Diagnostic performance of [18F]PSMA-1007 PET/CT on hepatocellular carcinoma: a prospective clinical study

Ziel/Aim: A high expression of prostate-specific membrane antigen (PSMA) is not limited to prostate cancer but can be found on other tumor entities, such as hepatocellular carcinoma (HCC), and could possibly be used for theranostic purposes. Our aim was to investigate the diagnostic potential of the hepatobiliary excreted radiotracer [¹⁸F]PSMA-1007 on initial staging of HCC.

Methodik/Methods: This prospective clinical study (NCT05547919) included 10 patients (9 men, 1 women) with treatment-naïve, histopathological proven HCC (BCLC stage A: n=3; B: n=5; C: n=2). All patients underwent [¹⁸F]PSMA-1007 positron emission tomography (PET) with an unenhanced low-dose computed tomography (CT). All scans were analyzed visually and quantitatively. We assessed SUVmax of the primary tumor and SUVmean of non-affected liver parenchyma and calculated tumor-to-background-ratios (= SUVmax HCC/SUVmean liver, TBR) for each patient. In addition, we assessed possible eligibility for PSMA radioligand therapy (RLT) according to PROMISE criteria. Presence of local lymph node and distant metastases was noted for [¹⁸F]PSMA-1007 PET/CT and compared to the results of contrast-enhanced CT of the trunk and magnetic resonance imaging of the upper abdomen.

Ergebnisse/Results: [¹⁸F]PSMA-1007 PET showed a high tracer uptake in 7 of 10 patients (PROMISE Score 2: n=4; PROMISE Score 3: n=3), a mediocre or missing tracer uptake was found in 3 patients (PROMISE Score 0: n=1; PROMISE Score 1: n=2). Mean TBR was 4.0±4.5 (range 0.5 – 17.0 in all 10 patients; range 2.3 – 17.0 in 7 patients with high tracer uptake; range 0.5 – 1.2 in 3 patients with low tracer uptake). [¹⁸F]PSMA-1007 PET did not reveal new distant metastatic lesions compared to contrast enhanced CT. In one patient local lymph node metastases were considered PSMA-negative despite a high tracer uptake in the primary tumor.

Schlussfolgerungen/Conclusions: [¹⁸F]PSMA-1007 can be used for depiction of untreated HCC and shows a 4 times higher uptake relative to background, indicative for excellent image contrast. As a novel image biomarker, the herein observed discrepant findings relative to conventional imaging suggest a complementary role of PSMA PET, e.g., for outcome prediction. Last, high tracer accumulation in 70% of the patients suggests a possible use for PSMA RLT in an end-stage setting.