Higher SUV mean in baseline F18-PSMA 1007 PET is associated with longer survival in patients undergoing Radioligand Therapy with [177Lu]Lu-PSMA I&T

Introduction: There is increasing evidence that quantified 68Ga-PSMA PET signal can identify high-risk prostate cancer patients (PC) scheduled for radioligand therapy (RLT). Investigating baseline variables including quantification from [ 18 F]-PSMA PET, we aimed to determine prognosticators for overall survival (OS) for PC patients treated [ 177 Lu]Lu-PSMA I&T.

Methods: In this retrospective study, 96 PC patients treated with [ 177 Lu]Lu-PSMA I&T were analyzed. Whole body tumor burden derived from baseline [ 18 F]-PSMA 1007 PET was quantified, including SUVmean, SUVmax, PSMA tumor volume (PSMA-TV) and total lesion PSMA (TL-PSMA = PSMA-TV*SUVmean). Baseline laboratory values (hemoglobin, C-reactive protein (CRP), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alkaline phosphatase (AP)) were also collected. We performed univariable cox regression analysis, followed by multivariable and Kaplan Meier analyses.

Results: Median OS of was 13 months, while 39 patients died. Univariable analysis provided the following significant parameters: SUV mean , CRP, LDH und hemoglobin. Multivariable cox regression revealed baseline SUV mean (per unit, HR, 0.89, 95% CI 0.81-0.97; P=0.01), CRP (per mg/dl, HR, 1.09, 95% CI 1.001-1.17; P=0.04), LDH (per U/l, HR, 1.002, 95% CI 1.000-1.004; P=0.01) and hemoglobin (per g/dl, HR, 0.74, 95% CI 0.60-0.92; P<0.01) as independent prognosticators for OS. Using a median SUVmean of 9.6, Kaplan Meier analyses revealed significant segregation between individuals with SUV mean below (9 months) or above the median (16 months, HR 1.8, 95% CI 0.95-3.42; P=0.04).

Conclusions: Lower CRP, lower LDH, higher hemoglobin, and higher baseline SUV mean determined from [ 18 F]-PSMA PET were independent predictors of OS in mCRPC patients scheduled for RLT with [177Lu]Lu-PSMA I&T, thereby emphasizing the importance of SUV mean for outcome prediction in PSMA RLT as described in the TheraP trial.