IT1t inhibits CXCL12/CXCR4 interaction with an IC50 of 2.1 nM. is a potent CXCR4 antagonist.

CXCL12-CXCR4:2.1 nM, HIV-1 (X4):14.2 nM (in MT-4 cells), HIV-1 (X4):19 nM (in PBMCs)

IT1t, a drug-like isothiourea derivative, exhibits potent, dose-dependent inhibition of the CXCL12/CXCR4 interaction, boasting an IC50 value of 2.1 nM, and similarly impedes calcium flux with an IC50 of 23.1 nM. Notably, IT1t demonstrates strong electron density within the binding cavity of the CXCR4 homodimer's both subunits. Its binding mode in CXCR4 dimers reveals interactions solely on the extracellular sides of helices V and VI, maintaining a minimal 4 Å gap between the intracellular regions, likely occupied by lipids. Both IT1t and the CVX15 peptide act as competitive inhibitors against CXCL12, sharing several crucial receptor-ligand contacts for CXCL12 binding, such as Asp187, Glu288 (7.39), and Asp972 (2.63), suggesting these areas as essential for binding. IT1t's interaction site indicates a significant anchor point within this domain. CXCR4 plays a critical role in chemotaxis, functions as a coreceptor for T-tropic HIV-1 entry, and is implicated in cancer metastasis.

IT1t effectively diminishes the development of early metastases in triple-negative breast cancer (TNBC) within the zebrafish xenograft model. Similarly, targeting CXCR4 to silence its expression markedly reduces tumor cell invasion at the metastatic site, akin to the results observed with the antagonist IT1t.