Plasma Nucleosome Profiling Reports on Tumor Burden and Molecular Subtypes in Small Cell Lung Cancer

Small cell lung cancer (SCLC) is an aggressive malignancy with dismal prognosis and marked transcriptional heterogeneity that drives distinct therapeutic vulnerabilities. The clinical translation of these molecular insights is limited by limited access to tumor biopsies. Here, we apply chromatin immunoprecipitation of cell-free nucleosomes carrying active histone modifications followed by sequencing (cfChIP-seq) to 441 plasma samples from individuals with advanced SCLC, other neuroendocrine carcinomas (NEC), non-SCLC cancers, and healthy controls. cfChIP-seq faithfully captured the epigenetic and transcriptional landscape of tumor-derived cfDNA, including SCLC tissue/cell-of-origin signatures, and yielded a quantitative score of tumor fraction that tracked radiographic burden and prognosis. Integrating plasma cfChIP-seq with matched tumor transcriptomes (n = 73, including 41 time-matched pairs), we show that cfChIP-seq levels at promoters of lineage-defining transcription factors (ASCL1, NEUROD1, POU2F3, and ATOH1) correlate strongly with tumor RNA and support noninvasive inference of SCLC transcriptional subtypes directly from plasma. These findings establish cfChIP-seq as a practical liquid-biopsy platform that reports real-time tumor state and subtype, enabling precision monitoring and laying the groundwork for subtype-informed therapeutic stratification in SCLC.

• Type: Epigenetics
• Archive: European Genome-phenome Archive (EGA)