A Study Testing if Patients With Advanced Prostate Cancer Who Are Responding Well to Combination Treatment Can Safely Reduce Their Medication to a Single Hormone Therapy, Compared to Continuing Their Current Drugs (STEPDOWNmHSPC)

Randomized Phase 2 Assessment of De-escalation to Androgen Deprivation Therapy Alone Versus Continuation of Doublet or Triplet Therapy in Responders With Metastatic Hormone-Sensitive Prostate Cancer

The goal of this randomized comparative study (a study where participants are placed into groups by chance) is to find out if reducing treatment to androgen deprivation therapy (ADT)-a treatment that lowers testosterone-by itself works just as well as continuing the original combination of drugs. This study involves adult men with metastatic hormone-sensitive prostate cancer (prostate cancer that has spread to other parts of the body but still responds to hormone treatments) who have responded very well after 6 to 7 months of their initial two-drug or three-drug treatment.

The main questions it aims to answer are:

1. Does reducing treatment to ADT alone work as well as the combination treatment at keeping the cancer from growing on imaging scans after 18 months, also known as radiographic progression-free survival (rPFS)?
2. Does reducing treatment to ADT alone work as well as the combination treatment at preventing a rise in prostate-specific antigen (PSA), known as PSA progression-free survival (PSA-PFS)?

Researchers will compare a continuation group, which continues their initial two-drug or three-drug treatment, to a reduced-treatment group, which stops taking the androgen receptor pathway inhibitor (ARPI)-a drug that blocks the effects of hormones on cancer cells. Researchers want to see if reducing the treatment safely controls the cancer while lowering drug side effects and financial costs.

Participants will:

1. Complete a 6- to 7-month initial period receiving a two-drug or three-drug treatment chosen by their doctor.
2. Have blood tests for PSA and testosterone, and undergo a specialized imaging scan called a prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) scan, to confirm the treatment is working very well before being assigned to a study group.
3. Stop taking the ARPI drug if assigned to the reduced-treatment group, or continue their current medications if assigned to the continuation group.
4. Go to check-up visits every 3 months for the first 24 months to complete physical exams, blood tests, and quality-of-life surveys.
5. Have a PSMA PET/CT scan every 6 months after being put into a group to check if the cancer has grown.

Study Overview

• Status: Not yet recruiting
• Conditions: Metastatic Prostate Cancer; Castration Sensitive Prostate Cancer
• Intervention / Treatment: Drug: Continuation of initial Androgen Deprivation Therapy (ADT) and Androgen Receptor Pathway Inhibitor (ARPI) combination therapy at standard doses; Other: De-escalation strategy

Detailed Description

This phase 2 randomized comparative study investigates the de-escalation of systemic therapy for patients with metastatic hormone-sensitive prostate cancer (mHSPC) (STEPDOWNmHSPC i.e. Strategy for Therapy Escalation Pruning in metastatic Hormone Sensitive Prostate Cancer)who have achieved an optimal response to initial treatment.

A. Background and Rationale:

In India, 40-60% of patients diagnosed with prostate cancer present with metastatic disease, a significantly higher rate than the 5-10% observed in Western cohorts. While indefinite doublet or triplet therapies (combining androgen deprivation therapy [ADT], androgen receptor pathway inhibitors [ARPI], and sometimes docetaxel) are the standard of care, they cause substantial cumulative physical, metabolic, and financial toxicities. Because a significant sub-population of patients achieves a deep response to these therapies, this trial evaluates whether carefully selected patients can safely de-escalate to ADT monotherapy without compromising oncological outcomes.

B. Study Objectives:

1. Primary Objective: To determine if de-escalation to ADT monotherapy is non-inferior to continuing doublet or triplet therapy regarding 18-month radiographic progression-free survival (rPFS) and PSA Progression-Free Survival (PSA-PFS).
2. Secondary Objectives: To compare overall survival, time to castration-resistant prostate cancer (CRPC), sustained complete PSMA PET responses at 12 and 24 months, quality of life (using EORTC QLQ-C30 i.e. European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30), incidence of severe adverse events, and economic burden between the two arms.

C. Study Design and Methodology:

1. Target Population: Adult men with histologically confirmed prostate adenocarcinoma, an ECOG (Eastern Co-operative Oncology Group) performance status of 0-2, and documented metastatic disease on PSMA PET/CT.
2. Run-In Phase: The study will initially enrol approximately 265 patients, who will undergo 6 to 7 months of standard doublet or triplet therapy.
3. Randomization: Following the run-in phase, patients who achieve an "optimal response"-defined as a serum PSA < 0.2 ng/mL, castrate testosterone levels (< 50 ng/dL), and a partial or complete response on PSMA PET/CT with no new lesions-will be randomized 1:1 into two arms. The trial targets 170 randomized patients (85 per arm) to account for an estimated 10% attrition rate.

