Introduction: The Observatory of Cancer was created in 2003 by the Regional Health Agency in Western France (Bretagne and Pays de la Loire). It collects data from almost 50 public hospitals and private institutions. Successive EMA approvals have been given for cetuximab: determining wild type RAS status (exons 2, 3 and 4 of KRAS and NRAS) is now mandatory prior to its initiation. Influence of RAS status on the efficacy and safety of cetuximab in metastatic colorectal cancer patients have been analyzed.
Methods: Data from 2 studies were collected. The first one was Erbitux Ouest with patients of 70 years and over who received cetuximab from April 2004 to December 2006 (115 patients – KRAS unknown). The 2nd was composed of wild-type KRAS patients receiving cetuximab from September 2007 to November 2011 (70 patients) for which NRAS was defined retrospectively.
Results: The second population was composed of more men than the first (76 % vs 57%) and more elderly (≥ 75 years old: 59% vs 39%). The average number of cures was 8.6 in the second population vs 7.8. In the first population, cetuximab was in association with irinotecan (87%) or folfiri (13%). In the second population, it was most various: almost folfiri (57%), irinotecan (21%), folfox (16%). Objective Response Rate has increased over time: for the first population, 19% and for the second 43% which could be explained by KRAS wild-type selection. Medical decision of treatment stop increased (18% vs 30%) and treatment arrest due to death decreased (6% vs 3%). There were more toxicities of grade III-IV in the second population (33% vs 18%). It might be due to increasing age (≥75 years old: 65% vs 48%) or increasing number of associations (such as folfox or folfiri). The median time between the first cure and date of death was, for the first population, 339 days [7;1510] and the second population 405 days [14;1643]. The survival rates (PFS and OS) will be shown during the meeting.
Conclusion: The use of cetuximab has varied over time in terms of association and selection. It was increasingly proposed to aged population. With the determination of RAS status, the use of cetuximab has been optimized leading to best treatment response including in elderly subjects and best management of toxicity.