Higher-order death receptor 5 (DR5) clustering can induce tumor cell death; however, therapeutic compounds targeting DR5 have achieved limited clinical efficacy. We describe HexaBody-DR5/DR5, an equimolar mixture of two DR5-specific IgG1 antibodies with an Fc-domain mutation that augments antibody hexamerization after cell surface target binding. The two antibodies do not compete for binding to DR5 as demonstrated using binding competition studies, and binding to distinct epitopes in the DR5 extracellular domain was confirmed by crystallography. The unique combination of dual epitope targeting and increased IgG hexamerization resulted in potent DR5 agonist activity by inducing efficient DR5 outside-in signaling and caspase-mediated cell death. Preclinical studies in vitro and in vivo demonstrated that maximal DR5 agonist activity could be achieved independent of Fc gamma receptor–mediated antibody crosslinking. Most optimal agonism was observed in the presence of complement complex C1, although without inducing complement-dependent cytotoxicity. It is hypothesized that C1 may stabilize IgG hexamers that are formed after binding of HexaBody-DR5/DR5 to DR5 on the plasma membrane, thereby strengthening DR5 clustering and subsequent outside-in signaling. We observed potent antitumor activity in vitro and in vivo in large panels of patient-derived xenograft models representing various solid cancers. The results of our preclinical studies provided the basis for an ongoing clinical trial exploring the activity of HexaBody-DR5/DR5 (GEN1029) in patients with malignant solid tumors.

中文翻译：

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双表位靶向和 DR5 抗体增强的六聚化作为一种​​通过 DR5 激动诱导有效抗肿瘤活性的新方法

高阶死亡受体5（DR5）聚集可诱导肿瘤细胞死亡；然而，靶向 DR5 的治疗性化合物的临床疗效有限。我们描述了 HexaBody-DR5/DR5，这是两种 DR5 特异性 IgG1 抗体的等摩尔混合物，具有 Fc 域突变，可在细胞表面靶标结合后增强抗体六聚化。两种抗体不竞争结合 DR5，如使用结合竞争研究所证明的，并且结合 DR5 胞外域中的不同表位已通过晶体学证实。双表位靶向和增加的 IgG 六聚化的独特组合通过诱导有效的 DR5 由外向内信号传导和半胱天冬酶介导的细胞死亡，产生有效的 DR5 激动剂活性。体外和体内的临床前研究表明，可以在不依赖 Fc γ 受体介导的抗体交联的情况下实现最大的 DR5 激动剂活性。在补体复合物 C1 存在下观察到最优化的激动作用，尽管不会诱导补体依赖性细胞毒性。据推测，C1 可以稳定 HexaBody-DR5/DR5 与质膜上的 DR5 结合后形成的 IgG 六聚体，从而加强 DR5 聚类和随后的外向内信号传导。我们在代表各种实体癌的大量患者来源的异种移植模型中观察到了有效的体外和体内抗肿瘤活性。我们的临床前研究结果为正在进行的临床试验提供了基础，该试验探索了 HexaBody-DR5/DR5 (GEN1029) 在恶性实体瘤患者中的活性。