864P - External validation of a prognostic score in first-line metastastic castration-resistant prostate cancer (mCRPC)

Abstract

BackgroundDue to improved outcome in mCRPC, most prognostic models may not reflect the current treatment landscape. Recently, Armstrong et al (Ann Oncol 2018) published a prognostic model based on the phase III PREVAIL trial. MethodsWe applied the Armstrong prognostic model to patients (pts) treated in the COU-AA-302 trial. Variables included in the model: albumin, ALP, Hb, LDH, NLR, number of bone metastases, pain, pattern of spread, PSA, time from diagnosis. Pts were categorized into low (<=3), intermediate (4-6) or high (7-10 risk factors) risk. A continuous score was calculated. Association with overall survival (OS), radiographic progression-free survival (rPFS) and time to PSA progression (TTPSAP) was calculated with Cox-regression models, with Kaplan Meier estimates for median values. C-indices were used to assess the performance of the continuous risk score. Results918 pts (84,4%) had data on all variables. Risk score (continuous) was associated with OS (HR 2.19; p<0.001) with a c-index of 0.68 (se=0.011). 483 (52.6%), 403 (43.9%) and 32 (3.5%) pts were classified as low-, intermediate- and high-risk. OS was longer in low- than in intermediate- (HR: 0.4; p<0.001) and high-risk (HR: 0.24; p<0.001) pts. rPFS was prolonged in low risk versus intermediate (HR: 0.57; p<0.001) and high-risk (HR: 0.41; p<0.001) pts. TTPSAP was also improved in low-risk vs intermediate (HR: 0.6; p<0.001) and high-risk (HR: 0.41; p<0.001) pts. The association of risk group with OS, rPFS and TTPSAP was independent of treatment arm (Table). KM estimates of median (95%CI) OS, rPFS and TTPSAP.Table864PTableOSrPFSTTPSAPLow41.7m (38.7-46.8)16.4m (13.8-19.1)11.1m (8.3-11.2)Intermediate24.6m (23.1-26.8)8.3m (8-11)5.6m (5.5-8.2)High16.7m (11.7-30.2)3.9m (3.6-4.1)5.3m (3.7-8.3) ConclusionsThe Armstrong model is valid for mCRPC pts treated with first-line abiraterone. Less pts with high-risk features were included in COU-AA-302 than PREVAIL. These results may improve individual prognostic estimation and patient stratification in clinical trials. Study carried out under YODA Project #2018-3813. Clinical trial identificationNCT00887198. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureD. Lorente: Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Sanofi; Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Janssen; Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Astellas; Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Bayer. All other authors have declared no conflicts of interest.