First in Human Study of M6223

Inclusion Criteria: * Participants have histologically or cytologically proven locally advanced or advanced solid malignancies who are refractory to or have progressed under standard treatment and have no other treatment options known to confer clinical benefit * Participants with Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 to 1 at Screening * Participant has a formalin-fixed paraffin-embedded block containing tumor tissue or a minimum of 15 (preferably 25) unstained tumor slides suitable for immunohistochemistry-based staining of protein expression * Participants with life expectancy of at least 12 weeks * Participants with measurable disease according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) * Adequate hematological, hepatic and renal function as defined in the protocol * Other protocol defined inclusion criteria may apply Exclusion Criteria: * Participants with persisting toxicity related to prior therapy Grade greater than (\>) 1 National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) Version 5.0, however, alopecia, sensory neuropathy Grade less than or equal to (\<=) 2, or other non-immune-related Grade \<= 2 not constituting a safety risk * Participants with prior organ transplantation including allogeneic stem cell transplantation * Participants with prior toxicity related to an immune checkpoint inhibitor Grade greater than equal to (\>=) 3 NCI-CTCAE Version 5.0 unless resolved to…