Phase II Trial of Chemotherapy plus Bevacizumab as Second-Line Therapy for Patients with Metastatic Colorectal Cancer That Progressed on Bevacizumab with Chemotherapy: The Gunma Clinical Oncology Group (GCOG) trial 001 SILK Study

Objectives: BRiTE and ARIES (observational cohort studies) provided valuable information on continued use of bevacizumab (BV) beyond progression (BBP). This trial evaluates the efficacy and safety of BBP for patients with metastatic colorectal cancer that progressed on first-line chemotherapy. Methods: A total of 39 patients received FOLFIRI + BV (after FOLFOX + BV) or FOLFOX + BV (after FOLFIRI + BV) as protocol treatment. The primary endpoint was the response rate. Secondary endpoints were overall survival (OS), total survival from initiation of first-line treatment (TS), progression-free survival (PFS), and safety. Results: All 39 treated patients were evaluated for toxic effects. Two patients did not meet all of the eligibility criteria and were excluded from efficacy analyses. The response rate was 16.2%. The disease control rate was 76%. The median PFS was 150 days (range 117-224). The median OS was 417 days (range 233-813). The median TS was 988 days (range 600-1,268). Grade 3/4 adverse events (% of patients) related to treatment were neutropenia (33%), fatigue (23%), and hypertension (18%). Conclusions: This is the first report to show the effect of BBP in patients who had progressive disease on first-line treatment including BV confirmed by RECIST criteria. This analysis suggests the possibility of prolonged survival with continued use of BV.