The efficacy of panitumumab in refractory metastatic colorectal cancer: A meta-analysis

Panitumumab, an anti-epithelial growth factor receptor (EGFR) antibody, has been known to be effective treatments for wild-type KRAS metastatic colorectal cancer (mCRC). However, the efficacy of panitumumab for refractory mCRC remains controversial. Thus, we performed this meta-analysis to clarify and evaluate the effectiveness of panitumumab in patients with refractory mCRC.

PubMed, Cochrane and Embase were searched up to October 2018 using appropriate key words. Only randomized controlled trials (RCTs) were included in the qualified studies. Odds ratio (OR) along with 95% confidence interval (95% CI) were utilized for main outcome analysis.

A total of 7 RCTs were included in this analysis. Overall survival (OS, OR=1.01, 95% CI 0.81-1.27; p=0.90) and progression free survival (PFS, OR =0.78, 95% CI 0.62-1.00; p=0.05) were not significantly different in mCRC patients pretreated with panitumumab, but the pooled OR for overall response rate (ORR) was 3.71 (95% CI 1.34-10.31;p=0.01), indicating that panitumumab improved the ORR. Moreover, subgroup analysis showed that patients treated with panitumumab plus irinotecan-based chemotherapy did not achieve any benefit in PFS (OR=0.91, 95% CI 0.68-1.22; p=0.53) or OS (OR=0.93, 95% CI 0.79-1.09; p=0.36) than controls. The results also indicated that the combination chemotherapy with either panitumumab or cetuximab was comparable in efficacy in terms of PFS (OR=0.80, 95% CI 0.62-1.04; p=0.10) and OS (OR=1.28, 95% CI 0.72-2.27, p=0.40).

The current analysis indicates that panitumumab was not associated with survival benefit but ORR was improved among pre-treated mCRC patients. Future investigations are needed to identify relevant biomarkers in selected patients that would most likely benefit from panitumumab therapy for refractory mCRC.