Arm A (Continuation): Patients will continue their initial ADT and ARPI regimen at the same doses.

Arm B (De-escalation): Patients will discontinue the ARPI and continue with ADT monotherapy.

D. Statistical Analysis:

To establish non-inferiority, the study utilizes a 15% margin with 80% power and a one-sided alpha of 0.10. Radiographic progression-free survival will be estimated using the Kaplan-Meier method, and treatments will be compared using a stratified log-rank test and Cox proportional hazards regression based on randomization stratification factors. The primary analysis will be performed on both the Intention-To-Treat (ITT) and Per-Protocol (PP) populations, requiring consistent findings in both to declare non-inferiority.

• Study Type: Interventional
• Enrollment (Estimated): 170
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Thyavihally B. Yuvaraja, MBBS, MS, MCh, DNB (Urology); Phone Number: +919321322505; Email: tb.yuvaraja@gmail.com

Study Locations

• India
  • Maharashtra
    • Mumbai, Maharashtra, India, 400053
      • Kokilaben Dhirubhai Ambani Hospital and Medical Research Institute
      • Contact: Thyavihally B. Yuvaraja, MBBS, MS, MCh, DNB (Urology); Phone Number: +919321322505; Email: tb.yuvaraja@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

Inclusion criteria for enrolment:

1. All patients of age group 18 to 80 years will be included
2. Patients who would voluntarily agree to sign informed consent form
3. Histologically confirmed adenocarcinoma of the prostate
4. Evidence of metastatic disease at diagnosis (de novo) or after definitive local therapy, documented on PSMA PET/CT
5. Intended to receive ADT plus an ARPI (abiraterone, enzalutamide, apalutamide or darolutamide) OR ADT plus ARPI plus docetaxel, as determined by the treating physician prior to enrolment
6. ECOG performance status 0-2
7. Adequate organ function: haemoglobin ≥ 9 g/dL; absolute neutrophil count ≥ 1.5 × 10⁹/L; platelets ≥ 100 × 10⁹/L; serum creatinine ≤ 1.5 × ULN or estimated GFR ≥ 45 mL/min; total bilirubin ≤ 1.5 × ULN; AST/ALT ≤ 2.5 × ULN
8. Life expectancy ≥ 12 months

Criteria for randomization ("optimal responder"):

1. Completion of 6-7 months of protocol-defined doublet or triplet therapy without unplanned interruption > 30 days
2. Serum PSA < 0.2 ng/mL at re-staging
3. Serum testosterone at castrate level (< 50 ng/dL)
4. PSMA PET/CT demonstrating partial or complete response as per PPP criteria: (i) no new PSMA-avid lesions; (ii) > 30 % decrease in total PSMA tumour volume compared with baseline; and (iii) no progression at existing sites
5. ECOG 0-2 at re-staging
6. Adequate organ function (as at baseline)
7. Ongoing willingness to participate and to comply with randomized treatment

Exclusion Criteria:

Exclusion criteria for enrolment:

1. Known small-cell, neuroendocrine or predominantly sarcomatoid histology
2. Prior systemic therapy for prostate cancer other than ≤ 90 days of ADT (± a short course of first-generation anti-androgen for flare prevention) at enrolment
3. Prior treatment with any ARPI, docetaxel, cabazitaxel, Ra-223 or 177Lu-PSMA
4. Uncontrolled hypertension (systolic ≥ 160 mm Hg or diastolic ≥ 100 mm Hg despite therapy), history of seizures or predisposing conditions (for enzalutamide candidates), unstable cardiac disease, recent myocardial infarction or stroke within 6 months
5. Known active second malignancy requiring systemic therapy (except adequately treated non-melanoma skin cancer)
6. Active uncontrolled infection including HIV, hepatitis B or C with detectable viral load, or tuberculosis on active treatment
7. Any contraindication to the chosen ARPI, docetaxel or ADT per respective product labels
8. Psychiatric or cognitive disorder limiting capacity to consent or comply with protocol

Exclusion criteria at randomization:

