Study of Orally Administered MOMA-341 in Participants With Advanced or Metastatic Solid Tumors

Inclusion Criteria: 1. Age ≥ 18 years 2. Participants have unresectable advanced or metastatic solid tumors with MSI-H or dMMR alterations and histologically confirmed disease. Participants must have previously received and progressed on an anti-PD-(L)1-based regimen, unless ineligible or in a region without access to anti-PD-(L)1 therapies 3. Have at least 1 lesion at baseline (measurable or non-measurable) suitable for repeat imaging evaluation by RECIST and/or PCWG-3 4. ECOG PS ≤ 2 5. Fully recovered from clinically relevant effects of prior therapy, radiotherapy, and/or surgery \*\*hormonal therapy allowed. Palliative radiotherapy allowed 6. Adequate organ function per local labs 7. Comply with contraception requirements 8. Written informed consent must be obtained according to local guidelines Exclusion Criteria: 1. Known Werner Syndrome 2. Active prior or concurrent advanced-stage malignancy (some exceptions allowed including early-stage cancers) 3. Clinically relevant cardiovascular disease 4. Known CNS metastasis associated with progressive neurological symptoms (stable doses of corticosteroids allowed) 5. Known active uncontrolled infection 6. Known allergy, hypersensitivity, and/or intolerance to MOMA-341 7. Impaired GI function that may impact absorption 8. Patient is pregnant or breastfeeding 9. Known to be HIV positive, unless all of the following criteria are met: 1. Undetectable viral load or CD4+ count ≥300 cells/μL 2. Receiving highly active antiretroviral therapy 3. No AIDS-related illness within the past 12 months 10. Active liver disease (some exceptions are allowed) 11. Prior or ongoing condition, therapy, or laboratory abnormality that, in the investigator's opinion, may affect safety of the patient, confound the results of the study, and/or interfere with the patients participation in the study