Inotuzumab ozogamicin (InO) is an antibody-drug conjugate that delivers calicheamicin to CD22-expressing cells. In a retrospective cohort of InO-treated patients with B-cell acute lymphoblastic leukemia, we sought to understand the genomic determinants of the response and resistance to InO. Pre- and post-InO–treated patient samples were analyzed by whole genome, exome, and/or transcriptome sequencing. Acquired mutations were observed in 11% (3/27) of post-InO-relapsed tumor samples, but not in refractory samples (0/16). There were multiple mutations per sample and the mechanisms of CD22 escape included epitope loss (protein truncation and destabilization) and epitope alteration. Two mutant cases were post-InO hyper-mutators resulting from error-prone DNA damage repair (nonhomologous/alternative end-joining repair, or mismatch repair deficiency), suggesting that hypermutation drove escape from CD22-directed therapy. -mutant relapses occurred after InO and subsequent hematopoietic stem cell transplantation (HSCT), suggesting that InO eliminated the predominant clones, leaving subclones with acquired mutations that conferred resistance to InO and subsequently expanded. Acquired loss-of-function mutations in , , and were observed, consistent with a compromise of the G1/S DNA damage checkpoint as a mechanism for evading InO-induced apoptosis. Genome-wide CRISPR/Cas9 screening of cell lines identified (terminal deoxynucleotidyl transferase) loss as a marker of InO resistance. In conclusion, genetic alterations modulating CD22 expression and DNA damage response influence InO efficacy. Our findings highlight the importance of defining the basis of CD22 escape and eradication of residual disease before HSCT. The identified mechanisms of escape from CD22-targeted therapy extend beyond antigen loss and provide opportunities to improve therapeutic approaches and overcome resistance. These trials were registered at as NCT01134575, NCT01371630, and NCT03441061.

中文翻译：

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B 细胞 ALL 对伊珠单抗奥佐米星的反应和耐药性的基因组决定因素


Inotuzumab ozogamicin (InO) 是一种抗体药物偶联物，可将加利车霉素递送至表达 CD22 的细胞。在接受 InO 治疗的 B 细胞急性淋巴细胞白血病患者的回顾性队列中，我们试图了解 InO 反应和耐药性的基因组决定因素。通过全基因组、外显子组和/或转录组测序对 InO 治疗前和治疗后的患者样本进行分析。在 11% (3/27) 的 InO 复发后肿瘤样本中观察到获得性突变，但在难治性样本中没有观察到 (0/16)。每个样本存在多个突变，CD22 逃逸的机制包括表位丢失（蛋白质截短和不稳定）和表位改变。两个突变病例是由易于出错的 DNA 损伤修复（非同源/选择性末端连接修复或错配修复缺陷）引起的 InO 后超突变，表明超突变导致逃避 CD22 定向治疗。 InO 和随后的造血干细胞移植 (HSCT) 后发生突变复发，表明 InO 消除了主要克隆，留下具有获得性突变的亚克隆，这些突变赋予 InO 抗性并随后扩展。观察到 、 、 和 中获得性功能丧失突变，这与 G1/S DNA 损伤检查点的妥协作为逃避 InO 诱导的细胞凋亡的机制一致。对细胞系进行全基因组 CRISPR/Cas9 筛选，发现（末端脱氧核苷酸转移酶）缺失是 InO 抗性的标志。总之，调节 CD22 表达和 DNA 损伤反应的基因改变会影响 InO 功效。我们的研究结果强调了在 HSCT 之前确定 CD22 逃逸基础和根除残留疾病的重要性。 已确定的逃避 CD22 靶向治疗的机制不仅限于抗原丢失，还为改进治疗方法和克服耐药性提供了机会。这些试验注册号为 NCT01134575、NCT01371630 和 NCT03441061。