Anti-Sox2 immunotherapy to prevent multiple myeloma relapse

项目总结/摘要 多发性骨髓瘤（MM）是一种骨髓浆细胞的血液恶性肿瘤，几乎普遍致命。 新疗法提高了生存率，并使几乎所有患者的初始疾病控制成为可能。尽管如此 虽然病情进展缓慢，但最终致命的疾病复发几乎是不可避免的。新的治疗方法专门针对 复发的机制有可能扩大现代MM所获得的生存率增量 疗法该提案进一步推进了一个长期目标，即开发一种通过以下方式预防MM复发的免疫疗法： 靶向干细胞抗原Sox 2。既往研究和初步数据显示，治疗后残留MM 细胞依赖Sox 2在体内存活，抗Sox 2免疫应答可预防MM的发展。 从它的惰性前体状况MGUS。在一项试验性临床试验中，抗CD 19 CAR T细胞用于 靶向罕见的克隆原性MM细胞，持久的抗-Sox 2 B和T细胞应答特异性地在 尽管体内CAR <100天，但治疗后5年临床上无MM的非凡应答者 活性（Garfall等人NEJM 2015; Garfall等人JCI Insight 2018）。这一结果可能是由CAR诱导的 免疫原性细胞死亡，导致持久的和临床上有活性的抗Sox 2免疫。这背后的假设 该建议是抗Sox 2 T细胞可以通过抑制或消除克隆性Sox 2-T细胞来预防MM复发。 在细胞减少治疗后持续表达MM细胞。为了验证这一假设，Sox 2特异性T细胞将被激活。 从MGUS患者和CAR T细胞（抗BCMA和/或抗CD 19）的长期应答者中分离，使用 临床数据和标本来自我们的实践和正在进行的MM临床试验。抗Sox 2 T细胞将是特征性的- 针对肽和HLA特异性进行鉴定，并且成对的抗Sox 2 TCRαβ异二聚体将被克隆、测序， 在体外对Sox 2反应性进行功能验证。有前途的TCR将被提名进行体内验证， 它们的体外抗原反应性和HLA限制性。MM患者源性异种移植物（PDX）将在 MISTRG 6小鼠，其支持多谱系人骨髓移植，并且独特地适合于 微环境依赖MM PDXs。用抗Sox 2 TCR转导的连续转移的T细胞 将在PDX中检测其作为克隆生长模型预防继发性PDX植入的能力 需要MM复发。在临床前模型中具有经验证的预防MM复发能力的抗Sox 2 TCR将 作为TCR工程化细胞疗法的临床转化的候选者;同样，经验证的抗原Sox 2 肽可以转化为疫苗疗法。这些候选疗法将具有广泛的潜力 应用于MM和Sox 2已成为重要癌基因的其他癌症。这一协作 该提案汇集了对独特临床样本的访问，人类T细胞生物学的专业能力， cer免疫学和专业知识，以迅速将结果转化为1期临床试验。

PROJECT SUMMARY/ABSTRACT Multiple myeloma (MM) is a hematologic malignancy of bone marrow plasma cells that is almost universally fatal. New therapies have improved survival and enabled initial disease control in almost all patients. Despite this progress, relapse with eventually fatal disease remains nearly inevitable. New treatments that specifically target the mechanisms of relapse have potential to amplify the incremental survival gains achieved with modern MM therapy. This proposal furthers a long-term goal to develop an immunotherapy that prevents MM relapse by targeting the stem-cell antigen Sox2. Prior studies and preliminary data show that post-treatment residual MM cells depend on Sox2 for survival in vivo and that anti-Sox2 immune responses may prevent development of MM from its indolent precursor condition MGUS. In a pilot clinical trial where anti-CD19 CAR T cells were used to target rare clonogenic MM cells, durable anti-Sox2 B and T cell responses were observed specifically in an extraordinary responder who is clinically MM-free five years post-treatment despite <100 days of in vivo CAR activity (Garfall et al NEJM 2015; Garfall et al JCI Insight 2018). This result is likely explained by CAR-induced immunogenic cell death, leading to durable and clinically active anti-Sox2 immunity. The hypothesis underlying this proposal is that anti-Sox2 T cells can prevent MM relapse by constraining or eliminating clonogenic Sox2- expressing MM cells that persist after cytoreductive therapy. To test this hypothesis, Sox2-specific T cells will be isolated from MGUS patients and long-term responders to CAR T cells (anti-BCMA and/or anti-CD19), using clinical data and specimens from our practice and ongoing MM clinical trials. Anti-Sox2 T cells will be character- ized for peptide and HLA specificity, and paired anti-Sox2 TCRαβ heterodimers will be cloned, sequenced, and functionally validated for Sox2 reactivity in vitro. Promising TCRs will be nominated for in vivo validation based on their in vitro antigen reactivity and HLA restriction. MM patient-derived xenografts (PDX) will be generated in MISTRG6 mice, which support multilineage human bone marrow engraftment and are uniquely suited to the microenvironment dependencies of MM PDXs. Adoptively transferred T cells transduced with anti-Sox2 TCRs will be tested in PDXs for their ability to prevent secondary PDX engraftment as a model of clonogenic growth required for MM relapse. Anti-Sox2 TCRs with validated ability to prevent MM relapse in preclinical models would be candidates for clinical translation as TCR-engineered cellular therapies; likewise, validated antigenic Sox2 peptides could be translated to vaccine therapies. These candidate therapeutics would have broad potential applications in MM and other cancers where Sox2 has emerged as an important oncogene. This collaborative proposal assembles access to unique clinical samples, specialized capabilities in human T cell biology and can- cer immunology, and expertise to rapidly translate findings to a phase 1 clinical trial.