Radium-223 Can Be ‘Integrated into Treatment Sequencing’ in Metastatic CRPC

Results from the REASSURE study (NCT02141438) analyzing radium-223 in patients with metastatic castration-resistant prostate cancer was safe and effective, and did not hinder subsequent treatments.

Results from the REASSURE study (NCT02141438) analyzing radium-223 in patients with metastatic castration-resistant prostate cancer was safe and effective, and did not hinder subsequent treatments.

Findings from the study, which were presented at the 2023 American Society of Clinical Oncology (ASCO) ASCO Annual Meeting, demonstrated that most patients completed five to six injections of radium-223 and no new safety signals were observed. In addition, treatment with radium-223 resulted in overall survival (OS) of approximately 18 months in patients with metastatic castration-resistant prostate cancer.

“Our observations in this study show that radium-223 can be integrated into the treatment sequence for patients with (metastatic castration-resistant prostate cancer),” Daniel Y. Song, MD, co-director of the prostate cancer multidisciplinary clinic and professor of radiation oncology and molecular radiation sciences at Johns Hopkins Sidney Kimmel Comprehensive Cancer Center in Baltimore, said during the poster presentation.

In this analysis, researchers focused on patients with confirmed metastatic castration-resistant prostate cancer from the United States who were scheduled to receive treatment with radium-223.

Researchers primarily focused on short- and long-term safety including second primary malignancies and the incidence of bone marrow suppression. In addition, researchers also monitored for patient-reported pain.

Researchers included 498 patients, with a median age of 74 years in this analysis who were enrolled in the REASSURE study from 2014 to 2017.

In the analysis, 81% of patients had bone metastases only. Between 5 and 6 injections of radium-223 were received by 69% of patients.

Most patients — 77% — received at least 1 prior life-prolonging therapy such as enzalutamide (Xtandi; 48%), abiraterone (Zytiga; 45%), cabazitaxel (6%), docetaxel (25%) or sipuleucel-T Provenge (Provenge; 24%).

Researchers noted that some patients in this analysis received concomitant enzalutamide (31%) and concomitant bone health agents (47%). Thirty-one percent of patients received at least 1 life-prolonging therapy after treatment with radium-223.

Song noted that 37% of patients had received prior chemotherapy and 16% of patients who did not receive prior chemotherapy required either therapeutic or preventive treatments for bone marrow suppression.

More than half of the patients (58%) in this analysis who reported pain at the start of the study experienced a clinically meaningful pain response during treatment.

Any-grade drug-related treatment-emergent adverse effects (AEs) occurred in 32% of patients, whereas AEs considered severe or worse were observed in 10% of patients. Four percent of patients discontinued treatment with radium-223 as a result of drug-related treatment-emergent AEs.

Treatment-emergent serious AEs occurred in 21% of patients, and drug-related serious AEs were observed in 6% of patients. The most common any-grade drug-related treatment-emergent AEs, which occurred in 5% or more patients, were fatigue (9%), diarrhea (10%), nausea (7%), and anemia (8%). Song noted in the presentation that these “were [AEs] which were known and previously established to be an inherent risk for radium-223.”

Four percent of patients had fractures and 2% developed bone disorders. Eleven patients had second primary malignancies were observed in 10 patients (2%).

During follow-up, 60% of patients died, and the median OS was 17.8 months.

Reference

Song DY, George S, Zimberg S. et al. Real-world safety and effectiveness of radium-223 (223Ra) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) treated in the US: The non-interventional REASSURE study. J Clin Oncol. 2023; 41:5050.