M9466 as Single Agent or in Combination With Tuvusertib in Advanced Solid Tumors (DDRiver 501)

Inclusion Criteria:

Module 1 Part A1 and Module 2 Part A1: Locally advanced or metastatic disease that is refractory to standard therapy or for which no standard therapy is judged appropriate by the Investigator
Eastern Cooperative Oncology Group Performance Status less than or equal to (<=) 1
Life expectancy of more than 6 months
Have adequate hematologic function
Participants who received chemotherapy, extensive radiotherapy, biological therapy (e.g. antibodies) or investigational agents will have a washout period of 4 weeks (6 weeks for nitrosourea, mitomycin-C) or 5 half-lives whichever is shorter, prior to starting study intervention with M9466 (± tuvusertib)
Other protocol defined inclusion criteria could apply

Exclusion Criteria:

Persistence of Adverse Events related to any prior treatments that have not recovered to Grade less than 1 by NCI Common Terminology Criteria for Adverse Events- v5.0 unless AEs are clinically nonsignificant and/or stable on supportive therapy in the opinion of the Investigator (e.g. neuropathy or alopecia)
Participant has a history of malignancy within 5 years before the date of enrollment (exceptions are squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix, benign prostate neoplasm/hypertropia, or malignancy that in the opinion of the Investigator, with concurrence of the Sponsor's Medical Monitor, is considered cured with minimal risk of recurrence within 3 years)
Participants with known brain metastases, except if clinically controlled, which is defined as individuals with Central Nervous System (CNS) tumors that have been treated, are asymptomatic and who have discontinued steroids (for the treatment of CNS tumors) for more than 28 days
Serious Gastrointestinal bleeding within 3 months, refractory nausea and vomiting, uncontrolled diarrhea, known malabsorption, significant small bowel resection or gastric bypass surgery, use of feeding tubes, other chronic gastrointestinal disease (including exocrine pancreatic insufficiency requiring pancreatic enzyme replacement therapy), and/or other situations that may preclude adequate absorption of oral medications
Cerebrovascular accident or stroke
Other protocol defined exclusion criteria could apply