Analytical Validation and Clinical Qualification of a New Immunohistochemical Assay for Androgen Receptor Splice Variant-7 Protein Expression in Metastatic Castration-resistant Prostate Cancer (original) (raw)
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Androgen receptor splice variant-7 expression emerges with castration resistance in prostate cancer
The Journal of clinical investigation, 2018
Liquid biopsies have demonstrated that the constitutively active androgen receptor splice variant-7 (AR-V7) associates with reduced response and overall survival (OS) from endocrine therapies in castration resistant prostate cancer (CRPC). However, these studies provide little information pertaining to AR-V7 expression in prostate cancer (PC) tissue. Following generation and validation of a novel AR-V7 antibody for immunohistochemistry, AR-V7 protein expression was determined for 358 primary prostate samples and 293 metastatic biopsies. Associations with disease progression, full length AR (AR-FL) expression, response to therapy, and gene expression was determined. We demonstrated that AR-V7 protein is rarely expressed (<1%) in primary PC but is frequently detected (75% of cases) following androgen deprivation therapy, with further significant (P = 0.020) increase in expression following abiraterone acetate or enzalutamide therapy. In CRPC, AR-V7 expression is predominantly (94% ...
2022
BackgroundTherapies targeting the androgen receptor (AR) have improved the outcome for patients with castration-sensitive prostate cancer (CSPC). Expression of the constitutively active AR splice variant-7 (AR-V7) has shown clinical utility as a predictive biomarker of AR-targeted therapy resistance in castration-resistant prostate cancer (CRPC), but its importance as predictive biomarker in CSPC remains understudied.MethodsWe explored multiple approaches to quantify AR-V7 mRNA and protein in prostate cancer cell lines and patient-derived xenograft (PDX) models, in both publicly available and independent institutional clinical cohorts, to identify reliable approaches for detecting AR-V7 mRNA and protein, and its association with clinical outcome.ResultsIn publicly available benign prostate, CSPC and CRPC cohorts, AR-V7 mRNA was much less abundant when detected using reads across splice boundaries than when considering isoform-specific exonic reads. The RM7 AR-V7 antibody had increas...
Journal of Clinical Oncology
PURPOSE Androgen receptor splice variant 7 (AR-V7) results in a truncated receptor, which leads to ligand-independent constitutive activation that is not inhibited by anti-androgen therapies, including abiraterone or enzalutamide. Given that previous reports suggested that circulating tumor cell (CTC) AR-V7 detection is a poor prognostic indicator for the clinical efficacy of secondary hormone therapies, we conducted a prospective multicenter validation study. PATIENTS AND METHODS PROPHECY ( ClinicalTrials.gov identifier: NCT02269982) is a multicenter, prospective-blinded study of men with high-risk mCRPC starting abiraterone acetate or enzalutamide treatment. The primary objective was to validate the prognostic significance of baseline CTC AR-V7 on the basis of radiographic or clinical progression free-survival (PFS) by using the Johns Hopkins University modified-AdnaTest CTC AR-V7 mRNA assay and the Epic Sciences CTC nuclear-specific AR-V7 protein assay. Overall survival (OS) and ...
European Urology Oncology
Background: In metastatic castration-resistant prostate cancer (mCRPC), androgen receptor splice variant 7 (AR-V7) expression is associated with a low response to androgen receptor signaling (ARS) inhibitors such as abiraterone or enzalutamide. Objective: To perform a highly sensitive assay for detecting AR-V7 (hsAR-V7) in circulating tumor cells (CTCs) and evaluate its ability to predict response to ARS inhibitors. Design, setting, and participants: From 41 mCRPC patients, CTCs were prospectively enriched using AdnaTest platform and analyzed for AR-V7 with and without the highly sensitive assay. Outcome measurements and statistical analysis: The first objective of the study was to compare AR-V7 detection rates with and without the highly sensitive assay. Next, we investigated how AR-V7 (detected without the highly sensitive assay) and hsAR-V7 status influenced prostate-specific antigen (PSA) response and long-term clinical outcomes (PSA progression-free survival [PFS] and radiological PFS) after ARS-inhibitor treatment. Finally, discriminatory abilities of the assays were assessed by C-index to compare their impact on long-term clinical outcomes.
