Scientists have created a molecular 'dimmer switch' that can paralyze parts of the immune system on demand and restart them instantly.
April 14, 2026
Original Paper
Reversible CD28 checkpoint modulation by cyclic peptides outperforms biologic blockade under exposure-limited conditions
bioRxiv · 10.64898/2026.04.09.717469
The Takeaway
Standard immune-blocking drugs stay in the body for weeks, leaving patients dangerously vulnerable to infections and cancer long after the treatment is needed. This new cyclic peptide provides the same surgical precision as heavy-duty antibodies but can be 'flushed' from the system, allowing doctors to restore a patient's natural defenses in a matter of hours if a complication arises.
From the abstract
CD28 co-stimulatory blockade is an established therapeutic strategy in autoimmune disease, yet every clinical-stage agent shares a structural limitation: high-affinity, long-lived receptor occupancy that precludes dynamic control of immune suppression. In chronic inflammatory conditions, where prolonged immunosuppression carries infection risk and necessitates treatment interruptions, no existing agent permits rapid restoration of immune function. We report CP8, a disulfide-constrained cyclic pe