PSMA-PET as a way to choose oligometastatic patients for intermittent androgen deprivation: Extended follow-up of a prospective cohort of patients.

e17113 Background: The use of PSMA PET/CT is better established for the staging of high-risk localized and biochemical recurrent prostate cancer; however no clinical trial assessed the importance of PSMA PET/CT in the mHSPC scenario, and the ideal therapeutic approach based on its result is yet unknown. Methods: This is an ambispective cohort of patients with oligorecurrent/oligometastatic (or/om) HSPC treated with fixed-duration ADT + ARPI in association with PSMA PET/CT-guided MDT (+ prostate radiation if de novo M1) from a single institution in Brasilia, Brazil. Descriptive statistics were used for the categorization of population and primary outcome was progression-free survival (PFS) after suspension of systemic therapy (defined as PSA > 0.2 ng/mL for previous prostatectomy or > 2+ nadir if presence of prostate in place). Analysis of testosterone recovery and other clinical and laboratorial factors were also conducted. All patients had confirmation of absence of any PSMA-avid disease before stopping systemic treatment (start of treatment interval). Results: Between 2019 and 2024, 30 patients with or/omHSPC were treated with fixed-duration ADT + ARPI and PSMA PET/CT-guided MDT. Median age of population at treatment start was 64 years-old (range: 47-85), 16 patients presented with de novo oligometastatic HSPC, and distribution across Gleason grades was: grade 1:2, grade 2: 4, grade 3: 10, grade 4: 4, and grade 5: 7 patients. Bone and nodal metastasis were presented by 13 and 25 patients, respectively. Median PSA at treatment start for oligorecurrent PC population was 3.01 ng/mL (range: 0.15-14.74). Median total testosterone level prior to ADT start was 347.5 ng/dL (range: 225-782). Distribution across NHA was: abiraterone/prednisone: 21, enzalutamide: 4, apalutamide: 4, abiraterone > enzalutamide: 1 patient. With a median follow-up of 20 months (95% Cl: 16.3-25.8) after ADT + ARPI suspension and 70% of patients already with testosterone recovery , only 1 patient presented disease progression (after 43 months since testosterone recovery). The follow-up time since testosterone recovery intervals is shown in the table below. Conclusions: The inclusion of novel technologies on the armamentarium of prostate cancer treatment, including molecular imaging methods, radiation techniques and systemic treatments opens the opportunity to offer more effective and safer treatment modalities and also the need to re-evaluate the rule of intermittent treatment in pre-selected patients. The results of this single-center cohort ambispective analysis are promising, and longer follow-up and future prospective trials are awaited. Follow-up time since testosterone recovery, months Patients, n < 6 4 7-12 6 13-18 3 19-24 7 ≥ 25 10