Sling Therapeutics closed a $123 million Series C to advance linsitinib, an oral thyroid eye disease (TED) candidate, through its Phase III confirmatory trial. The funding—led by Forbion with participation from TPG Life Sciences Innovations and Sectoral Asset Management—supports the Orbit study comparing linsitinib against placebo in patients with moderate to severe active TED. Biotech stakeholders will watch whether the oral formulation can match or exceed efficacy of current approved injectable biologics while offering a differentiated safety-and-convenience profile. A late-stage safety signal and adherence in a real-world dosing setting will be pivotal for commercial viability. The financing also underscores how even smaller developers can mobilize large late-stage capital when they can position a meaningful route-of-administration advantage in competitive autoimmune franchises.