Presenter: Axel Grothey, MD, Director, GI Cancer Research, West Cancer Center and Research Institute
Co-Authors: Scott Kopetz, MD Anderson Cancer Center, Houston, TX; Rona Yaeger, Memorial Sloan Kettering Cancer Center, New York, NY; Eric VanCutsem, University Hospital Gasthuisberg and University of Leuven, Leuven, Belgium; Harpreet Wasan, Hammersmith Hospital, Division of Cancer, Imperial College London, London, UK; Jayesh Desai, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia; Fortunato Ciardiello, University of Campania Luigi Vanvitelli, Naples, Italy; Takayuki Yoshino, National Cancer Center Hospital East, Kashiwa, Japan; Kati Maharry, Pfizer, New York, NY; Janna Christy-Bittel, Pfizer, New York, NY (retired); Ashwin Gollerkeri, Pfizer, New York, NY; Josep Tabernero, Vall d’Hebron University Hospital and Vall d’Hebron Institute of Oncology, UVic-UCC, Barcelona, Spain
Background: In the BEACON CRC study (NCT02928224), encorafenib plus cetuximab, with or without binimetinib, improved overall survival (OS) and response rate versus control (irinotecan or FOLFIRI, plus cetuximab) in patients with metastatic colorectal cancer (CRC) and BRAF V600E mutation with disease progression after 1 or 2 regimens.1 Elevations in carcinoembryonic antigen (CEA) and carbohydrate antigen (CA)19-9 are linked to poorer prognosis in CRC.
Objective: To explore the relationships between CEA, CA19-9, and clinical outcomes in the BEACON CRC study.
Methods: Patients were randomized to encorafenib, binimetinib, and cetuximab (EBC; N = 224), to encorafenib plus cetuximab (EC; N = 220), or to a control group (N = 221). Blood samples for CEA and CA19-9 were taken at baseline, at day 1 of subsequent cycles, and at the end of treatment. The study assessed the associations between baseline CEA and CA19-9 levels and clinical outcomes, and the change in CEA and CA19-9 levels from baseline to cycle 2 and clinical outcomes.
Results: Tertile (T) cutoffs for baseline CEA levels were T1, ≤8 µg/L; T2, >8 µg/L to ≤66 µg/L; and T3, >66 µg/L. The median OS varied by baseline CEA tertile: T1, 17.8 months; T2, 9.5 months; and T3, 7.2 months in the EBC arm; T1, 17.7 months; T2, 9.0 months; and T3, 6.1 months in the EC arm; T1, 9.5 months; T2, 4.8 months; and T3, 4.8 months in the control arm. In the experimental arms, CEA reductions were seen at cycle 2 for patients with T2 and T3 baseline CEA (EBC T2: 56% improved [shifted to lower tertile group], 32% stayed the same [remained in same tertile group], none worsened [shifted to higher tertile group], 11% discontinued; EBC T3: 56% improved, 36% stayed the same, 8% discontinued; EC T2: 60% improved, 28% stayed the same, none worsened, 12% discontinued; EC T3: 52% improved, 32% stayed the same, 13% discontinued). In the experimental arms, for patients with T3 baseline CEA, the median OS was longer in patients with improvement versus those without improvement in CEA: 7.4 months versus 4.6 months in the EBC arm; 7.0 months versus 3.7 months in the EC arm. In all arms, patients with larger decreases in CEA levels from baseline to first tumor assessment were more likely to respond to treatment or to achieve stable disease. Baseline CEA was not associated with overall response. Similar results were observed for CA19-9 levels.
Conclusion: Among patients receiving the EBC or EC regimen, lower baseline CEA was associated with longer OS; among patients with the highest baseline CEA, reduction in CEA with treatment was associated with improved OS. The baseline CEA and early on-treatment changes in CEA and CA19-9 levels may potentially identify a subgroup of patients with a numerically greater increase in survival and improved clinical outcomes with targeted therapy for metastatic CRC with BRAF V600E mutation.
- Kopetz S, Grothey A, Yaeger R, et al. Encorafenib, binimetinib, and cetuximab in BRAF V600E–mutated colorectal cancer. N Engl J Med. 2019;381:1632-1643.