Can PSMA-PET be a better way to select patients for an intermittent treatment? Results from a prospective cohort.

e17073 Background: The current strategy for advanced disease is continuous androgen suppression, but new technologies such as PSMA-PET may set a rule for identifying some patients for new strategies. The addition of novel hormone agent (NHA) to systemic treatment of metastatic hormone sensitive prostate cancer (HSPC) has been associated with overall survival benefit and metastasis directed therapy (MDT) has been demonstrated benefit postponing ADT. There is an increasing volume of data on the use of fixed-duration NHA for patients with recurrent HSPC, most of whom are expected to present oligometastatic disease if PSMA PET/CT scans are used. We evaluate clinical outcomes of intermittent androgen deprivation therapy in patients with oligorecurrent or oligometastatic HSPC (or/omHSPC)treated with ADT + NHA + MDT, based on PSMA-PET imaging. Methods: This is a prospective cohort of patients with or/omHSPC treated with fixed-duration ADT + NHA in association with PSMA PET/CT-guided MDT (+ primary tumor irradiation if de novo metastatic) from a single institution in Brazil. Descriptive statistics was used in order to characterize the study population and relapse-free survival (RFS) after systemic therapy discontinuation (defined as PSA > 0.2 ng/mL for previous prostatectomy or > 2+nadir if presence of primary tumor in place) was assessed. Analysis of testosterone recovery and other clinic laboratorial factors were also performed. All patients had an undetectable level of PSA and a PSMA-PET with a complete response to be elegible to the intermittent treatment. Results: Between 2019 and 2023, 20 patients with or/omHSPC were treated with fixed-duration ADT + NHA and PSMA PET/CT-guided MDT. The median age was 64 years-old (range: 47-85), 11 patients presented with de novo omHSPC, and distribution across Gleason grades was: grade 1: 2, grade 2: 3, grade 3: 9, grade 4: 3, and grade 5: 2 patients. Metastasis were diagnosed on bone (7) and/or lymph nodes (19). Median PSA at treatment start for orHSPC population was 3.01 ng/mL (range: 0.15-14.74). The median total testosterone level prior to ADT start was 327 ng/dL (range: 22-494). Distribution across NHA was: abiraterone/prednisone: 13, enzalutamide: 4, apalutamide: 2, abiraterone>enzalutamide: 1 patient. With a median follow-up of 13 months after ADT + NHA discontinuation, no patient has progressed, with 54.5% of patients already presenting testosterone recovery. Conclusions: The results of this single-center prospective cohort incorporating PET-PSMA for inclusion and monitoring patients with oligometastatic and oligorecurrent disease suggests that intermittent androgen blockage is promising in the era of NHA.