PO.IM01.11 · 免疫学
一种同类首创的VIP受体拮抗剂作为急性髓系白血病的免疫治疗药物
A first in class VIP receptor antagonist as an immunotherapeutic for acute myeloid leukemia
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
当前靶向PD-1和PD-L1的免疫检查点疗法在治疗急性髓系白血病(AML)中无效。血管活性肠肽(VIP)是一种由28个氨基酸组成的免疫抑制性神经肽，在近30%的AML患者中过表达，提示某些AML肿瘤可能利用VIP表达作为逃避免疫监视的机制。我们假设AML细胞分泌VIP，通过T细胞上的VIP-R(受体)发出信号以限制抗癌免疫。因此，用VIP-R拮抗剂靶向VIP信号可逆转免疫抑制并增强抗癌免疫。通过计算机建模、体外筛选T细胞活化增强作用以及在小鼠白血病模型中进行的原理验证性筛选，我们鉴定出一种新型VIP-R拮抗剂ANT308。与VIP相比，ANT308对VIP-R显示出更强的结合亲和力，并以200-400 nM范围的EC50增强人和小鼠T细胞的活化。免疫荧光实验显示ANT308与VIP受体VPAC1共定位。Co-IP和流式细胞术证实了ANT308与VPAC1的结合。此外，用ANT308治疗白血病小鼠诱导了强烈的T细胞介导的抗白血病活性。为改善ANT308的药代动力学，我们开发了一种新型融合肽，将ANT308与IgG4的Fc片段结合，命名为CAMV-01。在Jurkat T细胞活化实验中，CAMV-01的EC50为100-200 nM，并可减少T细胞耗竭。此外，CAMV-01在多种鼠白血病模型中显著提高了生存率，包括分泌VIP的模型(C1498)和VIP阴性细胞系P815。体外稳定性研究显示，CAMV-01在血浆中可保持稳定>4天，而ANT308肽仅稳定15分钟。以15mg/kg CAMV-01进行静脉(i.v.)或皮下(s.c.)注射的PK研究显示其在小鼠体内的半衰期为2周，而ANT308肽为15分钟。在接受单次静脉或皮下注射5mg/kg CAMV-01的Sprague-Dawley大鼠中，Cmax和t1/2分别估计为82 nM和165小时(i.v.)，以及0.7 nM和235小时(s.c.)。在P815小鼠模型中，皮下给予CAMV-01诱导的四聚体阳性CD8+ T细胞反应强于ANT308。总之，CAMV-01是一种新型、同类首创的靶向VIP免疫检查点的免疫治疗药物，具有稳健的药代动力学和药效学特征，在治疗AML方面具有广阔的应用前景。
查看英文原文 English abstract
Current immune checkpoint therapies targeting PD-1 and PD-L1 are ineffective in treating Acute Myeloid Leukemia (AML). Vasoactive Intestinal Peptide (VIP) is an immunosuppressive 28-amino acid neuropeptide overexpressed in nearly 30% AML patients, suggesting that some AML tumors may be using VIP expression as a mechanism to evade immune surveillance. We hypothesize that AML cells secrete VIP which signals through the VIP-R (receptor) on T cells to limit anti-cancer immunity. Therefore, targeting the VIP signaling with a VIP-R antagonist can reverse immunosuppression and potentiate anti-cancer immunity. Using in silico modeling, in vitro screening for potentiation of T cell activation, and proof-of-principle screening in mouse leukemia models, we identified a novel VIP-R antagonist, ANT308. ANT308 shows stronger binding affinity to VIP-R as compared to VIP and potentiates activation of human and mouse T cells with an EC 50 in the range of 200-400 nM. Immunofluorescence assays show that ANT308 colocalizes with the VIP receptor, VPAC1. Co-IP and flow cytometry confirmed ANT308 binding to VPAC1. In addition, ANT308 treatment of leukemic mice induced strong T cell-mediated anti-leukemic activity. To improve the pharmacokinetics of ANT308, we have developed a novel fusion peptide combining ANT308 and Fc fragment of IgG4 named CAMV-01. In a Jurkat T-cell activation assay, CAMV-01 has an EC 50 of 100-200 nM and reduces T cell exhaustion. Furthermore, CAMV-01 significantly improved survival in multiple murine leukemia models, including those that secrete VIP (C1498) and the VIP negative cell line P815. In vitro stability studies show that CAMV-01 remains stable in plasma for > 4 days, whereas the ANT308 peptide is stable for only 15 minutes. PK studies with intravenous (i.v.) or subcutaneous (s.c.) injection of 15mg/kg CAMV-01 show a half-life of 2 weeks in mice, compared to 15 minutes for the ANT308 peptide. Using Sprague-Dawley rats receiving a single i.v. or s.c injection of 5mg/kg CAMV-01, the C max and t 1/2 were estimated to be 82 nM and 165 hours (i.v.) respectively and 0.7 nM and 235 hours (s.c.) respectively. In a P815 mouse model, s.c. administration of CAMV-01 induced a stronger tetramer-positive CD8+ T-cell response compared to ANT308. In conclusion, CAMV-01 is a novel, first-in-class immunotherapeutic targeting the VIP immune checkpoint, with a robust pharmacokinetic and pharmacodynamic profile and promising potential for the treatment of AML.
利益披露 Disclosure
S. Balaji, None..
A. Ward, None..
Y. Wang, None..
J. Li, None..
S. Sarkar, None..
S. Mecorapaj, None..
T. Kalsang, None..
S. Wang, None..
C. Giver, None..
E. Waller, None.