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.

Real-world effectiveness, long-term safety and treatment pathway integration of radium-223 therapy in patients with metastatic castration-resistant prostate cancer

“…A number of clinical parameters have been associated with patient survival. In terms of patient demographics, age was found to be a predictor of OS ( 28 ), with an age of > 75 years being associated with reduced OS ( 63 ). Moreover, in an analysis of US electronic heath records of mainly Caucasian patients (73.5%), other race (Asian, Hispanic, Latino, or other) was associated with improved survival ( 63 ).…”

“…In terms of patient demographics, age was found to be a predictor of OS ( 28 ), with an age of > 75 years being associated with reduced OS ( 63 ). Moreover, in an analysis of US electronic heath records of mainly Caucasian patients (73.5%), other race (Asian, Hispanic, Latino, or other) was associated with improved survival ( 63 ). With regard to disease characteristics, visceral metastases ( 63 ) and prior SSEs ( 63 ) reduced OS, whereas bone-only metastases were associated with longer OS ( 41 ).…”

“…Moreover, in an analysis of US electronic heath records of mainly Caucasian patients (73.5%), other race (Asian, Hispanic, Latino, or other) was associated with improved survival ( 63 ). With regard to disease characteristics, visceral metastases ( 63 ) and prior SSEs ( 63 ) reduced OS, whereas bone-only metastases were associated with longer OS ( 41 ). Eastern Cooperative Oncology Group performance status (ECOG PS) was also prognostic of OS ( 59 , 62 ), with ECOG PS 2–3 ( 61 ) and ECOG PS 2–4 ( 63 ) associated with worse OS and ECOG PS 0–1 associated with increased OS ( 60 ).…”

“…With regard to disease characteristics, visceral metastases ( 63 ) and prior SSEs ( 63 ) reduced OS, whereas bone-only metastases were associated with longer OS ( 41 ). Eastern Cooperative Oncology Group performance status (ECOG PS) was also prognostic of OS ( 59 , 62 ), with ECOG PS 2–3 ( 61 ) and ECOG PS 2–4 ( 63 ) associated with worse OS and ECOG PS 0–1 associated with increased OS ( 60 ). Another clinical parameter prognostic of OS was number of prior systemic therapies ( 62 ).…”

“…Another clinical parameter prognostic of OS was number of prior systemic therapies ( 62 ). Prior chemotherapy use reduced OS ( 63 ), whereas no prior use of docetaxel increased OS ( 60 ). As discussed in section “2.1 Treatment completion,” the number of completed cycles of 223 Ra (5–6 vs. 1–4) was also a predictor of OS ( 28 ).…”