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INTRODUCTION: Enzalutamide is an oral androgen receptor (AR) signaling inhibitor that was specifically engineered to overcome castration-resistant prostate cancer (CRPC) harboring AR amplification or overexpression. Enzalutamide has demonstrated significant activity in men with metastatic CRPC. AIMS: To update the evidence and provide an overview of the available data on enzalutamide. EVIDENCE REVIEW: Peer reviewed articles published and listed in Medline Search were reviewed. In addition, relevant ASCO and ESMO abstracts were searched. The activity of enzalutamide is mediated by potently antagonizing the full-length AR, impairing translocation of the AR from the cytoplasm into the nucleus, and inhibiting the transcriptional activity of the AR by modulating the interaction of the AR with androgen-response elements in gene promoter regions. Enzalutamide has a favorable safety profile and the most common adverse events include fatigue, hot flashes and headache; 1% of patients experienced seizure. PLACE IN THERAPY: The AFFIRM phase III study evaluated the clinical utility of treatment with enzalutamide in men with docetaxel-refractory metastatic CRPC. Enzalutamide improved overall survival compared to placebo, with a median overall survival of 18.4 months versus 13.6 months respectively. CONCLUSION: Enzalutamide has demonstrated impressive efficacy in men with metastatic CRPC, moving swiftly from a phase I/II study to two pivotal phase III trials testing this agent in both chemotherapy-pretreated as well as chemotherapy-naïve CRPC patients. Ongoing studies are aiming to explore the utility of enzalutamide in earlier stages of the disease, and to investigate the optimal sequencing and combination of enzalutamide with other standard and novel therapies for prostate cancer.
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In sporadic clear cell renal cell carcinoma (CCRCC), the von Hippel Lindau (VHL) gene is inactivated by mutation or methylation in the majority of primary (P) tumors. Due to differing effects of wild-type (WT) and mutant (MT) VHL gene on downstream signaling pathways regulating angiogenesis, VHL gene status could impact clinical outcome. In CCRCC, comparative genomic hybridization analysis studies have reported genetic differences between paired P and metastatic (M) tumors. We thus sequenced the VHL gene in paired tumor specimens from 10 patients to determine a possible clonal relationship between the P tumor and M lesion(s) in patients with CCRCC. Using paraffin-embedded specimens, genomic DNA from microdissected samples (>80% tumor) of paired P tumor and M lesions from all 10 patients, as well as in normal tissue from 6 of these cases, was analyzed. The DNA was used for PCR-based amplification of each of the 3 exons of the VHL gene. Sequences derived from amplified samples were compared to the wild-type VHL gene sequence (GenBank Accession No. AF010238). Methylation status of the VHL gene was determined using VHL methylation-specific PCR primers after DNA bisulfite modification. In 4/10 (40%) patients the VHL gene status differed between the P tumor and the M lesion. As expected, when the VHL gene was mutated in both the P tumor and M lesion, the mutation was identical. Further, while the VHL genotype differed between the primary tumor in different kidneys or multiple metastatic lesions in the same patient, the VHL germline genotype in the normal adjacent tissue was always wild-type irrespective of the VHL gene status in the P tumor. These results demonstrate for the first time that the VHL gene status can be different between paired primary and metastatic tissue in patients with CCRCC.