Advanced Basal Cell Carcinoma

Eligibility Details: Key Inclusion Criteria: - Confirmed diagnosis of invasive BCC - Progression of disease on hedgehog inhibitor (HHI) therapy or intolerance of prior HHI therapy - At least 1 measurable lesion - ≥18 years of age - Hepatic function, renal function, bone marrow function in defined lab-value-ranges - Anticipated life expectancy >12 weeks - Consent to provide archived tumor biopsy material (all patients) - Group 2: consent to undergo research biopsies - Group 2: must not be a candidate for radiation therapy or surgery - Comply with study procedures and site visits - Sign Subject Information Sheet and Informed Consent Form Key Exclusion Criteria: - Ongoing or recent significant autoimmune disease - Prior treatment with specific pathway-blockers (PD-1/PD-L1) - Prior treatment with immune-modulating agents within 28 days before cemiplimab - Untreated brain metastasis that may be considered active - Immunosuppressive corticosteroid doses (>10mg prednisone) within 28 days prior to treatment with cemiplimab - Active infections requiring therapy, including HIV, hepatitis - Pneumonitis within the last 5 years - Cancer treatment other than radiation therapy, including investigational or standard of care, within 30 days prior to treatment with cemiplimab - Documented allergic reactions or similar to antibody treatments - Concurrent malignancies other than BCC, other than those with negligible risk of metastases or death - Any acute or chronic psychiatric problems - Having received a solid organ transplantation - Inability to undergo contrast radiological assessments - Breastfeeding, pregnant, women of childbearing potential not using contraception Note: Other protocol-defined inclusion/exclusion criteria apply