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

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 (SUV_max) <26.8 was 4 months versus 6.5 months for patients with PSMA SUV_max ≥26.8 (P=.117). The median PFS of patients with FDG SUV_max <11.4 was 9 months versus 4 months for patients with FDG SUV_max ≥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.