The treatment outcomes of patients with BRAFV600E–mutated metastatic colorectal cancer (mCRC): The Polish retrospective cohort study.

e15535 Background: BRAF V600E mutation is found in approximately 6-11% of metastatic colorectal cancer patients (mCRC). According to the international guidelines in BRAF V600E mutated mCRC, the triplet chemotherapy FOLFOXIRI (folinic acid, 5-fluorouracil, oxaliplatin, irinotecan) with bevacizumab and encorafenib plus cetuximab should be considered in 1 st and 2 nd line treatment setting, respectively. Methods: This retrospective and multicenter study evaluates clinical practices in BRAF V600E mutated mCRC patients treated between 2011 and 2023 in Poland. All patients were tested for BRAF and RAS mutations before starting the 1 st line treatment, using PCR from archival paraffin-embedded tumor tissue. Results: One hundred twenty-six patients (median age 68 years (range 45-85), 55% female and 45% male) from five oncology centers were included. The majority of patients had a right-sided primary tumor 69 (55%). The 1 st line of chemotherapy received 100 patients (79,4%). The majority of patients received doublet chemotherapy: FOLFOX (folinic acid, 5-fluorouracil, oxaliplatin), FOLFIRI (folinic acid, 5-fluorouracil, irinotecan), XELOX (capecitabine, oxaliplatin), FOLFIRI and bevacizumab: 30 (30%), 47 (47%), 5 (5%), 3 (3%), respectively. Only three patients (3%) received FOLFOXIRI, and one patient with bevacizumab. The median duration of 1 st line treatment for the overall population was 5.26 months (95% CI 2 days - 18.9 months). Subsequently, 50 (50%), 20 (20%), 6 (6%), and 1 (1%), patients received 2 nd , 3 rd , 4 th , and 5 th line therapy, respectively. The most frequently used 2 nd chemotherapy regimens were FOLFOX ( n = 8; 16%), FOLFOX plus bevacizumab ( n = 13; 26%), FOLFIRI ( n = 13; 26%), and FOLFIRI plus aflibercept ( n = 7; 14%). During the median follow-up period of 38.5 months (range 32.0 – N/A), 96 (79.3%) patients died. Median OS from mCRC diagnosis was 13.7 months (95% CI: 11.3-17.6). Conclusions: This study highlights the unmet need for effective treatment strategies for patients with BRAF V600E mutated mCRC in Poland.