Characteristics and Treatment Patterns for Non-Metastatic Castration Resistant Prostate Cancer Patients in Japan

Abstract

Background: The recent approval of second-generation androgen receptor inhibitors (ARis, eg, abiraterone, enzalutamide) is anticipated to change the non-metastatic castration resistant prostate cancer (nmCRPC) treatment landscape. Herein, we describe patient (pt) and physician characteristics and historical treatment patterns as a baseline to an evolving nmCRPC treatment landscape in Japan. Methods: Descriptive analyses were conducted using 2015-2017 Ipsos Global Oncology Monitor Database. Results: 1,114 nmCRPC pts (median age: 80 years; median BMI: 23.1 Kg/m2; ECOG score≤ 1: 88.8%) were included. Almost all (98.7%) pts were treated by urologists, 40.8% were stage III at initial diagnosis, and 54.5% had Gleason score between 8-10. The two most common hormone sensitive treatments which pts received preceding CRPC diagnosis were bicalutamide/leuprolide combination (42.4%) and bicalutamide/ goserelin combination (16.7%). The two most commonly prescribed treatments by 1st, 2nd, and 3rd nmCRPC regimen (R) were: 1R, bicalutamide/leuprolide combination (14.4%) and leuprolide (12.7%); 2R, bicalutamide/leuprolide combination (9.4%) and flutamide/leuprolide combination (7.7%); 3R, flutamide/leuprolide combination (8.4%) and estramustine/leuprolide combination (5.5%). The proportion of pts receiving abiraterone and enzalutamide were relatively low: 66 (5.9%) and 249 (22.4%) overall; 25 (2.2%) and 120 (10.8%) in 1R; 24 (4.1%) and 79 (13.5%) in 2R; and 17 (6.2%) and 52 (19.0%) in 3R. Most common treatment discontinuation reasons were treatment resistance, progression, and side effects. Conclusions: These data represent real-world treatment patterns in nmCRPC and may be reflective of a reticence to introduce pharmacotherapy in a largely asymptomatic disease. Future studies should evaluate utilization patterns after more experience with second generation ARis has accumulated and explore any putative relationship between tolerable pharmacotherapy and extent of utilization.