Study of HRO761 Alone or in Combination in Cancer Patients With Specific DNA Alterations Called Microsatellite Instability or Mismatch Repair Deficiency.

Key Inclusion criteria: * Patients with advanced unresectable or metastatic MSIhi or MMR deficient (dMMR) solid tumors who have progressed after or are intolerant to prior standard therapy. * Arm A and C: Patients must have progressed on the most recent therapy for advanced disease including one prior line of immune checkpoint inhibitor therapy. * Arm B: Patients should have received prior chemotherapy or targeted therapy, and patients should have received prior immune checkpoint inhibitor or should be expected to benefit from immune checkpoint inhibitor therapy. * Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 1 * Measurable disease as determined by RECIST version 1.1 * • All patients (Arm A, B and C) will have available archival tumor tissue obtained prior to study treatment initiation, to allow retrospective MSIhi/dMMR status confirmation. A newly obtained biopsy will only be collected at screening if there is no archival tumor tissue available and if safe and medically feasible according to treating institution's guidelines. Exceptions may be considered after documented discussion with Novartis. Key Exclusion criteria: * Impaired cardiac function or clinically significant cardiac disease * Clinically significant eye impairment * Patients with a primary Central Nervous System (CNS) tumor or tumor metastatic to the CNS * Human Immunodeficiency Virus (HIV) infection * Active Hepatitis B Virus (HBV), Hepatitis C Virus (HCV) or Tuberculosis infection. P…