Future prospects in the diagnosis and management of localized prostate cancer

Adjuvant hormone therapy after radical prostatectomy in high-risk localized and locally advanced prostate cancer: First multicenter, observational study in China

Objective

Potential of combined androgen blockade (CAB) has not been explored extensively in Chinese males with prostate cancer (PCa). Therefore, this study evaluated the 2-year prostate-specific antigen (PSA) recurrence rate and quality of life (QoL) in patients with high-risk localized and locally advanced PCa receiving adjuvant hormone therapy (HT) after radical prostatectomy (RP).

Methods

This prospective, multicenter, observational study conducted in 18 centers across China enrolled patients with high-risk factor (preoperative PSA>20 ng/mL or Gleason score >7) or locally advanced PCa. Different adjuvant HT were administered after RP according to investigator’s decision in routine clinical practice. Relationship of baseline and postoperative characteristics was assessed with recurrence rate. PSA recurrence rate and Functional Assessment of Cancer Therapy-Prostate (FACT-P) QoL scores were recorded at 12 months and 24 months. Kaplan-Meier analysis was used to construct the PSA recurrence rate during follow-up.

Results

A total of 189 patients (mean age: 66.9±6.5 years) were recruited, among which 112 (59.3%) patients showed serum PSA>20 ng/mL preoperatively. The highest postoperative pathological advancement noticed was from clinical T2 (cT2) to pathological T3 (pT3) (43.9%) stage. The majority of the patients (66.1%) received CAB as adjuvant HT, for a median duration of 20.0 months. The least recurrence (15.2%) was noticed in patients treated with CAB, followed by those treated with luteinizing hormone-releasing hormone agonist (LHRHa) (16.1%), and antiandrogen (19.0%), with non-significant difference noted among the groups. None of the baseline or postoperative characteristics was related with PSA recurrence in our study. The 24-month FACT-P QoL score of 119 patients treated for >12 months showed significant improvement above baseline compared with those treated for ≤12 months.

Conclusions

Adjuvant CAB therapy after RP showed reduction trend in 2-year PSA recurrence rate in high-risk Chinese patients with localized and locally advanced PCa, compared with adjuvant anti-androgens (AA) or LHRHa therapy. Further long-term therapy (>12 months) significantly improved QoL compared to short-term HT therapy, suggesting the beneficial effect of long-term CAB therapy in improving QoL.

Biomarkers in localized prostate cancer

Biomarkers can improve prostate cancer diagnosis and treatment. Accuracy of prostate-specific antigen (PSA) for early diagnosis of prostate cancer is not satisfactory, as it is an organ- but not cancer-specific biomarker, and it can be improved by using models that incorporate PSA along with other test results, such as prostate cancer antigen 3, the molecular forms of PSA (proPSA, benign PSA and intact PSA), as well as kallikreins. Recent reports suggest that new tools may be provided by metabolomic studies as shown by preliminary data on sarcosine. Additional molecular biomarkers have been identified by the use of genomics, proteomics and metabolomics. We review the most relevant biomarkers for early diagnosis and management of localized prostate cancer.

Oncolytic virus carrying shRNA targeting SATB1 inhibits prostate cancer growth and metastasis

Recent studies suggest that SATB1 is a promising therapeutic target for prostate cancer. To develop novel SATB1-based therapeutic agents for prostate cancer, in this study, we aimed to construct ZD55-SATB1, an oncolytic adenovirus ZD55 carrying shRNA targeting SATB1, and investigate its effects on the inhibition of prostate cancer growth and metastasis. ZD55-SATB1 was constructed and used to infect human prostate cancer cell lines DU145 and LNCaP. The inhibitory effect of ZD55-SATB1 on SATB1 expression was evaluated by reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. The cytotoxicity of ZD55-SATB1 was detected by MTT assay. Cell invasion was detected by Matrigel invasion assay. The in vivo antitumor activities of ZD55-SATB1 were evaluated in xenograft mouse model. We found that ZD55-SATB1 selectively replicated and significantly reduced SATB1 expression in DU145 and LNCaP cells. ZD55-SATB1 effectively inhibited the viability and invasion of DU145 and LNCaP cells in vitro and inhibited prostate cancer growth and metastasis in xenograft nude mice. In conclusion, replicative oncolytic adenovirus armed with SATB1 shRNA exhibits effective antitumor effect in human prostate cancer. Our study provides the basis for the development of ZD55-SATB1 for the treatment of prostate cancer.

