Cbl-b-IN-16 (compound 31) is an orally active inhibitor of the RING E3 ligase Cbl-b, with an IC50 of 30 nM. It enhances IL-2 production in human T cells with an EC50 of 230 nM and exhibits antitumor activity.

Cbl-b-IN-16 modulates the TCR signaling pathway by inhibiting Cbl-b ubiquitination and its transfer to Zap-70, with IC₅₀ values of 63 nM and 84 nM, respectively. At a concentration of 5 μM and an exposure time of 20 minutes, Cbl-b-IN-16 inhibits Cbl-b phosphorylation via SYK. This compound enhances the TCR signaling pathway by inhibiting effects, leading to an upregulation of pPLCγ1 levels in human T cells, with an EC₅₀ of 0.61 μM.