Randomized phase II study of SOX plus B-mab versus SOX plus C-mab in patients with previously untreated recurrent advanced colorectal cancer with wild-type KRAS (MCSGO-1107 study)

Background: Although chemotherapy for metastatic colorectal cancer (mCRC) has improved, the standard chemotherapy regimens for patients with RAS wild-type mCRC remain debated. This study aimed to compare S-1 and oxaliplatin (SOX) + bevacizumab (B-mab) with SOX + cetuximab (C-mab) in patients with previously untreated recurrent advanced CRC with wild-type KRAS. Methods: This randomized phase II, open-label, multicenter study compared the efficacy and safety of SOX+B-mab with SOX+C-mab in patients with previously untreated advanced CRC with wild-type KRAS. Between February 2012 and October 2016, 45 patients were enrolled. Results: Overall response rates were 59.1 and 435% (p = 0.29) and disease control rates were 90.9 and 913% (p = 0.96) in the SOX+B-mab and SOX+C-mab groups, respectively. Median overall survival (OS) was 253 and 155 months (HR = 0.607, p = 0.167) and median progression-free survival (PFS) were 11.7 and 55 months (HR = 0558, p = 0.077) in the SOX+B-mab and SOX+C-mab groups, respectively. The OS and PFS of patients with early tumor shrinkage (ETS) were not significantly different in the SOX+B-mab group. However, they were significantly better when ES was >= 20 in the SOX+C-mab group (p = 0.032 and p = 0.003, respectively). Conclusions: The efficacy and safety of SOX+B-mab and SOX+C-mab for wild-type KRAS recurrent advanced CRC as first-line chemotherapy were almost the same. Consideration of the treatment strategy based on ETS may improve patient prognosis, especially in patients receiving the SOX+C-mab regimen.

Automated summary

This study compared the efficacy and safety of SOX+B-mab and SOX+C-mab in patients with wild-type KRAS recurrent advanced CRC. The results showed that there was almost no difference in first-line chemotherapy between the two regimens, but the OS and PFS were significantly better in the SOX+C-mab group when early tumor shrinkage was >=20.