Development of a Dual and Selective Small Molecule Inhibitor of EGFR and PI3 Kinase to Treat BRAF Mutant Colorectal Cancer

尽管出现了越来越多的分子靶向药物，但患有这种疾病的患者的预后仍然不佳。 转移性结肠直肠癌（CRC）仍然较差，5年存活率<10%。靶向表皮的药剂 生长因子受体（EGFR）在CRC的临床治疗中取得了有限的成功， 治疗那些肿瘤不携带KRAS或BRAF突变的患者。约10%的 已知结直肠恶性肿瘤具有BRAF缬氨酸600（BRAFV缬氨酸）突变，赋予了极高的特异性。 预后不良。EGFR对MAP激酶通路的再激活和PIK 3A突变的共同发生 肿瘤抑制因子PTEN表达的缺失或缺失可使BRAFmt肿瘤对MEK或BRAF不敏感 抑制剂单一疗法。我们的中心假设是一种双重小分子抑制剂， 选择性地仅靶向EGFR和PI 3 KA与MAP激酶信号传导抑制剂的组合代表了一种新的治疗方法， 治疗BRAF突变型结直肠癌的可行策略。为了验证这一假设，我们设计了 这些小分子表现出对EGFR和PIK 3A家族成员的有效和选择性双重抑制。到 据我们所知，先导化合物MTX-211是这两种药物的首选选择性抑制剂 关键的致癌激酶。我们已经产生了晶体学证据，证实MTX-211结合到 这两种激酶以其计算设计预测的方式，采用翻转结合模式， 选择性和有效地抑制EGFR和PI 3 K。初步数据显示， 当用MTX-211和MEK的组合治疗时， 抑制剂曲美替尼。我们现在建议进行更广泛的MTX-211临床前试验， 从诊断为BRAFmt CRC的患者中建立的异种移植模型，以支持本临床研究的病例 将进行分子谱分析以阐明与遗传相关的标记。 敏感性以及导致进展的适应性信号变化。此外，我们建议 通过进行MTX-211与临床药物联合治疗的疗效比较研究， 已批准MEK与RAF抑制剂的比较，为这种有前途的候选药物的未来临床试验设计提供信息 来治疗这种顽固的疾病

Despite the emergence of an increased number of molecular targeted agents, the prognosis for patients with metastatic colorectal cancer (CRC) remains poor with 5 year survival rates of <10%. Agents targeting epidermal growth factor receptor (EGFR) have met with limited success in the clinical treatment of CRC and are limited to treatment of those patients whose tumors do not harbor mutations in KRAS or BRAF. Approximately 10% of colorectal malignancies are known to possess a BRAF valine 600 (BRAFV⁶⁰⁰) mutation, conferring an extremely poor prognosis. Reactivation of the MAP kinase pathway by EGFR and the co-occurrence of PIK3A mutations or loss of expression of the tumor suppressor PTEN serve to render BRAFmt tumors refractory to MEK or BRAF inhibitor monotherapies. Our central hypothesis is that a dual small molecule inhibitor that potently and selectively targets only EGFR and PI3KA in combination with an inhibitor of MAP kinase signaling represents a viable strategy for the treatment of BRAF mutant colorectal cancers. To test this hypothesis, we have designed small molecules that exhibit potent and selective dual inhibition of EGFR and PIK3A family members. To the best of our knowledge, the lead compound MTX-211 represents a first in class selective inhibitor of these two critical oncogenic kinases. We have generated crystallographic evidence confirming that MTX-211 binds to these two kinases in the manner predicted from its computational design, adopting a flipped binding mode to selectively and potently inhibit both EGFR and PI3K. Preliminary data have shown a striking increase in lifespan of mice implanted with patient-derived BRAFmt CRC when treated with the combination of MTX-211 and the MEK inhibitor trametinib. We now propose to carry out more extensive preclinical testing of MTX-211 in patient derived xenograft models established from patients diagnosed with BRAFmt CRC to bolster the case for this clinical development path. Molecular profiling will be carried out to elucidate markers that correlate with inherent sensitivity as well as the adaptive signaling changes that lead to progression. Additionally, we propose to maximize durability of response by carrying out comparative efficacy studies of MTX-211 combined with clinically approved MEK versus RAF inhibitors to inform the design of future clinical trials of this promising drug candidate for treatment of this recalcitrant disease.