S095029 as Monotherapy and in Combination With Sym021 in Patients With Advanced Solid Tumor Malignancies Followed by an Expansion Part With Triple Combinations in Patients With Metastatic Gastric or Colorectal Cancers

Dose escalation part: Inclusion Criteria: * Histologically or cytologically confirmed unresectable, locally advanced or metastatic solid tumor malignancies * Patients with a malignancy not amenable to surgical intervention * Patients with measurable disease and progression radiologically assessed * Patients with disease progression after treatment with available standard of care therapies that are known to confer clinical benefit or who are intolerant to treatment. * Patients with available archived tumor biopsy specimens or agree to mandatory biopsy * Estimated life expectancy ≥ 12 weeks * Adequate haematological function * Adequate renal function * Adequate hepatic function Exclusion Criteria: * Pregnant and lactating women * Major surgery within 4 weeks prior to the first IMP administration or not recovered from the surgery * Patients with serious/active/uncontrolled infection or infection requiring parenteral antibiotics, within 2 weeks prior to first IMP administration * Active Hepatitis B Virus infection * Carriers of HIV antibodies * Patients with active thrombosis, or a history of deep vein thrombosis or pulmonary embolism, within 4 weeks prior to first IMP administration * History of organ transplantation * History of gastrointestinal perforation, or intra-abdominal abscess within 28 days of inclusion * History of cirrhosis * History of pulmonary fibrosis or relevant uncontrolled chronic pulmonary condition * Treatment with systemic immunosuppressive therapy * Active autoimmune disease * Administration of a live vaccine within 28 days prior to inclusion