age 5.3 years (sd 2.0), have been vaccinated. 8 pts (40%) were receiving low dose qod steroids. Ab levels ≥ 5gpELISA units were documented in 73% (14/19) after 1 dose and 100% (18/18) after 2 doses of vaccine. No serious adverse events have been seen. Geometric mean titers (GMT) for the group were <0.6 gpELISA units at baseline (by definition), 16.0 after 1 dose and 115.1 gpELISA units after 2 doses of VARIVAX®. Pt use of steroids at time of vaccination had no effect on Ab response to VARIVAX®. GMT's for pts with complete data are presented below. (Table)

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The results of this study have shown that a 2 dose regimen of VARIVAX® is generally well-tolerated and highly immunogenic (based on Ab response) in children and adolescents with nephrotic syndrome who are not receiving immunosuppressive doses of steroids or cytotoxic agents. Additional evaluation of cell-mediated response to VARIVAX® is currently underway.

Funded by Merck & Co.