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Background: BRAF mutations portend a poor prognosis in metastatic colorectal cancer (mCRC). Whether these patients may benefit from more aggressive frontline chemotherapy with a triplet regimen such as FOLFOXIRI remains unclear. We used real-world data from a cohort of patients in the United States to assess the BRAF testing rate, determine the prevalence of FOLFOXIRI use, and compare survival outcomes in mCRC, stratified by BRAF mutation status and first-line therapy. Methods: A nationwide electronic health record–derived deidentified database was reviewed for patients diagnosed with mCRC between 2013 and 2018. Those with documented BRAF mutation testing who received standard first-line therapy were included. Kaplan-Meier estimates with corresponding log-rank tests and Cox proportional hazards modeling compared survival outcomes stratified by BRAF status and first-line therapy. Results: Of 4,457 included patients, 3,991 (89.5%) had BRAF wild-type (BRAFwt) and 466 (10.5%) had BRAF-mutated (BRAFmt) mCRC. Median overall survival (OS) was 15.4 months in the BRAFmt group versus 28.1 months in the BRAFwt group (hazard ratio [HR], 0.48; 95% CI, 0.41–0.56; P<.001). Only 3% of patients with BRAF mutations received first-line FOLFOXIRI ± bevacizumab, with a median OS of 13.8 months compared with 15.5 months in those treated with doublet chemotherapy ± bevacizumab (P=.38). In patients with BRAF mutations, propensity-weighted analysis did not detect a significant improvement in OS with FOLFIRI + bevacizumab (HR, 0.90; 95% CI, 0.58–1.39; P=.63) or FOLFOX/CAPEOX + bevacizumab (HR, 0.81; 95% CI, 0.52–1.26; P=.35) versus doublet chemotherapy alone. In 2018, only 56% of patients diagnosed with mCRC had documented BRAF testing at any time. Conclusions: This real-world data analysis confirms the negative prognostic impact of BRAF mutations in mCRC and suggests that FOLFOXIRI has not been widely adopted in the United States. The proportion of patients with documented BRAF testing in this real-world population was low at 56%. We were unable to show any significant difference in OS of patients with BRAFmt mCRC based on the first-line therapy received.

4030 Background: BRAF mutations portend a poor prognosis in metastatic colorectal cancer (mCRC). Recent trials have hypothesized that using more aggressive triplet-based chemotherapy regimens such as FOLFOXIRI in the frontline setting may improve outcomes in this patient population. In this study, we utilized real-world data to assess whether FOLFOXIRI is being used in the United States (US) and compared survival outcomes in BRAF mutated (BRAFmt) mCRC stratified by first line (1L) therapy. Methods: The nationwide Flatiron Health EHR-derived de-identified database was reviewed for patients diagnosed with mCRC between 2013 and 2018. Patients who had documented BRAF mutation testing and received a standard 1L therapy were included for analysis. Patients who did not have a visit or medication order within 90 days of metastatic diagnosis were excluded to ensure patients were engaged with care at the data-providing institution. Kaplan-Meier and Cox proportional hazard modeling were used to compare survival outcomes stratified by BRAF mutation status and 1L therapy received. Results: A total of 4,454 patients with documented BRAF mutational status were included, of which 3,988 (89.5%) were BRAF wild type (BRAFwt) and 466 (10.5%) were BRAFmt. Median OS was 15.4 months (mo) in the BRAFmt group compared to 28.1 mo in the BRAFwt group (HR 0.48, 95% CI 0.41- 0.56, p < 0.001). Only 3% (n = 16) of BRAFmt patients received 1L FOLFOXIRI +/- bevacizumab with a median OS of 13.8 mo compared to 15.5 mo in patients receiving a chemotherapy doublet (FOLFOX, CAPEOX, or FOLFIRI) +/- bevacizumab (95% CI 4.9 – not reached vs 14.3 – 19.0, p = 0.38). In BRAFmt patients, multivariate analysis (MVA) did not detect a significant improvement in OS with the use of FOLFIRI plus bevacizumab (HR 0.88, 95% CI 0.50-1.56, p = 0.67) or FOLFOX/CAPEOX plus bevacizumab (HR 0.89, 95% CI 0.59 – 1.34, p = 0.58) when compared to chemotherapy doublet alone. A MVA comparing 1L therapies in the BRAFwt group did not detect a significant improvement in OS with bevacizumab plus chemotherapy doublet compared to chemotherapy doublet alone. When stratified by 1L treatment regimen, similar proportions of BRAFmt patients received second line therapy. Conclusions: This analysis of real-world data confirms the negative prognostic impact of BRAF mutations in mCRC and suggests that FOLFOXIRI has not been widely adopted in the management of these patients in the US. We were unable to demonstrate any significant difference in OS of patients with BRAFmt mCRC based on type of 1L therapy received.

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