Baseline hematological parameters and outcomes in patients with prostate cancer treated with Lu-177 PSMA radioligand therapy (RLT): A multicenter real-world analysis.

Abstract

e17047 Background: Patients (Pts) with Prostate Cancer (PC) receiving RLT are at risk of developing cytopenias that can cause dose holds or early treatment discontinuation. However, the prognostic significance of baseline hematologic parameters, including hemoglobin (HGB), absolute lymphocyte count (ALC), platelet count (PLT) and absolute neutrophil count (ANC), remain poorly understood. Methods: We identified and retrospectively reviewed the electronic medical record of pts with metastatic castrate resistant prostate cancer (mCRPC) who received ≥1 cycle of RLT and had completed therapy at one of two academic institutions (Stanford University and Oregon Health & Science University) between 3/2019-9/2024. Clinical data, including baseline hematologic parameters, were collected. Associations between baseline hematological parameters and outcomes were statistically analyzed utilizing using Mann-Whitney U; time from first treatment to progression, next line of therapy, and overall survival (OS) were modelled using the Kaplan-Meier method and log rank. Results: A total of 180 patients were included, median age at diagnosis was 65 years. 76% identified as non-Hispanic White, median ECOG performance status was 1, median number of prior lines of therapy was 5 and median number of RLT cycles was 4. The median baseline values for hematologic parameters prior to initiation of RLT were HGB 12 g/dL, ALC 1100 cells/µL, PLT 219 platelets/ul, and ANC 4200 cells/µL. Overall, the median time from the first RLT dose to progression, time to next treatment, and overall survival was 7, 9, and 12 months, respectively. When hematological parameters were stratified by PSA50 and PSA 90 thresholds, no significant difference was observed. Stratification of patients by absolute neutrophil count (ANC) into three groups, low (<2500 cells/μL), normal (2500–6500 cells/μL), and high (>6500 cells/μL) revealed median overall survival times of 18 months, 14 months, and 10 months, respectively. Using the normal ANC group (2500–6500/μL) as the reference, the hazard ratio (HR) for patients with low ANC was 0.85 (95% CI 0.45–1.60, p=0.61), while patients with high ANC had a significantly increased risk of death, with an HR of 1.70 (95% CI 1.14–2.53, p=0.01). HGB < 10 g/dL was associated with a reduced OS (14.7 vs. 7.6 months; HR 2.04, 95% CI 1.32–3.13, p = 0.001). Neither PLT < 150 platelets/μL nor ALC < 1100 cells/μL were associated with OS. Conclusions: In a multicenter, real-world analysis, HGB and ANC identified as significant prognostic markers for OS with RLT treatment. Limitations include limited sample size and power and retrospective design with potential confounding. Further study is warranted to validate these findings in larger, prospective cohorts and to investigate the underlying mechanisms linking baseline hematologic parameters with clinical outcomes. Number of patients (N) Median Overall Survival (Months) Hazard Ratio (95% CI, p value) ANC <2500 cells/μL 16 18.8 0.85 (0.45–1.60, p=0.61) 2500–6500 cells/μL 121 14 reference >6500 cells/μL 43 10.4 1.7 (1.14–2.53, p=0.01) HGB <10 g/dL 32 7.6 2.04 (1.32–3.13, p=0.001) ≥10 g/dL 148 14.7 PLT <150 platelets/μL 23 12.0 0.95 (0.55-1.63, p= 0.86) ≥150 platelets/μL 157 12.2 ALC <1100 cells/μL 90 12.1 1.05 (0.74-1.5, p=0.79) ≥1100 cells/μL 90 12.0