Background RAS/BRAFV600E mutations are the most remarkable oncogenic driver mutations in colorectal cancer (CRC) and play an important role in treatment selection. No data are available regarding the clinical and prognostic features of patients with detailed RAS/BRAFV600E-mutant metastatic CRC (mCRC) in Japan. Methods A total of 152 chemotherapy-naïve patients with mCRC were included in this study between August 2018 and July 2019. Tumor samples were collected, and RAS/BRAFV600E status was investigated. RAS/BRAFV600E status was examined using a MEBGEN RASKET-B kit and polymerase chain reaction reverse sequence-specific oligonucleotide method. Results RAS/BRAFV600E mutations were detected in 54% of cases (KRAS codon 12, 26%; KRAS codon 13, 17%; KRAS non-Exon2, 5%; NRAS, 5%; and BRAFV600E, 7%). BRAFV600E-mutant CRC mainly existed in the right colon, whereas KRAS non-Exon2 and NRAS-mutant CRC was predominantly present in the left colon. KRAS non-Exon2 and NRAS-mutant CRC were associated with shorter survival time than RAS wild-type CRC (hazard ratio [HR], 2.26; 95% confidence interval [CI], 0.64–8.03; p = 0.19; HR, 2.42; 95% CI, 0.68–8.61; p = 0.16) and significantly shorter overall survival than KRAS Exon2-mutant CRC (HR, 3.88; 95% CI, 0.92–16.3; p = 0.04; HR, 4.80; 95% CI, 1.14–20.2; p = 0.02). Conclusions In our multicenter study, the findings elucidated the clinical and prognostic features of patients with detailed RAS/BRAFV600E-mutant mCRC in Japan.

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Background: RAS/BRAF V600E mutations are the most remarkable oncogenic driver mutations in colorectal cancer (CRC) and play an important role in treatment selection. No data are available regarding the clinical and prognostic features of patients with detailed RAS/BRAFV600E-mutant metastatic CRC (mCRC) in Japan.Methods: Chemotherapy-naïve patients with mCRC were included in this study between August 2018 and July 2019. Tumor samples were collected, and RAS/BRAFV600E status was investigated. RAS/BRAFV600E status was examined using a MEBGEN RASKET-B kit and polymerase chain reaction reverse sequence-specific oligonucleotide method.Results: RAS/BRAF V600E mutations were detected in 54% of cases (KRAS codon 12 = 26%; KRAS codon 13 = 11%; minor RAS [non-KRAS codon 12 and non-KRAS codon 13] = 10%; and BRAFV600E = 7%). BRAFV600E-mutant CRC mainly existed in the right colon, whereas minor RAS-mutant CRC was predominantly present in the left colon. Minor RAS-mutant CRC was associated with shorter survival time than RAS wild-type CRC (hazard ratio [HR] = 2.45; 95% confidence interval [CI] = 0.92–6.57; p = 0.073) and significantly shorter overall survival than major RAS-mutant CRC (HR = 4.77; 95% CI = 1.44–15.77; p = 0.010). The KRAS codon 12 mutant group showed significantly longer overall survival than the minor RAS mutant groups (HR = 0.06; 95% CI = 0.01–0.47; p < 0.00) and had extended progression-free survival compared with the codon 13 group.Conclusions: In our multicenter study, the findings elucidated the clinical and prognostic features of patients with detailed RAS/BRAFV600E-mutant mCRC in Japan.

Nivolumab improves overall survival (OS) in patients with advanced gastric cancer (AGC) refractory to at least two previous chemotherapy regimens. We investigated whether changes in body weight and nutrition from first-line chemotherapy to nivolumab affected its efficacy. The correlation between weight change and nutritional status up to the start of nivolumab treatment and OS and progression-free survival (PFS) after starting nivolumab treatment was determined. Nutritional status was examined using the C-reactive protein/albumin ratio (CAR). A loss in body weight (LBW) from the onset of the first treatment of <4.5% led to OS prolongation and improved PFS outcomes. The median OS values in the LBW < 4.5% and ≥4.5% groups were 11.4 and 3.6 months, respectively. Similarly, changes in CAR from first-line chemotherapy (ΔCAR) affected OS; the ΔCAR < 0.01 group had a better prognosis than the ΔCAR ≥ 0.01 group. The median OS values in the ΔCAR < 0.01 and ≥0.01 groups were 9.4 and 4.5 months, respectively. The median OS in the group with LBW < 4.5% and ΔCAR < 0.01 was 12.9 months. LBW and deterioration of nutritional status following first-line chemotherapy are poor prognostic factors in AGC patients who received nivolumab as third- or later-line therapy. Early intervention to maintain body weight and nutritional status may improve the efficacy of immune checkpoint inhibitors.