M9466 Alone or in Combination in Advanced Solid Tumors (DDriver 501)

Inclusion Criteria:

• Module 1 Part A1 and Module 2 Part A1: Locally advanced or metastatic disease thatis refractory to standard therapy or for which no standard therapy is judgedappropriate 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 (6weeks for nitrosourea, mitomycin-C) or 5 half-lives whichever is shorter, prior tostarting study intervention with M9466 (± tuvusertib)

• Module 3 Part A1:

• Histologically or pathologically confirmed diagnosis of prostate cancer

• Metastatic disease documented by positive bone scan or metastatic lesions on CTor MRI

• Participants with Metastatic Castration-Resistant Prostate Cancer (mCRPC) ormetastatic hormone-sensitive prostate cancer (mHSPC) are allowed. For mCRPC,serum testosterone levels ≤ 50 /dL (≤ 1.75 nmol/L).

• Ongoing ADT with a GnRH agonist or antagonist for participants who have notundergone bilateral orchiectomy must be initiated before first dose and mustcontinue throughout the study.

• Candidate for treatment with ·abiraterone acetate.

• Prior anticancer therapy allowed for mHSPC or mCRPC

• Other protocol defined inclusion criteria could apply

Exclusion Criteria:

• Persistence of Adverse Events related to any prior treatments that have notrecovered to Grade less than 1 by NCI Common Terminology Criteria for AdverseEvents- v5.0 unless AEs are clinically nonsignificant and/or stable on supportivetherapy 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 situof the cervix, benign prostate neoplasm/hypertropia, or malignancy that in theopinion of the Investigator, with concurrence of the Sponsor's Medical Monitor, isconsidered cured with minimal risk of recurrence within 3 years)

• Participants with known brain metastases, except if clinically controlled, which isdefined as individuals with Central Nervous System (CNS) tumors that have beentreated, are asymptomatic and who have discontinued steroids (for the treatment ofCNS tumors) for more than 28 days

• Serious Gastrointestinal bleeding within 3 months, refractory nausea and vomiting,uncontrolled diarrhea, known malabsorption, significant small bowel resection orgastric bypass surgery, use of feeding tubes, other chronic gastrointestinal disease (including exocrine pancreatic insufficiency requiring pancreatic enzyme replacementtherapy), and/or other situations that may preclude adequate absorption of oralmedications

• Cerebrovascular accident or stroke

• Module 3 only:

• Current evidence of any of the following:

1. Any medical condition that would make prednisone (or equivalent) usecontraindicated.
2. Any chronic medical condition requiring a higher dose of corticosteroidthan 10 mg prednisone (or equivalent) once daily.

• History of uncontrolled pituitary or adrenal dysfunction

• Hypokalemia

• Other protocol defined exclusion criteria could apply