OR26-03 Treatment With Linsitinib, An IGF-1 Receptor Inhibitor, Prevents Disease Development And Progression In An Experimental Model Of Thyroid Eye Disease

Disclosure: A. Gulbins: Grant Recipient; Self; Sling therapeutics, Inc. M. Horstmann: Grant Recipient; Self; Sling therapeutics, Inc. A. Daser: None. U. Flögel: None. M. Oeverhaus: Grant Recipient; Self; Sling therapeutics, Inc. B.E. Nikolaos: None. J.P. Banga: None. G. Krause: None. G.D. Hammer: Research Investigator; Self; Sling therapeutics, Inc. A.G. Spencer: Research Investigator; Self; Sling therapeutics, Inc. R. Zeidan: Research Investigator; Self; Sling therapeutics, Inc. A. Eckstein: Grant Recipient; Self; Sling therapeutics, Inc. S. Philipp: Grant Recipient; Self; Sling therapeutics, Inc. G. Görtz: Grant Recipient; Self; Sling therapeutics, Inc. Study objective: We investigated the effect of linsitinib, a small molecule inhibitor of the Insulin like growth factor 1 receptor (IGF-1R), on Graves’ disease and thyroid eye disease. Graves‘ disease (GD), also known as “Basedow's disease“, is the most common cause for hyperthyroidism, typically presenting in patients between 40-60 years. GD is an autoimmune condition of the thyroid which is caused by autoantibodies against the thyroid stimulating hormone receptor (TSHR). Thyroid eye disease (TED) is the most common extra thyroidal manifestation of GD and occurs in about 50% of the clinical cases. Methods: To induce Graves’ Disease in mice we immunized mice 3-times with a plasmid encoding for the A-subunit of the TSHR. During each active (early) and chronic (late) states of the autoimmune disease, linsitinib was administered orally for four weeks. Endocrine orbitopathy and inflammation were determined by histology and MRI. Results: As seen in the histology, linsitinib prevented autoimmune hyperthyroidism, morphological changes, formation of brown adipose tissue in the orbita and orbital T-cell and macrophage infiltration into the orbit in the active state as well as the chronic phase. To evaluate the effect of linsitinib during the course of therapy, living mice were examined via MRI. A distinctive migration of immune cells in the orbit with consecutive inflammation can be seen in the TSHR-immunized group, which is completely blocked by treatment with linsitinib. In addition, the orbital inflammation was partnered with the onset of muscle edema and formation of brown adipose tissue in TSHR-immunized mice, effects that were abrogated upon application of linsitinib. Conclusion: In summary, we demonstrate the development of GD and TED in a mouse model upon immunization against the TSHR. The IGF-1R antagonist linsitinib blocks the development of the local pathologies of GD and TED in an early and late phase of the autoimmune disorder and also prevents development of the autoimmune response. We show that treatment of immunized mice with linsitinib after disease onset significantly limited the severity of the disease, indicating the clinical significance of the findings and providing a path to therapeutic intervention of Graves’ Disease. Our data support the use of linsitinib as a novel first line treatment of thyroid eye disease. Presentation: Saturday, June 17, 2023