Is Eligibility Enough? Pretreatment Prediction of Failure to Reach a Second Cycle of [177Lu]Lu-PSMA Radioligand Therapy

Background/Objectives: Current guidelines define no absolute contraindication to prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT), yet some patients receive only a single cycle. We aimed to characterize this single-cycle attrition (SCA) and derive an exploratory pretreatment risk score predicting it.

Methods

Seventy consecutive patients with metastatic castration-resistant prostate cancer treated with [177Lu]Lu-PSMA RLT at one center (2022–2025) were reviewed; 58 were assessable. SCA was defined as permanent non-initiation of a second cycle. The analyses employed false-discovery-rate-adjusted nonparametric comparisons, receiver operating characteristic (ROC), Kaplan–Meier and univariable Cox methods, with optimism-corrected bootstrap internal validation.