European Urology, 2019
Background: Detection of androgen receptor splice variant-7 (AR-V7) mRNA in circulating tumour cells (CTCs) is associated with worse outcome in metastatic castrationresistant prostate cancer (mCRPC). However, studies rarely report comparisons with CTC counts and biopsy AR-V7 protein expression. Objective: To determine the reproducibility of AdnaTest CTC AR-V7 testing, and associations with clinical characteristics, CellSearch CTC counts, tumour biopsy AR-V7 protein expression[ 1 _ T D $ D I F F ] and overall survival (OS). Design, setting, and participants: CTC AR-V7 status was determined for 227 peripheral blood samples, from 181 mCRPC patients with CTC counts (202 samples; 136 patients) and matched mCRPC biopsies (65 samples; 58 patients). Outcome measurements and statistical analysis: CTC AR-V7 status was associated with clinical characteristics, CTC counts, and tissue biopsy AR-V7 protein expression. The association of CTC AR-V7 status and other baseline variables with OS was determined. Results and limitations: Of the samples, 35% were CTC+/AR-V7+. CTC+/AR-V7+ samples had higher CellSearch CTC counts (median CTC; interquartile range [IQR]: 60, 19-184 vs 9, 2-64; Mann-Whitney test p < 0.001) and biopsy AR-V7 protein expression (median Hscore, IQR: 100, 63-148 vs 15, 0-113; Mann-Whitney test p = 0.004) than CTC+/AR-V7À samples. However, both CTCÀ (63%) and CTC+/AR-V7À (62%) patients had detectable AR-V7 protein in contemporaneous biopsies. After accounting for baseline characteristics,
Cancers, 2019
Background: Circulating tumor cells (CTC), androgen receptor full-length (AR-FL), and androgen receptor splice variant 7 (AR-V7) are prognostic in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC). AR-V7 seems to predict resistance to androgen-receptor signaling inhibitors (ARSi). Methods: We assessed the association of CTC, AR-FL, and AR-V7 with prostate-specific antigen (PSA) response and overall survival (OS). We used a modified AdnaTest CTC-based AR-FL and AR-V7 mRNA assay. Chi-square test, Fisher Exact test, Kaplan–Meier method, log-rank test, Cox proportional hazards models were used as appropriate. Results: We enrolled 39 mCRPC pts, of those 24 started a first-line treatment for mCRPC (1L subgroup) and 15 had received at least two lines for mCRPC (>2L subgroup). CTC, AR-FL, and AR-V7 were enriched in >2L compared to 1L subgroup. Detection of these biomarkers was associated with a lower percentage of biochemical responses. Only 1/7 AR-V7+ pts ha...
The Journal of Urology, 2015
purpose of this study was to determine the tissue specific expression, co-localization, and ratio of AR and ARv7 in normal and hormonenaïve PCa. METHODS: Antibodies to detect full length AR and ARv7 were used on hormone-naïve tumor-adjacent normal prostate, high-grade intraepithelial neoplasia (HGPIN), primary PCa samples, and metastases (Mets). Tissue specific protein expression and co-localization of AR and ARv7 were quantified using multispectral imaging technology. Ratios of AR and ARv7 were determined. RESULTS: AR and ARv7 were observed in nuclei of stromal and epithelial cells from all normal and pathologic specimens. In epithelial tissue, nuclear expression of ARv7 was significantly increased in HGPIN and Mets compared to normal prostate, but not PCa. Expression of AR was increased in PCa and Mets but not HGPIN. The proportion of double negative (AR-/ARv7-) cells was lower in HGPIN, PCa, and Mets compared to normal prostate. The proportion of single positive AR-/ARv7þ was higher in HGPIN and the number of single positive ARþ/ARv7-cells was higher in PCa. Double positive ARþ/ ARv7þ cells were more abundant in Mets. In stromal tissues, expression of ARv7 was increased in HGPIN and Mets, but not PCa. Expression of AR was similar in HGPIN and PCa compared to normal prostate, but AR was significantly higher in Mets. The number of double negative AR-/ARv7-cells was lower in HGPIN and Mets. Single positive AR-/ARv7þ cells were increased in HGPIN. No changes were found in single positive ARþ/ARv7-cells. The proportion of double positive ARþ/ARv7þ cells was higher in Mets than normal tissue. The epithelial ratio of ARv7:AR was significantly higher in PCa than normal prostate tissue (p¼0.0003) but not HGPIN (p¼0.99) or Mets (p¼0.57). In the stroma, the ratio of ARv7:AR was higher in HGPIN (p¼0.02) but not PCa (p>0.99) or Mets (p>0.99). CONCLUSIONS: ARv7 is expressed in both the epithelia and stroma during early stages of prostate cancer, and expression of ARv7 is increased in HGPIN in the absence of changes in AR expression. These data support a potential role of ARv7 signaling in early stages of prostate cancer development.
2019
Adam Sharp , Jon C. Welti , Maryou B.K. Lambros , David Dolling , Daniel Nava Rodrigues , Lorna Pope , Caterina Aversa , Ines Figueiredo , Jennifer Fraser , Zai Ahmad , Changxue Lu , Pasquale Rescigno , Michael Kolinsky , Claudia Bertan , George Seed , Ruth Riisnaes , Susana Miranda , Mateus Crespo , Rita Pereira , Ana Ferreira , Gemma Fowler , Berni Ebbs , Penny Flohr , Antje Neeb , Diletta Bianchini , Antonella Petremolo , Semini Sumanasuriya , Alec Paschalis , Joaquin Mateo , Nina Tunariu , Wei Yuan , Suzanne Carreira , Stephen R. Plymate , Jun Luo , Johann S. de Bono *
Cells
Androgen receptor (AR) signaling remains crucial in castration-resistant prostate cancer (CRPC). Since it is also essential in immune cells, we studied whether the expression of AR full-length (ARFL) and its splicing variant ARV7 in peripheral blood mononuclear cells (PBMC) predicts systemic treatment response in mCRPC in comparison with circulating-tumor cells (CTC). We measured ARFL and ARV7 mRNA in PBMC and CTC from patients prior to receiving abiraterone (AA), enzalutamide (E), or taxanes by a pre-amplification plus quantitative reverse-transcription PCR. They were also tested in LNCaP-ARV7-transfected and in 22RV1 docetaxel-resistant (22RV1DR) cells. We studied 171 PBMC from 136 patients and from 24 non-cancer controls, and 47 CTC from 22 patients. High PBMC ARV7 levels correlated with worse AA/E and better taxane response. In taxane-treated patients high PBMC ARFL also correlated with longer progression-free survival (PFS). High ARV7 and ARFL expression were independently asso...