Preparation of site-specific antibody-drug conjugates by proximity-based sortase ligation

对于使用抗体药物缀合物（ADC）治疗癌症的兴趣日益增加， 越来越多的数据表明，与对照组相比， 1 -4.目前使用的两种ADC， 经FDA批准，维布妥昔单抗（Adcetris）和ado-曲妥珠单抗-美坦新偶联物（T-DM 1; Kadcyla） 在药物的位置和每个IgG的药物数量方面都是异质混合物。最近 有证据表明，差异标记的抗体，即在不同的位置和用不同的标记的抗体， 数量，可以有不同的治疗和药代动力学特性5，一些亚群可以显示 即使有，也很少有治疗活性，但大部分毒性是由治疗活性引起的。 开发位点特异性ADC，这些ADC在预定义的位置精确地用药物标记。 目前，存在四种用于产生位点特异性ADC的一般方法。其中包括 将半胱氨酸标签引入IgG的遗传密码，6，9使用非天然氨基酸，10添加 用酶（例如甲酰甘氨酸生成酶或 11和聚糖修饰（例如通过糖基转移酶）。 尽管具有独特的优点，但缺点可包括低产物产率、低效的药物缀合、不稳定和/或不稳定的药物缀合。 疏水性抗体-药物接头化学，或与糖基化抗体不相容。我们建议 进一步开发一种新的位点特异性生物缀合方法，基于邻近的分选酶连接（PBSL）， 可以高产率产生ADC，允许将不同的药物位点特异性地添加到重链和/或轻链中， 链，与糖基化IgG相容，并在抗体-药物接头化学中提供无限的灵活性。 因此，我们相信，这项技术将为现场生产提供一种新的、有利的途径， 这将是制药行业感兴趣的特定ADC。这项建议的具体目标是： 目的1：使用PBSL来产生位点特异性抗前列腺特异性膜抗原（PSMA）-MMAE ADC，并且 目的2：评价位点特异性抗PSM-MMAE ADC的结合和功效 体外

There has been growing interest in the use of antibody drug conjugates (ADCs) for the treatment of cancer as mounting data suggests an increase in anti-tumor effectiveness and reduced toxicity, compared with the administration of unlabeled antibodies in combination with chemotherapy.1-4 The two ADCs that are currently approved by the FDA, brentuximab vedotin (Adcetris) and ado-trastuzumab emtansine (T-DM1; Kadcyla) are both heterogeneous mixtures in terms of both the location of the drug and the number of drugs per IgG. Recent evidence has shown that differentially labeled antibodies, i.e. labeled at different locations and with different numbers, can have distinct therapeutic and pharmacokinetic properties5 and some subpopulations can show little, if any, therapeutic activity yet account for most of the toxicity.6-8 Therefore, there has been a movement towards the development of site-specific ADCs, which are precisely labeled with drugs at pre-defined locations. Currently, there are four general approaches for the generation of site-specific ADCs. These include the introduction of cysteine-tags into the genetic code of IgG,6, 9 the use of unnatural amino acids,10 the addition of peptide tags that are recognized and modified with enzymes (e.g. formylglycine generating enzyme or transglutaminase),8, 11 and glycan modifications (e.g. via glycotransferase).12 While each approach has its own unique advantages, shortcomings can include low product yields, inefficient drug conjugation, unstable and/or hydrophobic antibody-drug linker chemistry, or incompatibility with glycosylated antibodies. We propose to further develop a new site-specific bioconjugation approach, Proximity-Based Sortase Ligation (PBSL), that can produce ADCs in high yields, allows different drugs to be site-specifically added to the heavy and/or light chains, is compatible with glycosylated IgG, and offers unlimited flexibility in antibody-drug linker chemistry. Therefore, we believe that this technology will provide a new, favorable approach for the production of site- specific ADCs that will be of interest to the pharmaceutical industry. The specific aims for this proposal are: Aim 1: Use PBSL to produce site-specific anti-prostate specific membrane antigen (PSMA)-MMAE ADCs and characterize their properties; Aim 2: Evaluate the binding and efficacy of site-specific anti-PSMA-MMAE ADCs in vitro