Tetravalent antibodies with altered FcRn binding sites

描述(申请人提供)：已开发出许多肿瘤反应性单抗，但大多数抗肿瘤活性很小。通常，这可以通过使用抗体的多聚体形式来克服，这些抗体然后能够通过超交联其目标抗原在细胞中诱导死亡信号。此外，增加它们在体内的半衰期以最大限度地提高肿瘤的渗透率通常是有帮助的。虽然化学产生的四价抗体在体外非常有效，但由于它们的大小，它们的药代动力学很差。它们也很难生产，成本也很高，而且由不同种类的产品组成。由几个Fv片段组成的重组多价载体在体内没有效应功能，半衰期短。关于抗体的Fc区，与内皮细胞中的FcRns结合是延长其体内半衰期的关键。因此，免疫球蛋白Fc区的特定突变可以增加或减少FcRN的结合，从而增加或减少其血清半衰期。这项研究的目的是构建一组抗体，1)四价的，包含人的Fc区，以增强其诱导细胞凋亡的能力和降低免疫原性，2)具有与免疫球蛋白类似的大小，以良好的肿瘤穿透性，以及3)整合FcRN-突变，以改变其在体内的半衰期。具有更长和更短半衰期的构建将在体外和体内对携带人类肿瘤的小鼠进行评估。前者将被用作“裸体”抗体，半衰期长应该是有利的。后者将被用作免疫毒素，其中较短的半衰期可能会减少毒副作用，从而增加最大耐受量。

DESCRIPTION (provided by applicant): Many tumor-reactive monoclonal antibodies have been developed but most have little anti-tumor activity. Often this can be overcome by using multimeric forms of the antibody which are then able to induce death signals in the cell by hypercrosslinking their target antigen. In addition, increasing their in vivo half-life to maximize tumor penetration is often helpful. Although chemically-generated tetravalent antibodies are highly effective in vitro, they have poor pharmacokinetics due to their large size. They are also difficult and expensive to produce and consist of heterogeneous mixtures of products. Recombinant multivalent constructs comprised of several Fv fragments have no effector functions and short half lives in vivo. With regard to the Fc region of an antibody, binding to FcRns in endothelial cells is critical for prolonging their in vivo half life. Hence, specific mutations in the Fc region of an IgG can increase or decrease FcRn binding and thereby increase or decrease its serum half-life. The goal of this study is to construct a panel of antibodies that 1) are tetravalent and contain a human Fc region in order to enhance their ability to induce apoptosis and to decrease immunogenicity, 2) have sizes comparable to IgGs for good tumor penetration, and 3) incorporate FcRn-mutations, to alter their half life in vivo. Constructs with both longer and shorter half-lives will be evaluated in vitro and in vivo in mice with human tumors. The former will be used as "naked" antibodies where a long half-life should be advantageous. The latter will be used as immunotoxins, where a short half-life may reduce toxic side effects, thereby increasing the maximum tolerated dose.