Association of morphologic response with progression free survival in patients with metastatic colorectal cancer treated with bevacizumab-based chemotherapy: HGCSG0802.

Abstract

743 Background: It was reported that an optimal morphologic response to preoperative chemotherapy was associated with better overall survival (OS) in patients (pts) with colorectal liver metastases (CLM). We investigated association of morphologic response with progression free survival (PFS) in pts with unresectable CLM from HGCSG0802 observational cohort study in pts with mCRC treated with first-line bevacizumab (BV)-based chemotherapy. Methods: The objective of HGCSG0802 was to evaluate PFS, OS, time to treatment failure (TTF), response rate (RR), safety, etc. The key eligibility criteria were evaluable lesions, older than 20 years old, ECOG PS 0-2. Pts with CLM underwent contrast-enhanced CT at the start and every 8-weeks of BV-based chemotherapy. In this analysis, three blinded, independent radiologists evaluated images for morphologic response, based on metastases changing from heterogeneous masses with ill-defined margins into homogeneous hypoattenuating lesions with sharp borders. Association of morphologic response and pts characteristics, RR, and PFS were evaluated. PFS was analyzed with Kaplan-Meier method, log-rank test, and Cox proportional hazards model. Results: Of 108 pts (the full analysis set), 73 pts with CLM were evaluable for morphologic criteria. Eighteen pts (24.7%) had optimal morphologic response (OR), 31 (42.5%) had incomplete (IR), and 24 (32.9%) had no response (NR). The pts characteristics between those with OR, IR and NR were generally balanced. The median TTF was 7.2 months in NR versus 7.2 months in IR versus 6.8 months in OR (HR (OR/NR) = 0.91, HR (OR/IR) = 0.90; p = 0.93). RR was 77.8% in OR versus 64.5% in IR and 58.3% in NR (p = 0.528). The median PFS was 8.3 months in NR versus 8.5 months in IR versus 9.1 months in OR (HR (OR/NR) = 0.72, HR (OR/IR) = 1.04; p = 0.420). Conclusions: In this analysis, morphologic response might not be a prognostic marker in first-line BV-based chemotherapy in pts with CLM.