Development of a highly specific HER2 monoclonal antibody for immunohistochemistry using protein microarray chips

Area of Science:

• Oncology
• Molecular Biology
• Immunohistochemistry

Background:

• HER2 is a key driver gene in breast and gastric cancers, targeted by Herceptin.
• Immunohistochemistry (IHC) using rabbit HER2 antibody 4B5 is standard for HER2 amplification diagnosis.
• The 4B5 antibody exhibits cross-reactivity with HER4 and non-specific binding, leading to inaccurate staining.

Purpose of the Study:

• To develop a novel, highly specific antibody for HER2 detection.
• To validate the specificity and sensitivity of the new antibody against HER2 amplification.
• To assess the utility of the new antibody in clinical cancer diagnostics.

Main Methods:

• Protein lysate array analysis to identify off-target binding of the 4B5 antibody.
• Development and characterization of a novel mouse HER2 monoclonal antibody (UMAB36).
• Validation of UMAB36 in breast and gastric cancer samples using HER2 FISH as a reference.

Main Results:

• The 4B5 antibody showed cross-reactivity with HER4 and ZSCAN18, causing non-specific staining.
• UMAB36 demonstrated high specificity, binding only to HER2 across a proteome array.
• UMAB36 achieved 100% sensitivity and specificity in cancer samples compared to FISH, with no non-specific staining.

Conclusions:

• UMAB36 is a highly specific alternative to 4B5 for HER2 IHC.
• This novel antibody can improve the accuracy of HER2 amplification testing in gastric and breast cancers.
• UMAB36 offers a reliable tool for diagnosing HER2-driven malignancies.