Reusch Uwe, Duell Johannes, Ellwanger Kristina, Herbrecht Carmen, Knackmuss Stefan Hj, Fucek Ivica, Eser Markus, McAleese Fionnuala, Molkenthin Vera, Gall Fabrice Le, Topp Max, Little Melvyn, Zhukovsky Eugene A
a Affimed Therapeutics AG ; Heidelberg , Germany.
MAbs. 2015;7(3):584-604. doi: 10.1080/19420862.2015.1029216.
To harness the potent tumor-killing capacity of T cells for the treatment of CD19(+) malignancies, we constructed AFM11, a humanized tetravalent bispecific CD19/CD3 tandem diabody (TandAb) consisting solely of Fv domains. The molecule exhibits good manufacturability and stability properties. AFM11 has 2 binding sites for CD3 and 2 for CD19, an antigen that is expressed from early B cell development through differentiation into plasma cells, and is an attractive alternative to CD20 as a target for the development of therapeutic antibodies to treat B cell malignancies. Comparison of the binding and cytotoxicity of AFM11 with those of a tandem scFv bispecific T cell engager (BiTE) molecule targeting the same antigens revealed that AFM11 elicited more potent in vitro B cell lysis. Though possessing high affinity to CD3, the TandAb mediates serial-killing of CD19(+) cells with little dependence of potency or efficacy upon effector:target ratio, unlike the BiTE. The advantage of the TandAb over the BiTE was most pronounced at lower effector:target ratios. AFM11 mediated strictly target-dependent T cell activation evidenced by CD25 and CD69 induction, proliferation, and cytokine release, notwithstanding bivalent CD3 engagement. In a NOD/scid xenograft model, AFM11 induced dose-dependent growth inhibition of Raji tumors in vivo, and radiolabeled TandAb exhibited excellent localization to tumor but not to normal tissue. After intravenous administration in mice, half-life ranged from 18.4 to 22.9 h. In a human ex vivo B-cell chronic lymphocytic leukemia study, AFM11 exhibited substantial cytotoxic activity in an autologous setting. Thus, AFM11 may represent a promising therapeutic for treatment of CD19(+) malignancies with an advantageous safety risk profile and anticipated dosing regimen.
为了利用T细胞强大的肿瘤杀伤能力来治疗CD19(+)恶性肿瘤，我们构建了AFM11，这是一种人源化四价双特异性CD19/CD3串联双体（TandAb），仅由Fv结构域组成。该分子具有良好的可制造性和稳定性。AFM11具有2个与CD3结合的位点和2个与CD19结合的位点，CD19是一种从早期B细胞发育到分化为浆细胞过程中均表达的抗原，作为治疗B细胞恶性肿瘤的治疗性抗体开发靶点，它是CD20的一个有吸引力的替代物。将AFM11与靶向相同抗原的串联单链抗体片段双特异性T细胞衔接器（BiTE）分子的结合和细胞毒性进行比较，结果显示AFM11在体外引发了更强的B细胞裂解。尽管该TandAb对CD3具有高亲和力，但与BiTE不同，它介导CD19(+)细胞的连续杀伤，其效力或功效对效应细胞：靶细胞比例的依赖性很小。TandAb相对于BiTE的优势在较低的效应细胞：靶细胞比例下最为明显。尽管有二价CD3结合，但AFM11介导的T细胞活化严格依赖于靶标，这通过CD25和CD69的诱导、增殖和细胞因子释放得以证明。在NOD/scid异种移植模型中，AFM11在体内诱导Raji肿瘤的剂量依赖性生长抑制，并且放射性标记的TandAb在肿瘤中表现出良好的定位，但在正常组织中则不然。在小鼠静脉注射后，半衰期为18.4至22.9小时。在一项人类离体B细胞慢性淋巴细胞白血病研究中，AFM11在自体环境中表现出显著的细胞毒性活性。因此，AFM11可能是一种有前景的治疗CD19(+)恶性肿瘤的药物，具有有利的安全风险特征和预期的给药方案。
