Immunotherapy for Prostate Cancer: An Evolving Landscape

Worldwide, prostate cancer is the second most common cancer in males, with approximately 1.1 million diagnoses and 307,000 deaths in 2012. The disease occurs mostly in older men, i.e., those past the age of 65. For clinically localized disease, standard treatment regimens include radical prostatectomy and/or radiation therapy. Androgen ablation, including bilateral orchiectomy or the administration of either LHRH agonists or antiandrogens, decreases tumor burden and improves median progression-free survival by 12–18 months. Despite its initial efficacy in controlling disease, most patients on hormonal therapy will eventually progress to castration-resistant prostate cancer (CRPC), and about 70% of patients will develop metastases, which are localized to the bone in 80–90% of cases. To date, there is no curative treatment for metastatic castration-resistant prostate cancer (mCRPC), although a number of treatments prolong survival and provide palliative benefit. First-line treatments for mCRPC include the antiandrogens enzalutamide and abiraterone acetate, as well as chemotherapeutic agents such as docetaxel. The prognosis for patients with mCRPC is variable, with median overall survival (OS) ranging from approximately 16–34 months.