Prognostic value of the BIO-Ra Score in metastatic castration-resistant prostate cancer patients treated with Radium-223 after the European Medicines Agency restricted use: secondary investigations of the multicentric BIO-Ra study

The multicentric retrospective BIO-Ra study combined inflammatory indices from peripheralblood and clinical factors in a composite prognostic score for metastatic castration-resistantprostate cancer patients receiving Radium-223 (Ra-223). In the present study, we evaluated (i) theprognostic power of the BIO-Ra score in the framework of the restricted use of Ra-223 promoted bythe European Medicines Agency in 2018; (ii) the treatment completion prediction of the BIO-Ra score.Four hundred ninety-four patients from the BIO-Ra cohort were divided into three risk classes accordingto the BIO-Ra score to predict the treatment completion rate (p < 0.001 among all the three groups).Patients receiving Ra-223 after restriction (89/494) were at later stages of the disease compared withthe pre-restriction cohort (405/494), as a higher percentage of BIO-Ra high-risk classes (46.1% vs.34.6%) and lower median Overall survival (12.4 vs. 23.7 months, p < 0.001) was observed. Despitethis clinically relevant difference, BIO-Ra classes still predicted divergent treatment completion ratesin the post-restriction subgroup (72%, 52.2%, and 46.3% of patients belonging to low-, intermediate-,and high-risk classes, respectively). Although the restricted use has increased patients at higher riskwith unfavourable outcome after Ra-223 treatment, the BIO-Ra score maintains its prognostic value.