Androgen receptor splice variant 7 in castration-resistant prostate cancer: Clinical considerations

Constitutively-active ligand-independent splice variants of the androgen receptor are an adaptive response by prostate cancer cells to escape androgen deprivation therapy and novel androgen receptor-directed treatments. Androgen receptor splice variant 7 is the most common splice variant detected in clinical biospecimens, and emerging data now suggest that the presence of tumoral androgen receptor splice variant 7 might be indicative of primary and acquired resistance to next-generation androgen pathway inhibitors, such as abiraterone and enzalutamide. At the same time, taxane chemotherapy might retain its efficacy regardless of androgen receptor splice variant 7 status, thus suggesting the potential for a predictive biomarker guiding treatment selection in men with metastatic castration-resistant prostate cancer. Herein, we review the preclinical data elucidating the structure and function of androgen receptor splice variant 7, we describe the existing clinical data using this biomarker in metastatic castration-resistant prostate cancer, and we highlight potential therapeutic strategies to target androgen receptor splice variant 7-expressing prostate cancer.