Inclusion Criteria:

        Dose Escalation:

        • Histologically or cytologically confirmed non-CNS solid tumor that is metastatic or
        unresectable and for whom there is no available standard therapy.

        Expansion:

        • Histologically or cytologically confirmed diagnosis of relapsed or refractory, advanced
        and/or metastatic melanoma, NSCLC, or CRC who are not anymore candidates for standard
        therapy

        Dose Escalation and Expansion:

          -  Measurable disease according to RECIST 1.1

          -  Eastern Cooperative Oncology Group (ECOG) 0-1

          -  Acceptable bone marrow and hematological, liver and renal functions

          -  Acceptable coagulation status

        Exclusion Criteria:

        Uncontrolled intercurrent illness, including but not limited to:

          -  Ongoing or active infection treated with intravenous anti-infective therapy less than
             2 weeks prior to first dose

          -  Symptomatic congestive heart failure, unstable angina pectoris or cardiac arrhythmia.

          -  Uncontrolled hypertension despite optimal medical management.

          -  Evidence of significant autoimmune disease suggesting risk for immune-related adverse
             events (irAEs).

          -  History of irAEs that led to treatment discontinuation of prior ICP inhibitor

          -  • History of chronic liver disease or evidence of hepatic cirrhosis.

          -  History of non-infectious pneumonitis that required steroids or currently has
             pneumonitis.

          -  History of organ allograft (except for corneal transplant) or autologous or allogeneic
             bone marrow transplant, or stem cell rescue within 3 months prior to the first dose of
             GEN1042.

          -  Serious, non-healing wound, skin ulcer (of any grade), or bone fracture.

          -  Any history of intracerebral arteriovenous malformation, cerebral aneurysm, or
             progressive brain metastases or stroke.

        Prior therapy:

          -  Radiotherapy within 14 days prior to first GEN1042 administration

          -  Treatment with an anti-cancer agent (within 21 days or after at least 5 half-lives of
             the drug, whichever is shorter), prior to GEN1042 administration.

          -  History of ≥ grade 3 allergic reactions to monoclonal antibody (mAb) therapy

          -  Toxicities from previous anti-cancer therapies that have not resolved