mCRPC: Full-length AR Copy Number Prognostic for Outcomes

Share this content:
Full-length androgen receptor copy number derived from circulating tumor cells detected using a liquid biopsy.
Full-length androgen receptor copy number derived from circulating tumor cells detected using a liquid biopsy.

ORLANDO, FL Full-length androgen receptor (AR-FL) copy number derived from circulating tumor cells detected using a liquid biopsy is associated with clinical outcomes for patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone or enzalutamide, according to a study presented at 2017 Genitourinary Cancers Symposium.1

For this prospective biomarker study, investigators enrolled 202 patients with mCRPC who were beginning therapy with abiraterone or enzalutamide and consented to collection of circulating tumor cells. Median follow-up was 12.9 months.

"We used a qRT-PCR assay to interrogate circulating tumors cells for AR-FL to seek associations between baseline AR-FL status and PSA [prostate-specific antigen] response rate, PSA progression-free survival, clinical/radiographic progression-free survival, and overall survival," explained study author Emmanuel S. Antonarakis, associate professor of oncology and urology at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center in Baltimore, Maryland.

Higher AR-FL levels correlated with positive AR-V7 detection. The median number of AR-FL copies was 35.5 and 1.4 in AR-V7 positive and AR-V7 negative circulating tumors cells, respectively (P < .001).

Investigators also observed a significant association between AR-FL copy number and PSA50 response, with higher AR-FL levels correlating with lower PSA50 responses (P < .001).

AR-FL level was prognostic for PSA progression-free survival, progression-free survival, and overall survival (P < .001).

"Higher AF-FL levels correlated with inferior clinical outcomes, and generally remained significant in multivariable models," said Dr Antonarakis. "AR-V7 remained independently prognostic for all outcomes in multivariable analysis."

RELATED: Adjuvant Trials in Post-radical Prostatectomy Prostate Cancer Are Feasible

The findings suggest that AR-FL quantification, in addition to AR-V7, could serve as a molecular biomarker of sensitivity to abiraterone and enzalutamide.

Reference

  1. Silberstein J, Luber B, Wang H, et al. Clinical significance of AR mRNA quantification from circulating tumor cells (CTCs) in men with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone (Abi) or enzalutamide (Enza). Paper presented at: 2017 Genitourinary Cancers Symposium; February 16-18, 2017; Orlando, FL.

Related Resources

You must be a registered member of Cancer Therapy Advisor to post a comment.

Sign Up for Free e-newsletters

Regimen and Drug Listings

GET FULL LISTINGS OF TREATMENT Regimens and Drug INFORMATION

Bone Cancer Regimens Drugs
Brain Cancer Regimens Drugs
Breast Cancer Regimens Drugs
Endocrine Cancer Regimens Drugs
Gastrointestinal Cancer Regimens Drugs
Gynecologic Cancer Regimens Drugs
Head and Neck Cancer Regimens Drugs
Hematologic Cancer Regimens Drugs
Lung Cancer Regimens Drugs
Other Cancers Regimens
Prostate Cancer Regimens Drugs
Rare Cancers Regimens
Renal Cell Carcinoma Regimens Drugs
Skin Cancer Regimens Drugs
Urologic Cancers Regimens Drugs