Circulating Tumor Cells as Prognostic Marker in Japanese patients with Kras Wild-type Metastatic Colorectal Cancer Receiving Panitumumab after Progression on Cetuximab
- *Corresponding Author:
- Satoshi Matsusaka
Department of Gastroenterology
Cancer Institute Hospital
Japanese Foundation for Cancer Research
3-8-31 Ariake, Koto-ku
E-mail: [email protected]
Received Date: November 14, 2013; Accepted Date: December 09, 2013; Published Date: December 11, 2013
Citation: Ohhara Y, Matsusaka S, Watanabe T, Shinozaki E, Suenaga M, et al. (2013) Circulating Tumor Cells as Prognostic Marker in Japanese patients with Kras Wild-type Metastatic Colorectal Cancer Receiving Panitumumab after Progression on Cetuximab. J Cytol Histol 5:204. doi:10.4172/2157-7099.1000204
Copyright: © 2013 Ohhara Y, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Background: Panitumumab has a high affinity for epidermal growth factor receptor. Its utility as a salvage therapy is unknown in cetuximab-resistant colorectal cancer. We assessed the prognostic and predictive role of circulating tumor cells (CTCs) in KRAS wild-type metastatic Colorectal Cancer (mCRC) patients treated with panitumumab after progression on cetuximab.
Methods: Panitumumab (6 mg/kg every 2 weeks) was administered as salvage therapy in a patient with cetuximab-resistant mCRC. The CTC count in whole blood at baseline was determined using immunomagnetics.
Results: Nineteen patients were enrolled in the study between July 2010 and March 2011. Five patients had Stable Disease (SD) with a response rate of 0%. Four patients reached long-SD, which was defined as continuous SD of more than 120 days. All of these four patients had <2 CTCs. Multivariate analysis revealed that ≥2 CTCswas an independent predictor of Progression-Free Survival (PFS) (hazard ratio: 7.275, P=0.013). Patients with ≥2 CTCs had a shorter median PFS than those with <2 CTCs (1.8 versus 3.6 months, P=0.008). No statistically significant difference was observed in median overall survival between patients with ≥2 CTCs and those with <2 CTCs (3.2 versus 6.7 months, P=0.164).
Conclusions: These results suggest that <2 CTCs indicates that panitumumab may be effective in patients with KRAS-wild-type mCRC after progression on cetuximab.