Lineberger Comprehensive Cancer Center, Departments of Genetics, Pharmacology, Pathology & Laboratory Medicine, Laboratory Animal Medicine, Biostatistics, and Medicine, Divisions of Neuropathology, Hematology/Oncology, School of Medicine, and Neurology and Neurosciences Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Neuro Oncol. 2017 Oct 19;19(11):1481-1493. doi: 10.1093/neuonc/nox052.
Triple-negative breast cancer (TNBC), lacking expression of hormone and human epidermal growth factor receptor 2 receptors, is an aggressive subtype that frequently metastasizes to the brain and has no FDA-approved systemic therapies. Previous literature demonstrates mitogen-activated protein kinase kinase (MEK) pathway activation in TNBC brain metastases. Thus, we aimed to discover rational combinatorial therapies with MEK inhibition, hypothesizing that co-inhibition using clinically available brain-penetrant inhibitors would improve survival in preclinical models of TNBC brain metastases.
Using human-derived TNBC cell lines, synthetic lethal small interfering RNA kinase screens were evaluated with brain-penetrant inhibitors against MEK1/2 (selumetinib, AZD6244) or phosphatidylinositol-3 kinase (PI3K; buparlisib, BKM120). Mice bearing intracranial TNBC tumors (SUM149, MDA-MB-231Br, MDA-MB-468, or MDA-MB-436) were treated with MEK, PI3K, or platelet derived growth factor receptor (PDGFR; pazopanib) inhibitors alone or in combination. Tumors were analyzed by western blot and multiplexed kinase inhibitor beads/mass spectrometry to assess treatment effects.
Screens identified MEK+PI3K and MEK+PDGFR inhibitors as tractable, rational combinations. Dual treatment of selumetinib with buparlisib or pazopanib was synergistic in TNBC cells in vitro. Both combinations improved survival in intracranial SUM149 and MDA-MB-231Br, but not MDA-MB-468 or MDA-MB-436. Treatments decreased mitogen-activated protein kinase (MAPK) and PI3K (Akt) signaling in sensitive (SUM149 and 231Br) but not resistant models (MDA-MB-468). Exploratory analysis of kinome reprogramming in SUM149 intracranial tumors after MEK ± PI3K inhibition demonstrates extensive kinome changes with treatment, especially in MAPK pathway members.
Results demonstrate that rational combinations of the clinically available inhibitors selumetinib with buparlisib or pazopanib may prove to be promising therapeutic strategies for the treatment of some TNBC brain metastases. Additionally, effective combination treatments cause widespread alterations in kinase pathways, including targetable potential resistance drivers.
三阴性乳腺癌（TNBC）缺乏激素和人表皮生长因子受体 2 受体的表达，是一种侵袭性亚型，常转移至大脑，且没有美国食品和药物管理局（FDA）批准的系统治疗方法。先前的文献表明，TNBC 脑转移中存在丝裂原活化蛋白激酶激酶（MEK）通路的激活。因此，我们旨在发现具有 MEK 抑制作用的合理组合疗法，假设使用临床上可穿透大脑的抑制剂进行联合抑制，将改善 TNBC 脑转移的临床前模型中的存活。
使用源自人类的 TNBC 细胞系，评估了具有穿透大脑的 MEK1/2（selumetinib，AZD6244）或磷脂酰肌醇 3 激酶（PI3K；buparlisib，BKM120）抑制剂的合成致死性小干扰 RNA 激酶筛选。用 MEK、PI3K 或血小板衍生生长因子受体（PDGFR；pazopanib）抑制剂单独或联合治疗携带颅内 TNBC 肿瘤（SUM149、MDA-MB-231Br、MDA-MB-468 或 MDA-MB-436）的小鼠。通过 Western blot 和多重激酶抑制剂珠/质谱分析来评估治疗效果。
筛选确定 MEK+PI3K 和 MEK+PDGFR 抑制剂是可行的、合理的组合。在体外，selumetinib 与 buparlisib 或 pazopanib 的双重治疗对 TNBC 细胞具有协同作用。两种组合均改善了颅内 SUM149 和 MDA-MB-231Br 的存活，但对 MDA-MB-468 或 MDA-MB-436 没有改善。治疗降低了敏感（SUM149 和 231Br）但不耐药模型（MDA-MB-468）中丝裂原活化蛋白激酶（MAPK）和 PI3K（Akt）信号。对 MEK ± PI3K 抑制后 SUM149 颅内肿瘤中激酶组学重编程的探索性分析表明，治疗后激酶组学发生了广泛变化，尤其是在 MAPK 途径成员中。
结果表明，临床上可用的抑制剂 selumetinib 与 buparlisib 或 pazopanib 的合理组合可能成为治疗某些 TNBC 脑转移的有前途的治疗策略。此外，有效的联合治疗会导致激酶途径的广泛改变，包括可靶向的潜在耐药驱动因素。
