• Signed a written informed consent form prior to any trial specific procedures.

• Men with histologically or cytologically confirmed adenocarcinoma of the prostate.

• Aged ≥18 years old at the time of signing informed consent.

• De novo metastatic disease defined by clinical or radiological evidence of metastases.

• Note: For patients with nodal metastases only, only patients with extra-pelvic enlarged lymph nodes (lymph nodes located above the iliac bifurcation) can be included if they have either:

⁃ At least one extra-pelvic lymph node ≥2 cm

⁃ At least one extra-pelvic lymph node ≥1 cm if the patients also have at least one pelvic lymph node ≥2 cm

• Measurable disease or bone lesions that are evaluable according to PCWG3 criteria.

• Ineligible for treatment with all of the following drugs: docetaxel, abiraterone, enzalutamide, apalutamide; AND meets at least one of the following frailty criteria:

∙ Activities of daily living (ADL) assessment (excluding urinary incontinence question) score 3 or 4/5, or;

‣ 4-Instrumental activities of daily living (4-IADL) assessment score 2 or 3/4, or;

‣ A Grade 3 event on the Cumulative Illness Score Rating-Geriatrics (CISR-G) questionnaire, or;

‣ Body mass index (BMI) ≤21 kg/m² and/or \>5% weight loss in the last 6 months, or;

‣ Timed up and go test (TUG) \>14 sec. Nota Bene: Regarding CISR-G assessment, more specifically genitourinary scoring, score N°4 is not applicable.

• Adequate bone marrow function: haemoglobin ≥80 g/L, white blood cells ≥3.0 x10⁹/L and platelets ≥80 x10⁹/L.

• Adequate liver function: alanine aminotransferase (ALT) \<2 x upper limit of normal (ULN) and bilirubin \<1.5 x ULN, (or if bilirubin is between 1.5-2 x ULN, they must have a normal conjugated bilirubin). For patients with documented liver metastasis, ALT \<5 x ULN is acceptable.

• Adequate renal function: calculated creatinine clearance \>30 ml/min (using the Modification of Diet in Renal Disease \[MDRD\] or Chronic Kidney Disease Epidemiology Collaboration \[CKD EPI) method).

⁃ For sexually active men, agreement to use adequate contraception for the duration of trial participation and up to 2 weeks after completing study treatment.

⁃ Affiliated to the social security system or in possession of equivalent private health insurance (according to local regulations for participation in clinical trials).

⁃ Willing and able to comply with the protocol for the duration of the trial including undergoing treatment and scheduled visits, and examinations including follow-up.