7967 Ruxolitinib Prevents Immune-Checkpoint Inhibitor-Related Diabetes Mellitus Via Inhibition Of Pathogenic IL-21 And IFNγ-Producing CD4+ T Cells

Abstract Disclosure: N.L. Huang: None. J. Ortega: None. S.J. Wang: None. L.N. Scott: None. K. Kimbrell: None. E. McCarthy: None. J. Olay: None. J.N. Nguyen: None. K. Kim: None. J. Lee: None. M.G. Lechner: None. The use of immune checkpoint inhibitor (ICI) therapy has revolutionized the treatment landscape for many advanced cancers by leveraging immune activation through the blockade of checkpoint proteins, including programmed death protein-1 (PD-1). Unfortunately, autoimmune attack of healthy tissue can occur in up to 60% of patients. ICI-induced Type 1 diabetes mellitus (ICI-T1DM) is a rare but life-threatening adverse event during ICI therapy that leads to rapid destruction of pancreatic islets, hyperglycemia, and lifetime dependence on insulin. While cytotoxic CD8+ T cells are recognized as important players in ICI-T1DM, the role for CD4+ helper T cells in disease pathogenesis is less well understood. Using a mouse model of ICI-autoimmunity, in which male and female NOD mice treated with anti-PD-1 (10mg/kg/day, i.p., twice weekly) develop multi-organ autoimmune infiltrates including insulitis and DM, we identified interleukin-21 (IL-21) and interferon gamma (IFNγ) CD4+ T cells as key contributors to ICI-T1DM. Antibody depletion of CD4+ T cells in NOD mice significantly delayed the onset of ICI-T1DM. Immunophenotyping of pancreatic islet infiltrates in ICI-treated mice revealed increased IL-21+ IFNγ+ CD4+ T follicular helper (Tfh; ICOS+ PD1+ CXCR5+) and T peripheral helper (Tph; ICOS+PD1+ CXCR5- CXCR6+) cells. In vitro, IL-21 increased effector CD8+ T cell function and IFNγ promoted production of T cell-attracting chemokines CXCL9, CXCL10, and CXCL16 by macrophages. Given the potential role for IL-21 and IFNγ to amplify ICI-DM progression, we sought to target these signaling pathways as potential interventions. Genetic inhibition of IL-21 or IFNγ signaling in NOD mice reduced insulitis and DM in anti-PD-1 treated mice. Considering that IL-21 and IFNγ act through JAK/STAT signaling in immune cells, we proposed to block this pathway to prevent ICI-DM using ruxolitinib, a clinically available JAK1/2 inhibitor. Indeed, ruxolitinib blocked STAT3 and STAT1 phosphorylation in mouse splenocytes in response to IL-21 or IFNγ, respectively, and completely protected ICI-treated NOD mice from DM. Finally, in a syngeneic tumor model, use of ruxolitinib after initiation of anti-PD-1 therapy did not abrogate ICI anti-tumor effects. Taken together, these data suggest that IL-21 and IFNγ producing CD4+ T cells are important drivers of ICI-T1DM, and that the use of JAK inhibitors may be a promising clinical intervention to reduce ICI-T1DM toxicities in patients. Presentation: 6/2/2024