Project 1 - Integrating targeted and immune therapies for BRAF mutant colorectal cancer

项目摘要 BRAF抑制剂对BRAF突变型(BRAFm)结直肠癌(应答率仅为5%)缺乏疗效 对BRAFm黑色素瘤的有效率为50%。作为我们先前孢子项目的一部分进行的关键研究 发现了在结直肠癌中存在的(但在黑色素瘤中没有)导致快速重新激活的反馈网络 BRAF抑制后的MAPK信号转导是抗性的主要驱动因素。这一关键发现导致了 基于BRAFi的治疗组合的临床试验旨在阻止MAPK重新激活，导致 BRAFm结直肠癌患者的应答率从5%提高到30%。尽管有这些治疗作用 进展，临床益处不是持久的，中位PFS只有4-5个月。在这里我们将探索 靶向MAPK抑制(MAPKi)和免疫检查点阻断之间的潜在协同性 (ICB)将免疫反应性较低的肿瘤转换为免疫原性较强的肿瘤。BRAFm CRC代表 探索潜在合作性的最佳人群，因为20%-30%的转移性BRAFm癌 MSI，它赋予ICB响应性。此外，我们观察到了5年的持久反应 在MSI BRAFm结直肠癌患者中，仅接受MAPKi治疗。在MSS BRAFm CRC患者中，我们看到明显的 在配对肿瘤活检中单独使用MAPKi诱导CD4+和CD8+T细胞，以及我们的临床前研究 小鼠模型显示MAPKi和PD-1IC在MSS BRAFm CRC中具有协同作用。我们 提出一项使用创新的免疫能力BRAFm CRC小鼠模型的全面努力， 治疗前和治疗中肿瘤活检的前沿分子和免疫分析，以及新的 联合应用MAPKi和ICB治疗BRAFm的临床试验 结直肠癌患者。目的1将确定MAPKi单独和与PD-1ICB联合使用对免疫原性的影响。 使用免疫学和转录图谱方法进行BRAFm CRC和抗肿瘤免疫 分析新的BRAFm结直肠癌模型和独特的配对治疗前和治疗中集合 接受BRAF/EGFR/Meki治疗的BRAFm结直肠癌患者的活检。AIM 2将进行临床试验和 新型免疫和靶向联合治疗BRAFm结直肠癌的相关性研究及临床评价 BRAF/MEK/PD-1联合抑制的疗效。我们将与病理核心合作 肿瘤活检的多重免疫分析，以及用于散装和单细胞分析的Biostats核心 RNAseq和全外显子组测序。这些研究将为指导未来的设计提供关键见解 审判。目标3将确定BRAFm对MAPKi和ICB联合的反应和抵抗机制 结直肠癌小鼠模型和联合ICB克服MAPKi/抗PD-1耐药性的测试策略 以及我们在目标1和2中的分析所定义的免疫抑制机制的调节剂。这些 研究将确定MAPKI和ICB在BRAFm结直肠癌中的潜在协同作用以及 对这种致命性结直肠癌亚型建立新的治疗模式的反应和抵抗

Project Summary BRAF inhibitors lack efficacy in BRAF mutant (BRAFm) CRC (response rate only 5%) in contrast to response rates of >50% in BRAFm melanoma. Key studies conducted as part of our prior SPORE project identified feedback networks present in CRC (but absent in melanoma) that lead to rapid reactivation of MAPK signaling following BRAF inhibition, as primary drivers of resistance. This critical discovery led to clinical trials of BRAFi-based therapeutic combinations designed to block MAPK reactivation, resulting in an increased response rate for BRAFm CRC patients from 5% to >30%. Despite these therapeutic advances, clinical benefit is not durable, with a median PFS of only 4-5 months. Here we will explore potential cooperativity between targeted MAPK inhibition (MAPKi) and immune checkpoint blockade (ICB) to convert less immune responsive tumors to more immunogenic tumors. BRAFm CRC represents a prime population for exploring potential cooperativity, as 20-30% of metastatic BRAFm CRCs harbor MSI, which confers responsiveness to ICB. Moreover, we have observed durable responses of >5 years in MSI BRAFm CRC patients receiving MAPKi alone. In MSS BRAFm CRC patients, we see marked induction of CD4+ and CD8+ T-cells with MAPKi alone in paired tumor biopsies, and our preclinical mouse models demonstrate a cooperative effect of MAPKi and PD-1 IC in MSS BRAFm CRC. We propose a comprehensive effort using innovative immune competent BRAFm CRC mouse models, cutting-edge molecular and immune analyses of paired pre- and on-treatment tumor biopsies, and novel clinical trials to explore combined MAPKi and ICB as a strategy to achieve durable benefit in BRAFm CRC patients. Aim 1 will define the effects of MAPKi alone and with PD-1 ICB on immunogenicity of BRAFm CRC and anti-tumor immunity using immunologic and transcriptional profiling approaches to analyze novel BRAFm CRC models and a unique collection of paired pre-treatment and on-treatment biopsies from BRAFm CRC patients given BRAF/EGFR/MEKi. Aim 2 will conduct clinical trials and correlative studies of novel immune and targeted combinations for BRAFm CRC, evaluating clinical efficacy of combined BRAF/MEK/PD-1 inhibition. We will collaborate with the Pathology Core for multiplexed immune analysis of tumor biopsies, and the Biostats Core for analysis of bulk and single cell RNAseq and whole-exome sequencing. These studies will provide key insights to guide design of future trials. Aim 3 will define mechanisms of response and resistance to combined MAPKi and ICB in BRAFm CRC mouse models, and test strategies to overcome resistance to MAPKi/anti-PD-1 using combined ICB and modulators of immunosuppressive mechanisms defined by our analyses in Aims 1 and 2. These studies will define the potential synergy between MAPKi and ICB in BRAFm CRC and mechanisms of response and resistance to establish a new therapeutic paradigm for this lethal CRC subtype