Predictive Factors for Metastatic Castration-Resistant Prostate Cancer (mCRPC) Patients Undergoing 177Lu-PSMA-617 Radioligand Treatment.

Objective: To determine prognostic factors in patients with metastatic castration-resistant prostate cancer (mCRPC) undergoing 177Lutetium-Prostate-specific membrane Antigen-617 radioligand therapy (177Lu-PSMA RLT).

Study design: Descriptive, analytical study. Place and Duration of the Study: Department of Medical Oncology and Nuclear Medicine, Balikesir Ataturk City Hospital, Balikesir, Turkiye, from 2021 to 2024.

Methodology: The study retrospectively examined patients diagnosed with metastatic castration-resistant prostate cancer (mCRPC) and received 177Lu-PSMA RLT. Data were collected from electronic health records of the hospital, including patient characteristics, clinical and pathological details, and blood test outcomes. Pre-treatment blood markers were documented, including platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), albumin-to-alkaline phosphatase ratio (AAPR), prognostic nutritional index (PNI), haemoglobin, albumin, lymphocyte and platelet (HALP) scores, and the systemic ımmune-ınflammation index (SII). Treatment-related adverse events were recorded, and their associations with other factors were assessed using Spearman's correlation analysis. Survival analysis was conducted using the Kaplan-Meier method, and group comparisons were performed using the log-rank test. Univariate and multivariate Cox regression analyses were conducted to identify factors affecting survival.

Results: This study included 31 patients with median age of 69 (57-80) years. Twenty-three (74.2%) patients undergoing 177Lu-PSMA RLT experienced at least one adverse event, while seven (22.6%) experienced serious adverse events. The presence of visceral metastasis (p = 0.023), fatigue (p = 0.032), anorexia (p = 0.048), and nephropathy (p = 0.001) were significantly associated with poor overall survival (OS). In a multivariate model, visceral metastasis (HR = 24.10; 95% CI: 1.26-461.47; p = 0.035), fatigue (HR = 6.17; 95% CI: 1.65-23.02; p = 0.007), and nephropathy (HR = 10.14; 95% CI: 2.52-40.87; p = 0.001) remained significant prognostic factors. Patients with visceral metastases (OS 20.79 months; 95% CI: 16.77-24.81; p = 0.001), anorexia (OS 15.57 months; 95% CI: 7.17-23.97; p = 0.036), fatigue (OS of 13.32 months; 95% CI: 5.39-21.25; p = 0.023), and nephropathy (OS of 14.96 months; 95% CI: 6.22-15.13; p <0.001), showed significant association with survival.

Conclusion: Adverse events during 177Lu-PSMA RLT had independent prognostic factors for survival.

Key words: Metastatic castration-resistant prostate cancer, Lutetium, Radioligand therapy.