PROBLEM TO BE SOLVED: To provide a method of diagnosis and therapy of cancers expressing the HER2 receptor.SOLUTION: The invention provides antibodies or fragments thereof that recognizes an epitope of a HER2 receptor truncated form, the epitope being defined by a specific sequence. The invention also provides a method of cancer diagnosis, which comprises the detection of the presence of the HER2 receptor truncated form consisting of a specific amino acid sequence in a patient sample.【課題】HER2受容体を発現する癌の診断および治療方法の提供。【解決手段】特定の配列によって規定されるHER2受容体末端切断形態のエピトープを認識する抗体またはその断片。癌を診断する方法であって、患者サンプル中の、特定のアミノ酸配列からなるHER2受容体末端切断形態の存在を検出するステップを含む、方法。【選択図】なし