After joining the study, you will be randomly assigned to receive either saruparib or a placebo. A placebo is an inactive substance that looks like the real medication but contains no active ingredient.

This assignment is done by chance, similar to flipping a coin. Neither you nor your doctor will know which treatment you are receiving during the study. This is called a double-blind design.

The study medication will be added to your standard treatment, which includes radiation therapy and androgen deprivation therapy. Androgen deprivation therapy is a hormone treatment that lowers male hormone levels in your body.

You will take the study medication by mouth. The medication comes in the form of tablets.

If you are assigned to receive saruparib, you will take saruparib tablets. If you are assigned to the placebo group, you will take placebo tablets that look identical to the saruparib tablets.

The exact dosage, frequency, and duration of taking the tablets will be explained to you by the study staff based on the study protocol.

Throughout the study, you will continue receiving androgen deprivation therapy using a medication called a gonadotropin releasing hormone analogue. This medication helps lower testosterone levels in your body.

Some participants may also receive abiraterone acetate, which is another medication used to lower hormone levels. Abiraterone acetate is available as ZYTIGA in two strengths: 250 mg tablets or 500 mg film-coated tablets.

If prescribed, abiraterone acetate is taken by mouth according to the dosing schedule provided by your doctor.

During the study, you will have regular imaging scans to monitor your condition. These scans help doctors see if there are any changes in your body.

The scans may include computed tomography (also called CT scan), magnetic resonance imaging (also called MRI), and bone scans. These are imaging tests that create pictures of the inside of your body.

You may also have a specialized scan called prostate-specific membrane antigen-positron emission tomography (also called PSMA-PET). This is a type of scan that can detect prostate cancer cells in your body.

These scans will be performed at specific time points throughout the study as outlined in the study schedule.

You will need to attend regular visits throughout the study. During these visits, the study staff will check your health and how you are responding to the treatment.

At these visits, blood samples may be collected to measure various markers, including prostate-specific antigen (also called PSA), which is a protein produced by prostate cells that can indicate disease activity.

Blood samples may also be taken to measure the levels of the study medication in your blood. This is called pharmacokinetic testing and helps understand how your body processes the medication.

Your overall health status will be assessed using the Eastern Cooperative Oncology Group performance status scale, which measures how the disease affects your daily living abilities.

During the study, you will be asked to complete questionnaires about your quality of life and symptoms.

These questionnaires include the EORTC-QLQ-C30, which asks about your general well-being and physical functioning, and the EORTC-QLQ-PR25, which asks specifically about urinary symptoms related to prostate conditions.

Your answers will help doctors understand how the treatment affects your daily life and symptoms.

Throughout the study and for 6 months after taking the last dose of study medication, you must use a condom during any sexual activity.

You must not father children or donate sperm from the time you join the study until 6 months after your last dose of study medication.

These measures are necessary to prevent potential risks to unborn children.

The study will continue for an extended period to assess long-term outcomes. The estimated end date for the study is April 2036.

During this time, doctors will monitor for the appearance of distant metastases, which means cancer spreading to other parts of your body beyond the pelvis.

The study will also track other important outcomes, including overall survival, which means how long participants live, and prostate cancer-specific survival, which means survival specifically related to prostate cancer.

If your disease progresses and you require additional treatment, information about any new treatments you receive will be collected as part of the study follow-up.