Key Inclusion Criteria:  Histologically confirmed diagnosis of CSCC CSCC of advanced stage Males or females at least 18 years of age at the time of consent Signed informed consent provided prior to any study procedures Ability to and willing to understand informed consent and comply with protocol requirements and procedures No more than two prior lines of systemic treatment for advanced disease Patients must have at least one lesion that is considered as measurable according to the Study Response Criteria Eastern Cooperative Oncology Group performance status 0 or 1 Adequate function of bone marrow, liver, kidneys Availability of tumor tissue sample (either an archival specimen or a fresh biopsy material) at Screening  Key Exclusion Criteria:  Prior systemic treatment for advanced disease with any anti-EGFR agent Active central nervous system metastasis Systemic anti-cancer therapy within five half-lives or two weeks, whichever is shorter, prior to first dose of the study drug Persistent toxicities from previous systemic anti-neoplastic treatments Wide-field radiotherapy within four weeks, or focal radiation for analgesic purpose or for lytic lesions at risk of fracture within two weeks prior to first dose of the study drug, or no recovery from side effects of such intervention Major surgery within four weeks prior to first dose of the study drug, or no recovery from side effects of such intervention Active infection requiring therapy Concomitant use of systemic steroids at dose of >10 mg of prednisone or its equivalent per day Known or suspected allergy/hypersensitivity to the study drug or any component of the study drug, other monoclonal antibodies, premedication medicines Concurrent participation in another investigational therapeutic clinical trial Pregnant or breast-feeding females Mental or medical conditions that prevent the patient from giving informed consent or participating in the trial Other severe acute or chronic medical or psychiatric conditions or laboratory abnormality that may increase the risk associated with the study participation or the study drug administration or may interfere with the interpretation of study results and, in the judgment of the Investigator, would make the patient inappropriate for enrollment in this study  Note: Other protocol defined Inclusion/Exclusion criteria apply.