Abatacept use for 24 weeks has a limited effect on salivary gland inflammation in Sjögren's disease patients.

Objectives: This study aimed to assess (1) effects of abatacept on salivary gland histology of Sjögren's disease (SjD) patients, (2) the predictive value of salivary gland histopathological characteristics at baseline for clinical response to abatacept treatment.

Methods: Patients (n=41) who participated in the Dutch ASAP-II and ASAP-III trials and international abatacept trial (IM101603) from whom a labial (n=13) or parotid (n=28) salivary gland biopsy was obtained at baseline and after 24 weeks of treatment with abatacept were included. Biopsies were analysed for SjD related histopathological features before and after abatacept (n=25) or placebo (n=16) treatment. Histopathological data at baseline were compared between clinical responders and non-responders to abatacept treatment.

Results: Comparison between abatacept- and placebo-treated patients revealed virtually no differences in histopathological parameters of parotid and labial salivary gland biopsies of SjD patients at baseline and 24 weeks after therapy. In labial glands, only the number of IgA plasma cells/mm2 differed between the two groups over time (p=0.034). Correspondingly in parotid glands, the number of IgA plasma cells increased in the abatacept group (p=0.049) after 24 weeks. The number of CD20+ B-cells/mm2 in parotid glands of the placebo group increased compared to baseline (p=0.021). There were no evident differences in baseline histopathological parameters between CRESS or ClinESSDAI responders and non-responders treated with abatacept.

Conclusions: Abatacept has limited effects on salivary gland histology in SjD patients after 24 weeks of treatment. Besides possibly affecting numbers of IgA plasma cells and preventing increases in B-lymphocyte infiltration, salivary gland histopathology could not predict response to abatacept treatment in SjD patients.