A Phase II Study of Third-Line Combination Chemotherapy with Bevacizumab Plus S-1 for Metastatic Colorectal Cancer with Mutated KRAS (SAVIOR Study)

No salvage treatment had been established for metastatic colorectal cancer (mCRC) with mutated KRAS before the emergence of the new drugs regorafenib and TAS-102. We performed a phase II study of third-line chemotherapy with combined bevacizumab and S-1 for mCRC. Methods: Subjects were mCRC patients with mutated KRAS who showed disease aggravation even after two regimens with oxaliplatin and irinotecan. Bevacizumab was given intravenously every 2 weeks, and S-1 was administered orally on days 1-28 of a 42-day cycle. The primary endpoint was disease control rate (DCR). Results: In total, 31 subjects were enrolled between August 2009 and June 2011. Three subjects in whom antitumor effects could not be evaluated were excluded. The median follow-up period was 8.6 months. The DCR was 67.9%, the response rate 0%, median progressionfree survival 3.7 months, and overall survival 8.6 months. In 30 subjects evaluated for safety, there was no treatment-related death. The most common adverse events were anorexia (grade ≥ 3, 20%), diarrhea (grade 3, 10%), and decreased hemoglobin (grade ≥ 3, 17%). Conclusions: The results suggest that third-line chemotherapy with combined bevacizumab and S-1 is safe and may delay the progression of mCRC resistant to oxaliplatin and irinotecan with mutated KRAS.