Phase 3 prognostic analysis of the automated bone scan index (aBSI) in men with bone-metastatic castration-resistant prostate cancer (CRPC).
Armstrong, AJ; Edenbrandt, L; Bondesson, E; Anand, A; Nordle, O; Carducci, MA; Morris, MJ
Published in: Journal of Clinical Oncology
5006 Background: Quantitative measures of metastatic bone disease are needed in men with mCRPC. We recently demonstrated the validity/reproducibility of a computational approach to bone scan imaging that employs artificial intelligence called the automated BSI (aBSI), which quantifies the percent of skeletal mass involved by cancer. We aimed to extend the prognostic validation of aBSI in a multinational prospective phase 3 clinical study of men with bone-metastatic CRPC. Methods: Whole-body bone scans were acquired at screening in a placebo-controlled phase 3 trial of men with mCRPC and bone metastases and treated with tasquinimod/placebo (n = 1,245). The prospective aBSI biomarker analysis plan was locked in Sept 2014 prior to treatment unblinding. All scans generated at 241 trial sites in 37 countries were assessed for image quality and analyzed using the EXINI bone v.2 software and were blindly associated with outcomes. Baseline aBSI was evaluated for its independent prognostic association with overall survival (OS), radiographic progression-free survival (rPFS), and symptomatic skeletal related events (SSEs). Results: The aBSI-population (721 pts) was representative of the entire trial population based on patient characteristics at screening and OS outcomes. Median aBSI was 1.07 (SE 0.05). The aBSI-population was divided into quartiles (n = 180-181) with aBSI-levels of 0 - 0.3 (Q1); > 0.3 - 1.1 (Q2); > 1.1 - 4.0 (Q3); and > 4.0 (Q4) and median OS ranging from 35 months (Q1) to 13 mo (Q4) (p < 0.0001). Baseline aBSI was significantly associated with OS (HR 1.2 per doubling of BSI; p < 0.0001) and remained independently associated with OS after adjustment for treatment, PSA, CRP, LDH and albumin. Baseline aBSI was also strongly associated with rPFS (p = 0.0005), time to symptomatic progression (p < 0.0001), and time to SSE (p = 0.001). Conclusions: This analysis represents the first phase 3 evaluation of aBSI as a clinically validated prognostic biomarker for OS, rPFS, and SSEs in men with bone-metastatic CRPC, providing independent prognostic information over commonly measured clinical characteristics. Clinical trial information: NCT01234311.