Key Inclusion Criteria:

          -  Patient must have a known diagnosis of NSCLC, HCC, or HNSCC as defined in the protocol

          -  Patient must be willing and able to provide blood samples at the indicated time points

          -  Patient must be willing and able to have excisional or core needle biopsies of tumor
             prior to initiation of cemiplimab as defined in the protocol

          -  Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

          -  Patient is determined to be a surgical candidate for resection of their tumor

          -  Adequate organ and bone marrow function as defined in the protocol

        Key Exclusion Criteria:

          -  Patients who have had any systemic anti-cancer therapy or radiotherapy within 6 months
             prior to entering the study for their current tumor or a different primary tumor

          -  Patients whose tumor burden, or pace of tumor growth, in the opinion of the
             Investigator will not permit delaying surgery

          -  Patients who have participated in a study of an investigational agent or an
             investigational device within 4 weeks of study therapy or 5 half-lives (whichever is
             longer)

          -  Patients who have had major surgery within 14 days prior to initiation of neoadjuvant
             Therapy

          -  Patients with metastatic disease for whom the intent of surgery would not be curative

          -  Uncontrolled, intercurrent illness as defined in the protocol and as determined by the
             Investigator

          -  Is receiving systemic steroid therapy or any other form of immunosuppressive therapy
             within 7 days prior to the first dose of study treatment

          -  Has active autoimmune disease that has required systemic treatment in the past 1 year

          -  Has a known, additional malignancy that is progressing and/or requires active
             treatment. Exceptions include patients with: basal cell carcinoma of the skin or
             squamous cell carcinoma of the skin that has undergone potentially curative therapy;
             in situ cervical or anal cancer; prostate cancer on stable dose of hormonal therapy
             without rising PSA; breast cancer who have been treated with curative intent, who may
             be on hormonal therapy.

          -  Encephalitis, meningitis, or uncontrolled seizures in the year prior to informed
             consent

          -  History of interstitial lung disease (eg, idiopathic pulmonary fibrosis, organizing
             pneumonia) or active, noninfectious pneumonitis that required immune-suppressive doses
             of glucocorticoids to assist with management. A history of radiation pneumonitis in
             the radiation field is permitted as long as pneumonitis resolved ≥6 months prior to
             study treatment.

          -  Uncontrolled infection with human immunodeficiency virus (HIV), HBV or hepatitis C
             infection (HCV); or diagnosis of immunodeficiency as defined in the protocol

        Note: Other protocol defined Inclusion/Exclusion criteria apply