TAT-10: Changes to Alkaline Phosphatase Dynamics and Overall Survival in Metastatic Castration-Resistant Prostate Cancer Patients Treated with Radium-223 in an International Early Access Program

Kanazawa, Japan (UroToday.com) Identifying a reliable marker that is highly correlated with improved overall survival and reduced adverse events for Ra223 treatment would greatly aid the clinical management of metastatic castration-resistant prostate cancer (mCRPC) patients. Bone alkaline phosphate (ALP) is a marker for osteoblasts in bone tissue.

Previous studies (the ALSYMPCA trial) had shown significantly longer overall survival (OS) in patients with a confirmed ALP decline from baseline at week 12 compared to those with no ALP decline. This study continues the study of a correlation with ALP decline with improved outcomes in an international early access program (EAP).

696 patients were recruited from 14 countries. Treatment consisted of 55 kBq/kg administered by IV every 4 weeks for up to 6 cycles. 398 patients (57%) showed confirmed ALP decline compared to 298 (43%) with no decline. Those patients with ALP decline were more likely to complete the full treatment of 5-6 Ra223. To test the positive correlation of ALP decline with OS and time to first symptomatic skeletal events (SSE), a hazard ratio (HR) was calculated from Cox proportional hazards model. The result showed both longer OS (HR of .229) and longer time to first SSE (HR of .474) for patients with ALP decline.

Presented By: Joe M. O’Sullivan from The Center for Cancer Research and Cell Biology, Queen’s University, Belfast, and the Northern Ireland Cancer Center, Belfast, Northern Ireland

Written By: William Carithers, Lawrence Berkeley National Laboratory

at the 10th International Symposium on Targeted Alpha Therapy (TAT-10)  May 31 - June 1, 2017 - Kanazawa, Japan.