Radium-223 helps delay radiographic progression in metastatic prostate cancer
Click Here to Manage Email Alerts
The addition of six cycles of radium-223 to first-line enzalutamide extended radiographic PFS for men with metastatic castration-resistant prostate cancer, according to results of a randomized phase 3 trial.
The combination also significantly extended OS, findings of an interim analysis presented at ESMO Congress showed.
A phase 2 trial showed the combination of radium-223 and enzalutamide (Xtandi; Astellas Pharma, Pfizer) reduced serum bone metabolism markers vs. enzalutamide alone for men with metastatic castration-resistant prostate cancer. The regimen also appeared safe.
Silke Gillessen, MD, medical oncologist at Università della Svizzera italiana in Switzerland, and colleagues conducted the multicenter, open-label PEACE III trial to confirm whether the addition of radium-223 to enzalutamide delayed disease progression.
The analysis included 446 men (median age, 70 years; interquartile range, 65-76) with metastatic castration-resistant prostate cancer with at least two bone metastases, with or without additional lymph node metastases. Trial protocol excluded men with visceral metastases.
As of March 2019, all patients also received zoledronic acid or denosumab.
Researchers randomly assigned men 1:1 to 160 mg enzalutamide daily alone or in combination with radium-223 dosed at 55 kBq/kg via IV monthly for 6 months.
Radiologic PFS served as the primary endpoint. OS, time to pain progression, time to subsequent systemic anti-neoplastic therapy and time to first symptomatic skeletal event served as secondary endpoints.
Median follow-up was 42.2 months.
The majority (87.9%) of men assigned radium-223 completed all six cycles.
Results showed significantly longer radiographic PFS among men assigned radium-223 (19.4 months vs. 16.4 months; HR = 0.69; 95% CI, 0.54-0.87).
A preplanned interim analysis — performed after 80% of events — showed the combination also improved OS (median, 42.3 months vs. 35 months; HR = 0.69; 95% CI, 0.52-0.9).
The study will continue to a final OS analysis “because of nonproportionality,” Gillessen and colleagues wrote.
Nearly all men in both cohorts experienced treatment-emergent adverse events (100% for combination vs. 96.4% for enzalutamide alone). A higher percentage of men assigned radium-223 with enzalutamide experienced grade 3 or higher treatment-emergent adverse events (65.6% vs. 55.8%).
The most common grade 3 or higher treatment-related adverse events among men assigned the combination included hypertension (34%), fatigue (6%), neutropenia (5%) and anemia (5%).
Collapse
Gillessen S, et al. Abstract LBA1. Presented at: European Society for Medical Oncology Congress; Sept. 13-17, 2024; Barcelona, Spain.
Read more about
Click Here to Manage Email Alerts