PSMA-ligand uptake in posttherapeutic 177Lu-PSMA scintigraphy to assess response in patients with mCRPC

Ziel/Aim The aim of this retrospective study was to evaluate the value of posttherapeutic whole-body-scintigraphy as prognostic marker of overall survival (OS) and PSA progression-free survival (PSA PFS) in patients with metastatic castration resistant prostate cancer (mCRPC) receving (PSMA)-targeted radioligand therapy (RLT).

Methodik/Methods Posttherapeutic whole-body scintigraphy of 301 mCRPC patients at the time of 1st and 2nd Cycle (CY) of 177Lu-PSMA were evaluated by one nuclear medicine physician. PSMA-ligand uptake was stratified in either high or low PSMA-ligand uptake (> or ≤ salivary gland uptake) at the time of 1st cycle. In patients with bone metastases, the extent of infiltration of the appendicular skeleton was measured. Its difference between the 1st and 2nd posttherapeutic scan was subgrouped into response (>5mm decrease), stable disease (±5mm) and progression (>5mm increase). Statistical analysis included the Kaplan-Meier method.

Ergebnisse/Results Median OS was 13,8 months (mo), median PSA PFS was 16 weeks (we). High and low PSMA-ligand uptake was observed in 202/301 (67,1%) and 97/301 (32,2%) patients, respectively. Patients with high PSMA-ligand uptake had a significantly longer PSA PFS (median PSA PFS, 24,57 vs. 9 we; HR 0,32, 95% CI, 0,23-0,45, p < 0,05). OS was not significantly different between both groups (median OS 14,8 vs. 11,7 mo; HR 0,84, 95% CI, 0,59-1,18, p = 0,31). 186/301 (61,8%) patients presented with metastases in appendicular skeleton. Differences between infiltration extent indicated response, stable disease and progression in 45, 66 and 75 patients, respectively. Both OS (median OS, 15,9 vs. 10,5 vs. 7,5 mo; global p < 0,05) and PSA PFS (median PSA PFS 32,4 vs. 16 vs. 9 we; global p < 0,05) correlated significantly.

Schlussfolgerungen/Conclusions This preliminary analysis indicates that despite high PSMA-ligand uptake in posttherapeutic 177Lu-PSMA scintigraphy is associated with longer PSA PFS, in contrast to PPRT it is not correlated with longer OS. However, intratherapeutic changes of the infiltration of the appendicular skeleton hold promise serving as potential new prognostic imaging biomarker for PSA PFS and OS.

Publication History

Article published online:
08 April 2021