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

Purpose: 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.

Methods: 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.

Results: 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).

Conclusions: 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.