068 Lenabasum reduces IFNγ and pIRF3 in dermatomyositis skin: Biomarker results from a double-blind phase 3 international randomized controlled trial

Dermatomyositis is an autoimmune skin disease with limited treatment options, and lenabasum a cannabinoid type 2 receptor agonist anti-inflammatory properties. Our previous work showed that IFNg IL31 are increased in DM vs. from healthy controls reduces 1 interferon (IFN-1) IL-31 production by PBMCs vitro. Lenabasum 20 mg BID improved CDASI activity (CDASI-A) scores placebo at year international, double-blind, randomized Phase 3 trial. Imaging mass cytometry was done on 66 total FFPE biopsies obtained Baseline Week 16 trial, testing expression of 12 intracellular biomarkers 9 cell types using zero-based, linear mixed effects model Spearman’s correlation for statistical analyses. Subjects both groups had similar immune infiltrates except plasmacytoid dendritic cells were group (p<0.05). At 16, subjects treated significant decrease (p<0.05) phosphorylated-IRF3 (activated transcription factor IFN-1) expression. There trend towards (p=0.08). Absolute change CDASI-A positively correlated staining (R=0.636, p=0.026). These results suggest clinical benefit may be mediated part through reduction pIRF3 (IFN-1 Type 1)