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Updated: May 6, 2026
A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer
Published on: March 6, 2018
Clinical Trial Protocol for the Apa/Enza-short Study: A Randomized Nationwide Study of Shortened 12-Month Duration of
Mahtab Hamidikia1, Tanja C van Dijk1, John W M Martens1
1Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
Abstract:
Continuous treatment with an androgen receptor pathway inhibitor (ARPI) plus androgen deprivation therapy (ADT) in low-volume metastatic castration-sensitive prostate cancer (mCSPC) may lead to overtreatment, resulting in increased toxicity and higher costs. Evidence to guide a shorter duration of ARPI therapy is currently lacking. The Apa/Enza-short trial evaluates whether a 12-mo course of apalutamide or enzalutamide is noninferior to continuous treatment in low-volume mCSPC. This randomized, open-label, noninferiority study enrolls 400 patients across Dutch hospitals. After 12 mo of ADT + ARPI, eligible patients are randomized to continue or discontinue ARPI treatment, with reinitiation permitted upon prostate-specific antigen (PSA) increase. The primary end point is clinical progression-free survival (cPFS). If noninferiority is demonstrated, this strategy could maintain efficacy while reducing treatment-related toxicity and health care costs.
Insights
A 12-month course of androgen receptor pathway inhibitors (ARPI) with androgen deprivation therapy (ADT) may be as effective as continuous treatment for low-volume metastatic castration-sensitive prostate cancer (mCSPC), potentially reducing toxicity and costs.
Area of Science:
- Oncology
- Urology
- Clinical Trials
Background:
- Continuous androgen receptor pathway inhibitor (ARPI) plus androgen deprivation therapy (ADT) in low-volume metastatic castration-sensitive prostate cancer (mCSPC) may cause overtreatment, leading to increased toxicity and costs.
- Limited evidence exists to guide shorter durations of ARPI therapy in this patient population.
Purpose of the Study:
- To evaluate if a 12-month course of apalutamide or enzalutamide is noninferior to continuous treatment in patients with low-volume mCSPC.
- To assess the potential for reduced toxicity and healthcare costs with a shorter ARPI treatment duration.
Main Methods:
- Randomized, open-label, noninferiority study (Apa/Enza-short trial) enrolling 400 patients in Dutch hospitals.
- Patients received 12 months of ADT + ARPI, then were randomized to continue or discontinue ARPI.
- Reinitiation of ARPI was permitted upon prostate-specific antigen (PSA) increase.
- Primary endpoint: clinical progression-free survival (cPFS).
Main Results:
- Noninferiority of 12-month ARPI treatment compared to continuous treatment needs to be demonstrated.
- Data on clinical progression-free survival (cPFS) will determine the study outcome.
Conclusions:
- Demonstrating noninferiority could establish a shorter ARPI treatment strategy for low-volume mCSPC.
- This approach may maintain treatment efficacy while minimizing adverse effects and healthcare expenditures.
