Differential Receptor Tyrosine Kinase PET Imaging for Therapeutic Guidance
Differential Receptor Tyrosine Kinase PET Imaging for Therapeutic Guidance
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DOI：
10.2967/jnumed.115.169417
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发表时间：
2016-09-01
影响因子：
9.3
通讯作者：
Mahmood, Umar
中科院分区：
文献类型：
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作者：
Wehrenberg-Klee, Eric;Turker, N. Selcan;Mahmood, Umar
磷脂酰肌醇 3-激酶/蛋白激酶 B/哺乳动物雷帕霉素靶点 (PI3K/AKT/mTOR) 通路的抑制剂有望治疗乳腺癌，但对这些治疗的耐药性可能是通过反馈环路产生的，反馈环路会增加受体酪氨酸激酶 (RTK)、表皮生长因子受体 1 (EGFR) 和人表皮生长因子受体 3 (HER3) 的表面表达，从而导致持续的生长通路信号传导。我们开发了 PET 探针，提供了一种在体内对这种反应进行成像的方法，确定哪些肿瘤可能使用这种逃逸途径，同时避免了重复活检的需要。方法：通过酶消化从单克隆抗体中产生抗 EGFR-F(ab')(2) 和抗 HER3-F(ab')(2)，与 DOTA 缀合，并用 Cu-64 标记。使用浓度不断增加的 AKT 抑制剂 GDC-0068 或 PI3K 抑制剂 GDC-0941 处理一组乳腺癌细胞系。使用蛋白质印迹比较 EGFR 和 HER3 治疗前和治疗后的表达，并通过结合研究与探针积累相关。 HCC-70 或 MDA-MB-468 裸鼠异种移植物用 AKT 抑制剂或 PI3K 抑制剂处理，并用 EGFR 或 HER3 PET 探针成像。结果：通过蛋白质印迹评估，HER3 和 EGFR PET 探针积累的变化与 RTK 表达变化相关（R-2 为 0.85-0.98）。 HCC70 肿瘤的 EGFR PET 探针 PET/CT 成像显示，媒介物治疗肿瘤的 SUV 为 0.32 +/- 0.03，GDC-0941 治疗肿瘤为 0.50 +/- 0.01，GDC-0068 治疗肿瘤为 0.62 +/- 0.01（与媒介物比较，P < 0.01）。 MDAMB468 肿瘤的 HER3 PET 探针 PET/CT 成像显示，媒介物治疗肿瘤的 SUV 为 0.35 +/- 0.02，GDC-0068 治疗肿瘤的 SUV 为 0.73 +/- 0.05 (P < 0.01)。结论：我们使用 EGFR 和 HER3 特异性 PET 探针进行的影像学研究表明，RTK 表达的变化表明对 PI3K 和 AKT 抑制剂的耐药性可以在治疗开始后几天内观察到，并且变化幅度足以进行可靠的临床解释。对这些 RTK 反馈回路的无创 PET 监测应有助于快速评估对 PI3K 和 AKT 抑制剂的耐药性，并指导针对个体患者选择适当的组合治疗方案。
Inhibitors of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway hold promise for the treatment of breast cancer, but resistance to these treatments can arise via feedback loops that increase surface expression of the receptor tyrosine kinases (RTK) epidermal growth factor receptor 1 (EGFR) and human epidermal growth factor receptor 3 (HER3), leading to persistent growth pathway signaling. We developed PET probes that provide a method of imaging this response in vivo, determining which tumors may use this escape pathway while avoiding the need for repeated biopsies. Methods: Anti-EGFR-F(ab')(2) and anti-HER3-F(ab')(2) were generated from monoclonal antibodies by enzymatic digestion, conjugated to DOTA, and labeled with Cu-64. A panel of breast cancer cell lines was treated with increasing concentrations of the AKT inhibitor GDC-0068 or the PI3K inhibitor GDC-0941. Pre- and posttreatment expression of EGFR and HER3 was compared using Western blot and correlated to probe accumulation with binding studies. Nude mice xenografts of HCC-70 or MDA-MB-468 were treated with either AKT inhibitor or PI3K inhibitor and imaged with either EGFR or HER3 PET probe. Results: Changes in HER3 and EGFR PET probe accumulation correlate to RTK expression change as assessed by Western blot (R-2 of 0.85-0.98). EGFR PET probe PET/CT imaging of HCC70 tumors shows an SUV of 0.32 +/- 0.03 for vehicle-, 0.50 +/- 0.01 for GDC-0941-, and 0.62 +/- 0.01 for GDC-0068-treated tumors, respectively (P < 0.01 for both comparisons to vehicle). HER3 PET probe PET/CT imaging of MDAMB468 tumors shows an SUV of 0.35 +/- 0.02 for vehicle- and 0.73 +/- 0.05 for GDC-0068-treated tumors (P < 0.01). Conclusion: Our imaging studies, using PET probes specific to EGFR and HER3, show that changes in RTK expression indicative of resistance to PI3K and AKT inhibitors can be seen within days of therapy initiation and are of sufficient magnitude as to allow reliable clinical interpretation. Noninvasive PET monitoring of these RTK feedback loops should help to rapidly assess resistance to PI3K and AKT inhibitors and guide selection of an appropriate combinatorial therapeutic regimen on an individual patient basis.