Safety and efficacy of filgotinib, lanraplenib and tirabrutinib in Sjogren's syndrome: a randomized, phase 2, double-blind, placebo-controlled study

Objective. The aim of this study was to characterize the safety and efficacy of filgotinib, lanraplenib and tirabrutinib in patients with active SS. Methods. This multicentre, double-blind study randomized patients with active primary or secondary SS [EULAR SS disease activity index (ESSDAI) >= 5) to receive filgotinib 200 mg (Janus kinase-1 inhibitor), lanraplenib 30 mg (spleen tyrosine kinase inhibitor), tirabrutinib 40 mg (Bruton's tyrosine kinase inhibitor), or placebo. The composite primary end point was the week-12 proportion of patients fulfilling protocol-specified improvement criteria (based on CRP and SS-related symptoms). The EULAR SS patient-reported index (ESSPRI) and the ESSDAI change from baseline (CFB) were secondary end points. Exploratory end points included disease-related biomarkers. Treatment-emergent adverse events (AEs) represented safety outcomes. Results. The mean of the baseline ESSDAI was 10.1, and of ESSPRI was 6.2 in the 150 patients who were treated; 125 completed the 24-week placebo-controlled treatment period. At week 12, 43.3% of the filgotinib group achieved the primary end point (P = 0 .17 vs placebo) vs 42.3% (P = 0 .16), 34.7% (P = 0 .33), and 26.7% of lanraplenib, tirabrutinib, and placebo groups, respectively. Neither secondary end point was met. Biomarker reductions included immunoglobulins classically associated with SS disease activity. Filgotinib ESSDAI CFB appeared more pronounced in subgroups with baseline ESSDAI >= 14 or without DMARDs/CSs. Most AEs were Grade 1 or 2. Conclusion. Three drugs with disparate mechanisms were tested, but no significant differences vs placebo in primary or secondary end points were observed. These results may be considered hypothesis-generating, given the drug tolerability, subgroup analysis, and biomarker findings.