Four-timepoint PET scans with three tracers to map differences between prostate cancer metastases

Four-Timepoint Multi-tracer PET Imaging to Characterize Metastatic prOstate Cancer Heterogeneity

This will test whether repeating PET scans with three different tracers can map active, treatment‑resistant versus treatment‑sensitive metastases in men with metastatic castration‑resistant prostate cancer who have at least three metastases.

Quick facts

• Phase: NA
• Study type: Interventional
• Enrollment: 45 (estimated)
• Ages: 18 Years and up
• Sex: Male
• Sponsor: CHU de Quebec-Universite Laval (other)
• Drugs / interventions: chemotherapy, radiation
• Locations: 1 site (Québec, Quebec)
• Trial ID: NCT07302763 on ClinicalTrials.gov

What this trial studies

This open-label, single-arm imaging study will enroll 45 participants with metastatic castration‑resistant prostate cancer and at least three metastatic lesions. Participants will receive multi-tracer PET/CT imaging with 18F‑FDG, a PSMA tracer (68Ga or 18F chosen at the first PSMA scan and kept for consistency), and 68Ga‑DOTATATE at multiple timepoints to quantify lesion-level phenotypes and monitor changes over time. Required reference imaging includes conventional bone scan or 18F‑Na PET/CT plus CT/MRI (or 18F‑FDG‑PET/CT), and scans will be compared across visits to characterize intra-patient heterogeneity and phenotypic plasticity. The trial is planned at up to four Canadian sites, led by CHU de Québec‑Université Laval, with sequential competitive enrollment.

Who should consider this trial

Good fit: Men (assigned male at birth) aged 18 or older with histologically confirmed prostate adenocarcinoma who have castration‑resistant disease after an androgen‑receptor pathway inhibitor and at least three metastatic lesions on conventional imaging, and who are eligible for taxane chemotherapy or PSMA radioligand therapy.

Not a fit: Patients with fewer than three metastatic lesions, non‑adenocarcinoma prostate cancers, those not meeting CRPC criteria, or individuals unable to undergo PET/CT imaging are unlikely to benefit from this imaging protocol.

Why it matters

Potential benefit: If successful, the approach could let doctors identify which metastases are active or resistant and guide more personalized treatment choices without invasive biopsies.

How similar studies have performed: Prior PET studies using PSMA and FDG have demonstrated lesion‑level heterogeneity in metastatic prostate cancer, but the combined multi‑tracer, multi‑timepoint approach including DOTATATE is relatively novel and not yet proven.

Eligibility criteria

Inclusion Criteria:

1. Assign male at birth, any gender ≥ 18 years old;
2. Histologically or cytologically proven adenocarcinoma of the prostate;
3. Metastatic disease documented by at least 3 metastatic active lesions\*, \*\* on whole body bone scan and/or measurable soft tissue on CT-scan (lymph nodes and visceral lesions);
4. CRPC \& post-androgen receptor pathway inhibitor (ARPI) defined by progression under continuous castration (measured serum testosterone ≤50 ng/dL \[1.73 nM\]) AND an ARPI (darolutamide, apalutamide, enzalutamide or abiraterone acetate);
5. Eligible for taxane chemotherapy or PSMA-radioligand therapy (before imaging); 6-Able and willing to provide signed informed consent and to comply with protocol requirements.

   * Metastatic lesions on imaging are defined either: ≥ 10 mm on CT scan or caliper (for lymph nodes, see below), ≥ 20 mm on chest X-ray, lymph node ≥ 10 mm or having grown by ≥ 5 mm from baseline CT, any metastasis described on bone scan counts as a lesion. Of note: A bone lesion that has been treated by radiation is excluded from the lesions counted in the criterion of ≥ 3 lesions.

     * The reference imaging (scan with 3 metastases) confirming eligibility must be done either: 1) after biochemical progression on treatment OR 2) ≥ 90 days after last treatment has begun if imaging was performed while patient was still responding (to avoid disappearance of metastasis due to response).

Exclusion Criteria:

* 1\. Another non-cutaneous malignancy or melanoma diagnosed in the past 5 years; 2. Currently under a randomized controlled trial with unknown allocation; 3-Any disease or condition limiting the patient's capacity to execute the study procedures, based on the investigators' opinion;

Where this trial is running

Québec, Quebec

• CHU de Québec-Université Laval — Québec, Quebec, Canada (RECRUITING)

Study contacts

• Principal investigator: Frédéric Pouliot, MD, PhD — CHU de Québec-Université Laval
• Study coordinator: Marie-Christine Dubé, PhD

Conditions: mCRPC, oncology, molecular imaging tracers