Outcomes of patients (pts) with BRAF mutated (BRAF MT) Colorectal Cancer (CRC): The Royal Marsden Experience.

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644 Background: BRAF MT metastatic CRC (mCRC) is associated with a poor prognosis. For the first time, we report outcomes for BRAF MT mCRC at a single tertiary centre, compared to a matched control group, since introduction of routine somatic BRAF and RAS mutation testing. Methods: Pts with BRAF MT mCRC (diagnosed Oct 2010-Nov 2014) were compared to a matched group of BRAF wildtype (WT) pts treated in same time period who were randomly selected after matching for age, sex and stage. Demographic, tumour characteristic and treatment data were collected. Overall (OS) and progression-free survival (PFS) were calculated using the Kaplan-Meier method and comparisons made using χ² test or Cox regression. Results: Of 503 pts tested, 59 (11.7%) had BRAF MT tumours (16 early stage, 16 recurrent and 27 de novo metastatic). Median age (years) at diagnosis was 68 (27-85) compared with 70 (29-85) for BRAF WT pts (p = 0.995). Median OS for pts with mCRC was 18.2 months (m) for BRAF MT and 41.1m for BRAF WT pts (HR 2.73 P < 0.01). For BRAF MT and BRAF WT pts with mCRC, median PFS on first-line treatment (1L) was 8.1m (n = 37) and 9.2m (n = 81) respectively (HR = 1.10 [P = 0.69]), PFS on 2L was 5.1m (n = 21) and 9.0m (n = 49) respectively (HR = 1.84 [P = 0.03]) while PFS on 3L was 1.7m (n = 10) and 6.6m (n = 20) respectively (HR = 2.75 [P = 0.02]). Fluoropyrimidine based doublet regimens were used in 94.6%, 85.7% and 20% of BRAF MT pts in 1L, 2L and 3L respectively compared with 87.2%, 92.5% and 52.4% in BRAF WT pts. Pts with localised disease had a recurrence rate of 50% (16/32) for pts with BRAF MT compared with 52.4% (33/63) for BRAF WT pts (p = 0.83). Conclusions: In this case-control study, poor OS of pts with BRAF MT mCRC is associated with reduced clinical benefit beyond 1L. Sequential doublet chemotherapy remains a reasonable option in these pts. The role of BRAF mutation in predicting recurrence of early CRC warrants further study. [Table: see text]