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

OBJECTIVE: 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 progression-free 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.