PO.TB10.18 · 肿瘤生物学
通过免疫原性张力图谱量化肿瘤免疫逃逸
Quantifying tumor immune escape through immunogenic tension mapping
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摘要 Abstract
中文摘要
预测免疫治疗的应答仍然具有挑战性,因为诸如TMB、PD-L1表达和整体免疫浸润等生物标志物仅提供肿瘤生物学的静态快照,无法捕捉免疫压力随时间累积的影响。免疫压力会在肿瘤演化上留下可辨识的印迹,刻画这些特征可能有助于区分那些经免疫编辑塑造的肿瘤与那些已逃脱免疫监视的肿瘤。将观测到的肿瘤基因组与患者特异性的中性预期进行比较,为揭示此类演化偏离提供了一个直接的框架。我们利用TCGA结直肠癌数据,生成了突变特征匹配的中性模拟,并量化了每个肿瘤在多个演化指标上偏离的程度。观测到的编码突变表现出明显大于中性模拟的离散度。尽管该队列整体上看似接近中性,但在某一指标上表现出强烈偏离的肿瘤,在其他指标上也一致地偏离,揭示出一个处于更强选择压力之下的连贯亚群。这些强烈偏离的肿瘤与公认的超突变类别相吻合——包括POLE突变的超突变肿瘤和MSI-H/富含插入缺失的肿瘤——并表现出陡峭的TMB梯度(各四分位数间为44.8对5.3 mut/Mb)。它们还表现出更强的免疫相关特征,包括显著更高的CD8相关浸润,以及在极端病例中升高的CD103比值,提示免疫活性对观测到的演化偏离有贡献。为评估更广泛的突变模式是否能够捕捉更深层的演化结构,我们将观测和模拟的突变目录嵌入到一个基因组基础模型中。所得的潜在空间清晰地将强烈偏离的肿瘤与接近中性的病例区分开来,并且也区分了分子亚型和每个样本的突变特征构成。这些发现提示,零样本序列表征捕捉到了与免疫驱动的肿瘤演化相关的上下文模式。由于这些嵌入以比经典汇总更精细的分辨率编码突变上下文,它们能够恢复在低维度指标中仍被掩盖的演化轨迹和潜在机制。总之,这些结果表明,即使在队列层面的平均值看似中性时,与免疫相关的演化偏离仍可被检测到。偏离中性预期最强烈的肿瘤对应于超突变生物学特征和增强的CD8驱动的免疫活性。基于演化的方法——尤其是与基础模型嵌入相结合时——提供了一个可扩展的框架,用于量化历史免疫压力,并在传统生物标志物之外改进免疫学分层。
查看英文原文 English abstract
Predicting response to immunotherapy remains challenging because biomarkers such as TMB, PD-L1 expression, and bulk immune infiltration offer only static snapshots of tumor biology and fail to capture the cumulative influence of immune pressure over time. Immune pressure leaves discernible footprints on tumor evolution, and characterizing these signatures may help distinguish tumors shaped by immune editing from those that have escaped immune surveillance. Comparing observed tumor genomes with patient-specific neutral expectations provides a direct framework for revealing such evolutionary deviations. Using TCGA colorectal cancers, we generated mutational-signature-matched neutral simulations and quantified how far each tumor diverged across multiple evolutionary metrics. Observed coding mutations showed substantially greater dispersion than neutral simulations. Although the cohort appeared near-neutral overall, tumors showing strong deviation in one metric consistently deviated across others, revealing a coherent subset under stronger selective pressure. These strongly deviated tumors aligned with well-established hypermutated categories-including POLE-mutated hypermutated tumors and MSI-H/indel-rich tumors-and displayed steep TMB gradients (44.8 vs 5.3 mut/Mb across quartiles). They also exhibited stronger immune-associated features, including significant higher CD8-related infiltration and elevated CD103 ratios in extreme cases, suggesting that immune activity contributes to the observed evolutionary divergence. To evaluate whether broader mutation patterns capture deeper evolutionary structure, we embedded observed and simulated mutation catalogs into a genomic foundation model. The resulting latent space clearly distinguished strongly deviated tumors from near-neutral cases, and also separated molecular subtypes and each sample's mutational-signature composition. These findings suggest that zero-shot sequence representations capture contextual patterns linked to immune-driven tumor evolution. Because these embeddings encode mutation context at a finer resolution than classical summaries, they can recover evolutionary trajectories and underlying mechanisms that remain obscured in low-dimensional metrics. Together, these results show that immune-linked evolutionary divergence is detectable even when cohort-level averages appear neutral. Tumors that diverge most strongly from neutral expectation correspond to hypermutated biology and increased CD8-driven immune activity. Evolution-based approaches-especially when combined with foundation-model embeddings-offer a scalable framework for quantifying historical immune pressure and refining immunologic stratification beyond conventional biomarkers.
利益披露 Disclosure
J. Koh,
Inocras Korea Employment, Stock Option.