ACORN: Observational Study of Bevacizumab in Combination With First-Line Chemotherapy for Treatment of Metastatic Colorectal Cancer in the UK.

Introduction: Survival in metastatic colorectal cancer is worse than expected in the United Kingdom. Real-world data are needed to better understand UK-specific treatment practices that may explain this.

Patients And Methods: The Avastin ColORectal Non-interventional (ACORN) study is a multicenter, prospective, UK-based, observational, phase 4 study (ClinicalTrials.gov, NCT01506167) that recruited patients with metastatic colorectal cancer scheduled to receive bevacizumab in combination with first-line chemotherapy as part of routine clinical practice. Primary end points included progression-free survival, overall survival (OS), serious adverse events (AEs), and grade 3 to 5 bevacizumab-related AEs.

Results: A total of 714 patients were recruited between August 30, 2012, and February 4, 2014. Median follow-up was 16.4 months. Median first-line chemotherapy duration was 5.6 months, with capecitabine/oxaliplatin (265 [37.1%]) being the most common regimen. Median total chemotherapy duration was 8.1 months and did not vary by geographic location in the UK. Median progression-free survival (95% confidence interval) was 8.7 (8.2-9.1) months, and median OS was 17.8 (16.1-19.3) months. There was no significant difference in efficacy by chemotherapy regimen administered. Ninety-nine patients (13.9%) received bevacizumab after disease progression. The safety profile of bevacizumab was consistent with previous studies.

Conclusion: ACORN provided evidence that there were no clear differences observed in outcomes between bevacizumab with capecitabine-based chemotherapy and fluorouracil-based regimens, and confirmed the safety profile of bevacizumab in a real-world UK-based population. The lower-than-expected OS is likely due to the short total chemotherapy duration, less frequent use of bevacizumab after disease progression, and higher rates of in-situ primary tumors.