Abstract
18F-Fluciclovine-based positron emission tomography (PET) imaging is recommended in the USA for biochemical recurrence (BCR) after prostate cancer treatment. However, prostate-specific membrane antigen (PSMA)-based PET imaging is more common worldwide, supported by international guidelines, and is now approved by the Food and Drug Administration in the USA for initial staging of primary prostate cancer. Little is known about the molecular profiles of lesions detected by PSMA-targeted PET/computed tomography (CT) versus 18F-fluciclovine PET/CT. We examined the expression of PSMA (FOLH1) and the fluciclovine transporter genes LAT1–4 and ASCT1/2 in a combined cohort of more than 18 000 radical prostatectomy specimens and their associations with clinical outcomes. Expression of PSMA and all but one fluciclovine transporter gene was higher in prostate cancer than in benign tissue. PSMA expression was associated with Gleason score (GS) ≥8 and lymph node involvement (LNI), and had a positive linear correlation with Decipher risk score. By contrast, expression of the fluciclovine transporters LAT2, LAT3, and ASCT2 was negatively associated with GS ≥ 8, LNI, and high Decipher score. The top decile of PSMA expression was associated with poorest metastasis-free survival (MFS), while the bottom deciles of LAT3 and ASCT2 expression were associated with poorest MFS.
We measured the expression of genes that encode the targets for two different radiotracers in PET (positron emission tomography) scans of the prostate. We found that PSMA gene expression (PSMA-based tracer) is associated with worse clinical outcomes, while expression of ASCT2, LAT2, and LAT3 genes (fluciclovine tracer) is associated with better outcomes.
In this study we characterize the expression of proteins associated with positron emission tomography tracer targets in the radical prostatectomy cohort of transcriptomic profiles to date. Expression of prostate-specific membrane antigen and fluciclovine transporter genes is correlated with variable clinical outcomes and molecular subtypes, which may reflect differences in the underlying tumor biology.
