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Development and characterization of 1C6-203, a new monoclonal antibody specific to human thymidine phosphorylase
1Second Department of Surgery and Medicine, Kamakura, Kanagawa, Japan. kono@asahikawa-med.ac.jp
Abstract:
Thymidine phosphorylase (dThdPase) is an essential enzyme for activation of the oral cytostatic drug capecitabine and its intermediate metabolite, doxifluridine, to 5-fluorouracil in tumors. Methods to estimate dThdPase expression in tumor tissue might be useful to predict the efficacy of capecitabine and doxifluridine in cancer patients. We established a new monoclonal antibody (MAb), 1C6-203, applicable for dThdPase immunohistochemistry and compared its staining characteristics with those of a previously established MAb, 654-1. In 4% paraformaldehyde-fixed colorectal carcinoma, 1C6-203 and 654-1 stained cancer cells in 19/30 and 9/30 patients, respectively. In 10% formalin-fixed colorectal carcinoma, 1C6-203 and 654-1 stained cancer cells in 18/30 and 6/30 patients, respectively. In negative 10% formalin-fixed tissues, microwave treatment improved the positivity of 654-1-stained cancer cells. These results suggest that an epitope recognized by 1C6-203 is resistant to epitope masking by formaldehyde fixation, whereas that for MAb 654-1 is sensitive. Therefore, MAb 1C6-203 might be more suitable than MAb 654-1 for evaluating dThdPase expression in colorectal carcinoma.
Insights
A new antibody, 1C6-203, effectively detects thymidine phosphorylase (dThdPase) in colorectal cancer. This enzyme is crucial for capecitabine drug activation, making 1C6-203 a promising tool for predicting treatment efficacy.
Area of Science:
- Biochemistry
- Oncology
- Immunohistochemistry
Background:
- Thymidine phosphorylase (dThdPase) is vital for activating oral chemotherapies like capecitabine and doxifluridine to 5-fluorouracil within tumors.
- Accurate assessment of dThdPase expression in tumor tissues is essential for predicting patient response to these drugs.
Purpose of the Study:
- To establish and characterize a new monoclonal antibody (MAb), 1C6-203, for immunohistochemical detection of dThdPase.
- To compare the performance of MAb 1C6-203 with a previously established MAb, 654-1, in evaluating dThdPase expression in colorectal carcinoma.
Main Methods:
- Development of a novel monoclonal antibody (MAb) 1C6-203 targeting thymidine phosphorylase (dThdPase).
- Immunohistochemical staining of colorectal carcinoma tissues fixed with 4% paraformaldehyde and 10% formalin using both MAb 1C6-203 and MAb 654-1.
- Evaluation of microwave treatment's effect on MAb 654-1 staining in formalin-fixed tissues.
Main Results:
- MAb 1C6-203 demonstrated higher cancer cell staining rates (19/30 in 4% PFA, 18/30 in 10% formalin) compared to MAb 654-1 (9/30 in 4% PFA, 6/30 in 10% formalin).
- The epitope recognized by MAb 1C6-203 is resistant to formaldehyde fixation-induced masking, unlike the epitope for MAb 654-1.
- Microwave treatment improved MAb 654-1 staining in negative formalin-fixed tissues, indicating epitope sensitivity.
Conclusions:
- MAb 1C6-203 exhibits superior performance for dThdPase detection in colorectal carcinoma, particularly in formalin-fixed tissues.
- The epitope stability of MAb 1C6-203 makes it a more reliable tool for assessing dThdPase expression.
- This antibody holds potential for predicting capecitabine and doxifluridine efficacy in cancer patients.