Dual PSMA/FDG-PET/CT Versus PSMA-Only Analysis in Patients With mCRPC

By Emily Menendez - Last Updated: July 5, 2023

The VISION trial examined the health-related quality of life of patients with metastatic castration-resistant prostate cancer (mCRPC) who were treated with 177Lu-PSMA-617 (Pluvicto) plus standard of care.

Researchers from the All India Institute of Medical Sciences sought to assess the eligibility status of patients with mCRPC for Pluvicto by comparing dual 68Ga-PSMA-11 and 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) scans with scans obtained during the VISION trial. The tumor heterogeneity of prostate-specific membrane antigen (PSMA)/FDG was also evaluated as a potential predictor of the efficacy of Pluvicto radioligand therapy (RLT).

A group of 25 patients with mCRPC who were referred for Pluvicto underwent both 68Ga-PSMA-11 and FDG-PET/CT scans within 2 to 4 weeks. The eligibility status for PSMA RLT was based on VISION trial criteria and the interpretation of dual tracer PET/CT. Patients with any discordant PSMA-negative/FDG-positive lesions were deemed ineligible for RLT. A total of 21 (84%) patients were eligible for PSMA RLT, while 4 (16%) patients were deemed ineligible. The primary end point was progression-free survival (PFS), where a P value less than .05 was considered significant.

In eligible patients who underwent PSMA RLT, both PET/CT scans were assessed for visual and quantitative heterogeneity parameters. Of the 17 patients who underwent RLT, 9 had “PSMA>FDG” disease and 8 had “PSMA≤FDG” disease. The median PFS of patients with “PSMA>FDG” disease was 9 months versus 4 months for patients with “PSMA≤FDG” disease (P=.034).

The median PFS of patients with PSMA maximum standardized uptake value (SUVmax) <26.8 was 4 months versus 6.5 months for patients with PSMA SUVmax ≥26.8 (P=.117). The median PFS of patients with FDG SUVmax <11.4 was 9 months versus 4 months for patients with FDG SUVmax ≥11.4 (P=.115).

Researchers concluded that dual tracer PSMA/FDG-PET/CT does not provide more information than PSMA-only analysis when assessing a patient’s suitability for undergoing PSMA RLT. However, visually assessed tumor heterogeneity on dual tracer PET/CT scans may serve as a predictor of outcomes following RLT.