A Study to Learn About Two Medicines (Apalutamide and Enzalutamide) in People With Metastatic Castration-sensitive Prostate Cancer (mCSPC)

December 4, 2025 updated by: Pfizer

Real-world Clinical Outcomes With Androgen Receptor Pathway Inhibitors (ARPIs) in Metastatic Castration-sensitive Prostate Cancer (mCSPC) in the Flatiron Health Electronic Health Records (EHR) Database

The purpose of this study is to learn about how long apalutamide and enzalutamide are taken by men to treat mCSPC.

Prostate cancer is one of the most common cancers in men. The prostate is a gland in the male body that helps make semen. Metastatic cancer is a cancer that has spread to other parts of the body. Castration-sensitive prostate cancer means the cancer is being controlled by keeping the testosterone levels as low as would be expected if the testicles were removed by surgery.

This is a real-world study, not a clinical study. This means that researchers will look at what happens when men receive the treatments prescribed by their own doctor as part of their usual healthcare treatment. In this study, researchers will use information from cancer clinics (Flatiron Health electronic health records).

The study will include patients' information from the database for men who:

  • Were identified to have mCSPC.
  • Started treatment with apalutamide or enzalutamide (index date) for mCSPC.
  • Were 18 years of age or older on the index date. Men in this study will be taking apalutamide or enzalutamide for treatment of their mCSPC. The study will compare how long men take apalutamide or enzalutamide. This study will use patient information from cancer clinics. Information from start of apalutamide or enzalutamide treatment until information is available in the database will be used to describe how long patients receive treatment.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Actual)

1300

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • New York
      • New York, New York, United States, 10001
        • Pfizer, Inc

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Men with metastatic castration-sensitive prostate cancer who initiated apalutamide or enzalutamide and met eligibility criteria will be included in the study. Patients will be identified from the Flatiron Health electronic health records database.

Description

Inclusion Criteria:

  • Male patients diagnosed with metastatic prostate cancer
  • Initiated apalutamide or enzalutamide for the first-line treatment of metastatic castration-sensitive prostate cancer (mCSPC). Initiation date of first treatment defines the index date.
  • Index date on or after 1 January 2020
  • Evidence of androgen deprivation therapy (ADT) use between 90 days prior to the index date and 6 months following the index date
  • Age ≥18 years on the index date -≥6 months of clinical activity following the index date, unless the patient died

Exclusion Criteria:

  • Evidence of castration-resistance prior to the index date
  • Received chemotherapy, androgen receptor pathway inhibitor, radiopharmaceuticals, immunotherapy, PARP inhibitor, or estrogens prior to the index date
  • Evidence of ADT use between 1 year and 91 days prior to the index date
  • Had a prior history of other cancers

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Enzalutamide cohort
Patients initiating enzalutamide for mCSPC
Drug: Enzalutamide
As provided in real-world setting
Other Names:
  • XTANDI
Apalutamide cohort
Patients initiating apalutamide for mCSPC
Drug: Apalutamide
As provided in real-world setting
Other Names:
  • ERLEADA

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Treatment duration
Time Frame: Up to approximately 65 months
Treatment duration will be defined as the time from index date to the discontinuation (i.e., addition of subsequent treatment, treatment gap of 90 days, death) of the index treatment for any reason. Patients without an event will be censored on the date of last confirmed clinical activity.
Up to approximately 65 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Pfizer

Collaborators

Astellas Pharma Inc

Investigators

  • Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

July 21, 2025

Primary Completion (Actual)

October 31, 2025

Study Completion (Actual)

October 31, 2025

Study Registration Dates

First Submitted

July 18, 2025

First Submitted That Met QC Criteria

July 18, 2025

First Posted (Actual)

July 25, 2025

Study Record Updates

Last Update Posted (Actual)

December 8, 2025

Last Update Submitted That Met QC Criteria

December 4, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • C3431053

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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