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

项目摘要 BRAF抑制剂在BRAF突变型（BRAFm）CRC中缺乏疗效（缓解率仅5%）， BRAFm黑色素瘤的缓解率>50%。作为我们先前SPORE项目的一部分进行的关键研究 发现CRC中存在的反馈网络（但在黑色素瘤中不存在）导致快速重新激活 BRAF抑制后的MAPK信号传导，作为抗性的主要驱动因素。这一重大发现导致了 基于BRAFi的治疗组合的临床试验旨在阻断MAPK再激活，导致 BRAFm CRC患者的应答率从5%增加至> 30%。尽管这些治疗 然而，临床获益并不持久，中位PFS仅为4-5个月。在这里我们将探讨 靶向MAPK抑制（MAPKi）和免疫检查点阻断之间的潜在协同性 (ICB)将免疫应答性较低的肿瘤转化为免疫原性较强的肿瘤。BRAFm CRC代表 这是探索潜在协同性的主要人群，因为20-30%的转移性BRAFm CRCs具有 MSI，赋予ICB响应能力。此外，我们观察到>5年的持久反应 在单独接受MAPKi的MSI BRAFm CRC患者中。在MSS BRAFm CRC患者中， 在成对的肿瘤活检组织中，单独用MAPKi诱导CD 4+和CD 8 + T细胞，以及我们的临床前 小鼠模型证明MAPKi和PD-1 IC在MSS BRAFm CRC中的协同作用。我们 提出了一个全面的努力，使用创新的免疫能力BRAFm CRC小鼠模型， 对配对的治疗前和治疗中的肿瘤活检进行尖端的分子和免疫分析， 探索MAPKi和ICB联合作为BRAFm持久获益策略的临床试验 CRC患者。目的1将定义单独的MAPKi和与PD-1 ICB一起对免疫原性的影响。 BRAFm CRC和抗肿瘤免疫，使用免疫学和转录谱分析方法， 分析新的BRAFm CRC模型和独特的配对治疗前和治疗中 来自给予BRAF/EGFR/MEKi的BRAFm CRC患者的活组织检查。Aim 2将进行临床试验， BRAFm CRC的新型免疫和靶向组合的相关研究，评估临床 联合BRAF/MEK/PD-1抑制的功效。我们将与病理学核心合作， 肿瘤活检的多重免疫分析，以及用于分析批量和单细胞的Biostats Core RNAseq和全外显子组测序。这些研究将提供关键的见解，以指导未来的设计 审判目的3将明确BRAFm对MAPKi和ICB联合作用的应答和耐药机制 CRC小鼠模型和使用组合ICB克服对MAPKi/抗PD-1的抗性的测试策略 和我们在目的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 CRC中的潜在协同作用以及 为这种致命的CRC亚型建立一种新的治疗模式

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