Overcoming immune checkpoint inhibition with therapeutic plasma exchange and radiotherapy in melanoma

摘要 PD-1导向的免疫检查点抑制物(ICI)显著提高了转移性黑色素瘤的存活率 与传统的化疗相比。不幸的是，只有不到一半的黑色素瘤患者对ICI有反应 治疗。抗PD1/PD-L1 ICI耐药性延伸到黑色素瘤之外，导致15%-35%的反应 大多数癌症的发病率。黑色素瘤分泌导致ICI耐药的因子，包括可溶性PD-L1(Spd-L1) PD-L1阳性细胞外小泡(evPD-L1)。我们最近发现SPD-L1和evPD-L1在 外周血通过与PD-1受体的相互作用直接杀伤效应CD8+T细胞(图4)。他们 也间接地“猝灭”可用的治疗性抗PD-1抗体，导致低ICI应答率(图5)。 因此，迫切需要将这些可溶性形式从循环中移除，以拯救黑色素瘤患者 来自ICI抵抗组织。 我们先前已经证明，立体定向全身放射治疗(SBRT)可以提高系统免疫功能 反应，即所谓的“非范围效应”。异位效应是SBRT诱导新抗原的结果，促进了细胞免疫。 炎性细胞因子、上调主要组织相容性复合体和B7家族共刺激 抗原提呈细胞上的分子招募效应性T细胞。不幸的是，非局域效应很少被观察到。 因此，ICI和放射治疗的联合研究正在进行中。而SBRT激活了反- 黑色素瘤免疫通过提供新的抗原和危险信号，肿瘤释放这些免疫抑制 细胞外形式的PD-L1可以杀死激活的效应T细胞(图1)。放射治疗增加肿瘤SPD- L1/evPD-L1释放，我们已报道高水平的血浆Spd-L1和/或evPD-L1水平预示不良 对治疗和生存的反应。 最近，我们发现治疗性血浆置换(TPE)，一种安全和常用的 其他医学适应症的程序(如自身免疫性疾病、重症肌无力、多发性硬化症等)， 将SPD-L1和evPD-L1安全地从循环中移除。因此，我们假设移除 TPE循环Spd-L1和evPD-L1可克服PD-L1/PD-1介导的免疫调节 ICI+SBRT治疗转移性黑色素瘤患者的有效率和生存率。如果成功，我们的建议 概念可以很容易地在前瞻性随机临床试验中进行研究，并涉及许多中心， 定期进行TPE。此外，我们的新概念可以在其他患有PD的癌症组织中探索。 L1/PD-1抵抗，在患者血液中检测到升高的Spd-L1和evPD-L1。 图1：胞外形式的PD-L1(1)evPD-L1和(2)Spd-L1对PD-(L)1抑制剂产生耐药性 通过竞争超过PD-(L)1抑制剂和杀死CD8+效应T细胞来治疗癌症(另见图4)。 治疗性抗PD-L1抑制剂的有效性被可溶性PD-L1和evPD-L1释放所“猝灭” 来自肿瘤细胞，这限制了它的可用性。此外，Spd-L1和evPD-L1可与T细胞表面结合 PD-1受体和竞争优势的抗PD-1抑制剂。 放射治疗 肿瘤细胞 1 PD-L1+电动汽车 PD1 免疫细胞 PD-L1-抑制剂 ADAM10/ ADAM17 2. PD-L1sPD-L1 PD-1-抑制剂PD1

ABSTRACT PD-1-directed immune checkpoint inhibitors (ICI) have significantly improved survival in metastatic melanoma compared to traditional chemotherapy. Unfortunately, less than half of patients with melanoma respond to ICI treatment. Anti-PD1/PD-L1 ICI resistance extends beyond melanomas, resulting in a meager 15-35% response rate for most cancers. Melanomas secrete factors that lead to ICI resistance, including soluble PD-L1 (sPD-L1) and PD-L1-positive extracellular vesicles (evPD-L1). We recently discovered that both sPD-L1 and evPD-L1 in the peripheral blood directly kill effector CD8+ T cells through interaction with the PD-1 receptor (Fig 4). They also indirectly “quench” the available therapeutic anti-PD-1 antibody resulting in low ICI response rates (Fig 5). Thus, there is an urgent need to remove these soluble forms from circulation to rescue patients with melanoma from ICI resistance. We have previously shown that stereotactic body radiotherapy (SBRT) can improve systemic immune responses, known as “abscopal effect.” Abscopal effect is the result of SBRT inducing neoantigens, pro- inflammatory cytokines, and up-regulating major histocompatibility complex and B7 family co-stimulatory molecules on antigen presenting cells to recruit effector T cells. Unfortunately, abscopal effect is rarely observed in patient, and therefore, ICI and radiotherapy combination studies are ongoing. While SBRT activates anti- melanoma immunity by providing neoantigens and danger signals, tumors release these immunosuppressive extracellular forms of PD-L1 that kill activated effector T cells (Fig 1). Radiotherapy increases tumor sPD- L1/evPD-L1 release, and we have reported that high plasma sPD-L1 and/or evPD-L1 levels portend poor response to therapy and survival. Recently, we have discovered that therapeutic plasma exchange (TPE), a safe and commonly performed procedure for other medical indications (e.g. autoimmune diseases, myasthenia gravis, multiple sclerosis, etc), removes both sPD-L1 and evPD-L1 safely from the circulation. Therefore, we hypothesize that the removal of circulating sPD-L1 and evPD-L1 by TPE may overcome PD-L1/PD-1-mediated immune regulation to improve ICI + SBRT response rates and survival in patients with metastatic melanoma. If successful, our proposed concept can be readily investigated in a prospective randomized clinical trial and involve many centers that routinely perform TPE. Furthermore, our novel concept can be explored in other cancer histologies with PD- L1/PD-1 resistance where elevated sPD-L1 and evPD-L1 are detected in patients’ blood. Figure 1: Extracellular forms of PD-L1 (1) evPD-L1 and (2) sPD-L1 cause resistance to PD-(L)1 inhibitor therapy in cancer by outcompeting PD-(L)1 inhibitors and killing CD8+ effector T cells (see also Figure 4). The availability of therapeutic anti-PD-L1 inhibitors is “quenched” by soluble PD-L1 and evPD-L1 released from tumor cells which limits its availability. Furthermore, sPD-L1 and evPD-L1 can bind to T cell surface PD-1 receptors and outcompete anti-PD-1 inhibitors. Radiotherapy Tumor Cell 1 PD-L1+ EVs PD1 Immune Cell PD-L1-Inhibitor ADAM10/ ADAM17 2 PD-L1sPD-L1 PD-1-Inhibitor PD1