Bevacizumab plus chemotherapy continued beyond first progression in patients with metastatic colorectal cancer previously treated with bevacizumab plus chemotherapy: ML18147 study KRAS subgroup findings

BackgroundML18147 evaluated continued bevacizumab with second-line chemotherapy for patients with metastatic colorectal cancer (mCRC) progressing after the standard first-line bevacizumab-containing therapy.Patients and methodsEvaluating outcomes according to tumor Kirsten rat sarcoma virus oncogene (KRAS) status was an exploratory analysis. KRAS data were collected from local laboratories (using their established methods) and/or from a central laboratory (mutation-specific Scorpion amplification-refractory mutation system). No adjustment was made for multiplicity; analyses were not powered to detect statistically significant differences.ResultsOf 820 patients, 616 (75%) had unambiguous KRAS data; 316 (51%) had KRAS wild-type tumors and 300 (49%) had mutant KRAS tumors. The median progression-free survival (PFS) was 6.4 months for bevacizumab plus chemotherapy and 4.5 months for chemotherapy [P < 0.0001; HR = 0.61; 95% confidence interval (CI): 0.49–0.77] for wild-type KRAS and 5.5 and 4.1 months, respectively (P = 0.0027; HR = 0.70; 95% CI: 0.56–0.89) for mutant KRAS. The median overall survival (OS) was 15.4 and 11.1 months, respectively (P = 0.0052; HR = 0.69; 95% CI: 0.53–0.90) for wild-type KRAS and 10.4 versus 10.0 months, respectively (P = 0.4969; HR = 0.92; 95% CI: 0.71–1.18) for mutant KRAS. In both analyses, no treatment interaction by KRAS status was observed (PFS, P = 0.4436; OS, P = 0.1266).ConclusionsBevacizumab beyond first progression represents an option for patients with mCRC treated with bevacizumab plus standard first-line chemotherapy, independent of KRAS status.