Site-selective antibody modification by cysteine-to-lysine transfer (CLT)

随着CRUK最近强调，我们中每2人中就有1人在一生中患有癌症，在开发新药和改进肿瘤学诊断方面取得进展的要求是我们社会的高度优先事项。目前化疗药物的技术水平仍然严重依赖非靶向细胞毒素，导致严重的副作用，在许多情况下是无法忍受的。相比之下，将细胞毒素附着到递送剂上，这种递送剂专门针对肿瘤的“弹头”，提供了诱人的“神奇子弹”化疗的可能性。抗体-药物结合物(ADC)代表了最有希望开发的这类药物之一，在过去的几年中有3个ADC获得了临床批准。然而，人们普遍认为，目前ADC的分子结构仍远未达到最佳，迫切需要这一领域的新技术来帮助其实现其临床潜力。最值得注意的是，目前使用的将细胞毒药物连接到抗体上的方法导致了高度复杂的产品混合物。其结果是一种包含大量不同种类的药物，每一种都有不同的药理特征。在这个项目中，我们提议开创一种新的产生ADC的化学方法，将药物附着在抗体的特定位置，产生优质的均一偶联物。至关重要的是，我们的策略将不需要对抗体进行基因工程来结合反应手柄，因此直接适用于天然的“现成”抗体。这将使世界各地的研究人员最大限度地获得同质ADC，并确保生产产量保持尽可能高，最终降低这些相对复杂的生物制药的成本。我们将通过靶向抗体表面的特定赖氨酸氨基酸来实现这一目标。这是一个具有挑战性的目标，因为存在大量的赖氨酸；因此，我们建议开发新的方法，在这种方法中，偶联试剂由邻近的半胱氨酸氨基酸引导到特定的位置。这种史无前例的半胱氨酸到赖氨酸转移(CLT)方法将在抗体和药物之间产生酰胺键，这些键已经被非常好地表征，并已知在体内非常稳定。这将带来高度的信心，这将有助于在外地迅速采取行动。总体而言，CLT平台将代表生产ADC的最佳方法，并促进这些令人兴奋的靶向疗法的更广泛成功。

With CRUK recently highlighting that 1 in 2 of us will have cancer in our lifetimes, the requirement for progress in developing new medicines and improved diagnostics for oncology is a high priority for our society. The current state of the art in chemotherapeutics still relies heavily on untargeted cytotoxins, leading to severe side-effects which are intolerable in many cases. In contrast, the attachment of cytotoxins to a delivery agent, which targets the 'warhead' specifically to the tumor, offers the enticing possibility of 'magic-bullet' chemotherapies. Antibody-Drug Conjugates (ADCs) represent amongst the most promising class of such drugs in development, with 3 ADCs achieving clinical approval in the last few years. However, it is widely considered that the molecular construction of ADCs currently is still far from optimal, and that new technologies in this area are urgently required to help enable them to achieve their clinical potential. Most notably current approaches employed to attach the cytotoxic drugs to the antibodies lead to a highly complex mixture of products. The result is a drug which contains a vast number of distinct species, each with a different pharmacological profile. In this project we are proposing to pioneer a new chemical approach for the generation of ADCs, which attaches the drugs at specific locations on the antibody, generating superior homogeneous conjugates. Our strategy, crucially, will not require genetic engineering of the antibodies to incorporate reactive handles, and is thus applicable directly to native 'off-the-shelf' antibodies. This will maximise the accessibility of homogenous ADCs to researchers across the world and ensure that the production yields are maintained as high as possible, ultimately reducing the cost of these relatively complex biopharmaceuticals. We will achieve goal this by targeting specific lysine amino-acids on the surface of the antibodies. This is a challenging aim as there are numerous lysines present; and as such we are proposing to develop new methodology, in which the conjugation reagent is guided to a specific location by a neighbouring cysteine amino-acid. This unprecedented cysteine-to-lysine transfer (CLT) approach will generate amide linkages between the antibody and the drug which are already extremely well characterised and known to be robustly stable in vivo. This will afford a high-level of confidence which will facilitate rapid uptake in the field. Overall this CLT platform will represent an optimum approach for producing ADCs and facilitate the wider success of these exciting targeted therapies.