Sling Therapeutics said it has closed a $123 million Series C financing round to bankroll a global Phase 3 study of linsitinib, an oral therapeutic candidate for thyroid eye disease. The fundraising was led by Forbion and included returning investor TPG Life Sciences Innovations along with new backer Sectoral Asset Management.
Linsitinib is designed to inhibit IGF-1R, a protein implicated in the pathophysiology of thyroid eye disease and the same molecular target as currently approved therapies. Sling emphasized that, unlike treatments administered by infusion or injection, linsitinib is delivered orally.
The company reported that its Phase 2b/3 LIDS trial met its primary objective of reducing proptosis - the forward displacement of the eye that characterizes the disease. Sling also said linsitinib demonstrated a differentiated safety profile in that study, noting fewer issues related to hearing impairment, alterations in blood sugar and menstrual cycle changes compared with known concerns.
The U.S. Food and Drug Administration has granted Fast Track designation to linsitinib. That designation increases the frequency of interactions between Sling and the agency during development and allows the program to be eligible for rolling review, accelerated approval and priority review if the relevant criteria are satisfied.
Sling has launched its Phase 3 ORBIT trial in adults with moderate to severe active thyroid eye disease. The company said the trial design was agreed with the FDA following an End-of-Phase 2 meeting earlier this year.
"The data generated to date give us confidence in linsitinib’s potential to meaningfully address important limitations of current TED therapies," Sling Chief Executive Ryan Zeidan said.
Sling noted that linsitinib has been administered to more than 900 patients across 15 clinical trials spanning multiple disease settings. The company framed that cumulative experience as supporting its ongoing development program.
Thyroid eye disease affects more than 200,000 people in the United States, Sling said. The illness primarily affects women with hyperthyroidism caused by Graves' disease and is characterized by tissue accumulation behind the eyes, which can push the eyeballs forward and produce swelling that, in severe cases, may impair vision.
This financing will support the planned global ORBIT Phase 3 program, which aims to further evaluate linsitinib's efficacy and safety in adults with moderate to severe active disease. The company did not provide additional operational details beyond the start of the trial and the agreed-upon design with the FDA.