Use of trastuzumab to improve accuracy in the selection of patient from the treatment
Authors: Se Hun Kang, Ho-Young Lee, Nam Suk Baek, Sun-Young Kong, Byoung Chul Yoo, Seok-Ki Kim, Eun Sook Lee
Journal: Cancer Research (2008)

AACR Annual Meeting-- Apr 12-16, 2008; San Diego, CA

2141 

Purpose: Trastuzumab is effective antibody for breast cancer treatment, which targets on her2/neu receptor. To select proper patient for Trastuzumab treatment, evaluation of her2/neu expression is necessary. The most ideal method should be using Trastuzumab whether than other antibody. Most commonly used test is herceptest (Dako), which is immunohistochemistry (IHC) with polyclonal rabbit anti-human c-erbB-2 antibody (Dako). Only 40% of patients, who were positive in herceptest, have response to Trastuzumab. In this research, we developed new her2 test using Trastuzumab to improve the accuracy in the selection of patients.    Method: Firstly, we tried live cell imaging with Quantum dot (Q-dot, 655nm, invitrogen) conjugated Trastuzumab and anti-human c-erbB-2 antibody (Dako). For her2 over expression cell lines, AU565, SK-BR-3, HCC 1569, JIMT-1 and for her2 negative cell lines, HCC70, and MCF7 were used. JIMT-1 over-expresses her2 but is resistant to Trastuzumab. Q-dot conjugated antibody was incubated 30minutes with each cell lines, and after then washed out.    Secondly, we applied the Trastuzumab to immunohistochemitry. We made cellblock with the same cell lines, which were used for live cell imaging. In the process of IHC, proteinase K (0.02mg/ml) was applied 3 minutes in the 37°C for recovery of antigenicity. Trastuzumab was applied for 90 minutes. For the secondary antibody, HRP conjugated Goat Anti-Human IgG (Zymed) was used for Trastuzumab IHC. Also Hercept test (Dako) was done for each cellblock to compare the result with Trastuzumab IHC.    Thirdly, IHC using Quantum dot conjugated Goat Anti-Human IgG (invitrogen) was done. The other process was same as above. The only difference was using quantum dot conjugated antibody for the secondary antibody. For IHC imaging, fluorescence microscopy was used for imaging.    Result:    In the live cell imaging with Q-dot conjugated Trastuzumab, Trastuzumab was bound to cellular membrane in AU565, SK-BR3, HCC 1569 but Q-dot conjugated anti Her2 antibody was positive in all her2 overexpression cell lines even in JIMT-1. In the her2 negative cell lines, there was negative result.    In the cell block IHC with Trastuzumab, SK-BR-3, AU565, HCC 1569 were positive, but JIMT-1 was negative. In the herceptest, all her2 expression cell line showed positive result. The all her2 negative cell lines showed negative result.    The Q-dot Trastuzumab IHC, showed same result as Trastuzumab IHC.    Conclusion: Commonly used herceptest could select her2 expression regardless of the response to Trastuzumab. We developed IHC using Trastuzumab, and it could select cell line, which not only overexpressed her2 but also had response to Trastuzumab. For the selection of the patients for Trastuzumab treatment, her2 overexpression and the response to Trastuzumab must be evaluated at once. Our new method could be one of breakthrough for the accurate patient selection for Trastuzumab treatment.