Abstract
PurposePSMA imaging is frequently used for monitoring of androgen deprivation therapy (ADT) in prostate cancer. In a previous study, [18F]-JK-PSMA-7 exhibited favorable properties for tumor localization after biochemical recurrence. In this retrospective study, we evaluated the performance of [18F]-JK-PSMA-7 under ADT.ProceduresWe examined the performance of [18F]-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 [68Ga]PSMA-11 or [18F]DCFPyL (second cohort). Finally, we compared detection rates between [18F]-JK-PSMA-7, [68Ga]PSMA-11, and [18F]DCFPyL.ResultsIn the first cohort, we detected [18F]-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 × 10−5) 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 × 10−2). In the second cohort (PSA < 2 ng/ml), the detection rate was 79.3 % (46/58) for [68Ga]PSMA-11 or [18F]DCFPyL. Again, the detection rate was significantly higher (p = 1.1 × 10−2) 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 [18F]-JK-PSMA-7 and [68Ga]PSMA-11 or [18F]DCFPyL in patients with PSA levels < 2 ng/ml (p = 0.4295).Conclusion[18F]-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.
Highlights
Several PSMA ligands are available for PET imaging in patients with prostate cancer, including [68Ga]PSMA-11, [18F]DCFPyL, and [18F]PSMA-1007 [1,2,3,4]
We examined 70 prostate patients under continuous androgen deprivation therapy (ADT) with [18F]-JK-PSMA-7 (Table 1)
In agreement with Ceci and colleagues [15], whose best nomogram-derived probability threshold was associated with a sensitivity of 84.7 %, we determined a PSA threshold for which ≥ 85 % of the patients with [18F]-JK-PSMA-7 positive will undergo PET imaging
Summary
Several PSMA ligands are available for PET imaging in patients with prostate cancer, including [68Ga]PSMA-11, [18F]DCFPyL, and [18F]PSMA-1007 [1,2,3,4]. PSMA PET scans are often in high demand for monitoring of patients with relapsed or metastasized prostate cancer. Under continuous androgen deprivation therapy (ADT) in castration-resistant prostate cancer (CRPC) with PSA values of 9 2 ng/ml, Fendler and colleagues reported PSMA positivity in 196/200 patients [9]. These patients had mainly received [68Ga]PSMA-11 (n = 195) while some were examined with [18F]DCFPyL (n = 5). PSMA-specific PET tracers are not negatively affected by ADT once metastases have become castrate resistant
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