Hormone therapy in advanced prostate cancer

Advances in engineering local drug delivery systems for cancer immunotherapy

Cancer immunotherapy aims to leverage the immune system to suppress the growth of tumors and to inhibit metastasis. The recent promising clinical outcomes associated with cancer immunotherapy have prompted research and development efforts towards enhancing the efficacy of immune checkpoint blockade, cancer vaccines, cytokine therapy, and adoptive T cell therapy. Advancements in biomaterials, nanomedicine, and micro-/nano-technology have facilitated the development of enhanced local delivery systems for cancer immunotherapy, which can enhance treatment efficacy while minimizing toxicity. Furthermore, locally administered cancer therapies that combine immunotherapy with chemotherapy, radiotherapy, or phototherapy have the potential to achieve synergistic antitumor effects. Herein, the latest studies on local delivery systems for cancer immunotherapy are surveyed, with an emphasis on the therapeutic benefits associated with the design of biomaterials and nanomedicines. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Emodin down-regulates androgen receptor and inhibits prostate cancer cell growth

Hormone-refractory relapse is an inevitable and lethal event for advanced prostate cancer patients after hormone deprivation. A growing body of evidence indicates that hormone deprivation may promote this aggressive prostate cancer phenotype. Notably, androgen receptor (AR) not only mediates the effect of androgen on the tumor initiation but also plays the major role in the relapse transition. This provides a strong rationale for searching new effective agents targeting the down-regulation of AR to treat or prevent advanced prostate cancer progression. Here, we show that emodin, a natural compound, can directly target AR to suppress prostate cancer cell growth in vitro and prolong the survival of C3(1)/SV40 transgenic mice in vivo. Emodin treatment resulted in repressing androgen-dependent transactivation of AR by inhibiting AR nuclear translocation. Emodin decreased the association of AR and heat shock protein 90 and increased the association of AR and MDM2, which in turn induces AR degradation through proteasome-mediated pathway in a ligand-independent manner. Our work indicates a new mechanism for the emodin-mediated anticancer effect and justifies further investigation of emodin as a therapeutic and preventive agent for prostate cancer.

Early versus late hormonal therapy: debating the issues

Hormonal therapy for prostate cancer has traditionally been reserved for advanced disease, but current evidence suggests that earlier use can confer a survival advantage. Survival benefit has been observed among patients with TNM stage T3 tumors who were treated with hormonal therapy plus external irradiation. Patients with nodal metastases (D1) who received immediate treatment with hormonal therapy after radical prostatectomy and pelvic lymphadenectomy also survived longer than those who were treated only after disease progression. The patients included in these studies are distinguished from those exhibiting "biochemical" failure (ie, increased levels of prostate-specific antigen, despite local therapy). It is in these patients that the use of hormonal therapy is, at present, controversial. For the purpose of identifying the subgroup of patients who might specifically benefit from early hormonal treatment, various schemas for defining predictors of poor outcome have been developed, including nomograms and artificial neural network programs. As with hormonal therapy, the use of chemotherapy in prostate cancer has been regarded as a palliative option for hormone-refractory disease. However, positive experience with early chemotherapy in other cancers suggests that such strategies might be similarly beneficial in prostate cancer. Limited clinical data show that chemotherapy combined with hormonal therapy can increase the initial response rate and prolong survival in locally advanced disease (T3 or D2), but not in metastatic tumors. An international trial is under way to evaluate the role of adjuvant chemotherapy in patients with localized prostate cancer who are at high risk of relapse after radical prostatectomy. Thus, accumulating evidence provides a rationale for continued investigation into the use of early hormonal therapy in selected patients.