Ultra-sensitive detection of somatic mutations in androgen receptor conferring resistance to anti-androgen therapy in prostate cancer.

Prostate cancer (PCa) is primarily driven by androgen receptor (AR) signaling, where a potent form of androgen, such as dihydrotestosterone (DHT), binds with AR to promote tumor cell proliferation and survival. Somatic mutations in AR gene are recognized as key predictive indicators of therapeutic resistance to anti-androgen therapy in advanced stages of PCa. To enable minimally invasive detection of these alterations, we developed an ultrasensitive digital droplet PCR (ddPCR) assay capable of quantifying absolute copies of AR mutant alleles relative to wild-type AR using cell-free circulating DNA isolated from the patient's plasma. This approach demonstrated a reliable surveillance of hotspot AR mutation that emerges in response to drug treatment. Furthermore, quantitative plasma cell-free DNA (cfDNA) levels provide a dynamic proxy for tumor burden, with sharp post-therapy declines serving as a real-time indicator of treatment efficacy. These findings highlight the prototype standardization of cfDNA-based AR mutation assay in Indian PCa patients, establishing a framework to enable personalized treatment strategies, real-time disease monitoring, and therapeutic response.