Real-world patient characteristics associated with survival of 2 years or more after radium-223 treatment for metastatic castration-resistant prostate cancer (EPIX study)

Abstract

Background: The real-world EPIX study was conducted to gather information about the characteristics of patients with metastatic castration-resistant prostate cancer (mCRPC) who survived ≥2 years after treatment with the alpha-emitter radium-223.

Methods: This retrospective study of electronic health records in the US Flatiron database (NCT04516161) included patients with mCRPC treated with radium-223 between January 2013 and June 2019. Median overall survival (OS) and prostate-specific antigen (PSA) response (≥50% reduction) from start of radium-223 treatment were the primary and secondary endpoints, respectively. Patient characteristics were compared between those who survived ≥2 years versus <2 years, including a subgroup who survived <6 months.

Results: In the 1180 patients identified, median OS was 12.9 months (95% CI: 12.1-13.7), and 13% of patients with data at 6 months had a PSA response. The survival groups included 775 patients (65.7%) who survived <2 years (including 264 (22.4%) who survived <6 months) and 185 patients (15.7%) who survived ≥2 years; 220 patients (18.6%) had incomplete follow-up data and were censored. On multivariate analysis, age >75 years, Eastern Cooperative Oncology Group performance status (ECOG PS) 2-4, visceral metastases, prior symptomatic skeletal events (SSEs), and prior chemotherapy were independently prognostic of reduced OS. For patients with survival ≥2 years versus <2 years, median age was 71 versus 75 years, 4% versus 14% had ECOG PS 2-4, 4% versus 10% had visceral metastases, 38% versus 44% had prior SSEs, and 16% versus 32% had prior chemotherapy.

Conclusions: In this study of men with mCRPC treated in real-world clinical practice, median OS was consistent with that seen in the phase 3 ALSYMPCA trial. Patients who survived ≥2 years after the start of radium-223 were younger and had better ECOG PS, lower disease burden, and less use of prior chemotherapy than those who survived <2 years.

Conflict of interest statement

DJG reports grants and/or fees from Acerta Pharma, the American Association for Cancer Research, Astellas, AstraZeneca, Axess Oncology, Bayer, BMS, Calithera, Capio Biosciences, EMD Serono, Exelixis, Flatiron, Ipsen, UroGPO, Janssen, Leidos Biomedical Research, Merck Sharp & Dohme, Michael J Hennessey Associates, Millennium Med Publishing, Modra Pharmaceuticals, Myovant Sciences, NCI, Nektar Therapeutics, Novartis, Pfizer, Physician Education Resource, Sanofi, UroToday, and Vizuri Health Sciences. NA serves as a consultant for Astellas, AstraZeneca, Aveo, Bayer, Bristol Myers Squibb, Calithera, Clovis, Eisai, Eli Lilly, EMD Serono, Exelixis, Foundation Medicine, Genentech, Janssen, Merck, MEI Pharma, Nektar, Novartis, Pfizer, Pharmacyclics, and Seattle Genetics. OS reports grants and/or fees from Advanced Accelerator Applications, Astellas, AstraZeneca, Bayer, Bellicum, Blue Earth Diagnostics, Inc., Bristol Myers Squibb, Celgene, Constellation, Dendreon, EMD Serono, Innocrin, Invitae, Johnson & Johnson, Merck, Myovant, Pfizer, Sanofi, and SOTIO. CNS serves as a consultant for Pfizer, MSD, Merck, AstraZeneca, Astellas, Sanofi-Genzyme, Roche-Genentech, Incyte, Immunomedics (now Gilead), BMS, Janssen, Foundation Medicine, Medscape, and UroToday. BT reports grants and fees from Amgen, Astellas, Bayer, Ferring, Janssen, and Sanofi-Genzyme. FS reports fees from Astellas, AstraZeneca, Bayer, Janssen, Merck, Pfizer, and Sanofi. KM reports fees from Astellas, Bayer, BMS, Ferring, Janssen, MSD, Novartis, Pfizer, and Roche. NC, HG, JR, XJ, PS, and FV are employees of Bayer. CSH reports grants and/or fees from Aptevo, Asana Aragon Pharma, Astellas, AstraZeneca, Bayer, Blue Earth Diagnostics, Churchill Pharma, Clovis, Dendreon, eFFECTOR Therapeutics, Endocyte, Emergent BioSolutions, Ferring, Genentech, Hinova, Hoffman-La Roche, Janssen, Medivation, Myriad, Orion, and Pfizer. NS serves as a consultant/advisor for AbbVie, Bayer, Janssen Scientific Affairs, Dendreon, Tolmar, Ferring, Astellas, Amgen, Pfizer, AstraZeneca, BMS, Myovant Sciences, Merck, Sanofi-Genzyme, Invitae, Myriad, Phosphorous, Sema4, Foundation Medicine, Guardant; serves on speakers’ bureau for Janssen, Bayer, Dendreon.

© 2022. The Author(s).

Figures

Fig. 1. Patient flow diagram.

aPatients with metastatic castration-resistant prostate cancer treated with radium-223 any time between January 2013 and June 2019.

Fig. 2. Overall survival.

Kaplan–Meier estimate; full-analysis set.