A phase II, open‐label study to assess safety and clinical utility of 68Ga‐THP‐PSMA PET/CT in patients with high‐risk primary prostate cancer or biochemical recurrence after radical treatment

1259 Objectives: The primary objective of the study was to evaluate the impact of a novel, kit-based formulation of 68Ga‐THP‐PSMA positron emission tomography/computed tomography (PET/CT) on the management of patients with prostate cancer (PCa). The secondary objective of the study was to evaluate the safety of 68Ga‐THP-PSMA in patients with PCa.\n Methods: Patients with histopathologically proven prostate cancer with potentially operable, untreated disease, Gleason score \u003e4+3 , or PSA \u003e20 ng/mL or clinical stage \u003eT2c were eligible for Group A. Patients with a first biochemical recurrence and eligible for salvage treatment after radical prostatectomy (Group B) or radical radiotherapy (Group C) were also eligible for the study. Hormone therapy within three months excluded patients from any group. All eligible patients underwent evaluation with PET/CT 60 minutes following administration of 160±30 MBq of 68Ga-THP‐PSMA in a single intravenous bolus. A change in management was reported when the predefined clinical management of the patient altered as a result of scan findings. Safety was assessed by means of physical examination, vital signs, cardiovascular profile, performance status, laboratory evaluations (haematology, biochemistry, urinalysis and PSA), recording of concurrent illness/therapy and Adverse Events (AEs). AEs, regardless of suspected relationship to study treatment, were recorded from 68Ga‐THP‐PSMA administration until 30 days after.\n Results: A total of 49 patients were evaluated in the study; 20 patients in Group A, 21 in Group B and 8 in Group C. The median age of all patients was 67.0 years (range: 43-80 years). Twenty-one patients (42.9%) had a change in management plan as a result of the 68Ga-THP‐PSMA PET/CT scan, 6 patients (30.0%) in Group A and 15 patients (51.7%) in Groups B+C. 68Ga‐THP‐PSMA was well tolerated. No patients experienced Serious Adverse Events (SAEs), discontinued the study due to AEs, or died during the study. Eleven AEs were reported in 5 patients (10.2%), all of which were treatment emergent AEs (TEAEs). Of these, two were attributed to 68Ga-THP-PSMA (pruritis in one patient and intravenous catheter site rash in another). The highest grade TEAEs were Common Terminology Criteria for Adverse Events (CTCAE) Grade 3, experienced by 2 patients. One patient experienced 2 CTCAE Grade 3 TEAEs of syncope and 1 patient experienced a Grade 3 TEAE of palpitations. However, none of the Grade 3 events were considered related to 68Ga‐THP‐PSMA.\n Conclusions: 68Ga‐THP‐PSMA PET/CT had a major clinical impact in patients with prostate cancer. Management plans changed in nearly one third of patients with primary untreated prostate cancer and in over half of patients with biochemical recurrence. These results are comparable with management change figures reported with other types of PSMA PET tracers. 68Ga‐THP‐PSMA was well tolerated. No patients experienced SAEs or discontinued the study due to AEs. These results together with the simple cold kit manufacturing process of 68Ga‐THP‐PSMA are promising for larger scale accessibility and serve as a basis for a multicentre phase III study evaluation.