DataSheet_1_In Vitro Sensitivity to Venetoclax and Microenvironment Protection in Hairy Cell Leukemia.zip

Current standard treatment of patients with hairy cell leukemia (HCL), a chronic B-cell neoplasia of low incidence that affects the elderly, is based on the administration of purine analogs such as cladribine. This chemotherapy approach shows satisfactory responses, but the disease relapses, often repeatedly. Venetoclax (ABT-199) is a Bcl-2 inhibitor currently approved for the treatment of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) in adult patients ineligible for intensive chemotherapy. Given that HCL cells express Bcl-2, our aim was to evaluate venetoclax as a potential therapy for HCL. We found that clinically relevant concentrations of venetoclax (0.1 and 1 µM) induced primary HCL cell apoptosis in vitro as measured by flow cytometry using Annexin V staining. As microenvironment induces resistance to venetoclax in CLL, we also evaluated its effect in HCL by testing the following stimuli: activated T lymphocytes, stromal cells, TLR-9 agonist CpG, and TLR-2 agonist PAM3. We found decreased levels of venetoclax-induced cytotoxicity in HCL cells exposed for 48 h to any of these stimuli, suggesting that leukemic B cells from HCL patients are sensitive to venetoclax, but this sensitivity can be overcome by signals from the microenvironment. We propose that the combination of venetoclax with drugs that target the microenvironment might improve its efficacy in HCL.

毛细胞白血病（hairy cell leukemia, HCL）是一种累及老年人群的低发病率慢性B细胞肿瘤，当前其标准治疗方案以嘌呤类似物（purine analogs，如克拉屈滨（cladribine））给药为基础。这类化疗方案虽可取得较为理想的临床应答，但疾病往往会反复复发。维奈克拉（venetoclax, ABT-199）作为Bcl-2抑制剂，目前已获批用于治疗不符合强化化疗指征的成人慢性淋巴细胞白血病（chronic lymphocytic leukemia, CLL）与急性髓系白血病（acute myeloid leukemia, AML）。鉴于HCL细胞表达Bcl-2蛋白，本研究旨在评估维奈克拉作为HCL潜在治疗手段的可行性。研究团队通过膜联蛋白V染色结合流式细胞术检测证实，临床相关浓度（0.1 μM与1 μM）的维奈克拉可在体外诱导原发性HCL细胞发生凋亡。由于肿瘤微环境会诱导慢性淋巴细胞白血病细胞对维奈克拉产生耐药性，本研究同时针对以下刺激因素开展实验，以评估维奈克拉对HCL的作用效果：活化T淋巴细胞、基质细胞、Toll样受体9（TLR-9）激动剂CpG以及Toll样受体2（TLR-2）激动剂PAM3。结果显示，经上述任意一种刺激因素处理48小时后，HCL细胞的维奈克拉诱导细胞毒性水平均有所降低，这表明HCL患者的白血病B细胞对维奈克拉具有敏感性，但该敏感性可被肿瘤微环境传递的信号所抵消。本研究认为，将维奈克拉与靶向肿瘤微环境的药物联合应用，或可提升其在HCL治疗中的临床疗效。