GEN1042 Safety Trial and Anti-tumor Activity in Participants With Malignant Solid Tumors

Key Inclusion Criteria: Monotherapy - Dose Escalation and Dose Expansion Parts * Participants with non-CNS solid tumors that is metastatic or unresectable and for whom there is no available standard therapy. * Participants with a confirmed diagnosis of relapsed or refractory, advanced and/or metastatic melanoma, NSCLC, or CRC and for whom there is no available standard therapy Combination Therapy - Dose Expansion Part * Participants with unresectable Stage III or Stage IV melanoma with no prior systemic anticancer therapy for unresectable or metastatic disease. Primary ocular or mucosal melanoma is excluded. * Participants with Stage IV metastatic or recurrent NSCLC with no prior systemic anticancer therapy, no actionable mutation. * Participants with recurrent or metastatic HNSCC with no prior systemic therapy administered in the recurrent or metastatic setting. * Participants with confirmed metastatic PDAC with no previous radiotherapy, surgery, chemotherapy, or investigational therapy for the treatment of metastatic disease. General (all phases): * Must be age ≥ 18 years of age on the day of signing informed consent, or the legal age of consent in the jurisdiction in which the trial is taking place. * Measurable disease according to RECIST 1.1 * Eastern Cooperative Oncology Group (ECOG) 0-1 * Normal or adequate liver, renal, cardiac and bone marrow function Key Exclusion Criteria: Monotherapy - Dose Escalation and Dose Expansion Parts * Treatment with an anti-canc…