Biomarkers of Castrate Resistance in Prostate Cancer: Androgen Receptor Amplification and T877A Mutation Detection by Multiplex Droplet Digital PCR

Abstract

Androgen Receptor (AR) alterations (amplification, point mutations, and splice variants) are master players in metastatic castration resistant prostate cancer (CRPC) progression and central therapeutic targets for patient management. Here, we have developed two multiplexed droplet digital PCR (ddPCR) assays to detect AR copy number (CN) and the key point mutation T877A. Overcoming challenges of determining gene amplification from liquid biopsies, these assays cross-validate each other to produce reliable AR amplification and mutation data from plasma cell free DNA (cfDNA) of advanced prostate cancer (PC) patients. Analyzing a mixed PC patient cohort consisting of CRPC and hormone sensitive prostate cancer (HSPC) patients showed that 19% (9/47) patients had AR CN amplification. As expected, only CRPC patients were positive for AR amplification, while interestingly the T877A mutation was identified in two patients still considered HSPC at the time. The ddPCR based analysis of AR alterations in cfDNA is highly economic, feasible, and informative to provide biomarker detection that may help to decide on the best follow-up therapy for CRPC patients.

The androgen receptor-targeted proteolysis targeting chimera and other alternative therapeutic choices in overcoming the resistance to androgen deprivation treatment in prostate cancer

“…Similarly, AR mutations were rarely found in untreated PCa patients, and they were often found to emerge in patients who had been treated with anti-androgens for a long period of time [ 14 ]. The first identified AR mutation was the AR mutation (T877A) which is also the most frequently found mutation in PCa patients [ 19 ]. Later, more AR mutations had been discovered and analysed using gene sequencing [ 20 ].…”

Liquid Biopsy and Cancer: An Ongoing Story

“…Recently, Young et al developed two multiplexed droplet digital PCR (ddPCR) assays to detect AR copy number and the key point mutation T877A. These assays cross validate each other to produce reliable AR amplification and mutation data from plasma cfDNA of advanced prostate cancer patients [ 10 ]. Facilitated by the rapid development of next-generation sequencing (NGS) technologies, cfDNA has shown utility for the management of several cancer types, including colorectal cancer.…”