Orthogonal interleukin-2 receptor subunit beta (orthoIL-2Rβ) (orthoIL-2Rβ)

The orthogonal interleukin-2 receptor subunit beta (orthoIL-2Rβ) is a protein engineered through protein-structure-based design to possess a mutated binding interface that specifically recognizes a complementary orthogonal IL-2 ligand, such as STK-009, while remaining unresponsive to wild-type IL-2 (Sockolosky et al., 2018, Science). In the SYNCAR-001 therapeutic system, this receptor is co-expressed with a CD19-targeted chimeric antigen receptor (CAR) on T cells to enable precise, ligand-dependent control of cell expansion and fitness (Synthekine, 2024). By utilizing an orthogonal signaling pair, the therapy avoids the systemic toxicities and off-target effects—such as the activation of regulatory T cells—typically associated with native IL-2 administration (Silva et al., 2019, Nature). Upon binding its specific ligand, orthoIL-2Rβ activates the JAK/STAT signaling pathway, mimicking the natural proliferative signals required for robust anti-tumor activity (Synthekine, 2023). This technology is primarily aimed at treating B-cell malignancies, including non-Hodgkin lymphoma and chronic lymphocytic leukemia, by ensuring the persistence of CAR-T cells in the immunosuppressive tumor microenvironment (NCT05612035). Ultimately, orthoIL-2Rβ serves as a synthetic rheostat that allows clinicians to modulate the potency and longevity of adoptive cell therapies in vivo.

Other names

Orthogonal IL-2 receptor betaortho-IL-2RbetaModified IL-2 receptor subunit betaSTK-009 receptor

Selective agonism of the engineered orthogonal receptor to induce JAK/STAT signaling and T-cell expansion.