[F]-JK-PSMA-7 PET/CT Under Androgen Deprivation Therapy in Advanced Prostate Cancer.

Purpose: PSMA imaging is frequently used for monitoring of androgen deprivation therapy (ADT) in prostate cancer. In a previous study, [F]-JK-PSMA-7 exhibited favorable properties for tumor localization after biochemical recurrence. In this retrospective study, we evaluated the performance of [F]-JK-PSMA-7 under ADT.

Procedures: We examined the performance of [F]-JK-PSMA-7 in 70 patients (first cohort) with increasing or detectable PSA values under ADT (PSA < 2 ng/ml for 21/70 patients). We further analyzed 58 independent patients with PSA levels < 2 ng/ml under ADT, who were imaged with [Ga]PSMA-11 or [F]DCFPyL (second cohort). Finally, we compared detection rates between [F]-JK-PSMA-7, [Ga]PSMA-11, and [F]DCFPyL.

Results: In the first cohort, we detected [F]-JK-PSMA-7-positive lesions in 63/70 patients. In patients with PSA levels ≥ 2 ng/ml, the detection rate was 100 % (49/49). In patients with PSA < 2 ng/ml, the detection rate was significantly lower (66.7 %, 14/21, p = 9.7 × 10) and dropped from 85.7 % (12/14, PSA levels between 0.3 and 2.0 ng/ml) to 28.6 % (2/7) for PSA levels < 0.3 ng/ml (p = 1.73 × 10). In the second cohort (PSA < 2 ng/ml), the detection rate was 79.3 % (46/58) for [Ga]PSMA-11 or [F]DCFPyL. Again, the detection rate was significantly higher (p = 1.1 × 10) for patients with PSA levels between 0.3 and 2.0 ng/ml (87.0 %, 40/46) relative to those with PSA levels < 0.3 ng/ml (50 %, 6/12). No significant difference was found between [F]-JK-PSMA-7 and [Ga]PSMA-11 or [F]DCFPyL in patients with PSA levels < 2 ng/ml (p = 0.4295).

Conclusion: [F]-JK-PSMA-7 PET showed a high detection rate in patients with PSA levels ≥ 0.3 ng/ml under ADT. The lower PSA threshold of 0.3 ng/ml for high detection rates was consistent across the three PSMA ligands. Thus, PSMA imaging is suitable for clinical follow-up of patients with increasing PSA levels under ADT.