New data support the use of radium-223 earlier in the disease course for patients with castration-resistant prostate cancer (CRPC).
In a prospective, single-arm phase 3b study, 708 patients with metastatic CRPC (135 asymptomatic) received radium-223 55 kBq/kg intravenously every 4 weeks for up to 6 cycles. Co-primary endpoints were safety and overall survival.
The findings, published in BMC Cancer, show that overall survival (HR, 0.486), time to disease progression (HR, 0.722) and time to first symptomatic skeletal event (HR, 0.328) were better in asymptomatic than symptomatic patients.
A lower proportion of asymptomatic patients reported treatment-emergent adverse events (TEAEs, 61% vs 79%), grade 3-4 TEAEs (29% vs 40%) and drug-related TEAEs (28% vs 44%). There were 2 treatment-related deaths, both in patients with baseline symptomatic disease.
The authors concluded that using radium-223 earlier in the disease course, when patients are asymptomatic or minimally symptomatic, could lead to improved outcomes.
“Use of radium-223 in this group of 135 asymptomatic patients seems to be safe in the setting of this international early access program,” they said. However, they added that “caution is still warranted in daily clinical practice, as the subgroup size from this study was small, the drug is not approved in this setting, and the final results of prospective studies have to be awaited”.