Proapoptotic effect of endocannabinoids in prostate cancer cells

In the early stages, prostate cancer is androgen‑ dependent; therefore, medical castration has shown significant results during the initial stages of this pathology. Despite this early effect, advanced prostate cancer is resilient to such treatment. Recent evidence shows that derivatives of Cannabis sativa and its analogs may exert a protective effect against different types of oncologic pathologies. The purpose of the present study was to detect the presence of cannabinoid receptors (CB1 and CB2) on cancer cells with a prostatic origin and to evaluate the effect of the in vitro use of synthetic analogs. In order to do this, we used a commercial cell line and primary cultures derived from prostate cancer and benign prostatic hyperplasia. The presence of the CB1 and CB2 receptors was determined by immunohistochemistry where we showed a higher expression of these receptors in later stages of the disease (samples with a high Gleason score). Later, treatments were conducted using anandamide, 2-arachidonoyl glycerol and a synthetic analog of anandamide, methanandamide. Using the MTT assay, we proved that the treatments produced a cell growth inhibitory effect on all the different prostate cancer cultures. This effect was demonstrated to be dose-dependent. The use of a specific CB1 receptor blocker (SR141716) confirmed that this effect was produced primarily from the activation of the CB1 receptor. In order to understand the MTT assay results, we determined cell cycle distribution by flow cytometry, which showed no variation at the different cell cycle stages in all the cultures after treatment. Treatment with endocannabinoids resulted in an increase in the percentage of apoptotic cells as determined by Annexin V assays and caused an increase in the levels of activated caspase-3 and a reduction in the levels of Bcl-2 confirming that the reduction in cell viability noted in the MTT assay was caused by the activation of the apoptotic pathway. Finally, we observed that endocannabinoid treatment activated the Erk pathway and at the same time, produced a decrease in the activation levels of the Akt pathway. Based on these results, we suggest that endocannabinoids may be a beneficial option for the treatment of prostate cancer that has become nonresponsive to common therapies.

Closed-form solution of the convolution integral in the magnetic resonance dispersion model for quantitative assessment of angiogenesis

Prostate cancer (PCa) diagnosis and treatment is still limited due to the lack of reliable imaging methods for cancer localization. Based on the fundamental role played by angiogenesis in cancer growth and development, several dynamic contrast enhanced (DCE) imaging methods have been developed to probe tumor angiogenic vasculature. In DCE magnetic resonance imaging (MRI), pharmacokinetic modeling allows estimating quantitative parameters related to the physiology underlying tumor angiogenesis. In particular, novel magnetic resonance dispersion imaging (MRDI) enables quantitative assessment of the microvascular architecture and leakage, by describing the intravascular dispersion kinetics of an extravascular contrast agent with a dispersion model. According to this model, the tissue contrast concentration at each voxel is given by the convolution between the intravascular concentration, described as a Brownian motion process according to the convective-dispersion equation, with the interstitium impulse response, represented by a mono-exponential decay, and describing the contrast leakage in the extravascular space. In this work, an improved formulation of the MRDI method is obtained by providing an analytical solution for the convolution integral present in the dispersion model. The performance of the proposed method was evaluated by means of dedicated simulations in terms of estimation accuracy, precision, and computation time. Moreover, a preliminary clinical validation was carried out in five patients with proven PCa. The proposed method allows for a reduction by about 40% of computation time without any significant change in estimation accuracy and precision, and in the clinical performance.