Pre- or post-chemotherapy: effect on PSMA uptake

radiographic progression-free survival [8,9].There are two additional ongoing Phase 3 studies evaluating the benefit of PSMA RLT prior to chemotherapy: SPLASH (NCT04647526) and ECLIPSE (NCT05204927).Elevated PSMA expression has been correlated with improved response to PSMA RLT [10].Conversely, patients exhibiting low PSMA expression or discordant metastases generally demonstrate suboptimal responses [11].The change in PSMA expression with different therapies may impact the timing when one would prefer to use PSMA RLT.It is unknown how taxane-based chemotherapy impacts PSMA expression, and therefore it is not clear in what setting PSMA expression is highest.In this study, we aimed to measure the impact of taxane-based chemotherapy on PSMA uptake. Materials and methods Study populationWe conducted a retrospective study of all patients imaged before and after a minimum of two cycles of taxane-based chemotherapy (including cabazitaxel/ docetaxel alone or with platinum based chemotherapy) at our institution between June 2021 and Apr 2024, who had a pre-chemotherapy PSMA PET performed within six months prior to the first cycle and post-chemotherapy PET before initiation of subsequent therapy.Patients who were administered ARPIs simultaneously or with a history of prior taxane based therapy in a mCRPC setting were excluded from the study.