Dissecting the regulation of antibody immunotherapy by Fc gamma receptor IIB

生物疗法是制药行业发展最快的领域之一，这在很大程度上是由单克隆抗体（mab）的成功推动的。自1997年利妥昔单抗获批以来，单克隆抗体现已成功用于治疗多种疾病，从癌症到自身免疫。由于人口老龄化，这些疾病的数量正在迅速增加，因此需要新的更有效的治疗方法。为了保持基于单克隆抗体的治疗方法的增长并提高其有效性，我们需要更好地了解其作用机制并开发新的抗体格式以克服任何限制。在这些新形式中，多特异性抗体具有同时参与目标以驱动独特生物反应的能力。mAb依赖于它们的Fc区发挥功能，在Fc受体与免疫效应细胞结合后触发免疫反应。通常，治疗性单克隆抗体是IfG同型的，因此Fc γ受体（FcyRs）主要参与其调控和作用方式。人类有6个fcyr；5通常会触发效应细胞和单一抑制受体FcyRIIB的激活，在小鼠中也有类似的情况。我们最近的研究表明，根据抗体靶点和/或特异性mAb，这种抑制性受体实际上对mAb免疫治疗有非常不同的影响。原则上，这似乎与FcyRIIB促进高阶受体聚集的能力有关，从而导致更有效的信号传导，但这尚未得到正式证明。我们还进行了令人惊讶的观察，表明FcyRIIB调节单克隆抗体和单克隆抗体样试剂（如多特异性）的半衰期。该项目的目的是探索FcyRIIB的这些基本特性，以充分阐明它是否以及如何调节mAb聚集，是否涉及与激活FcyR的简单竞争，以及它如何促进mAb半衰期。第二个目标是制定策略来潜在地克服这些抑制方面，以促进mAb免疫治疗。具体来说，使用一组现有的和新的小鼠模型，缺乏FcyRIIB和表达修饰版本的受体（例如信号缺陷），我们将探索单克隆抗体的半衰期和活性是如何调节的。这将通过使用各种已建立的和新颖的单抗格式来实现，旨在了解驱动生物学的相互作用的分子基础。由于FcyR基因库随细胞类型、位置和疾病状态而变化，这些技术需要仔细评估。例如，激活和抑制FcyR的比例可能会对生物学产生很大影响，并将通过仔细测量和使用缺乏一种或全部激活FcyR的小鼠和/或表达人类FcyR的小鼠来评估。该研究成果将促进对FcyRIIB如何调节单克隆抗体半衰期和活性的基本理解，为开发更有效的单克隆抗体疗法提供信息，从而改善癌症和自身免疫等疾病患者的健康。此外，所生成的工具将更好地了解FcyRIIB对单克隆抗体的调控作用，帮助所有研究单克隆抗体的研究人员（基础科学家、小型生物技术公司、开发/生产这些试剂的大型制药公司）。

Biological therapies are one of the fastest growing sectors of the pharmaceutical industry, driven in large part by the success of monoclonal antibodies (mAbs). Since the approval of rituximab in 1997, mAbs are now successfully employed in the treatment of multiple diseases, ranging from cancer to autoimmunity. These diseases are rapidly increasing in number due to our aging population and so new and more effective treatments are required. To maintain this growth in mAb-based treatments and increase their effectiveness we need to better understand their mechanisms of action and develop new antibody formats to overcome any limitations. Amongst these new formats are multi-specific antibodies which have the ability to engage targets simultaneously to drive unique biological responses.mAb depend on their Fc region for function, triggering immune responses following engagement of Fc receptors on immune effector cells. Typically, therapeutic mAbs are of the IfG isotype and so Fc gamma Receptors (FcyRs) are centrally involved in their regulation and mode of action. In humans there are 6 FcyRs; 5 which typically trigger activation of the effector cell and a single inhibitory receptor FcyRIIB, with a similar situation in the mouse.Our recent work has demonstrated that this inhibitory receptor can in fact have very differing effects on mAb immunotherapy, according to the antibody target and/or the specific mAb. Principally, this appears to be related to the ability of FcyRIIB to facilitate higher order clustering of receptors, leading to more potent signalling, however this has not been demonstrated formally. We have also made a surprising observation indicating that FcyRIIB regulates the half-life of mAb and mAb-like reagents such as multi-specifics. The aim of the proposed project is to explore these basic properties of FcyRIIB, to fully elucidate if and how it regulates mAb clustering, whether simple competition with activatory FcyR is involved and how it contributes to mAb half-life. A secondary aim is to develop strategies to potentially overcome these inhibitory aspects to boost mAb immunotherapy. Specifically, using a panel of existing and novel mouse models, lacking FcyRIIB and expressing modified versions of the receptor (eg signalling defective) we will explore how mAb half-life and activity is regulated. This will be achieved using a variety of established and novel mAb formats, designed to understand the molecular basis of the interactions driving the biology. As the FcyR repertoire varies with cell type, location and disease status, these technologies will require careful assessment. For example, the ratio of activatory: inhibitory FcyR may well influence the biology and will be assessed through careful measurement and also the use of mice lacking one or all of the activatory FcyR and/or mice expressing human FcyR. The research outcomes will foster basic understanding of how FcyRIIB regulates mAb half-life and activity, serving to inform the development of more effective mAb therapies and so improve the health of those with diseases such as cancer and autoimmunity. In addition, the tools generated will yield better basic understanding of mAb regulation by FcyRIIB assisting all researchers working with mAb (basic scientists, small biotechs, large pharma developing/producing these reagents).