Autologous red blood cell therapy safely shifted immune response against myelin in early MS trial

# What the trial tested Researchers at the University of Zurich evaluated an experimental, autologous cell therapy for multiple sclerosis (MS) that attaches small myelin protein fragments to a patient's own red blood cells. The modified red blood cells are transfused back into the patient so that when they are naturally cleared, the myelin fragments enter disposal pathways that promote immune tolerance.

# How the approach is meant to work Red blood cells have a short lifespan and are continuously recycled by the body. The trial leverages the body's existing disposal mechanisms that normally help prevent immune responses to self components. Presenting myelin fragments through that pathway is intended to teach the immune system to accept myelin rather than attack it. The goal is antigen-specific tolerance that reduces autoimmune damage to myelin without broadly suppressing immune defenses.

# Trial design and sponsor The Phase 1b trial (NCT06430671) was sponsored by Cellerys, a company co-founded by several researchers on the study team. Ten people with MS received the autologous, myelin-coupled red blood cell treatment. The trial focused on safety and on measuring immune and biomarker changes rather than testing clinical efficacy.

# Key immunological and biomarker results

# Clinical and imaging outcomes

# Interpretation and next steps The investigators concluded the approach is a promising antigen-specific cell therapy strategy for restoring tolerance to myelin. Cellerys is developing the treatment under the name CLS12311 and will likely pursue further clinical testing to assess efficacy, optimal dosing, and durability of immune effects.

# Practical implications for people with MS This strategy is intended to reduce autoimmune attacks on myelin while avoiding the broad immune suppression of many current MS therapies. If later trials confirm benefit and safety, the approach could offer a targeted alternative for slowing or stopping immune-driven myelin damage. At present, evidence is limited to early safety and immunological signals in a small group of participants.

# Bottom line Coupling myelin peptides to a patient's red blood cells produced measurable changes consistent with increased immune tolerance and lower markers of nerve damage in a Phase 1b study. The treatment was well tolerated and is moving forward in development, but larger trials are needed to establish clinical benefit and long-term safety.