Sling Therapeutics Raises $123M Series C to Push Oral Thyroid Eye Disease Drug Into Phase 3
核心洞察
Sling Therapeutics (搜索) raised a $123 million Series C led by Forbion (搜索) to fund a late-stage trial of its oral thyroid eye disease (搜索) drug linsitinib.
The global Phase 3 'Orbit' study will enroll about 130 adults with moderate-to-severe active TED, dosed at 150 mg or placebo twice daily for 24 weeks.
An earlier late-stage trial showed a statistically significant 52% response rate at 24 weeks with no drug-related hearing loss or tinnitus reported.
Sling Therapeutics (搜索) has raised $123 million in a Series C financing to advance its experimental oral drug linsitinib into late-stage testing for thyroid eye disease (搜索) (TED), the privately held biotechnology company announced Wednesday. The round was led by venture-capital firm Forbion (搜索), with participation from TPG Life Sciences Innovations and Sectoral Asset Management. As part of the financing, Sling appointed Regina Salvat of Forbion and François Beaubien of Sectoral Asset Management to its board.
The proceeds will fund a late-stage trial of linsitinib in roughly 130 adults with moderate-to-severe active TED, an immune condition characterized by inflammation and swelling around the eyes that can lead to eye bulging and vision loss. Participants will receive either 150 mg of linsitinib or placebo twice daily for 24 weeks.
Prior Data and the Phase 3 'Orbit' Study
Data from an earlier late-stage trial of linsitinib showed that treatment was associated with a statistically significant 52% response rate after 24 weeks, and the drug reduced eye bulging, meeting the study's main goal. No drug-related cases of hearing loss or tinnitus were reported. The earlier trial also demonstrated a differentiated safety profile for concerns linked to similar treatments, including hearing problems and changes in blood sugar and menstrual cycles.
Sling's new global Phase 3 study, "Orbit," could confirm the results observed in the previous trial. The company did not disclose when it expects topline data.
Positioning Against Injected Biologics
Sling is trying to stand out with an oral drug that could become a more convenient alternative to Amgen's Tepezza and Viridian Therapeutics' Lumvoa (搜索). Like both of those medicines, linsitinib blocks a protein called IGF-1R (搜索) that drives inflammation in TED. But Tepezza and Lumvoa are antibodies administered via injection or intravenous infusion, whereas linsitinib is taken orally twice daily — a potential advantage, according to Ryan Zeidan, the biotech's president and CEO.
Similar oral drugs have been tested in oncology, where they have largely struggled. But blocking IGF-1R (搜索) is a more proven approach in TED, and Zeidan said linsitinib impacts that protein more precisely than its antibody counterparts, yielding a potentially "different clinical profile." It is also more targeted than the IGF-1R inhibitors studied in cancer, which hit multiple other pathways and could not have been developed for TED, he said.
"It's a tricky target to hit," Zeidan told BioPharma Dive.
Sling also believes linsitinib's design should help it dodge many of the side effects associated with approved TED medicines, such as hearing loss, hyperglycemia and fertility issues. Testing so far has suggested the drug could prove to be more durable than biologics, Zeidan added.
Zeidan told Reuters that linsitinib could offer an alternative for patients whose needs are not well met by current biologics, including those concerned about hearing loss linked to Tepezza and Lumvoa (搜索) or those for whom intravenous therapy is not practical. If approved, linsitinib would become the first oral drug approved for thyroid eye disease (搜索).
A Crowded and Competitive Field
A surge of research into new drugs for TED has fueled the advancement of companies such as Sling, Ethyreal Bio and Khartis in recent months. Immunology biotech Khartis Therapeutics (搜索) emerged from stealth with $95 million in August 2026, unveiling a lead programme that is also an oral IGF-1R (搜索) inhibitor. Khartis has not yet started clinical trials for its asset, meaning Sling is the only biotech with an oral IGF-1R inhibitor in late-stage clinical trials.
Other drugmakers, including Immunovant and Argenx, have seen prospective treatments for the inflammatory eye condition fall short in testing.
Eli Lilly is also eyeing the TED treatment space. Earlier this month, the big pharma company outlaid $2.875 billion to acquire Merida Biosciences (搜索). Merida's lead programme, MER511 (搜索), is in Phase I development for Graves' disease (搜索) and TED. MER511 is a fusion protein containing a portion of the thyroid-stimulating hormone receptor (TSHR (搜索)) ectodomain.
Zeidan said the company is considering testing linsitinib in earlier stages of disease or against the chronic form of TED.
"We have some really interesting commercial expansion opportunities and new patient indications that would benefit from this drug, that are unique to a small molecule oral therapeutic," he said.