A Trial to Learn How Safe AZD9750 is and How Well it Works in People With Metastatic Prostate Cancer When Given With or Without Other Anticancer Drugs

* Inclusion Criteria:

  * Participant must be ≥18 years or the legal age at the time of signing the informed consent form.
  * Histologically or cytologically confirmed diagnosis of adenocarcinoma of the prostate.
  * Documented metastatic disease.
  * Serum testosterone levels ≤ 50 ng/dL.
  * Evidence of disease progression with one of the following:

    1. PSA progression defined by a minimum of 3 rising PSA levels with an interval of ≥ 1 week between each determination.
    2. Radiographic progression of soft tissue disease by RECIST v1.1 with or without PSA progression.
    3. Radiographic progression of bone metastasis with 2 or more documented new bone lesions on a bone scan with or without PSA progression.
  * ECOG performance status score of 0 or 1.
  * Adequate bone marrow and organ function.
  * Part A (Module 1)

    * (a) Part A1 dose escalation: at least 1 prior ARPI and, if applicable, at least 1 taxane-based chemotherapy (regardless of whether in HSPC or CRPC setting).
    * (b) Part A2 backfill: at least 1 but no more than 2 prior ARPIs and, if applicable, at least 1 but no more than 2 prior taxane-based chemotherapies (regardless of whether in HSPC or CRPC setting).
  * Part B (Module 1)

    * (a) B1/B2 dose optimization/expansion: at least 1 but no more than 2 prior ARPIs and, if applicable, at least 1 but no more than 2 prior taxane-based chemotherapies (regardless of whether in HSPC or CRPC setting).
    * (b) B3 dose expansion (no taxane cohort): at least 1 but no more than 2 prior ARPIs for metastatic prostate cancer (regardless of whether in HSPC or CRPC setting). No prior taxane is allowed for inclusion in this cohort.
* Exclusion Criteria:

  * Participants with pathological finding consistent with any presence of small cell carcinoma, predominant neuroendocrine carcinoma, or any predominant histology other than prostate adenocarcinoma.
  * Brain metastases, or spinal cord compression.
  * Any clinically significant cardiac disorders including QT prolongation, abnormal electrocardiogram (ECG).
  * Any clinically significant cardiovascular diseases including symptomatic heart failure, uncontrolled hypertension, acute coronary syndrome, cardiomyopathy, valvular heart disease, atrial fibrillation, stroke.
  * Active gastrointestinal disease or other condition that will interfere significantly with the absorption, distribution, metabolism of AZD9750 and relevant combination IMPs.
  * Participants with any known predisposition to bleeding (eg, active peptic ulceration, recent \[within 6 months\] hemorrhagic stroke, proliferative diabetic retinopathy).
  * Prior treatment with an AR-PROTAC.

Other protocol-defined inclusion/exclusion criteria apply.