Left Versus Right: Does Location Matter for Refractory Metastatic Colorectal Cancer Patients in Phase 1 Clinical Trials?

Purpose: Location of the primary tumor is prognostic and predictive of efficacy with VEGF-inhibitors (I) versus EGFR-I given first-line to metastatic colorectal cancer (mCRC) patients. However, little is known regarding the effect of location on prognosis and prediction in refractory mCRC. We assessed the efficacy of VEGF-I and EGFR-I in regards to location of the primary tumor in patients with refractory mCRC enrolled in early phase studies. Methods: A historical cohort analysis of mCRC patients, including 44 phase I trials our institution, from March 2004 to September 2012. Median Progression free survival (mPFS) and overall survival (mOS) were estimated from Kaplan-Meier curves and groups were statistically compared with the log-rank test. Results: One hundred thirty-nine patients with a median age 59 (33–81). 73.9% received 3+ lines of therapy. All KRAS wild-type patients had received prior EGFR-I. Location: right 20.9%, left 61.9%, and transverse 4.3%. For survival analysis, transverse CRC were included with right. Of the 112 patients, mOS was left (N = 80) 6.6 months versus right (N = 32) 5.9 months, P = 0.18. mPFS was left (n = 86) 2.0 months versus right (N = 35) 2.0 months, P = 0.76. In subgroup analysis, survival was significant for KRAS wild-type patients with left-sided mCRC had mOS of 6.2 months with other agents versus 9.4 months with EGFR-I (P = 0.03). Conclusions: In phase 1 clinical trials, although location alone was not prognostic in heavily pretreated patients, left-sided mCRC had improved survival with EGFR-I. Despite progression on EGFR-I, left-sided KRAS wild mCRC patients should be considered for phase 1 studies of agents targeting growth factor pathways.