IPCU 2017

Changes in alkaline phosphatase (ALP) dynamics and overall survival (OS) in metastatic castration-resistant prostate cancer (mCRPC) patients treated with radium-223.

Identifying a reliable marker of efficacy for radium-223 dichloride (Ra-223) would aid in the clinical management of mCRPC patients (pts).

In exploratory analyses of mCRPC pts with bone metastases treated with Ra-223 in the ALSYMPCA trial, OS was significantly longer in patients with a confirmed decline in ALP levels from baseline at week 12, compared with pts without a confirmed ALP decline. Here, we present data on ALP dynamics and OS and time to first symptomatic skeletal events (SSE) in pts treated with Ra-223 in an international EAP.

This was a prospective single-arm phase IIIb study of CRPC patients with symptomatic or asymptomatic bone metastases (no visceral disease) recruited from 14 countries. Patients received Ra-223 50 kBq/kg (55 kBq/kg after NIST update) iv, every 4 weeks for up to 6 cycles. Co-primary endpoints were safety and OS. Exploratory analyses investigated whether a confirmed decline (any magnitude) in ALP levels was associated with OS and time to first SSE.

696 ppatients received at least one Ra-223 cycle. Of those, 398 (57%) patients had a confirmed decline in ALP and 298 (43%) had no confirmed ALP decline. Key baseline characteristics are shown in the poster. More patients with a confirmed ALP decline (374, 94%) received 5–6 Ra-223 injections than those with no ALP decline (99, 33%). Hazard ratios (HR) for confirmed ALP decline at week 12 vs no decline suggest a strong association of ALP decline with both longer OS (HR 0.299, 95% CI 0.227–0.395) and longer time to first SSE (HR 0.474, 95% CI 0.340–0.662) (Poster).

In this early access program (EAP), which is relevant for patients currently treated in clinical practice, decline in ALP was associated with longer OS and time to the first SSE.

Neal Shore, Carolina Urologic Research Center, Myrtle Beach, SC, USA; Daniel Heinrich Akershus University Hospital, Lørenskog, Norway; Silke Gillessen, Kantonsspital St Gallen, St Gallen, Switzerland; Axel Heidenreich, University Hospital, University Hospital Cologne, Germany; Daniel Kejzman, Meir Medical Center, Kfar-Saba, Israel; Joe M. O’Sullivan, The Centre for Cancer Research and Cell Biology, Belfast, Northern Ireland; Joan Carles Vall d’ Hebron University Hospital, Vall d’Hebron Institute of Oncology, Barcelona, Spain; Manfred Wirth, University Hospital Carl-Gustav Carus, Dresden, Germany; Kurt Miller, Charité University Medicine Berlin, Berlin, Germany; Giuseppe Procopio, Fondazione IRCCS - Istituto Nazionale dei Tumori - S.C. Medicina Oncologica 1, Milan, Italy; Monica Seger-Van Tol, Pharmaceutical Division of Bayer, Whippany, New Jersey, USA; Sten Nilsson, Karolinska University Hospital, Stockholm, Sweden; Fred Saad, University of Montreal Hospital Centers, Montreal, Canada

E02227717 BHC US AbstractPosters01 Dec16 v01025x