Open-Label Extension Study on Long-Term Safety of Enzalutamide in Prostate Cancer Patients from Previous Clinical Trials

The primary objective of this Phase 2 open-label extension study is to collect long-term **safety** data in subjects with **prostate cancer** who continue to derive clinical benefit from treatment with **enzalutamide**. This assessment is crucial as it provides insights into the prolonged safety profile of enzalutamide, a therapeutic agent used in the management of prostate cancer, ensuring that the benefits of continued treatment outweigh potential risks. The study involves participants who have previously been part of an enzalutamide clinical study sponsored by Astellas or Medivation/Pfizer, which has completed at least the primary analysis or the study-specified evaluation period. There are no secondary objectives listed for this study.

The clinical trial involves a total of **392 male participants** who are currently receiving treatment for **prostate cancer**. The study population consists of adult males, specifically those in the age range of 18 to 64 years and 65 years and older. Participants were selected based on their ongoing clinical benefit from treatment with Enzalutamide, as assessed by the investigator, in a previous study sponsored by Astellas or Medivation/Pfizer. The trial does not include female subjects or vulnerable populations. Participants are required to maintain specific lifestyle considerations, such as the use of two forms of birth control if they have a female partner of childbearing potential, and they must agree to avoid sperm donation during the study and for at least three months after the final administration of Enzalutamide. The selection criteria ensure that participants are able to continue their treatment regimen from the prior study and comply with study requirements, including the ability to swallow Enzalutamide capsules.

The clinical trial is a **Phase II** open-label extension study designed to collect long-term safety data for subjects with **prostate cancer** who have previously participated in an enzalutamide clinical study. The trial is structured to include subjects who are continuing to derive clinical benefit from treatment with **enzalutamide**, as assessed by the investigator. The study is not randomized or blinded, as it is an extension of a prior study where participants are already receiving treatment. The trial is expected to run until January 17, 2025, with an estimated recruitment start date of January 17, 2017.

Participants will undergo a series of study visits, beginning with an inclusion (screening) visit to confirm eligibility based on criteria such as current treatment with enzalutamide and the ability to comply with study requirements. Follow-up visits will be scheduled to monitor the safety and efficacy of the treatment, with the primary objective being the collection of long-term safety data. The end-of-study visit will conclude the participant's involvement, ensuring all necessary data is collected and any final assessments are completed.

The expected length of participant involvement is up to 36 months, aligning with the maximum treatment period for enzalutamide. Conditions that may lead to early termination from the study include the investigator's assessment of no further clinical benefit from the treatment, inability to comply with study requirements, or withdrawal of consent by the participant. Participants are required to continue using two forms of birth control throughout the study and for three months after the final administration of enzalutamide to prevent pregnancy. The study is conducted under the sponsorship of Astellas Pharma Europe B.V., with enzalutamide being administered in the form of soft capsules via the oral route.

The clinical trial involves the administration of **enzalutamide**, marketed under the product name MDV3100, which is provided in the form of a soft capsule. The pharmaceutical form is specifically designed for oral administration. The maximum daily dose of enzalutamide is 160 mg, with a total maximum dose of 175,360 mg over a treatment period of up to 36 months. The active substance, enzalutamide, is of chemical origin and is produced by Astellas Pharma Europe B.V. The trial aims to collect long-term safety data for subjects with prostate cancer who have previously participated in an enzalutamide clinical study.

In addition to enzalutamide, the study includes the administration of **abiraterone**, which is also of chemical origin. Abiraterone is provided in a pharmaceutical form denoted as PHF00245MIG and is administered orally. The maximum daily dose for abiraterone is 1000 mg, with a total maximum dose of 1,096,000 mg over the same 36-month treatment period. Abiraterone serves as an auxiliary treatment in the study.

Another auxiliary treatment used in the study is **prednisolone**, which is chemically derived and provided in the same pharmaceutical form as abiraterone, PHF00245MIG. Prednisolone is administered orally with a maximum daily dose of 10 mg and a total maximum dose of 10,960 mg over the 36-month period. The inclusion of prednisolone is intended to complement the therapeutic regimen in the study.

The efficacy of the clinical trial will be assessed through the collection of long-term safety data for subjects with prostate cancer who are continuing to derive clinical benefit from treatment with **Enzalutamide**. The trial is an open-label extension study for subjects who previously participated in an Enzalutamide clinical study sponsored by Astellas or Medivation/Pfizer. The primary objective is to evaluate the sustained clinical benefit as assessed by the investigator, focusing on subjects who have completed the primary analysis or the study-specified evaluation period in the parent study.