Inclusion Criteria:  Age ≥18 years on the day the consent is signed. Patients with histologically confirmed diagnosis of unresectable, locally advanced or metastatic solid tumor for which standard treatment options are not available, no longer effective, or not tolerated. Patient should have a documented disease progression on prior therapy before entry into this study. Patients must have at least one measurable target lesion as per RECIST 1.1. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Patient with no available archived material must have one or more tumor lesions amenable to biopsy. Adequate organ function as assessed by laboratory tests within 72 hours prior to the start of treatment.  A female patient must use a highly effective method of birth control during study treatment and until 120 days after last dose of study treatment.  Dose Expansion  Patients who have had prior checkpoint inhibitor (CPI) treatment in the past 6 months must have documented confirmed radiographic progression from it prior to study entry. Patients must have received and progressed on only one prior regimen in the metastatic setting comprising an PD-(L)1 plus chemotherapy.  Exclusion Criteria:  Patients with previously treated brain metastases may participate provided they are radiologically stable, clinically asymptomatic and are off immunosuppressive therapies for at least 4 weeks. Low dose of steroid <10 mg/day prednisone or equivalent) is allowed.  Patients who have received prior:  Small molecule inhibitors, and/or other similar investigational agent: ≤ 2 weeks or 5 half-lives, whichever is shorter. Chemotherapy, other monoclonal antibodies, antibody-drug conjugates, or other similar experimental therapies: ≤3 weeks or 5 half-lives, whichever is shorter. Radioimmunoconjugates or other similar experimental therapies ≤6 weeks or 5 half-lives, whichever is shorter. Patients who have received 4-1BB agonists in the past.  Patients who had a major surgery within 4 weeks prior to first administration of IMP.  Dose Expansion:  Patient who received therapy with an irinotecan containing regimen. Patient must not be on warfarin, strong cytochrome P450 (CYP) 3A4 inducers, strong CYP3A4 inhibitors, or strong UGT1A1 inhibitors.