AUTHOR=Kurreck Annika , Heinemann Volker , Fischer von Weikersthal Ludwig , Decker Thomas , Kaiser Florian , Uhlig Jens , Schenk Michael , Freiberg-Richter Jens , Peuser Bettina , Denzlinger Claudio , Graeven Ullrich , Heinrich Kathrin , Held Swantje , Stahler Arndt , Alig Annabel Helga Sophie , Jelas Ivan , von Einem Jobst C. , Stintzing Sebastian , Giessen-Jung Clemens , Modest Dominik P. TITLE=Response and Disease Dynamics in Untreated Metastatic Colorectal Cancer With Bevacizumab-Based Sequential vs. Combination Chemotherapy—Analysis of the Phase 3 XELAVIRI Trial JOURNAL=Frontiers in Oncology VOLUME=12 YEAR=2022 URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2022.751453 DOI=10.3389/fonc.2022.751453 ISSN=2234-943X ABSTRACT=Introduction

Early tumor shrinkage (ETS), depth of response (DpR), and time to DpR represent exploratory endpoints that may serve as early efficacy parameters and predictors of long-term outcome in metastatic colorectal cancer (mCRC). We analyzed these endpoints in mCRC patients treated with first-line bevacizumab-based sequential (initial fluoropyrimidines) versus combination (initial fluoropyrimidines plus irinotecan) chemotherapy within the phase 3 XELAVIRI trial.

Methods

DpR (change from baseline to smallest tumor diameter), ETS (≥20% reduction in tumor diameter at first reassessment), and time to DpR (study randomization to DpR image) were analyzed. We evaluated progression-free survival and overall survival with ETS as stratification parameter according to treatment arm, molecular subgroup, and sex.

Results

In 370 patients analyzed, a higher rate of ETS (60.9% vs. 43.5%; p = 0.001) and significantly greater DpR (-40.0% vs. -24.7%; p < 0.001) were observed in the initial combination therapy arm. The improvement was pronounced in RAS/BRAF wild-type tumors. ETS correlated with improved survival irrespective of treatment arm (PFS: p < 0.001; OS: p = 0.012) and molecular subgroup (PFS: p < 0.001; OS: p < 0.001). Male patients in contrast to female patients with ETS had survival benefit (PFS: p < 0.001, HR 0.532; OS: p < 0.001, HR 0.574 vs. PFS: p = 0.107; OS: p = 0.965).

Conclusions

Initial irinotecan-based combination therapy with bevacizumab improved ETS and DpR in mCRC patients with a particularly high irinotecan sensitivity of RAS/BRAF wild-type tumors. ETS seems to be a suitable prognostic marker for fluoropyrimidine- and bevacizumab-based combinations in mCRC. This finding was rather driven by male patients, potentially indicating that ETS might be less predictive of long-term outcome in an elderly, female population.