E. Yaghoubian1, M. Jelenik2, M. Becker1, K. Bennet1, K. Zia1, F. E. Escorcia3, R. L. Wong1, P. Chablani1, L. Appleman1, A. Saoudi1, S. Huq1, A. C. Olson4, H. Wang5, H. D. Skinner4, and R. B. Patel1; 1UPMC Hillman Cancer Center, Pittsburgh, PA, 2University of Pittsburgh, Pittsburgh, PA, 3Molecular Imaging Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 4Department of Radiation Oncology, UPMC Hillman Cancer Center, Pittsburgh, PA, 5Department of Biostatistics, School of Public Health, University of Pittsburgh, Pittsburgh, PA
Purpose/Objective(s): The VISION study demonstrated an overall survival benefit in patients with metastatic castration-resistant prostate cancer receiving Pluvicto (PRPT) over standard-of-care and led to its FDA approval. A full course of PRPT is given over 6 cycles; however, not all patients complete treatment. Factors influencing treatment completion (TC) are underexplored. Therefore, we examined potential factors impacting a patient’s ability to complete PRPT treatment. Materials/
Methods: A retrospective analysis was conducted on patients who received PRPT at our institution between July 2022 and February 2024. The influence of baseline patient characteristics including age, pre-PRPT PSA, previous therapies, and hematologic lab values including hemoglobin (Hb), white blood cell count (WBC), platelets (PLT), absolute neutrophil count (ANC), absolute lymphocyte count (ALC), neutrophil percentage (NP), and lymphocyte percentage (LP) were analyzed. The association between pretreatment factors and TC were assessed using univariate and multivariate logistic regression analyses (MLRA). Results: 71 patients met inclusion criteria. 32 of 71 (45%) completed all 6 cycles of PRPT. On univariate analysis, Hb, PSA, and NP were associated with PRPT treatment completion. Baseline Hb was found to have the most significant predictive value in determining who would complete treatment. Patients who completed PRPT treatment had a mean baseline Hb of 12.0 compared to a mean Hb of 10.8 in those who discontinued (OR 1.504, 95% CI: 1.106-2.044; p=0.009). Lower pre-treatment PSA was also significantly associated with TC; cut point analysis determined that the best cut point for starting PSA to predict TC was 34 (OR: 0.065, 95% CI: 0.016-0.255; p<0.0001). MLRA revealed that only baseline Hb levels (OR: 1.438, 95% CI: 1.016-2.036; p=0.041) remained associated with TC after adjustment for other clinical variables. Conclusion: Our findings suggest that a higher baseline Hb and PSA cut point of less than or equal to 34 may serve as useful clinical markers for TC in patients undergoing PRPT. Incorporating these parameters into clinical decision-making may help identify patients at higher risk of treatment discontinuation and guide personalized interventions to improve treatment adherence and outcomes in this population.
