selectION Therapeutics

Executive Summary

selectION Therapeutics is a German biotech company pioneering a first-in-class approach to treating T cell-mediated autoimmune diseases. Its lead candidate, si-544, is a potent and selective blocker of the Kv1.3 potassium channel, which is overexpressed on activated pathogenic T cells. By targeting these cells specifically, si-544 aims to deactivate disease-causing T cells while preserving the rest of the immune system, offering a potentially disease-modifying therapy that addresses the root cause of autoimmunity. This mechanism contrasts with current immunosuppressive treatments that broadly suppress immune function and do not halt disease progression. Autoimmune conditions such as multiple sclerosis, rheumatoid arthritis, and psoriasis affect millions globally, and si-544 could represent a paradigm shift in their management. Currently in Phase 2 clinical development, si-544 has demonstrated favorable safety and tolerability in earlier trials, along with evidence of target engagement. The company is evaluating the drug in multiple autoimmune indications, with initial focus on plaque psoriasis and possibly other T cell-driven diseases. If successful, si-544 could become the first disease-modifying treatment for a range of autoimmune disorders, offering durable remission without general immunosuppression. The company is privately held and has not disclosed specific financial details, but the high unmet need and novel mechanism make it an attractive candidate for partnerships or acquisition. Upcoming catalysts include Phase 2 data readouts and potential strategic collaborations.

Upcoming Catalysts (preview)

• Q4 2026Phase 2 top-line data for si-544 in plaque psoriasis35% success
• TBDPartnership or licensing deal for si-544 in autoimmune indications40% success
• Q2 2026FDA Fast Track or orphan drug designation for si-54460% success