Prostate cancer (PCa) is one of the most common cancer in men. It affects older men and the incidence increases with age; the median age at diagnosis is 67 years. The diagnosis of PCa is essentially based on three tools: digital rectal exam, serum concentration of prostate specific antigen, and transrectal ultrasound-guided biopsy. Currently, the therapeutic treatments of this cancer are different and range from the prostatectomy to hormonal therapy, to radiation therapy, to immunotherapy, and to chemotherapy. However, additional efforts are required in order to find new weapons for the treatment of metastatic setting of disease. The purpose of this review is to highlight new therapeutic strategies based on gene interference; in fact, numerous siRNA and miRNA in the therapeutic treatment of PCa are reported below.

The presence of an aberrantly activated epidermal growth factor receptor (EGFR) in many epithelial tumors, due to its overexpression, activating mutations, gene amplification and/or overexpression of receptor ligands, represent the fundamental basis underlying the use of EGFR tyrosine kinase inhibitors (EGFR-TKIs). Drugs inhibiting the EGFR have different mechanisms of action; while erlotinib and gefitinib inhibit the intracellular tyrosine kinase, monoclonal antibodies like cetuximab and panitumumab bind the extracellular domain of the EGFR both activating immunomediated anti-cancer effect and inhibiting receptor function. On the other hand, interleukin-8 has tumor promoting as well as neo-angiogenesis enhancing effects and several attempts have been made to inhibit its activity. One of these is based on the use of the old sulfone antibiotic dapsone that has demonstrated several interleukin-8 system inhibiting actions. Erlotinib typically gives a rash that has recently been proven to come out via up-regulated keratinocyte interleukin-8 synthesis with histological features reminiscent of typical neutrophilic dermatoses. In this review, we report experimental evidence that shows the use of dapsone to improve quality of life in erlotinib-treated patients by ameliorating rash as well as short-circuiting a growth-enhancing aspect of erlotinib based on increased interleukin-8 secretion.

Immunotherapy with checkpoint inhibitors is beginning to be recognized as a valid weapon for the treatment of metastatic prostate cancer (PCa) when chemotherapy fails. Ipilimumab (ipi) is a fully humanized monoclonal antibody that blocks the activity of CTLA4. It also has a molecular weight of 148 kDa and is water-soluble at physiological pH. Ipi was first approved by the FDA for the treatment of malignant melanoma and is currently being studied in metastatic castration-resistant prostate cancer, with promising early results. Areas covered: The aim of this review is to collate the most significant preclinical and clinical studies available that look at ipi to propose new strategies for the future. Expert opinion: Additional studies are required to reduce toxicity and increase the activity of ipi in PCa. A possible strategy is to combine ipi with standard anti-cancer therapeutics such as vaccines, PDL1 inhibitors, antiandrogen drugs, and chemotherapy agents. Several initial results have suggested that combination strategies are useful to increase the activity in mCRPC, even if the toxicity of the treatment can increase. The activity of combined treatments is still not predictable, but considering the ongoing studies, we believe that they have good potential that will lead to the discovery of an optimal therapeutic strategy.