Tetravalent antibodies with altered FcRn binding sites

描述（由申请人提供）：许多肿瘤反应性单克隆抗体已经开发出来，但大多数抗肿瘤活性很小。这通常可以通过使用多聚体形式的抗体来克服，这些抗体随后能够通过超交联其靶抗原在细胞中诱导死亡信号。此外，增加它们的体内半衰期以最大限度地提高肿瘤穿透性通常是有帮助的。虽然化学生成的四价抗体在体外非常有效，但由于其体积较大，其药代动力学较差。它们的生产难度大、成本高，而且是由多种产品混合而成。由多个Fv片段组成的重组多价结构体在体内无效应功能且半衰期短。就抗体的Fc区而言，与内皮细胞中的FcRns结合对于延长其体内半衰期至关重要。因此，IgG Fc区的特异性突变可以增加或减少FcRn结合，从而增加或减少其血清半衰期。本研究的目标是构建一组抗体，1)是四价的，含有人类Fc区，以增强其诱导细胞凋亡和降低免疫原性的能力，2)具有与igg相当的大小，以良好的肿瘤穿透，3)包含fcrn突变，以改变其在体内的半衰期。具有较长和较短半衰期的构建体将在体外和体内对患有人类肿瘤的小鼠进行评估。前者将用作“裸”抗体，其半衰期长是有利的。后者将用作免疫毒素，其半衰期短可减少毒副作用，从而增加最大耐受剂量。

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.