Castration With Abiraterone 250 mg Without LHRH Analogs or Blockers in Patients With Prostate Cancer Requiring Hormonal Intensification (Multicenter Phase 2)

December 9, 2025 updated by: SMED Clinical Research

Hypothesis

The use of Abiraterone 250 mg with food + prednisone, without LHRH analogs or blockers (ADT), achieves castration-level testosterone at 30 days in ≥80-90% of cases.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Design

  • Type: Phase 2, prospective, open-label, multicenter, single-cohort.

  • Inclusion Criteria:

    • Patients with standard indication for intensification:

      • M0 high/very high risk candidates for RT (Abiraterone [ABI] for 2 years + ADT for 3 years per STAMPEDE), or
      • mHSPC: candidates for doublet (ADT+ABI) or triplet (ADT+Docetaxel+ABI); without ADT during the first 30 days.

Objectives and Endpoints

Primary:

  1. Proportion of patients with serum testosterone ≤50 ng/dL (and sensitivity analysis ≤20 ng/dL) at Day 30 (±3) without receiving ADT.
  2. Time to castration (first day with T ≤50 ng/dL within D1-D30).

Secondary:

  • Absolute and % change in PSA between D0 and D30; PSA50 and PSA90 rates at D30.
  • Safety (CTCAE v5.0): hypertension, hypokalemia, hepatotoxicity, fluid retention, adrenal insufficiency.

Procedures and Timeline

  • Screening (≤7 days): consent, medical history, ECOG, BP, ECG, labs: CBC, liver profile, creatinine, K+, PSA, testosterone.
  • Day 0: start ABI 250 mg + prednisone 5-10 mg/day; education on "with food" administration.
  • Day 30 (±3): AE, BP, K+, LFT, T, PSA → endpoint evaluation.
  • Safety follow-up: until Day 60.

Ethical and Regulatory Considerations

  • In Argentina and Bolivia, time to access intensified treatment with Abiraterone (doublet or triplet) exceeds two months in the public system, so waiting time is not altered and patients may benefit from early intensified castration if trial is positive.
  • The 250 mg "with food" regimen has pharmacokinetic/economic support in literature; detailed in consent. Multiple studies confirm ABI 250 mg with food equals 1000 mg, and NCCN guidelines recommend this dosing in low-access settings. The SPARE study evaluated safety of ABI without ADT in metastatic castration-resistant prostate cancer, showing equivalence.
  • The 30-day window without LHRH is limited, and all patients will receive standard treatment.

Rescue and Safety Criteria • Key AE management:

  • Hypokalemia: supplement; consider eplerenone (preferred over spironolactone for lower androgenic interaction); adjust steroid.
  • Hypertension: optimize antihypertensives.
  • Hepatotoxicity: pauses/adjustments per AAP guidelines.

Sample Size and Justification

  • One-sample binomial test to reject p≤0.70 (unacceptable null) in favor of p≥0.90 (target).

  • With n=24 per cohort and success defined as ≥20/24 patients achieving castration at D30:

    • α (one-sided) ≈ 0.042 if true p=0.70.
    • Power ≈ 0.91 if true p=0.90.

Variables and Analysis

  • Primary: proportion with T ≤50 ng/dL at D30 (main analysis) and T ≤20 ng/dL (sensitivity).

    o Estimate 95% CI and one-sided binomial test vs 70%. Cohort success if ≥20/24 meet criteria.

  • Secondary:

    • PSA: absolute and % change, PSA50/PSA90 rates at D30.
    • Safety: AE rates (CTCAE v5.0).

Quality and Logistics

  • Testosterone measurement (validated method; preferably LC-MS/MS) to avoid variability.
  • Written instructions for administration with food (same time, similar meal).
  • Home BP and AE recording (card/app).

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Phase 2

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

  • Argentina
      • Buenos Aires, Argentina, 5044
  • Spain
      • Hermosillo, Spain
      • Santa Cruz de la Sierra, Spain, 10260
        • Recruiting
        • Instituto Oriente Boliviano
        • Contact:
        • Principal Investigator:
          • Lucia Ritcher

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

Description

Inclusion Criteria:

  • Age ≥18 years.
  • Histologically confirmed prostate adenocarcinoma.
  • Treated at Hospital Durand (Argentina) or Instituto Oncológico del Oriente Boliviano (Bolivia).
  • Indicated for hormonal intensification (high/very high risk candidates for RT, or mHSPC for doublet/triplet).
  • No prior ADT.
  • ECOG 0-2; adequate hepatic/renal function; K+ ≥3.5 mmol/L; controlled BP.

Exclusion Criteria:

  • Hypersensitivity to ABI/prednisone; moderate-severe hepatic impairment; uncontrolled hypertension; refractory hypokalemia.
  • Concurrent therapy with strongly contraindicated/inducing drugs affecting ABI levels without possibility of adjustment.

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

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: single-cohort
Abiraterone 250 mg with food + prednisone, without LHRH analogs or blockers (ADT), achieves castration-level testosterone at 30 days in ≥80-90% of cases.
Drug: Abiraterone 250 mg with food + prednisone
Abiraterone 250 mg with food + prednisone, without LHRH analogs or blockers (ADT), achieves castration-level testosterone at 30 days in ≥80-90% of cases

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Response rate
Time Frame: 3 months
Response per PCWG3
3 months

Collaborators and Investigators

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

Sponsor

SMED Clinical Research

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)

December 1, 2025

Primary Completion (Estimated)

December 31, 2026

Study Completion (Estimated)

March 30, 2027

Study Registration Dates

First Submitted

December 9, 2025

First Submitted That Met QC Criteria

December 9, 2025

First Posted (Actual)

December 23, 2025

Study Record Updates

Last Update Posted (Actual)

December 23, 2025

Last Update Submitted That Met QC Criteria

December 9, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • TN-2025-0003

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

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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