Abstract
Introduction: Panitumumab is an EGFR inhibitor approved for use in metastatic refractory colorectal cancer. It is unclear whether patients who have progressed on cetuximab may benefit from subsequent panitumumab therapy. This retrospective analysis was conducted to describe the experience at The Ohio State University with panitumumab including in patients who have progressed on cetuximab. Methods: Patients who received at least 1 dose of panitumumab between September 2006 and December 2011 were identified using the hospital’s pharmacy database. Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 was used to assess responses and Kaplan-Meier curves were used to estimate progression-free survival (PFS) and overall survival (OS). Results: Eighty-seven patients (median age 61 years) were identified. Sixty-seven percent of patients had tumors with wild-type KRAS, 3.4% had tumors with mutated KRAS and the KRAS status was unknown in 29.9%. Twenty-four percent of the patients had an ECOG performance status of 2 or above and 59.8% of patients had received ≥ 2 prior lines of chemotherapy. Thirty-two percent of patients received single-agent panitumumab while 68% received it in combination with chemotherapy. Of the patients with KRAS wild-type tumors, 10 (17.2%) had objective responses (3 complete, 7 partial) and 26 (44.8%) had stable disease. Median PFS and OS were 5.0 and 9.0 months. The presence of a rash, improved ECOG performance status and coadministration with either irinotecan or FOLFIRI, led to a significantly better OS in univariate analysis. Among patients who had clinical benefit with cetuximab, 71% had subsequent clinical benefit with panitumumab therapy. Conclusions: In our single institution analysis of patients who received panitumumab, the number of prior lines of therapy did not significantly affect OS, suggesting that panitumumab retains its efficacy in the 2nd and 3rd line setting. Additionally, panitumumab can benefit patients who previously had clinical benefit with cetuximab.
Highlights
Panitumumab is an epidermal growth factor receptor (EGFR) inhibitor approved for use in metastatic refractory colorectal cancer
About 20% of the patients present with metastatic disease and the 5-year overall survival with treatment is ~10% [2]. Cytotoxic agents such as 5-Fluorouracil (5-FU), oxaliplatin and irinotecan are well established in the treatment of metastatic colorectal cancer and have in recent years been combined with targeted therapies, which have become an important component of systemic therapy
In this study we found a response rate of 17% to panitumumab therapy which is similar to prior phase III study results when panitumumab is given in the refractory setting [4]
Summary
Panitumumab is an EGFR inhibitor approved for use in metastatic refractory colorectal cancer. It is unclear whether patients who have progressed on cetuximab may benefit from subsequent panitumumab therapy. About 20% of the patients present with metastatic disease and the 5-year overall survival with treatment is ~10% [2] Cytotoxic agents such as 5-Fluorouracil (5-FU), oxaliplatin and irinotecan are well established in the treatment of metastatic colorectal cancer (mCRC) and have in recent years been combined with targeted therapies, which have become an important component of systemic therapy. Panitumumab is a fully humanized monoclonal IgG-2 antibody targeting epidermal growth factor receptor (EGFR) and was approved by the Food and Drug Administration (FDA) in September 2006 as therapy in mCRC. The mutational status of KRAS was shown to predict responses to EGFR-targeted therapy in a study published in 2006 [3], and KRAS mutation testing became a NCCN recommendation in November 2008
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
