Department of Urology, The James Buchanan Brady Urological Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
The Institute for Cancer Research, London, UK; The Royal Marsden NHS Foundation Trust, London, UK.
Eur Urol. 2018 May;73(5):727-735. doi: 10.1016/j.eururo.2017.08.009. Epub 2017 Sep 1.
Androgen receptor splice variant 7 (AR-V7) has been implicated in resistance to abiraterone and enzalutamide treatment in men with metastatic castration-resistant prostate cancer (mCRPC). Tissue- or cell-based in situ detection of AR-V7, however, has been limited by lack of specificity.
To address current limitations in precision measurement of AR-V7 by developing a novel junction-specific AR-V7 RNA in situ hybridization (RISH) assay compatible with automated quantification.
DESIGN, SETTING, AND PARTICIPANTS: We designed a RISH method to visualize single splice junctions in cells and tissue. Using the validated assay for junction-specific detection of the full-length AR (AR-FL) and AR-V7, we generated quantitative data, blinded to clinical data, for 63 prostate tumor biopsies.
We evaluated clinical correlates of AR-FL/AR-V7 measurements, including association with prostate-specific antigen progression-free survival (PSA-PFS) and clinical and radiographic progression-free survival (PFS), in a subset of patients starting treatment with abiraterone or enzalutamide following biopsy.
Quantitative AR-FL/AR-V7 data were generated from 56 of the 63 (88.9%) biopsy specimens examined, of which 44 were mCRPC biopsies. Positive AR-V7 signals were detected in 34.1% (15/44) mCRPC specimens, all of which also co-expressed AR-FL. The median AR-V7/AR-FL ratio was 11.9% (range 2.7-30.3%). Positive detection of AR-V7 was correlated with indicators of high disease burden at baseline. Among the 25 CRPC biopsies collected before treatment with abiraterone or enzalutamide, positive AR-V7 detection, but not higher AR-FL, was significantly associated with shorter PSA-PFS (hazard ratio 2.789, 95% confidence interval 1.12-6.95; p=0.0081).
We report for the first time a RISH method for highly specific and quantifiable detection of splice junctions, allowing further characterization of AR-V7 and its clinical significance.
Higher AR-V7 levels detected and quantified using a novel method were associated with poorer response to abiraterone or enzalutamide in prostate cancer.
雄激素受体剪接变异体 7（AR-V7）已被证实与转移性去势抵抗性前列腺癌（mCRPC）患者接受阿比特龙和恩扎鲁胺治疗的耐药性有关。然而，由于缺乏特异性，组织或细胞内原位检测 AR-V7 一直受到限制。
通过开发一种新的、与自动化定量兼容的特定剪接 AR-V7 RNA 原位杂交（ISH）检测方法来解决当前在 AR-V7 精确测量方面的局限性。
设计、设置和参与者：我们设计了一种用于在细胞和组织中可视化单个剪接接头的 ISH 方法。使用经过验证的全长 AR（AR-FL）和 AR-V7 特异性检测的检测方法，我们生成了 63 例前列腺肿瘤活检的定量数据，这些数据是在对临床数据不知情的情况下获得的。
我们评估了 AR-FL/AR-V7 测量的临床相关性，包括与前列腺特异性抗原无进展生存期（PSA-PFS）以及临床和影像学无进展生存期（PFS）的关联，这些相关性是在一组接受阿比特龙或恩扎鲁胺治疗的患者的活检后开始的。
从 63 个活检标本中的 56 个（88.9%）生成了定量的 AR-FL/AR-V7 数据，其中 44 个是 mCRPC 活检。在 44 例 mCRPC 标本中检测到 34.1%（15/44）的 AR-V7 阳性信号，这些标本均同时表达 AR-FL。AR-V7/AR-FL 比值中位数为 11.9%（范围 2.7-30.3%）。AR-V7 的阳性检测与基线时高疾病负担的指标相关。在 25 例接受阿比特龙或恩扎鲁胺治疗前的 CRPC 活检中，阳性 AR-V7 检测，但不是更高的 AR-FL，与 PSA-PFS 更短显著相关（风险比 2.789，95%置信区间 1.12-6.95；p=0.0081）。
我们首次报道了一种用于特异性和可量化检测剪接接头的 ISH 方法，该方法允许进一步对 AR-V7 及其临床意义进行表征。
使用一种新方法检测到的更高水平的 AR-V7 与前列腺癌对阿比特龙或恩扎鲁胺的反应较差相关。
