Chiaki Kondoh1,2, Yoshitsugu Horio3, Yuko Hayashi4, Hiromichi Ebi4,5,6, Toyoaki Hida3, Yoshinori Hasegawa2, Yasushi Yatabe1. 1. Department of Pathology and Molecular Diagnostics, Aichi Cancer Centre, Nagoya, Japan. 2. Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan. 3. Department of Thoracic Oncology, Aichi Cancer Centre, Nagoya, Japan. 4. Division of Molecular Therapeutics, Aichi Cancer Centre Research Institute, Aichi, Japan. 5. Precision Medicine Centre, Aichi Cancer Centre, Aichi, Japan. 6. Division of Advanced Cancer Therapeutics, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Abstract
AIMS: Anaplastic lymphoma kinase (ALK) immunohistochemistry has shifted from being a screening tool to being a sole determinant for ALK-targeted therapy. Recent articles have referred to small-cell lung cancer (SCLC) transformation as a resistance mechanism after ALK inhibitor treatments, but few reports have addressed ALK expression in treatment-naive SCLC in a comprehensive manner. Therefore, we examined ALK expression and the mechanisms in treatment-naive SCLCs. METHODS AND RESULTS: We examined ALK expression in a consecutive series of SCLC tumours, and the expression mechanism was analysed regarding gene rearrangement, copy number changes, and point mutations. We also examined whether SCLC with ALK expression can be suppressed by crizotinib treatment in vitro. Immunohistochemical results revealed that ALK was expressed in 16 of 142 (11.3%) SCLCs. The expression was focal and less intense, which is in contrast to strong and uniform expression in adenocarcinoma with ALK rearrangement. Two combined SCLCs showed a positive reaction restricted to the SCLC component. None of the known genetic alterations, including rearrangement, amplification, copy number gain, or point mutations, were associated with ALK expression. A SCLC cell line, SKLC2, which expressed ALK without known genetic alterations, was not inhibited by a practically achievable serum concentration of crizotinib. CONCLUSIONS: Anaplastic lymphoma kinase immunohistochemistry for treatment-naive SCLCs should not be used as a predictive biomarker for ALK inhibitor therapy, because the positive reactions were due to intrinsic expression of normal ALK transcript.
AIMS: Anaplastic lymphoma kinase (ALK) immunohistochemistry has shifted from being a screening tool to being a sole determinant for ALK-targeted therapy. Recent articles have referred to small-cell lung cancer (SCLC) transformation as a resistance mechanism after ALK inhibitor treatments, but few reports have addressed ALK expression in treatment-naive SCLC in a comprehensive manner. Therefore, we examined ALK expression and the mechanisms in treatment-naive SCLCs. METHODS AND RESULTS: We examined ALK expression in a consecutive series of SCLC tumours, and the expression mechanism was analysed regarding gene rearrangement, copy number changes, and point mutations. We also examined whether SCLC with ALK expression can be suppressed by crizotinib treatment in vitro. Immunohistochemical results revealed that ALK was expressed in 16 of 142 (11.3%) SCLCs. The expression was focal and less intense, which is in contrast to strong and uniform expression in adenocarcinoma with ALK rearrangement. Two combined SCLCs showed a positive reaction restricted to the SCLC component. None of the known genetic alterations, including rearrangement, amplification, copy number gain, or point mutations, were associated with ALK expression. A SCLC cell line, SKLC2, which expressed ALK without known genetic alterations, was not inhibited by a practically achievable serum concentration of crizotinib. CONCLUSIONS:Anaplastic lymphoma kinase immunohistochemistry for treatment-naive SCLCs should not be used as a predictive biomarker for ALK inhibitor therapy, because the positive reactions were due to intrinsic expression of normal ALK transcript.
Authors: Dilara Akhoundova; Martina Haberecker; Ralph Fritsch; Sylvia Höller; Michael K Kiessling; Markus Rechsteiner; Jan H Rüschoff; Alessandra Curioni-Fontecedro Journal: Front Oncol Date: 2022-06-07 Impact factor: 5.738