Efficacy and safety of novel CD80 IL15 IL15Ra expressing autologous AML vaccines

描述（由申请人提供）：我们的目标是使用优化的、基因工程的、自体AML细胞疫苗提高老年急性髓性白血病（AML）患者的生存率。同种异体造血干细胞移植（HSCT）和供体白细胞输注（DLI）由于移植物抗白血病（GVL）效应的优越结果，为免疫治疗在消除微小残留病（MRD）方面的有效性提供了令人信服的证据。然而，60岁以下的患者通常不适合进行同种异体造血干细胞移植，因为合并并发症或缺乏供体，并且结果令人沮丧。我们的假设是，通过自体AML疫苗联合CD80表达IL-15和IL-15R¿，将引发有效的抗白血病反应，从而提高老年患者缓解诱导后的无复发生存率。免疫治疗耐药的机制包括白血病特异性或相关抗原的无效呈现和效应细胞激活不足。以前通过体外分化为AML来源的树突状细胞来改善AML细胞抗原呈递的努力是不成功的。然而，AML转导共同表达缺失的CD80共刺激因子和il - 2或GM-CSF，在小鼠AML和人类离体实验中有效地刺激特异性抗白血病免疫。尽管在英国批准了一项使用CD80/IL2表达辐照AML疫苗的i期试验，但人们仍然担心，IL2表达不仅可能刺激细胞溶解T细胞和NK细胞的活化，还可能刺激免疫抑制T调节细胞（Treg）的活化。最近IL15， a ？c链细胞因子与IL2共享刺激NK和CD8+记忆T细胞的能力，显示出适合刺激抗肿瘤免疫的独特特性。IL-15主要由表达IL-15受体α （IL15R¿）的细胞向表达il - 15r亚基(IL2/15R¿和？常见的(?)c)亚基)。IL15可促进记忆性CD8+ T细胞扩增，与IL2相比，其对Treg的诱导作用较弱，并可保护免疫效应器免受Treg抑制。与IL2不同，IL15不会在受刺激的T细胞中引起活化诱导的细胞死亡。IL15与膜结合的IL15R¿（mIL-15R¿）共同表达，作为分泌复合物（IL15/sIL15R¿），或作为IL15/IL15R¿融合蛋白，大大提高了IL15的稳定性和疗效。我们已经生成并将测试表达CD80和1)IL-15/ mIL-15R¿，2)IL-15/IL-15R¿或3)IL-15/IL-15R¿融合蛋白的三顺子慢病毒载体，以确定哪种是临床试验的最佳选择。Aim 1的离体研究将对人类免疫效应物与辐照的自体AML细胞共培养诱导的抗白血病反应的特异性、性质和强度进行一对一的比较，用测试的人类IL-15慢病毒载体转导，与表达人类CD80/IL-2的对照载体进行比较。Aim 2的体内研究将测试用小鼠IL-15载体与IL-2对照载体转导的平行疫苗对抗小鼠32Dp210白血病的安全性、毒性和有效性。具有最佳安全性和生存结果的AML疫苗将在具有免疫衰老特征的老年小鼠中进行测试。这些研究将直接为UCSF针对不符合HSCT条件的bb60患者的1期临床AML疫苗试验的设计提供信息。

DESCRIPTION (provided by applicant): Our goal is to improve survival in older acute myeloid leukemia (AML) patients using optimized, genetically engineered, autologous AML cell vaccines. Compelling evidence for the efficacy of immunotherapy in eliminating minimal residual disease (MRD) is provided by the superior outcomes of allogeneic hematopoietic stem cell transplants (HSCT) and donor leukocyte infusion (DLI) due to graft vs leukemia (GVL) effects. However, patients > 60 yo are often ineligible for allo-HSCT, due to co-morbidities or lack of a donor, and have dismal outcomes. Our hypothesis is that co-expression of IL-15 and IL-15R¿ by autologous AML vaccines combined with CD80 expression, will elicit potent anti-leukemic responses that will improve relapse-free survival in older patients after remission induction. Mechanisms of resistance to immunotherapy include ineffective presentation of leukemia-specific or -associated antigens and inadequate effector cell activation. Previous efforts to improve antigen presentation of AML cells by in vitro differentiation into AML-derived dendritic cells were unsuccessful. However, transduction of AML to co-express the missing CD80 co-stimulator, and IL2 or GM-CSF, efficiently stimulates specific anti-leukemic immunity in murine AML and in human ex vivo assays. Despite approval in the UK, of a Phase-I trial using a CD80/IL2 expressing irradiated AML vaccines, concerns remain that IL2 expression may stimulate not only the activation of cytolytic T and NK cells, but also immune inhibitory T regulatory cells (Treg). Recently IL15, a ?c chain cytokine that shares with IL2 the ability to stimulate NK and CD8+ memory T cells, has shown unique properties suited to stimulating anti-tumor immunity. IL15 is primarily trans-presented by cells expressing IL-15 receptor alpha (IL15R¿) to responding cells expressing IL15R subunits (IL2/15R¿ and ? common (?c) sub-units). IL15 improves memory CD8+ T cell expansion, shows less Treg induction than IL2, and can protect immune effectors from Treg suppression. Unlike IL2, IL15 does not cause activation induced cell death in stimulated T cells. Co-expression of IL15 with membrane-bound IL15R¿ (mIL-15R¿), as a secreted complex (IL15/sIL15R¿), or as an IL15/IL15R¿ fusion protein, greatly increases IL15 stability and efficacy. We have generated and will test tricistronic lentiviral vectors expressing CD80 and either 1) IL15/mIL-15R¿, 2) IL-15/sIL-15R¿, or 3) IL-15/IL-15R¿ fusion protein to determine which is optimal for clinical trial. Ex vivo studies in Aim 1 will provde a head-to-head comparison of the specificity as well as the nature, and magnitude of anti-leukemia responses induced by co-culture of human immune effectors with irradiated, autologous AML cells, transduced with the test human IL-15 lentiviral vectors vs a control vector expressing human CD80/IL-2. In vivo studies in Aim 2 will test the safety, toxicity, and efficacy of parallel vaccines transduced with murine IL-15 vectors vs the IL-2 control vector against murine 32Dp210 leukemia. The AML vaccine with best safety and survival outcomes will then be tested in aged mice that recapitulate features of immune senescence. Studies will directly inform the design of a Phase 1 clinical AML vaccine trial at UCSF for patients >60, ineligible for HSCT.