SOTIO Biotech, a clinical-stage biopharmaceutical company owned by PPF Group and headquartered in Prague with offices in Basel and Boston, announced that the US FDA has granted Fast Track Designation (FTD) to SOT109, a CDH17-targeting antibody-drug conjugate (ADC). The designation relates to the molecule’s potential as a treatment for patients with advanced unresectable or metastatic colorectal cancer who have exhausted standard treatment options.
CDH17 (cadherin-17) remains one of the few high-prevalence, tumor-selective antigens in colorectal cancer for which no approved targeted therapy exists. Expressed in more than 90% of colorectal tumors but with limited distribution in healthy adult tissue, CDH17 offers a therapeutic window that has eluded earlier non-ADC approaches. SOT109 is designed to exploit this biology: a fully human anti-CDH17 monoclonal antibody, sourced through a licensing agreement with Biocytogen using that company’s RenMab platform, is conjugated via Synaffix’s SYNtecan E linker-payload system to an exatecan-based topoisomerase I inhibitor payload at a drug-to-antibody ratio of four. The exatecan class is pharmacologically validated in approved ADCs, but SOT109 is a distinct molecular entity with no prior regulatory history.
The preclinical package supporting the FTD was built across two years of IND-enabling work. First data presented at World ADC London in March 2025 showed SOT109 producing complete responses in multiple colorectal cancer xenograft models, with favorable tolerability in mice at doses up to 150 mg/kg and no dose-limiting toxicities reported at that level. A subsequent non-human primate study confirmed a favorable pharmacokinetic and safety profile, with the therapeutic index described as wide relative to the exatecan payload class.
Expanded data presented at the AACR Annual Meeting in April 2025 reinforced those findings. SOT109 produced significant and sustained tumor regressions across both cell-derived xenograft and patient-derived xenograft models of colorectal cancer, with complete responses observed in several. Doses tested in mouse studies were well tolerated, and non-human primate data confirmed the pharmacokinetic and safety profile. No granular numeric values — tumor growth inhibition percentages, IC₅₀ figures, or p-values — have been disclosed in publicly accessible summaries; the full poster data remain behind the AACR paywall. The totality of this preclinical package constitutes the evidence base the FDA reviewed when evaluating the FTD application.