背景:白细胞介素-1受体辅助蛋白(IL1RAP)在急性髓性白血病(AML)大母细胞和白血病干细胞(LSCs)上高表达,但不是在正常造血干细胞(HSC),提供瞄准和消除疾病的机会,同时保留正常的造血功能。在这里,我们报道了新型抗IL1RAP/CD3T细胞接合剂(TCE)BIF002在AML中的活性。
方法:通过光电定位和单细胞测序,从从免疫小鼠收集的CD138+B细胞中分离IL1RAP抗体。产生并表征单个小鼠单克隆抗体(mAb),我们从其中产生BIF002,一种使用Fab臂交换的抗人IL1RAP/CD3TCE。在人IgG1Fc中引入突变以减少FcγR结合。使用多种细胞系和患者来源的AML样品在体外和体内表征BIF002的抗白血病活性。
结果:发现IL1RAP在大多数人AML细胞系和原代母细胞中高表达,包括从头和复发/难治性(R/R)白血病患者的CD34+LSC富集亚群,但不是正常的HSC。在来自健康供体和IL1RAPhighAML细胞系和原代母细胞的T细胞的共培养中,BIF002在亚纳摩尔浓度下诱导剂量和效应物对靶(E:T)比率依赖性T细胞活化和白血病细胞裂解。BIF002与人T细胞一起静脉内给药导致白血病细胞的消耗,并显著延长IL1RAPhighMOLM13或AML患者来源的异种移植物的存活,没有脱靶副作用,与对照组相比。值得注意的是,BiF002有效地重定向T细胞以消除LSCs,与来自载体-(中位生存期:26天;p=0.0004)或同种型对照抗体+T细胞治疗的供体(26天;p=0.0002)的骨髓(BM)的受体相比,来自BIF002+T细胞治疗的供体(中位生存期未达到;全部存活>200天)的骨髓(BM)的次级受体没有发生疾病。
结论:新型抗IL1RAP/CD3TCE,BIF002根除LSCs并显著延长AML异种移植物的存活时间,代表一个有希望的人,AML的新疗法。
BACKGROUND: 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.
METHODS: 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.
RESULTS: 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).
CONCLUSIONS: The novel anti-IL1RAP/CD3 TCE, BIF002, eradicates LSCs and significantly prolongs survival of AML xenografts, representing a promising, novel treatment for AML.