1. Serum PSA ≥ 0.2 ng/mL or any PSA rise above nadir of ≥ 25 %
2. Any new lesion on PSMA PET or conventional imaging
3. Progression at existing sites per PCWG4 or PPP
4. Testosterone ≥ 50 ng/dL (non-castrate)
5. Development of symptomatic disease (e.g. new bone pain requiring opioid therapy, cord compression, pathological fracture)
6. Grade ≥ 3 ongoing toxicities attributable to current therapy that precludes continuation
7. Withdrawal of consent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Arm A - Continuation; Patients continue the same ADT and ARPI that were administered during the run-in phase, at the same doses, until radiographic progression, unacceptable toxicity, death, withdrawal of consent, or end of assessment. Docetaxel will have been completed by month 6 and is therefore not continued.	Drug: Continuation of initial Androgen Deprivation Therapy (ADT) and Androgen Receptor Pathway Inhibitor (ARPI) combination therapy at standard doses; Arm-A serves as the standard-of-care control arm, in which patients continue their intensified combination therapy despite having achieved a deep clinical and molecular response. The intervention strictly involves continuing the identical Androgen Deprivation Therapy (ADT) and Androgen Receptor Pathway Inhibitor (ARPI) regimen-such as abiraterone, enzalutamide, apalutamide, or darolutamide-administered during the 6-to-7-month run-in phase, maintained at original doses.
Experimental: Arm B - De-escalation; Patients discontinue the ARPI (and any corticosteroid associated with abiraterone) at the randomization visit. ADT is continued uninterrupted at the same schedule as during the run-in phase. No other systemic anti-cancer therapy is administered unless progression is documented.	Other: De-escalation strategy; The experimental intervention is a response-adapted de-escalation to Androgen Deprivation Therapy (ADT) monotherapy, achieved by completely discontinuing Androgen Receptor Pathway Inhibitor (ARPI) treatment (and associated corticosteroids). This de-escalation is initiated only after patients complete a 6-to-7-month run-in phase of standard doublet or triplet therapy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
18-month radiographic progression-free survival (rPFS)	Time from randomization to the earliest of: radiographic progression per PCWG4 on PSMA PET; unequivocal progression on PSMA PET (≥ 2 new lesions or PPP progression); or death from any cause. Patients without an event at 18 months are censored at last assessment.	Assessed from the date of randomization up to 18 months, with routine PSMA PET/CT imaging conducted every 6 months (patients without an event at 18 months are censored at their last assessment)
PSA progression-free survival	Time from randomization to confirmed PSA progression per PCWG4 (≥ 25 % rise and ≥ 2 ng/mL above nadir, confirmed ≥ 3 weeks later), or death	Assessed from the time of randomization until confirmed PSA progression or death, evaluated every 3 months for the first 24 months and every 6 months thereafter, through the total follow-up period (minimum 24 months post-randomization; up to 60 months)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to CRPC	Time from randomization to castration resistance per EAU/PCWG4 definition	Through study completion, an average of 5 years
Overall survival	Time from randomization to death from any cause	Assessed continuously from the date of randomization until death from any cause, with survival follow-up conducted every 6 months until study conclusion (up to approximately 60 months total duration)
PSMA PET complete response	Proportion with sustained PSMA PET complete response per modified PPP/RECIP at 12 and 24 months	From randomization, at 12 and 24 months
Change in Quality of Life Measured by the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30)	Change from baseline in health-related quality of life assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30). The EORTC QLQ-C30 includes a Global Health Status/Quality of Life (GHS/QoL) scale, functional scales, and symptom scales/items. All scales and single items range from 0 to 100. For the Global Health Status and functional scales, a higher score represents a higher/better level of functioning and quality of life. For symptom scales and items, a higher score represents a higher/worse level of symptoms or problems.	Assessed via changes from baseline, measured at screening, at the 6-7 month re-staging/randomization visit, and every 3 months post-randomization for the first 24 months
Incidence of Toxicity	Incidence of grade ≥3 AEs per CTCAE (Common Terminology Criteria for Adverse Events) v5.0	Monitored continuously and evaluated at every scheduled visit (every 3 months during the 6-7 month run-in phase, every 3 months for the first 24 months post-randomization, and every 6 months (up to 60 months)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Biomarker-outcome associations	Baseline and on-treatment PSMA PET metrics	PSMA PET metrics, are assessed at baseline, at the 6-to-7-month re-staging visit, every 6 months post-randomization up to 60 months

Collaborators and Investigators

• Sponsor: Kokilaben Dhirubhai Ambani Hospital and Medical Research Institute

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): September 1, 2029
• Study Completion (Estimated): September 1, 2031

Study Registration Dates

• First Submitted: September 14, 2026
• First Submitted That Met QC Criteria: September 23, 2026
• First Posted (Actual): September 24, 2026

Study Record Updates

• Last Update Posted (Actual): October 7, 2026
• Last Update Submitted That Met QC Criteria: October 4, 2026
• Last Verified: October 1, 2026

More Information

Terms related to this study

• Keywords: Androgen Deprivation Therapy; Prostate-Specific Antigen; Androgen Antagonists; Metastatic Hormone-Sensitive Prostate Cancer; Androgen Receptor Pathway Inhibitors
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Prostatic Diseases; Male Urogenital Diseases; Prostatic Neoplasms; Physiological Effects of Drugs; Hormones, Hormone Substitutes, and Hormone Antagonists; Hormone Antagonists; Pharmacologic Actions; Chemical Actions and Uses; Androgen Antagonists
• Other Study ID Numbers: 040/2026; CTRI/2026/09/117118 (Registry Identifier: Clinical Trials Registry - India)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No