Patients aged 2 to 5 years with polyarticular-course juvenile idiopathic arthritis (pJIA) receiving 2 to 24 months of weekly subcutaneous abatacept maintain effective diphtheria and tetanus vaccination protection without new safety signals, according to study results published in Pediatric Rheumatology.
In this substudy of a 24-month, single-arm, open-label, multicenter, Phase 3 trial (ClinicalTrials.gov Identifier: NCT01844518), 29 patients aged 2 to 5 years with active pJIA who were previously vaccinated against diphtheria/tetanus received weight-tiered (10-<25 kg [50 mg], 25-<50 kg [87.5 mg]) weekly subcutaneous abatacept for 4 months. Patients who met the JIA-American College of Rheumatology criteria 30% improvement at month 4 continued to receive treatment for another 20 months, and stable doses of concomitant methotrexate and low-dose oral corticosteroids were permitted at baseline; however, concomitant use of tumor necrosis factor inhibitors was prohibited. A single blood sample was taken to assess antibody levels to tetanus and diphtheria.
Results indicated that after ≥2 months of treatment with abatacept, all patients had protective antibody levels to tetanus. A total of 26 patients (89.7%) had protective antibody levels to diphtheria, and the remaining 3 patients had a protective antibody level to diphtheria of 0.1 IU/mL. There was no evident effect of methotrexate and/or low-dose corticosteroids on antibody levels. There were 4 serious adverse events, including febrile convulsions, tendon disorder, limb abscess, cellulitis, and an overdose of mild intensity (administration of a higher abatacept dose because of misclassification by weight tier).
Study limitations included potential generalizability because all participants were of a similar background (100% white; 86% from Europe). According to the researchers, these findings should be interpreted with caution because of the small sample size and the fact that this was not a classically designed vaccination study.
“All patients maintained protective antibody levels to tetanus, and all but 3 to diphtheria following vaccination prior to study enrollment,” the researchers concluded. “Addition of [methotrexate] and/or low-dose corticosteroid to [subcutaneous] abatacept treatment did not appear to prevent the maintenance of protective antibody levels in this population. Immune system maturation takes place over the early years of life; therefore, ensuring that very young patients who are receiving immunosuppressive medication can maintain protective antibody levels in response to vaccination is important.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Brunner HI, Tzaribachev N, Cornejo GV, et al. Maintenance of antibody response to diphtheria/tetanus vaccine in patients aged 2-5 years with polyarticular-course juvenile idiopathic arthritis receiving subcutaneous abatacept [published online February 22, 2020]. Pediatr Rheumatol. doi:10.1186/s12969-020-0410-x