Clinical Characteristics Associated with High [⁶⁸Ga]Ga-PSMA-11 Uptake and Preliminary Therapeutic Outcomes in...

Adenoid cystic carcinoma (ACC) is a rare cancer that arises from the salivary glands. Recent studies have shown that prostate-specific membrane antigen (PSMA) expression is high in ACC. We conducted a prospective study to evaluate clinical factors associated with high [⁶⁸Ga]Ga-PSMA-11 uptake and to report preliminary therapeutic outcomes of ¹⁷⁷Lu-PSMA therapy in recurred or metastatic ACC.

Thirty patients were prospectively enrolled. Any focal accumulation of [⁶⁸Ga]Ga-PSMA-11 not explained by physiological uptake was defined as pathological lesions. Clinicopathological features relevant for high [⁶⁸Ga]Ga-PSMA-11 uptake in recurred or metastatic ACC were analyzed. Therapeutic outcomes of patients who received ¹⁷⁷Lu-PSMA therapy under compassionate use were also reviewed as a secondary component.

A total of 238 lesions were evaluated, and the SUV_max ranged between 0.9 and 11.0, showing mild to moderate PSMA uptake. Higher SUV_max was observed in lung and bone metastases. The longest tumor diameter (R = 0.190, P = 0.009) and tumor % growth rate (R = 0.220, P = 0.006) were significantly correlated with SUV_max. A longer duration from diagnosis was a relevant factor for high [⁶⁸Ga]Ga-PSMA-11 uptake. Seven patients received ¹⁷⁷Lu-PSMA therapy, but therapeutic outcomes were limited.

High [⁶⁸Ga]Ga-PSMA-11 uptake in recurred or metastatic ACC was associated with location of metastases, longer tumor diameter, high tumor % growth rate, and a longer duration from diagnosis. While ¹⁷⁷Lu-PSMA therapy was performed in a limited cohort and outcomes were preliminary, these findings provide exploratory insights into potential factors relevant for patient selection and warrant further investigation in larger studies.

The online version contains supplementary material available at 10.1007/s13139-025-00955-9.