Promoting cancer cells' antigen presentation for serving as better targets for T cell immunotherapy

细胞毒性T细胞(CTL)在识别细胞表面主要组织相容性复合体(MHC)呈递的抗原肽后杀伤肿瘤细胞，是包括免疫治疗在内的精确医学的目标。然而，肿瘤细胞采用几种机制来避免肿瘤特异性抗原(TSA或TAA)的呈递，因此，它们可以逃避CTL介导的细胞死亡。这导致许多免疫疗法即使在适当刺激免疫(例如CTL)的情况下也无法控制肿瘤的生长。大多数针对抗原提呈的免疫治疗主要集中在专业的抗原提呈细胞，而很少针对肿瘤细胞本身，从而导致疗效不佳。因此，增强肿瘤细胞中抗原呈递过程的免疫疗法和产品是一个未得到满足的需求。这个项目的目的是开发一种小分子，可以促进抗原呈递给CTL。我们打算针对两种细胞内蛋白，即Survivin(SVN)和KRAS，这两种蛋白是在肿瘤形成和转移中起重要作用的TAA。在这个项目中，我们将筛选能够特异性靶向和降解SVN和KRAS的小分子，然后增强癌细胞中的抗原递呈。这些小分子可以单独用于临床(直接杀死肿瘤细胞)，或者更重要的是，与免疫疗法(如肿瘤治疗性疫苗)结合使用。在联合治疗的情况下，小分子的剂量预计将比单一治疗少。最终，我们希望这将通过细胞毒性T细胞的作用导致肿瘤细胞死亡。我们还相信，这些分子可以提高现有免疫疗法的有效性。一旦这些小分子被表征并在体外抗原提呈试验中进行测试，我们将在体内模型中测试小分子与肿瘤治疗性疫苗的联合治疗。我们将与正在开发治疗性疫苗(SVN和KRAS)的OVM合作。SVN治疗性疫苗正在进行I期临床试验。如果小分子与治疗性疫苗协同作用，OVM将对这项技术的许可感兴趣。目标：1.小分子的筛选和表征**作为已建立的合作的一部分，我们已经识别和修饰了结合和抑制SVN的小分子。我们将进一步修饰这些分子，使它们更好地在肿瘤细胞内呈递抗原。有了这一经验，我们将识别和筛选靶向KRAS的小分子。我们将使用自然质谱学和晶体浸泡等技术来表征新的小分子与相关目标蛋白的结合亲和力。还将对每个小分子的关键结构参数进行优化，以最大限度地提高生物活性。测试小分子在增强肿瘤细胞中的抗原提呈上的作用*在这里，我们将使用识别肿瘤细胞提呈的抗原肽的T细胞克隆。这一实验系统已经在肿瘤科建立。开发的小分子也可以用体内异种移植瘤模型进行测试。我们之前已经为SVN(LQZ-7I)制造和修饰了小分子，令人高兴的是，在我们的分析中，该分子显示了对肿瘤细胞的结合和抑制(图1)。与肿瘤治疗性疫苗的联合治疗OVM是牛津大学派生的一家中小企业，开发肿瘤治疗性疫苗。基于SNV的治疗性疫苗(OVM-200)正在英国进行第一阶段临床试验。以KRAS为基础的疫苗(OVM-400)正在开发中。在目标1和目标2中开发的小分子将与OVM-200或OVM-400一起进行测试。

Cytotoxic T cells (CTLs), which kill tumour cells upon recognition of antigenic peptides presented by the major histocompatibility complex (MHC) on the cell surface, are the goal of precision medicine including immunotherapies. However, tumour cells engage several mechanisms to avoid the presentation of tumour-specific antigens (TSAs or TAAs) and consequently, they can escape CTL-mediated cell death. This contributes to the failure of many immunotherapies to control tumour growth even when immunity (e.g. CTLs) has been properly stimulated. Most immunotherapies targeting antigen presentation focus on professional antigen-presenting cells and rarely on tumour cells themselves, which leads to poor efficacy. Hence, immunotherapies and products that enhance the antigen presentation process in tumour cells are an unmet need. The aim of this project is to develop a small molecule that can facilitate antigen presentation to CTLs. We intend to target two intracellular proteins, namely survivin(SVN) and KRAS, which are TAAs that are important in tumour formation and metastasis. In this project, we will screen small molecules that can specifically target and degrade SVN and KRAS followed by enhanced antigen presentation in the cancer cells.The small molecules can be clinically utilised alone (directly kill tumour cells) or more importantly, in combination with immunotherapies such as tumour therapeutic vaccines. In the case of combination therapy, the dose of the small molecules will be expected less than the single therapy. Ultimately, we hope that this will bring about tumour cell death via the action of cytotoxic T cells. We also believe that these molecules can improve the effectiveness of existing immunotherapies.Once the small molecules are characterised and tested in in vitro antigen presentation assays, we will test in the in vivo models the combination therapy of small molecules with tumour therapeutic vaccines. We will collaborate with OVM which is developing therapeutic vaccines (SVN and KRAS). SVN therapeutic vaccine is in Phase I clinical trial. If the small molecules synergise with the therapeutic vaccines, OVM would be interested in licensing-in the technology. Aims:1. Screen and characterisation of small molecules**As part of an established collaboration, we have identified and modified small molecules that bind and inhibit SVN. We will further modify these molecules to make them better for antigen presentation inside tumour cells. With that experience, we will identify and screen small molecules targeting KRAS. We will characterise the binding affinity of the new small molecules to the relevant target proteins using techniques including native mass spectrometry and crystal soaking. Optimisation of the key structural parameters of each small molecule will also be performed so as to maximise biological activity.2. Test the small molecules on enhancing antigen presentation in tumour cells*Here we will engage T cell clones that recognise the antigenic peptides presented by tumour cells. This experimental system is already set up in the Department of Oncology. The small molecules developed can also be tested using in vivo xenograft tumour models. We have previously made and modified small molecules for SVN (LQZ-7I) and, pleasingly, the molecule shows binding and inhibition of tumour cells in our assays (Fig. 1).3. Combination therapy with tumour therapeutic vaccines OVM is an Oxford University spinout SME that develops tumour therapeutic vaccines. The SNV-based therapeutic vaccine (OVM-200) is in Phase I clinical trial in the UK. The KRAS-based vaccine (OVM-400) is in its development pipeline. The small molecules developed in Aim 1 & 2 will be tested in combination with OVM-200 or OVM-400.