The interleukin-1 receptor accessory protein (IL1RAP) is highly expressed on acute myeloid leukemia (AML) bulk blasts and leukemic stem cells (LSCs), but not on normal hematopoietic stem cells (HSCs), providing an opportunity to target and eliminate the disease, while sparing normal hematopoiesis. Herein, we report the activity of BIF002, a novel anti-IL1RAP/CD3 T cell engager (TCE) in AML. Antibodies to IL1RAP were isolated from CD138+ B cells collected from the immunized mice by optoelectric positioning and single cell sequencing. Individual mouse monoclonal antibodies (mAbs) were produced and characterized, from which we generated BIF002, an anti-human IL1RAP/CD3 TCE using Fab arm exchange. Mutations in human IgG1 Fc were introduced to reduce FcγR binding. The antileukemic activity of BIF002 was characterized in vitro and in vivo using multiple cell lines and patient derived AML samples. IL1RAP was found to be highly expressed on most human AML cell lines and primary blasts, including CD34+ LSC-enriched subpopulation from patients with both de novo and relapsed/refractory (R/R) leukemia, but not on normal HSCs. In co-culture of T cells from healthy donors and IL1RAPhigh AML cell lines and primary blasts, BIF002 induced dose- and effector-to-target (E:T) ratio-dependent T cell activation and leukemic cell lysis at subnanomolar concentrations. BIF002 administered intravenously along with human T cells led to depletion of leukemic cells, and significantly prolonged survival of IL1RAPhigh MOLM13 or AML patient-derived xenografts with no off-target side effects, compared to controls. Of note, BiF002 effectively redirects T cells to eliminate LSCs, as evidenced by the absence of disease initiation in secondary recipients of bone marrow (BM) from BIF002+T cells-treated donors (median survival not reached; all survived > 200 days) compared with recipients of BM from vehicle- (median survival: 26 days; p = 0.0004) or isotype control antibody+T cells-treated donors (26 days; p = 0.0002). The novel anti-IL1RAP/CD3 TCE, BIF002, eradicates LSCs and significantly prolongs survival of AML xenografts, representing a promising, novel treatment for AML.

中文翻译：

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IL1RAP 特异性 T 细胞接合器耗竭急性髓系白血病干细胞


白细胞介素-1 受体辅助蛋白 （IL1RAP） 在急性髓系白血病 （AML） 大量原始细胞和白血病干细胞 （LSC） 上高度表达，但在正常造血干细胞 （HSC） 上不高表达，为靶向和消除疾病提供了机会，同时保留了正常的造血功能。在此，我们报道了 BIF002 的活性，BIF002 是一种新型抗 IL1RAP/CD3 T 细胞接合器 （TCE） 在 AML 中的作用。通过光电定位和单细胞测序，从免疫小鼠收集的 CD138+ B 细胞中分离 IL1RAP 抗体。生产并表征个体小鼠单克隆抗体 （mAb），我们从中生成 BIF002，一种使用 Fab 臂交换的抗人 IL1RAP/CD3 TCE。引入人 IgG1 Fc 突变以减少 FcγR 结合。使用多种细胞系和患者来源的 AML 样本在体外和体内表征 BIF002 的抗白血病活性。发现 IL1RAP 在大多数人 AML 细胞系和原代母细胞中高表达，包括来自新发和复发/难治性 （R/R） 白血病患者的 CD34+ LSC 富集亚群，但在正常 HSC 上不高表达。在来自健康供体的 T 细胞与 IL1RAPhigh AML 细胞系和原代原始细胞的共培养中，BIF002 诱导亚纳摩尔浓度的剂量和效应-靶标 （E：T） 比率依赖性 T 细胞活化和白血病细胞裂解。与对照组相比，BIF002 与人 T 细胞一起静脉内给药导致白血病细胞耗竭，并显着延长了 IL1RAPhigh MOLM13 或 AML 患者来源的异种移植物的生存期，且无脱靶副作用。 值得注意的是，BiF002 有效地重定向 T 细胞以消除 LSC，这可以通过来自载体 - （中位生存期：26 天;p = 0.0002;p = 0.0002）的 BM 受体相比，来自载体 - （中位生存期：26 天;p = 0.0004）或同种型对照抗体 + T 细胞处理的供体 （26 天;p = 0.0002） 的骨髓 （BM） 的次级受者没有发病。新型抗 IL1RAP/CD3 TCE BIF002 可根除 LSC 并显着延长 AML 异种移植物的生存期，代表了一种有前途的新型 AML 治疗方法。