Prospective Evaluation of 68Ga-PSMA PET-CT for Recurrence Detection of Prostate Cancer and Its Impact on Patient Management

Single arm, phase II exploratory trial to prospectively evaluate the impact of 68Ga-PSMA-PET/CT on the therapeutic management of patients with biological recurrent prostate cancer and negative, equivocal or oligometastatic disease after routine imaging diagnostic work-up.

68Ga-PSMA-ligand PET-CT is a recently developed molecular imaging technique. It is based on the prostate specific membrane antigen (PSMA), a transmembrane protein with a large extracellular domain which is over-expressed on prostate cancer cells surface. Initial experiments used a ligand to the extracellular epitope of PSMA and labelled it with the isotope 68Ga, a positron emitter (68Ga-PSMA-HBED-CC) 5.

Recently published data based on more than 300 patients show recurrence detection rates and tumour to background ratios higher than choline PET-CT, even at low Prostate Specific Antigen (PSA) levels (sensitivity of 70% in PSA\<2ng/ml) 6,7. False-positive PSMA findings are not yet reported.

The therapeutic management of biochemical recurrence in prostate cancer depends on the localisation and the extent of the recurrent disease.

In this study, the hypothesis is that 68Ga-PSMA-ligand PET-CT, through its high diagnostic accuracy has a significant impact on the therapeutic management of patients with biochemical recurrence.

Primary objective:

To prospectively evaluate the impact of PSMA-PET/CT on the therapeutic management of patients with biological recurrent prostate cancer and negative, equivocal or oligometastatic disease after routine imaging diagnostic work-up.

The treatment management decision will be recorded at the urologic tumor board (UTB) before and after the PSMA-PET/CT result. Rate of decision change will be calculated.

Secondary objective(s)

1. To compare detection rates of PSMA PET/CT and Routine Imaging Workup
2. To search for a predictor of a positive PET scan
3. To assess diagnostic value of PSMA-PET/CT
4. To assess PSA response after targeted treatment for oligometastatic disease.
5. To evaluate the delay to start of Androgen Deprivation Therapy (ADT) from the UTB decision.
6. To evaluate the time to PSA progression.

Eligibility Criteria:
Inclusion Criteria:

* Age ≥ 18 years old.
* Histologically-proven prostate adenocarcinoma.
* Biochemical recurrence (BCR) after local treatment with radical curative intent based on PSA values 1:

  * Following Radical Prostatectomy +/- Radiotherapy: a serum PSA increase confirmed by a second PSA measurement higher than the first one with a value of 0.2 ng/mL or more within minimum of one week.
  * Following primary Radiotherapy: PSA value of 2 ng/ml above the nadir.
  * A continued rise in PSA level despite treatment with curative intent.
* Patients with negative, inconclusive or oligometastatic disease on the Routine Imaging Workup and susceptible to be treated with curative radical intent (salvage treatment).

  * Routing Imaging Workup exams are accepted when performed within 1 month before PSMA-PET/CT (this includes WB-MRI, prostatic/pelvic MRI, and/or Bone Scintigraphy).
* Patient treatment strategy based on routine diagnostic work-up needs to be recorded after discussion at the Urologic Tumor Board and available before the PSMA PET/CT.
* ECOG performance status ≤ 2
* Signed informed consent prior to any study related procedure.

Exclusion Criteria:

* Previous malignancy other than Prostate Cancer (except basocellular or squamous cell skin cancer).
* Patients treated with palliative chemotherapy or new hormonal therapies like Abiraterone/Enzalutamide.
* PSA rise while on active treatment (LHRH-agonist, LHRH-antagonist, anti-androgen, maximal androgen blockade, oestrogen). A minimal time window of 1 month is required.
* Medical castration with Testosterone \< 50 ng/dl (1.7 nmol/L).
* Metastatic patients before inclusion not considered for targeted therapy.
* Previous treatment with isotopes (Radium, Samarium, Strontium, etc.)
* All medical conditions that might interfere with the correct performance of imaging scans.
* Known allergy/sensitivity to 68Ga or HBED-CC coupled substance, or any of the ingredient(s) or excipient(s) of the study medication(s)