Department of Medicine, Roswell Park Comprehensive Cancer Center (Roswell Park), Buffalo, NY.
Department of Hematology, Cellular Therapy and Hemostaseology, Univeristy Hospital of Leipzig, Leipzig, Germany.
Blood Adv. 2023 Mar 14;7(5):718-733. doi: 10.1182/bloodadvances.2022007457.
Spatial heterogeneity is a common phenomenon in metastatic solid tumors and an evolving concept in multiple myeloma (MM). The interplay between malignant plasma cells (PCs) and the microenvironment has not yet been analyzed in MM. For this purpose, we performed bone marrow aspirates and imaging-guided biopsies of corresponding lesions in newly diagnosed MM (NDMM) and relapsed/refractory MM (RRMM) patients. PCs were isolated and subjected to whole-exome sequencing (WES). Non-PCs were studied with next-generation flow (NGF) and T-cell receptor sequencing (TCRseq) to analyze the connection between malignant and nonmalignant cells in the bone marrow and in lesions. Although we observed a strong overlap from WES, NGF, and TCRseq in patients with intramedullary disease, WES revealed significant spatial heterogeneity in patients with extramedullary disease. NGF showed significant immunosuppression in RRMM compared with NDMM as indicated by fewer myeloid dendritic cells, unswitched memory B cells, Th9 cells, and CD8 effector memory T cells but more natural killer and regulatory T cells. Additionally, fewer T-cell receptor (TCR) sequences were detected in RRMM compared with NDMM and healthy individuals. After induction therapy, TCR repertoire richness increased to levels of healthy individuals, and NGF showed more regulatory T cells and myeloid-derived suppressor cells, regardless of depth of response. Clinical significance of imaging-guided biopsies of lesions was demonstrated by detection of monoclonal PCs in patients without measurable residual disease (MRD) in aspirates from the iliac crest as well as identification of secondary primary malignancies in MRD- patients. Furthermore, site-specific clones with different drug susceptibilities and genetically defined high-risk features were detected by our workflow.
空间异质性是转移性实体瘤的常见现象，也是多发性骨髓瘤（MM）中的一个不断发展的概念。恶性浆细胞（PC）与微环境之间的相互作用尚未在 MM 中进行分析。为此，我们对新诊断的 MM（NDMM）和复发/难治性 MM（RRMM）患者进行了骨髓抽吸和相应病变的影像学引导活检。我们分离了 PC 并进行了全外显子组测序（WES）。我们使用下一代流式细胞术（NGF）和 T 细胞受体测序（TCRseq）研究了非 PC，以分析骨髓和病变中恶性细胞与非恶性细胞之间的联系。尽管我们在骨髓腔内疾病患者中观察到 WES、NGF 和 TCRseq 之间存在很强的重叠，但 WES 显示出骨髓外疾病患者存在明显的空间异质性。NGF 在 RRMM 中表现出明显的免疫抑制作用，与 NDMM 相比，髓样树突状细胞、未转换记忆 B 细胞、Th9 细胞和 CD8 效应记忆 T 细胞减少，而自然杀伤细胞和调节性 T 细胞增加。此外，RRMM 中的 T 细胞受体（TCR）序列比 NDMM 和健康个体少。诱导治疗后，TCR 库丰富度增加到健康个体的水平，无论反应深度如何，NGF 均显示出更多的调节性 T 细胞和髓源性抑制细胞。通过检测髂嵴抽吸物中无可测量残留疾病（MRD）的患者中的单克隆 PC 以及在 MRD 患者中鉴定继发性原发性恶性肿瘤，证明了病变影像学引导活检的临床意义。此外，我们的工作流程还检测到了具有不同药物敏感性和遗传定义的高危特征的特定部位克隆。
