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

ML18147 evaluated continued bevacizumab with second-line chemotherapy for patients with metastatic colorectal cancer (mCRC) progressing after the standard first-line bevacizumab-containing therapy. Evaluating 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. Of 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). Bevacizumab beyond first progression represents an option for patients with mCRC treated with bevacizumab plus standard first-line chemotherapy, independent of KRAS status.