Inclusion Criteria:
* Participants who had histologically or cytologically proven locally advanced or metastatic solid malignancies and who are refractory to or have progressed under standard treatment or for whom standard treatment is not expected to deliver clinical benefit
* Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 to 1 at Screening
* Adequate hematological function, hepatic function and renal function
* Ability to swallow oral dose forms (for example \[e.g.\] capsules)
* Fresh tumor biopsies mandatory for participants at Dose level 2 (DL2) and 6 participants upon potential determination of Recommended Dose for Expansion (RDE). Providing consent to fresh tumor biopsies taken during the Screening period and an on-treatment biopsy is mandatory
* Life expectancy of at least 12 weeks according to Investigator judgement
* Measurable disease according to The Response Evaluation Criteria in Solid Tumors (RECIST) v1.1
* Other protocol defined inclusion criteria could apply
Exclusion Criteria:
* Persisting toxicity related to prior therapy Grade greater than (\>) 1 National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) v5.0, however, alopecia, sensory neuropathy hypothyroidism and diabetes mellitus Grade less than or equal to (\<=) 2, despite treatment, are allowed
* Prior organ transplantation including allogeneic stem cell transplantation
* Participants with known brain metastases, except those meeting the following criteria: a) Brain metastases that have been treated locally and are clinically stable for at least 4 weeks prior to the start of treatment; b) No ongoing neurological symptoms that are related to the brain localization of the disease (sequelae that are a consequence of the treatment of the brain metastases are acceptable)
* Participants must be either off steroids or on a stable or decreasing dose of \< 10 milligrams (mg) daily prednisone (or equivalent)
* Current significant cardiac conduction abnormalities, including corrected QT interval (QTcF, corrected with Fridericia formula) prolongation of \> 470 milliseconds (ms) or impaired cardiovascular function, ventricular tachycardia (including Torsades de Pointes), or a history of paroxysmal atrial fibrillation, serious cardiac arrhythmia and family history of sudden death or long QT syndrome
* Active autoimmune disease that might deteriorate when receiving an immunostimulatory agent including but not limited to inflammatory bowel diseases, autoimmune hepatitis, interstitial lung disease of immunologic origin, systemic lupus erythematosus, et cetera (etc.), with the following exceptions: a) Participants with diabetes type I, psoriasis, hypo- or hyperthyroid disease not requiring immunosuppressive treatment are eligible
* Significant acute or chronic fungal, bacterial and/or viral infections requiring systemic therapy including coronavirus disease of 2019 (COVID-19)
* Known hypersensitivity to the trial treatment or to one or more of the excipients
* Other protocol defined exclusion criteria could apply
