– Cinrebafusp alfa (PRS 343) is an anticalin-based bispecific drug with high affinity for both CD137/HER2, displaying dissociation constants (Kd) of 0.3 nM to recombinant human HER2 and 5 nM to human monomeric CD137 (4-1BB). It promotes T-cell costimulation via tumor-localized, HER2-mediated 4-1BB clustering and activation, thereby enhancing T-cell receptor-driven responses and facilitating tumor cell eradication. This compound shows promising potential in research concerning HER2-positive solid tumors [1] [2].