Functional Characterisation of the ATOH1 Molecular Subtype Indicates a Pro-Metastatic Role in Small Cell Lung Cancer

Molecular subtypes of Small Cell Lung Cancer (SCLC) have been described based on differential expression of transcription factors (TFs) ASCL1, NEUROD1, POU2F3 and immune-related genes. We previously reported an additional subtype based on expression of the neurogenic TF ATOH1 within our SCLC Circulating tumour cell-Derived eXplant (CDX) model biobank. Here we show that ATOH1 protein is detected in 7/81 preclinical models and 16/102 clinical samples of SCLC. In CDX models, ATOH1 directly regulates neurogenesis and differentiation programs consistent with roles in normal tissues. In ex vivo cultures of ATOH1-positive CDX, ATOH1 is required for cell survival. In vivo, ATOH1 depletion slows tumour growth and suppresses liver metastasis. Our data validate ATOH1 as a bona fide lineage-defining transcription factor of SCLC with tumour cell survival and pro-metastatic functions. Further investigation to explore ATOH1 driven vulnerabilities for targeted treatment with predictive biomarkers is warranted.