PSMA PET/CT to assess the response to Androgen Receptor Pathway Inhibitors (ARPI) treatment
PSMA PET/CT is the current mainstay diagnostic tool to stage prostate cancer, especially valuable if metastatic, and to decide on the right treatment (suitability of radioligand therapy 177Lu-PSMA). The newest study has established that it can also be used to evaluate the effectiveness of the treatment with Androgen Receptor Pathway Inhibitors (ARPIs).
The cited study aimed at analysing PSMA PET/CT for the purposes of assessing the response to treatment with Androgen Receptor Pathway Inhibitors (ARPIs) and predicting Overall Survival (OS) in patients with Metastatic Castration-Resistant Prostate Cancer (mCRPC). The results demonstrate that PSMA PET/CT is indeed a valuable imaging biomarker when performed at 3 months after ARPI treatment initiation.
30 ARPI-treated mCRPC patients who underwent 68Ga-PSMA-11 PET/CT within 8 weeks before and 12 ± 4 weeks after treatment initiation were retrospectively analysed. Based on the total PSMA tumor volume (SUVbased) patients were then categorized as PSMA responders (PSMA-Rs: a complete/partial response or stable disease), or PSMA nonresponders (PSMA-NRs: disease progression). After a median follow-up of slightly over 2 years, the median OS was significantly longer for PSMA-R than PSMA-NR (54 vs. 22 months). Significant correlation was observed between PSMA- and PSA-based responses for the PSA decrease by at least 50%.