RGX-019

**RGX-019** is a humanized monoclonal antibody developed by Rgenix (now Inspirna) that selectively targets **MerTK** (myeloid-epithelial receptor tyrosine kinase), a TAM family receptor tyrosine kinase overexpressed in various solid and hematologic cancers as well as immune-suppressive M2 macrophages. It features a novel mechanism of action involving high-affinity binding to MerTK, blockade of ligand (e.g., Gas6) binding, transient receptor activation followed by internalization, lysosomal trafficking, and degradation, leading to suppression of tumor-promoting signaling (proliferation, migration, angiogenesis, survival), reduced cancer cell colony formation, and reprogramming of M2 macrophages to a pro-inflammatory M1 phenotype with cytokine release. Preclinical data show potent anti-tumor efficacy in models of melanoma, triple-negative breast cancer (TNBC), acute myeloid leukemia (AML), and multiple myeloma (MM), with favorable safety (no retinal toxicity in monkeys or humanized mice), distinguishing it from small-molecule inhibitors hampered by off-target effects. In-licensed from The Rockefeller University, it advanced to IND-enabling studies but remains preclinical as of latest reports.[1][2][4][9]