Genomic Copy-Number Variants Drive Apoptotic Resistance and Relapses on Immune Checkpoint Inhibitors

We investigated the genomic mechanisms underlying acquired resistance (AR) to immune checkpoint inhibitors (ICIs) across tumor types, specifically by examining how copy number variant (CNV)-driven subclonal evolution contributes to clinical relapses in melanoma patients. We analyzed longitudinal clinical melanoma samples from patients who experienced relapses on ICI therapy, complemented by isogenic human melanoma cell line models (M486) and murine melanoma tumor systems. Single-cell whole-genome sequencing (scWGS) was employed to resolve subclonal CNV patterns in AR tumors. The scWGS data revealed that AR-dominant subclones systematically deleted pro-apoptotic genes while amplifying anti-apoptotic genes and innate resistance pathway components. Notably, shared and private AR subclonal CNVs preexisted selective pressure, with convergent evolution targeting apoptosis-regulatory pathways and resulting in downregulated apoptotic/mitochondrial priming that enables ICI resistance. scWGS datasets from isogenic human melanoma cell lines, patient-matched tumor samples, and murine melanoma models will be made available through dbGaP, enabling researchers to access high-resolution subclonal CNV profiles that define the genomic landscape of acquired ICI resistance evolution.]]>