PDF(Pubmed)
Abstract：
New immune checkpoints are emerging in a bid to improve response rates to immunotherapeutic drugs. The adenosine A2A receptor (A2AR) has been proposed as a target for immunotherapeutic development due to its participation in immunosuppression of the tumor microenvironment. Blockade of A2AR could restore tumor immunity and, consequently, improve patient outcomes. Here, we describe the discovery of a potent, selective, and tumor-suppressing antibody antagonist of human A2AR (hA2AR) by phage display. We constructed and screened four single-chain variable fragment (scFv) libraries-two synthetic and two immunized-against hA2AR and antagonist-stabilized hA2AR. After biopanning and ELISA screening, scFv hits were reformatted to human IgG and triaged in a series of cellular binding and functional assays to identify a lead candidate. Lead candidate TB206-001 displayed nanomolar binding of hA2AR-overexpressing HEK293 cells; cross-reactivity with mouse and cynomolgus A2AR but not human A1, A2B, or A3 receptors; functional antagonism of hA2AR in hA2AR-overexpressing HEK293 cells and peripheral blood mononuclear cells (PBMCs); and tumor-suppressing activity in colon tumor-bearing HuCD34-NCG mice. Given its therapeutic properties, TB206-001 is a good candidate for incorporation into next-generation bispecific immunotherapeutics.
摘要：
新的免疫检查点正在出现，以提高对免疫治疗药物的反应率。腺苷A2A受体（A2AR）由于其参与肿瘤微环境的免疫抑制而被提议作为免疫治疗发展的靶标。阻断A2AR可以恢复肿瘤免疫,因此,改善患者预后。这里,我们描述了一种有效的发现，选择性,和通过噬菌体展示的人A2AR（hA2AR）的肿瘤抑制性抗体拮抗剂。我们构建并筛选了四个单链可变片段（scFv）文库-两个合成的和两个免疫的抗hA2AR和拮抗剂稳定的hA2AR。经过生物淘选和ELISA筛选，将scFv命中物重新格式化为人IgG,并在一系列细胞结合和功能测定中分类以鉴定前导候选物。候选铅TB206-001显示hA2AR过表达HEK293细胞的纳摩尔结合；与小鼠和食蟹猴A2AR的交叉反应性，但不与人A1，A2B，或A3受体；hA2AR在过表达hA2AR的HEK293细胞和外周血单核细胞（PBMC）中的功能拮抗作用；和结肠荷瘤HuCD34-NCG小鼠的肿瘤抑制活性。鉴于其治疗特性，TB206-001是掺入下一代双特异性免疫治疗剂的良好候选者。
