De-adoption of epidermal growth factor receptor (EGFR) inhibitors following recommendations for KRAS testing to guide treatment of metastatic colorectal cancer (mCRC).

Abstract

191 Background: KRAS mutation status is a predictive biomarker for resistance to EGFR antibodies among mCRC pts, and is recommended for use by ASCO and the FDA. Little is known about the uptake of clinical recommendations in oncology practice. We sought to study the effect of ASCO and FDA guidelines on the use of EGFR antibodies among a commercially insured population. Methods: The LifeLink Health Plan Claims Database (formerly the PharMetrics Patient-Centric Database) was used to create a cohort of >18 yo mCRC pts treated between 2004-2010. We identified treatment and diagnosis using ICD-9 or HCPCS (J) codes. We defined 1st-line therapy as any chemotherapy +/- bevacizumab given after the pt had a claim for mCRC, excluding pts treated with EGFR antibodies in the 1st line. 2nd-line therapy was defined as the initiation of a new chemotherapy agent (irinotecan/oxaliplatin) +/- EGFR antibody. We examined pts in two-month time intervals and calculated the fraction of pts in each interval who received EGFR antibody at any point beyond their 1st-line treatment. Chi 2 tests were used to compare treatment rates at the time points shown in the Table. Results: 5,099 pts received 2nd-line therapy of which 2,603 pts received an EGFR antibody. Median age was 61 years, with 57% males. 59% received an EGFR antibody as a single agent. The remainder received this in combination with one or more of the following agents: fluorouracil 13.5%, irinotecan 36.7%, oxaliplatin 3.9%, and bevacizumab 6.1%. Rates of EGFR antibody use are outlined in the Table. Conclusions: The utilization of EGFR antibodies for mCRC treatment decreased following the presentation of clinical trial data, publication of ASCO guidelines and FDA label change. These data suggest that oncologists respond rapidly to new evidence and professional guidelines, and readily accept the use of predictive biomarkers in clinical practice. [Table: see text]