P-268 - Impact of optimal morphologic response on survival in patients with KRAS wild-type unresectable colorectal liver metastases receiving an anti-EGFR o...

Date 04 July 2015
Event WorldGI 2015
Session Posters
Topics Anti-Cancer Agents & Biologic Therapy
Biomarkers
Colon Cancer
Rectal Cancer
Presenter T. Masuishi
Citation Annals of Oncology (2015) 26 (suppl_4): 1-100. 10.1093/annonc/mdv233
Authors T. Masuishi1, H. Taniguchi1, Y. Narita1, A. Komori1, S. Kadowaki1, T. Ura2, K. Muro1, M. Nomura1, M. Andoh1, T. Eto3
  • 1Aichi Cancer Center Hospital, Nagoya/JP
  • 2Aichi Cancer Center, Nagoya/JP
  • 3Tsuchiura Kyodo General Hospital, Tsuchiura/JP

Abstract

Introduction

FOLFIRI or FOLFOX with either bevacizumab (bev) or anti-EGFR therapy are considered as first-line treatment options for patients with KRAS wild-type colorectal liver metastases (CLM). Early tumor shrinkage (ETS) could be useful as a surrogate marker of the survival benefits of anti-EGFR, while the morphologic response (MR) has been reported to be an early prognostic marker in anti-VEGF therapy. However, little is known about the difference in the survival benefit of these agents according to ETS and MR.

Methods

A retrospective review of a prospectively maintained database of patients who underwent palliative chemotherapy at two institutions (2006-2013) was performed. Three radiologists independently reviewed 135 patients with KRAS wild-type unresectable CLM treated with bev- or anti-EGFR-containing regimens as first-line therapy to assess ETS (330% decrease from baseline) and MR according to morphologic criteria (Shindoh J, et al. J Clin Oncol 2012) at the first follow-up CT compared with baseline CT.

Results

The patients' characteristics were as follows: median age: 64 (range: 27-88), ECOG PS 0-1: 93%, liver-limited disease: 35%, bev/anti-EGFR: 62/38%. The median follow-up time was 24.2 months. In the entire population, progression-free survival (PFS) and overall survival rates showed no difference between bev and anti-EGFR (median PFS: 11.4 vs. 11.3 months, respectively). The optimal MR rate was higher with bev than anti-EGFR (40 vs. 12%, respectively), while the ETS rate was slightly lower (48 vs. 59%, respectively). In patients with ETS, median PFS with bev was shorter than with anti-EGFR (11.1 vs. 15.0 months, HR: 1.49). Conversely, in patients without ETS, the optimal MR rate was higher with bev than anti-EGFR (34 vs. 0%, respectively), and median PFS with bev was longer than with anti-EGFR (12.6 vs. 6.3 months, HR: 0.67).

Conclusion

The ETS rate was higher using anti-EGFR, while the optimal morphologic response rate was higher with bev. Patients showing an optimal morphologic response with bev can be expected to obtain long-term PFS, even in the absence of ETS.