785P - Early Neutropenia is Associated with Survival in Men with Metastatic Castration-Resistant Prostate Cancer (Mcrpc) When Treated with Cabazitaxel: an Analysis of Tropic Phase III Trial

Abstract

ABSTRACT Aim: In TROPIC trial cabazitaxel (CBZ) plus prednisone (P) showed a significant overall survival (OS) benefit versus mitoxantrone plus P in mCRPC patients progressing during or after docetaxel. The most common adverse event in this trial was grade ≥ 3 neutropenia (82%). In this post-hoc analysis of TROPIC, we analysed the influence of chemotherapy-induced neutropenia on OS. Methods: The lowest neutrophil count (ANC) was collected during the first cycle in 371 patients treated with CBZ. The influence of the lowest absolute neutrophil count (ANC) as a continuous variable after cycle 1 was evaluated in a Cox proportional-hazard survival model, adjusted for performance status, pain and measurable disease at baseline. Results: A low ANC during cycle 1, good performance status and absence of pain were associated with a significantly greater OS (Table 1). Median OS was 14.3 months (95% CI 12.9, 16.7) in pts. with Grad 0-2 Neutropenia and 15.4 months (95% CI 14.3, 17.9) in pts. with Grade 3-4 neutropenia. Variable HR 95% CI P value Lowest neutrophil count by Day 8 * 1.13 [1.02-1.26] 0.022 ECOG perfomance status (0-1 vs 2) 2.75 [1.72-4.41] Pain (No vs Yes) 2.07 [1.53-2.80] Measurable disease (No vs Yes) 1.15 [0.87-153] 0.324 * continuous variable - 67 missing values Conclusions: CBZ associated neutropenia needs to be managed carefully to avoid complications leading to treatment delay or discontinuation. Our results suggest that a low ANC during cycle 1 may be associated with an OS benefit. These data deserve confirmation in prospective studies. Source of funding: Sanofi. Disclosure: O. Sartor: Investigator and Consultant for sanofi; F. Stenner-Liewen: The author has received honoraria from Sanofi for advisory boards. All other authors have declared no conflicts of interest.