A real-life experience using panitumumab in chemo-refractory metastatic colorectal cancer patients: a retrospective analysis at the Jewish General Hospital, 2009-2012

Abstract

Background: Panitumumab is a fully human monoclonal antibody, directed against the epidermal growth factor receptor, that was shown to be effective in third-line metastatic colorectal cancer. We performed a retrospective analysis of patients with chemo-refractory non-KRAS-mutated metastatic colorectal cancer, who received panitumumab at the Jewish General Hospital in Montreal, Canada, between 2009 and 2012.

Methods: This chart review included 44 patients (median age: 60 years; performance status: 0-3), of whom 50% had already received three lines of treatment. The primary endpoint was progression-free survival (pfs). Secondary endpoints were overall survival and safety. Tumour progression was determined by radiologic assessments performed once every 3 months per clinical guidelines or by clinical deterioration as determined by the clinician-investigator.

Results: In our sample, median pfs was 21.86 ± 5.23 weeks (95% confidence interval: 12.9 to 36.9 weeks) and overall survival was 35.14 ± 7.75 weeks (95% confidence interval: 25.6 to 73.4 weeks) with a median of 5 cycles of panitumumab treatment. The most frequently reported toxicities with panitumumab were skin toxicity (16.2% grade 3) and hypomagnesemia (10.8% grade 3). No infusion reactions were reported.

Conclusions: Despite a small sample size from a single institution, our survival and efficacy data are encouraging and comparable to results obtained from the registration panitumumab trial. Our findings suggest that panitumumab can be effective and tolerable in a real-world setting.

Keywords: Metastatic colorectal cancer; overall survival; panitumumab; progression-free survival; safety.

FIGURE 1

consort diagram for the study.

FIGURE 2

(A) Progression-free survival (pfs) for 44 patients receiving irinotecan or panitumumab, or both. The solid line represents the pfs curve for patients treated at the Jewish General Hospital. (B) The pfs for 37 patients receiving panitumumab alone. The solid line represents the pfs curve for patients treated at the Jewish General Hospital. The dotted lines mark the 95% confidence limits.

FIGURE 3

(A) Overall survival (os) for 44 patients receiving panitumumab with or without irinotecan. The solid line represents the os curve of patients treated at the Jewish General Hospital (B) Overall survival (os) for 37 patients receiving panitumumab alone. The solid line represents the os curve of patients treated at the Jewish General Hospital. The dotted lines mark the 95% confidence limits.