Cetuximab (brand name Erbitux(R)) is a chimeric monoclonal antibody drug (IgG1/kappa) approved for treatment of KRAS wild-type metastatic colorectal cancers and squamous cell carcinoma of the head and neck.It is critical to assess the immunogenicity of the biosimilar compared with the innovator drug by comparable methods and existing regulatory guidances and White Papers for method development and validation address immunoassays in a limited manner.