Sling Therapeutics Presents Preclinical Data Demonstrating Treatment with Linsitinib Limits Progression of Thyroid Eye Disease at 45th Annual Meeting of European Thyroid Association

– Results highlighted in oral presentation show linsitinib significantly limited disease severity in early- and late-stage TED mouse models and prevented development of autoimmune response –

– Company currently evaluating linsitinib in ongoing global Phase 2b LIDS clinical trial in patients living with active, moderate to severe TED –

Ann Arbor, MI, September 11, 2023 — Sling Therapeutics, Inc., a biopharmaceutical company focused on late-stage development of an oral small molecule for the treatment of thyroid eye disease (TED), today announced the presentation of preclinical data demonstrating that treatment with linsitinib, an investigational small molecule insulin-like growth factor I receptor (IGF-1R) inhibitor, significantly limited disease severity in TED mouse models in early and late stages of the disease as well as prevented the development of autoimmune responses. The data are being highlighted today in an oral presentation at the 45th Annual Meeting of the European Thyroid Association (ETA) being held September 9-12, 2023, in Milan, Italy.

“We are pleased to have the opportunity to highlight the latest data from our linsitinib development program at the ETA Annual Meeting, which add to a growing body of evidence indicating its potential to be an effective, novel first-line oral treatment for people suffering from TED at all stages,” said Ryan Zeidan, Ph.D., President and Chief Executive Officer of Sling Therapeutics. “We look forward to further assessments of linsitinib as we continue to enroll people living with TED in our ongoing global Phase 2b LIDS clinical trial.”

In the preclinical study, researchers evaluated mice immunized with a plasmid encoding the A-subunit of thyroid stimulating hormone receptor (TSHR) that were orally administered linsitinib for four weeks. An autoimmune response against TSHR induces Graves’ disease, of which TED is a common manifestation. Results showed that treatment of immunized mice with linsitinib after disease onset significantly limited the

severity of the disease in both early and late stages of the disease. Treatment with linsitinib also prevented development of an autoimmune response including autoimmune hyperthyroidism, morphological changes, formation of brown adipose tissue in the orbita, and orbital immune cell infiltration into the orbit in all stages of TED in mouse models.

Sling Therapeutics is currently enrolling participants in the ongoing Phase 2b LIDS clinical trial, a global, randomized, double-mask, placebo-controlled study designed to evaluate the safety, pharmacokinetics and efficacy of linsitinib in patients with active, moderate to severe TED over 24 weeks of treatment. Participants are being enrolled at trial sites in the United States, Canada, Italy, Spain, and the UK.

For more information about the Phase 2b LIDS trial, visit https://clinicaltrials.gov/ct2/show/NCT05276063.

About Thyroid Eye Disease (TED)

TED is a debilitating autoimmune disease that affects about 20,000 people in the U.S. per year and has a similar prevalence in Europe. TED is characterized by excess fibrous tissue growth behind the eyes, and this inflammation can push the eyes forward or cause the eyes and eyelids to become red and swollen. As the disease progresses it can lead to pain, eye bulging, and double vision. TED predominantly affects women, and most frequently affects people with hyperthyroidism due to Graves’ disease.

About Sling Therapeutics

Sling Therapeutics, Inc., is a biopharmaceutical company focused on late-stage development of an oral small molecule for the treatment of TED. The company is advancing the evaluation of its lead product candidate, linsitinib, in a Phase 2b clinical trial based on extensive preclinical and clinical data. Linsitinib offers the potential of a convenient oral small molecule that could significantly reduce the treatment burden for people living with TED. For more information visit https://slingtx.com/.

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