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Clin Cancer Res. 2015 May 15;21(10):2315-24. doi: 10.1158/1078-0432.CCR-14-2666. Epub 2015 Feb 23.

Androgen Receptor Gene Aberrations in Circulating Cell-Free DNA: Biomarkers of Therapeutic Resistance in Castration-Resistant Prostate Cancer.

Author information

1
Vancouver Prostate Centre, Vancouver, British Columbia, Canada. Department of Medical Oncology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada.
2
Vancouver Prostate Centre, Vancouver, British Columbia, Canada.
3
Helen Diller Family Comprehensive Cancer Center, University of California at San Francisco, San Francisco, California.
4
Department of Urology, UCSF, UCSF Diller Comprehensive Cancer Center, San Francisco, California.
5
Department of Pathology and Laboratory Medicine, OHSU Knight Cancer Institute, Portland, Oregon.
6
Vancouver Prostate Centre, Vancouver, British Columbia, Canada. University of British Columbia, Vancouver, British Columbia, Canada.
7
Vancouver Prostate Centre, Vancouver, British Columbia, Canada. University of British Columbia, Vancouver, British Columbia, Canada. kchi@bccancer.bc.ca ccollins@prostatecentre.com.
8
Vancouver Prostate Centre, Vancouver, British Columbia, Canada. Department of Medical Oncology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada. University of British Columbia, Vancouver, British Columbia, Canada. kchi@bccancer.bc.ca ccollins@prostatecentre.com.

Abstract

PURPOSE:

Although novel agents targeting the androgen-androgen receptor (AR) axis have altered the treatment paradigm of metastatic castration-resistant prostate cancer (mCRPC), development of therapeutic resistance is inevitable. In this study, we examined whether AR gene aberrations detectable in circulating cell-free DNA (cfDNA) are associated with resistance to abiraterone acetate and enzalutamide in mCRPC patients.

EXPERIMENTAL DESIGN:

Plasma was collected from 62 mCRPC patients ceasing abiraterone acetate (n = 29), enzalutamide (n = 19), or other agents (n = 14) due to disease progression. DNA was extracted and subjected to array comparative genomic hybridization (aCGH) for chromosome copy number analysis, and Roche 454 targeted next-generation sequencing of exon 8 in the AR.

RESULTS:

On aCGH, AR amplification was significantly more common in patients progressing on enzalutamide than on abiraterone or other agents (53% vs. 17% vs. 21%, P = 0.02, χ(2)). Missense AR exon 8 mutations were detected in 11 of 62 patients (18%), including the first reported case of an F876L mutation in an enzalutamide-resistant patient and H874Y and T877A mutations in 7 abiraterone-resistant patients. In patients switched onto enzalutamide after cfDNA collection (n = 39), an AR gene aberration (copy number increase and/or an exon 8 mutation) in pretreatment cfDNA was associated with adverse outcomes, including lower rates of PSA decline ≥ 30% (P = 0.013, χ(2)) and shorter time to radiographic/clinical progression (P = 0.010, Cox proportional hazards regression).

CONCLUSIONS:

AR gene aberrations in cfDNA are associated with resistance to enzalutamide and abiraterone in mCRPC. Our data illustrate that genomic analysis of cfDNA is a minimally invasive method for interrogating mechanisms of therapeutic resistance in mCRPC.

PMID:
25712683
DOI:
10.1158/1078-0432.CCR-14-2666
[Indexed for MEDLINE]
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