Ficlatuzumab (development code AV-299) is an investigational, humanized monoclonal IgG1 antibody developed for the treatment of solid tumors, with a particular focus on squamous cell carcinoma of the head and neck (SCCHN) and non-small cell lung cancer (NSCLC). It functions as a hepatocyte growth factor (HGF) inhibitor. By binding with high affinity to HGF in the tumor microenvironment, ficlatuzumab prevents HGF from interacting with its receptor, c-Met (the mesenchymal-epithelial transition factor), on cancer cells and stromal cells. This blockade inhibits the activation of the HGF/c-Met signaling pathway, which is implicated in tumor growth, angiogenesis, invasion, metastasis, and resistance to other targeted therapies (such as EGFR inhibitors).