R428 (bemcentinib, BGB324), a selective small-molecule inhibitor of AXL, is currently being evaluated in phase II trials for the treatment of non-small-cell lung cancer (NSCLC) and acute myelocytic leukemia (AML). It has been found to induce apoptosis in cancer cells and to block tumor spread in models of metastatic breast cancer. The therapeutic potential of R428 has also been demonstrated in highly invasive esophageal adenocarcinoma cells and in ESCC cells.
R428 is a selective, small molecule inhibitor of Axl that blocks its catalytic and precancerous activities. R428 treatment reduced Axl-induced AKT phosphorylation, cancer cell invasion, angiogenesis, and the production of pro-inflammatory cytokines. It also reduced the expression of the cytokine granulocyte macrophage colony-stimulating factor and Snail in a dosage-dependent manner. Interestingly,using R428 to inhibit Axl-mediated cellular and molecular functions during cisplatin treatments achieved an enhanced suppression of liver metastases. Axl knockdowns in RAC cell lines reduced migration, invasion, and in vivo engraftment, accompanied by a downregulation in the activity of the Ral GTPase proteins (RalA and RalB). Similar effects were obtained using an A428 inhibitor. Blocking Axl functions also abrogated the phosphorylation of ERBB2 (Her-2/neu) at the Tyr877 residue, which reveals the cross-functional effects of R428 on different receptor signaling axes.
Cabozantinib (XL184) and R428 (BGB324) Inhibit the Growth of Esophageal Squamous Cell Carcinoma (ESCC)
