Examining progression-free survival in first- and second-line treatment for BRAF-mutant metastatic colorectal cancer (CRC).

Abstract

728 Background: BRAF mutated (BRAFm) CRC represents ~10% of all CRC and is associated with significantly poorer prognosis. However, responses to chemotherapy do still occur. Some data suggest that the poor prognosis associated with BRAFm CRC is dominated by substantially poorer second line PFS (PFS2), whereas first line PFS (PFS1) was similar for both BRAFm and BRAF wildtype (BRAFwt) CRC. Using a large multicenter dataset, our study aimed to examine PFS1 and PFS2 in BRAFm versus BRAFwt CRC. Methods: Prospectively collected data from the Treatment of Recurrent and Advanced Colorectal Cancer (TRACC) database was interrogated. PFS was calculated and compared in patients with BRAFm versus BRAFwt CRC. Median survival was determined by the Kaplan-Meier method and compared using the log rank test. Results: TRACC identified 523 CRC patients with known BRAF mutation status, who received first-line chemotherapy: 53 (10%) were BRAFm, while 470 (90%) were BRAFwt. At the time of data analysis, only 231 (44%) CRC patients had received second-line chemotherapy, of which 21 (9%) were BRAFm and 210 (91%) were BRAFwt. PFS1 analyses demonstrated significantly poorer survival in the BRAFm population (Median 7.8mo versus 11.5mo, HR 1.72, p = 0.0026). PFS2 analyses revealed similar findings for the BRAFm population, albeit non-significant due to smaller numbers (Median 5.5mo versus 7.7mo, HR1.26, p = 0.44). Conclusions: Our study demonstrated that BRAFm CRC was associated with poorer PFS in both first- and second-line settings. Additional analyses will be performed to examine the impact of different treatment strategies and other clinicopathological features.