Enabling effective anti-tumor immunity from targeted antibodies through dual innate and adaptive immune checkpoint blockade in non-immunogenic cancers

摘要 虽然免疫检查点阻断(ICB)已经成为各种癌症的有效治疗手段， 最初的单一治疗策略已被证明只对部分患者有益。这些研究已经 提示了T细胞在反应性癌症中的重要性，从而提出了改善T细胞刺激和 渗透已被列为优先事项。然而，我们最近的研究(Shuptrine等人，2017)发现了 CD47/Sirpα作为一种天然途径，调节抗体依赖细胞吞噬功能。 最关键的潜在抗肿瘤免疫介质。这表明补充性先天抗肿瘤 涉及抗体的效应器通路，特别是与ADCP有关的效应器通路，可能是 建立有效的抗肿瘤反应。使用CD47 InNatural进行的第一项临床研究的最新阳性结果 ICB(在耐药淋巴瘤中使用CD20单抗)强烈提示这可能是一种临床有效的手段 激发癌症患者的免疫力(Advani，NEJM，2018)。这可能是在HER2+的实体癌症中最好的探索 乳腺癌(BC)，目前正在使用我们最近确定功能的HER2单抗进行治疗 通过ADCP(Tsao等人，JCI-Insight，在审查中)。此外，我们最近还发布了积极的 针对HER2的疫苗策略的反应，记录了多克隆抗体(PAb)的诱导 在HER2+BC患者中(Crosby等人，CCR 2019)。我们现在已经鉴定了这些HER2抗体，以诱导抗 肿瘤是通过激活补体来发挥作用的，这使得我们能够研究PABS(与单抗相比 HER2-Abs)可能对肿瘤免疫产生不同的影响。基于我们最近的适应性ICB机制研究， (Crosby等人，2018)，我们的中心假设是HER2靶向单抗或Pabs诱导抗体依赖 CD47阻断增强的巨噬细胞吞噬功能(ADCP)在免疫上募集和启动效应T- 可通过使用CTLA4自适应ICB单抗进行扩展的细胞，并通过 PD1 ICB单抗的使用。在我们初步数据的指导下，这一假设将通过我们独特的 HER2+BC模式，可以通过以下组合进行询问，这些组合构成了我们的特定目标：1) HER2+CD47单抗2)HER2/CD47单抗+CTLA4/PD1 ICB组合和3)HER2疫苗+天然 CD47 ICB和CTLA4/PD1自适应ICB组合。这些研究将是第一次确定这些 天然和获得性ICB组合对抗体介导的抗肿瘤免疫的影响及其机制改变 肿瘤特异性和非特异性适应性反应，以及确定HER2多克隆抗体如何激活 补体和直接T细胞刺激可改变内源性HER2免疫中的抗肿瘤免疫 具有较少新表位且抗αpd1的竞争模型。这项拟议的研究意义重大， 因为如果基本机制和协同作用被确定为毒性最小，这些方法 可以与靶向单抗和疫苗一起用于其他实体癌症，以扩大和增强潜力 免疫疗法作为大多数癌症的一种治疗选择的效用。

Abstract While immune checkpoint blockade (ICB) has emerged as a validated therapeutic axis in a variety of cancers, initial monotherapy strategies have proven beneficial only to a subset of patients. These studies have suggested the importance of T-cells in responsive cancers, thus strategies to improve T-cell stimulation and infiltration have been prioritized. However, our recent studies (Shuptrine et al., 2017) have identified the CD47/SIRPα innate pathway, which governs antibody dependent cell phagocytosis (ADCP), as one of the most critical potential mediators of anti-tumor immunity. This suggests that complementary innate anti-tumor effector pathways involving antibodies, particularly relating to ADCP, may represent critical pathways to establish effective anti-tumor responses. Recent positive results from the first clinical study using CD47 innate ICB (with CD20 mAb in resistant lymphoma) strongly suggest that this may be a clinically effective means to stimulate immunity in cancers (Advani, NEJM, 2018). This may be best explored in solid cancers in HER2+ Breast Cancer (BC), which are currently treated using HER2 mAbs that we recently determined function through ADCP (Tsao et al., JCI-Insight, in review). Additionally, we have also recently published positive responses from a vaccine strategy targeting HER2, documenting the induction of polyclonal antibodies (pAbs) in HER2+ BC patients (Crosby et al., CCR 2019). We have now identified these HER2 pAbs to elicit anti- tumor effects through the activation of complement, allowing our study of how pAbs (in contrast to monoclonal HER2-Abs) may differentially impact tumor immunity. Based on our recent adaptive ICB mechanistic studies, (Crosby et al., 2018), our central hypothesis is that HER2-targeted mAbs or pAbs elicit antibody dependent phagocytosis (ADCP) that is enhanced by CD47 blockade to immunologically to recruit and prime effector T- cells that can be expanded through the use of CTLA4 adaptive ICB mAbs and functionally enhanced by the use of PD1 ICB mAbs. Guided by our preliminary data, this hypothesis will be tested by utilizing our unique HER2+ BC models that can be interrogated with the following combinations that comprise our specific aims: 1) HER2+CD47 mAbs 2) HER2/CD47 mAbs + CTLA4/PD1 ICB combinations and 3) HER2 vaccination + innate CD47 ICB and CTLA4/PD1 adaptive ICB combinations. These studies will be the first to determine how these innate and adaptive ICB combinations impact Ab-mediated anti-tumor immunity and mechanistically alter tumor-specific and non-specific adaptive responses, as well as determine how the HER2 pAb activation of complement and direct T-cell stimulation can alter anti-tumor immunity in an endogenous HER2 immune- competent model that possesses few neoepitopes and is αPD1 resistant. The proposed research is significant, because if fundamental mechanisms and synergies are identified with minimal toxicities, these approaches could be utilized with targeted mAbs and vaccines in other solid cancers to expand and enhance the potential utility of immunotherapy as a therapeutic option for the majority of cancers.