Extended half-life GlyTR1 combined with checkpoint blockade for Cancer Immunotherapy

摘要 不可切除的复发/转移性实体癌的治疗目前只是姑息性的，有一种 对新的作用机制和更多范式转换治疗选择的迫切需求尚未得到满足。抗原- 靶向癌症免疫疗法，如双特异性抗体(如双特异性T细胞结合蛋白或BITE)提供了 一种独特的癌症免疫治疗方法。然而，将这一治疗策略应用于实体癌症 受到可安全靶向的有限数量的蛋白质抗原的限制。此外，即使安全的细胞表面 识别抗原后，每个不同的抗原/癌症可能需要不同的双特异性抗体。这 将大大增加开发时间和成本。因此，仍然非常需要额外的安全抗原- 特异性免疫疗法，特别是对那些难治性/转移性实体癌患者，他们几乎没有 治疗选择。许多细胞表面癌特异性抗原不是蛋白质，而是复杂的 在正常组织中有限表达或不表达的碳水化合物。例如，β-1，6GlcNAc-分支的N- 多聚糖构成了在正常人细胞表面表达的复合型N-多聚糖的一小部分 但在不同的实体肿瘤中，受体酪氨酸的驱动突变显著上调 激酶/RAS/磷脂酰肌醇-3-激酶(PI3K)信号通路。β-1，6GlcNAc-的异常过表达 实体肿瘤中的分枝N-糖链驱动RTK信号转导、肿瘤生长、运动、侵袭和转移。AS β-1，6-GlcNAc-分支N-糖链既是多种癌症的标志物，也是多种癌症的驱动因素，是一个极好的靶点 用于抗原特异性免疫疗法。然而，针对β-1，6GlcNAc-支链N-糖链的抗体从未出现过 已生成。为了解决这个问题，我们产生了一种新的免疫疗法，可以很容易地针对异常 具有高度特异性的糖链抗原。我们将这项技术命名为“依赖多糖的T细胞招募器” (Glytr，发音为“blitter”)。由拜登癌症登月计划资助的国家癌症 我们开发并优化了GlyTR1双特异性蛋白，它能结合β1，6GlcNAc分支的N- T细胞中的糖链和CD3。GlyTR1双特异性蛋白诱导T细胞依赖的杀伤 S在体内外对实体瘤的EC50值低至~50毫微克分子，但不杀死正常细胞或触发 在人源化小鼠模型中的“靶标上，癌症外”毒性。GlyTR1正在进行后期IND启用 研究和FDA批准后，加州大学欧文癌症中心将进行剂量递增第一阶段临床 复发/转移性实体癌试验。然而，由于GlyTR1的半衰期很短，约为2.5小时，需要 在此，我们建议开发一种半衰期更长的GlyTR1版本。我们也 建议检查检查点抑制剂的潜在添加/协同活性。来自于此的数据 在我们的第一阶段试验中，GlyTR1的安全性得到确认后，该提案将用于通知未来的临床试验， 也就是说，是否应该寻求更长的半衰期GlyTR1和/或与检查点抑制剂联合治疗。

Abstract Treatment of non-resectable recurrent/metastatic solid cancers is currently palliative only and there is an urgent unmet need for novel mechanisms of action and additional paradigm shifting therapeutic options. Antigen- targeting cancer immunotherapies such as bi-specific antibodies (eg Bi-specific T cell engager or BiTE’s) provide a unique approach for cancer immunotherapy. However, applying this therapeutic tactic to solid cancers has been restricted by a limited number of protein antigens safe for targeting. Moreover, even if safe cell-surface antigens are identified, different bi-specific antibodies will likely be needed for each different antigen/cancer. This would greatly increase development time and costs. Thus, there remains a great need for additional safe antigen- specific immunotherapies, particularly for those with refractory/metastatic solid cancers who have few therapeutic options. Many cell surface cancer-specific antigens are not proteins but rather complex carbohydrates that have limited or no expression in normal tissues. For example, β1,6GlcNAc-branched N- glycans constitute a small subset of the complex-type N-glycans expressed at the surface of normal human cells but are markedly up-regulated in diverse solid cancers by driver mutations in the receptor tyrosine kinase/RAS/phosphoinositide-3-kinase(PI3K) signaling pathway. Aberrant over-expression of β1,6GlcNAc- branched N-glycans in solid tumors drives RTK signaling, tumor growth, motility, invasion, and metastasis. As both a marker and driver of many diverse cancers, β1,6 GlcNAc-branched N-glycans provide an excellent target for antigen-specific immunotherapies. However, an antibody to β1,6GlcNAc-branched N-glycans has never been generated. To address this issue, we generated a novel class of immunotherapeutics that readily target abnormal glycan antigens with high specificity. We have termed this technology ‘Glycan-dependent T cell Recruiter’ (GlyTR, pronounced ‘glitter’). With funding from the Biden Cancer Moonshot program of the National Cancer Institute, we developed and optimized the GlyTR1 bi-specific protein that binds both β1,6GlcNAc-branched N- glycans and CD3 in T cells. The GlyTR1 bi-specific protein induces T cell-dependent killing of a wide diversity of solid cancers in vitro and in vivo with EC50’s as low as ~50 femtomolar, yet does not kill normal cells or trigger “on-target, off-cancer” toxicity in humanized mouse models. GlyTR1 is undergoing late-stage IND-enabling studies and upon FDA approval, the UC Irvine Cancer Center will perform a dose-escalation Phase 1 clinical trial in relapsed/metastatic solid cancer. However, as GlyTR1 has a short half-life of ~2.5hrs and requires constant intravenous infusion, herein we propose to develop a longer half-life version of GlyTR1. We also propose to examine for potential additive/synergistic activity with checkpoint inhibitors. Data from this proposal will be used to inform future clinical trials following confirmation of safety of GlyTR1 in our Phase 1 trial, namely whether a longer half-life GlyTR1 and/or co-treatment with checkpoint inhibitors should be pursued.