Registry of Treatment Outcomes of Symptomatic Metastasized Castration Resistant Prostate Cancer Treated With Radium-223

Overview

Radium-223 is the 5th treatment for metastasized castration resistant prostate cancer with a proven overall survival benefit. The improved survival of Radium-223 over placebo was demonstrated in the ALSYMPCA trial, which included a miscellaneous patient population both docetaxel pretreated and non-pretreated. This registry aims to describe non-study patients treated with Radium-223 and prospectively evaluate treatment outcomes of patients with and without docetaxel pretreatment. Analgesic use and patient reported pain scores, efficacy of the subsequent therapy and overall survival will be evaluated. Moreover, clinical and explorative serum and blood biomarkers of Radium-223 efficacy will be explored.

Every year approximately 12,000 men are diagnosed with prostate cancer in the Netherlands and approximately 2,400 die of this disease. When prostate cancer is limited to the prostate, patients can be operated or radiated with a curative intention, however, metastasized disease is incurable. Initially, prostate cancer responds to testosterone at castration level and treatment with androgen receptor signaling inhibitors. However, after an average of 24 months, prostate cancer will reach a castration resistant stage (mCRPC), which is associated with high morbidity and mortality. Since the introduction of Docetaxel in 2004, multiple treatments for mCRPC have become available. All these treatments have a proven beneficial effect on quality of life and all expand life expectancy. An important clinical problem is that approximately 50% of older patients are not able or not willing to receive docetaxel treatment. These patients are also not eligible for treatments of docetaxel refractory disease. Therefore, there is a need for effective treatments with little site effects. In the phase 3, ALSYMPCA study 921 patients were randomized between Rad-223 (Xofigo®) and placebo in a 2:1 distribution1. Patients with symptomatic bone metastases, limited lymph node involvement, adequate bone marrow, kidney and liver functions were included in this trial. Patients were previously treated with docetaxel or could not receive docetaxel, declined docetaxel or docetaxel was not available. At a planned interim analysis after 538 deaths, the primary end point overall survival (OS) was 14.9 months in the Radium-223 treated arm and 11.3 months in the placebo arm (HR 0.70; 95% CI 0.58-0.83). All secondary end points were at the favor of Radium-223 treated patients, including time to first skeletal related event, quality of life and various biochemical end points. However, patient reported pain scores were not collected in the trial. Radium-223 treatment was well tolerated, with the most prominent side effects (all grades) thrombocytopenia 12 and 6%, neutropenia 5 and 1% and diarrhea 25 and 15% in the Radium-223 and placebo arm, respectively. A post-hoc analysis showed an equal efficacy of Radium-223 treatment in docetaxel pre-treated patients as in docetaxel naïve patients. In this registry the investigators aim to evaluate the efficacy of Radium-223 treatment and first subsequent therapy in a non-study population. Various parameters will be collected, including changes in patient reported pain score. Moreover, changes in serum and blood levels of biomarkers of bone metabolism and levels of blood osteoclast precursors in Radium-223 treated patients will be evaluated for their potential to predict treatment outcome.