A randomised phase II trial of three dosing regimens of radium-223 in patients with bone metastatic castration-resistant prostate cancer

C. N. Sternberg, F. Saad, J. N. Graff, A. Peer, U. N. Vaishampayan, E. Leung, E. Rosenbaum, H. Gurney, R. J. Epstein, I. D. Davis, B. Wu, L. Trandafir, V. J. Wagner, M. Hussain

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Abstract

Background: Radium-223 prolongs overall survival and delays symptomatic skeletal events (SSEs) in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases. The approved radium-223 regimen is 55 kBq/kg every 4 weeks (q4w) for six cycles (standard dose). We investigated different radium-223 regimens in patients with mCRPC. Patients and methods: Patients were randomised 1: 1: 1 to radium-223 standard-dose, high-dose (88 kBq/kg q4w for six cycles) or extended-schedule arms (55 kBq/kg q4w for 12 cycles). The primary end point, SSE-free survival (SSE-FS), was compared in patients treated with a high- versus standard-dose regimen, or with a standard dose in an extended (>6 to 12 cycles) versus standard schedule (six cycles). Results: A total of 391 patients were randomised; baseline characteristics were balanced between arms. On-treatment SSEs developed in 37/130 (28%), 42/130 (32%) and 48/131 (37%) patients in the standard-dose, high-dose and extended-schedule arms, respectively. There was no statistically significant difference in SSE-FS in the high- versus standard-dose arms [median 12.9 months versus 12.3 months; hazard ratio (HR) 1.06, 80% confidence interval (CI) 0.88–1.27, P = 0.70], and in the extended- versus standard-schedule arms (median 10.8 months versus 13.2 months; HR 1.26, 80% CI 0.94–1.69, P = 0.31). Overall survival in the three treatment arms was similar. As many as 370 (95%) patients received treatment (median of six cycles) in each arm. Grade ≥3 treatment-emergent adverse events (TEAEs) affected 34% of patients in the standard-dose, 48% in the high-dose and 53% in the extended-schedule arm, causing permanent discontinuation in 9%, 16% and 17% of patients, respectively. Conclusion: Radium-223 high-dose or extended-schedule regimens resulted in no change in SSE-FS or other efficacy end points and were associated with more grade ≥3 TEAEs. The extended-schedule regimen (beyond six doses) could not be implemented in a large proportion of patients due to disease progression. Therefore, the standard-dose schedule remains one of the standard therapies for patients with symptomatic mCRPC. Trial Registration: ClinicalTrials.gov NCT02023697.

Original languageEnglish
Pages (from-to)257-265
Number of pages9
JournalAnnals of Oncology
Volume31
Issue number2
DOIs
Publication statusPublished - Feb 2020

Keywords

  • bone metastases
  • mCRPC
  • radium-223 dose
  • safety
  • symptomatic skeletal events

Cite this

Sternberg, C. N., Saad, F., Graff, J. N., Peer, A., Vaishampayan, U. N., Leung, E., Rosenbaum, E., Gurney, H., Epstein, R. J., Davis, I. D., Wu, B., Trandafir, L., Wagner, V. J., & Hussain, M. (2020). A randomised phase II trial of three dosing regimens of radium-223 in patients with bone metastatic castration-resistant prostate cancer. Annals of Oncology, 31(2), 257-265. https://doi.org/10.1016/j.annonc.2019.10.025