Biomolecular, biochemical, and radiologic evaluation and safety of chemotherapy with bevacizumab in treatment of patients affected by mCRC.

Abstract

e14140 Background: Bevacizumab (BEV) combined with chemotherapy prolongs PFS and OS in treatment of mCRC regardless of KRAS status. This study investigated statistical significance of BEV clinical benefit (CB) in treatment of mCRC according to KRAS status and metastatic sites.We evaluated timing of response through correlation between tumor markers values (MKS) and clinical responses. Most severe toxicities were observed. Methods: 108 patients were treated with first-line Folfiri or FolFoX and BEV. KRAS status was detected. Before therapy patients were investigated with CT scan and with blood sample to define MKS; MKS after 2 months of chemotherapy and CT scan after 3 months were performed. Statistical analysis has benefited from chi-square test. Results: Overall response rate (RR) of 42% and CB of 82% were obtained, with correlation between MKS and clinical response of 90%. 49% of population presented only hepatic metastases while 51% showed multiple metastatic sites. RR in exclusive hepatic metastatic group was 48% vs 35% multiple metastatic sites (p=0.15), CB was 90% vs 71% respectively (p=0.01). KRAS mutations were investigated in 100 patients. 65 patients were wild-type (wt 65%) while 35 patients were mutated (mut 35%). RR in wt group was 51% vs 29% in mut (p=0.03), while CB was 86% vs 80% respectively (p=0.42). Correlation between MKS and clinical response was 91% in wt group vs 93% in mut. 72 patients (66%) experienced any grade toxicities. Most common G3-G4 toxicities were neutropenia (16%), diarrhea (4%) and vomiting (2%). G1-G2 BEV toxicities were bleeding (13%), hypertension (10%), deep vein thrombosis (5%), proteinuria (2%) and pulmonary embolism (1%); no G3-G4 toxicities were showed. Conclusions: RR in KRAS groups was different with an advantage, statistical significant, in KRAS wt, but this difference does not observe in CB. BEV provides significant RR and CB after short time of treatment and MKS are optimal parameters of early clinical response. BEV provides statistical significant CB in patients with only hepatic metastases vs patients with multiple metastatic sites. Treatment with BEV was well tolerated.