Neoadjuvant therapy before radical prostatectomy: Where have we been? Where are we going?

The influence of testosterone suppression on HER2 immunoexpression in prostatic neoplastic tissue

During initial risk assessments, the metastatic potential of prostate cancer (PCa) may not be fully considered. The tumor's multicentric origin, which is associated with genetic mutations, may explain existing treatment limitations. Investigating human epidermal growth factor receptor 2 (HER2) expression in patients with different stages of PCa may therefore increase understanding of the mechanisms associated with the development of castration resistance. The present study examined the association between HER2 expression and the histologic features of PCa subjected to radical prostatectomy (RP) and evaluated the role of testosterone suppression in HER2 expression. In group 1, specimens from individuals who underwent RP without prior neoadjuvant androgen deprivation therapy (ADT) were included (n=42). In group 2 (PCa with ADT), specimens from individuals who underwent RP and received neoadjuvant cyproterone acetate during distinct periods (200 mg daily for 1-24 months) were included (n=150; cohort derived from a previous study). Immunohistochemical expression of HER2 was associated with prognostic factors such as perineural invasion, extra-prostatic disease, T stage, serum prostate-specific antigen (PSA), angiolymphatic invasion and surgical margins. Univariate regression analysis indicated that perineural invasion, PSA, International Society of Urological Pathology, angiolymphatic invasion, margin, T stage and neoadjuvant ADT was associated with HER2 expression. Ordinal regression analysis indicated a significant effect of neoadjuvant ADT alone on HER2 expression (P<0.001). In addition, regression analysis indicated a significant effect of neoadjuvant ADT alone on HER2 expression (odd ratio=0.01; 95% CI, 0.00, 0.02; P<0.001). HER2 was expressed in PCa samples but was not associated with known prognostic factors. The use of short-acting ADT and the consequent blockage of testosterone effect may suppress the expression of HER2 in PCa cells.

Neoadjuvant therapy for localized prostate cancer: Examining mechanism of action and efficacy within the tumor

OBJECTIVES

Efforts to improve the clinical outcome for patients with localized high-risk prostate cancer have led to the development of neoadjuvant systemic therapies. We review the different modalities of neoadjuvant therapies for localized prostate cancer and highlight emerging treatment approaches including immunotherapy and targeted therapy.

METHODS

We performed a PubMed search of clinical trials evaluating preoperative systemic therapies for treating high-risk prostate cancer published after 2000, and those studies with the highest clinical relevance to current treatment approaches were selected for review. The database at clinicaltrials.gov was queried for neoadjuvant studies in high-risk prostate cancer, and those evaluating novel targeted therapies and immunotherapies are spotlighted here.

RESULTS

Neoadjuvant chemotherapy has become standard of care for treating some malignancies, including breast and bladder cancers. In prostate cancer, preoperative hormonal therapy or chemotherapy has failed to demonstrate improvements in overall survival. Nevertheless, the emergence of novel treatment modalities such as targeted small molecules and immunotherapy has spawned neoadjuvant clinical trials that provide a unique vantage from which to study mechanism of action and biological potency. Tissue-based biomarkers are being developed to elucidate the biological efficacy of these treatments. With targeted therapy, these can include phospho-proteomic signatures of target pathway activation and deactivation. With immunotherapies, including sipuleucel-T and ipilimumab, recruitment of immune cells to the tumor microenvironment can also be used as robust markers of a biological effect. Such studies can provide insight not only into mechanism of action for these therapies but can also provide paths forward to improving clinical efficacy like with rationally designed combinations and dose selection.

CONCLUSIONS

The use of neoadjuvant androgen-deprivation therapy and chemotherapy either singly or in combination before radical prostatectomy is generally safe and feasible while reducing prostate volume and tumor burden. However, pathologic complete response rates are low and no long-term survival benefit has been observed with the addition of neoadjuvant therapies over surgery alone at present, and therefore preoperative therapy is not the current standard of care in prostate cancer treatment.

Markers of field cancerization: proposed clinical applications in prostate biopsies

Field cancerization denotes the occurrence of genetic, epigenetic, and biochemical aberrations in structurally intact cells in histologically normal tissues adjacent to cancerous lesions. This paper tabulates markers of prostate field cancerization known to date and discusses their potential clinical value in the analysis of prostate biopsies, including diagnosis, monitoring progression during active surveillance, and assessing efficacy of presurgical neoadjuvant and focal therapeutic interventions.

Targeting tyrosine phosphorylation of PCNA inhibits prostate cancer growth

The proliferation cell nuclear antigen (PCNA) is a critical protein required for DNA replication in proliferating cells including cancer cells. However, direct inhibition of PCNA in cancer cells has been difficult due to the lack of targetable sites. We previously reported that phosphorylation of tyrosine 211 (Y211) on PCNA is important for the proliferative function of PCNA when this protein is associated with the chromatin in cancer cells. Here, we show that the Y211 phosphorylation of PCNA is a frequent event in advanced prostate cancer. To explore the potential of this signaling event in inhibition of cancer cell growth, we used a synthetic peptide, the Y211F peptide, which when present inhibits phosphorylation of Y211 on endogenous PCNA. Treatment with this peptide, but not a scrambled control peptide, resulted in S-phase arrest, inhibition of DNA synthesis, and enhanced cell death in a panel of human prostate cancer cell lines. In addition, treatment with the Y211F peptide led to decreased tumor growth in PC3-derived xenograft tumors in vivo in nude mice. Our study shows for the first time that PCNA phosphorylation at Y211 is a frequent and biologically important signaling event in prostate cancer. This study also shows a proof of concept that Y211 phosphorylation of PCNA may be used as a therapeutic target in prostate cancer cells, including cells of advanced cancers that are refractory to standard hormonal therapies.

Neoadjuvant hormonal therapy preceding radical prostatectomy for clinically localized prostate cancer: early postoperative complications and biochemical recurrence

Purpose

The effect of neoadjuvant hormonal therapy (NHT) on radical retropubic prostatectomy (RRP) for prostate cancer is various and remains a controversy for urologists. We conducted this study to comparatively evaluate whether NHT before RRP is indicated and beneficial in the aspects of postoperative complications, positive surgical margin, and biochemical recurrence.

Materials and Methods

Between September 2006 and December 2009, 69 men were scheduled for RRP as a treatment for clinically localized and locally advanced prostate cancer and were divided into two groups. Group 1 (n=31, 44.9%) was treated with RRP only, and group 2 (n=38, 55.1%) underwent RRP with preoperative NHT. We evaluated clinical parameters, surgical parameters, and the positive margin rate in surgical specimens and the biochemical recurrence rate.

Results

There were no statistical differences in age, body mass index (BMI), preoperative biopsy Gleason score, initial serum prostate-specific antigen (PSA) levels, International Prostate Symptom Score (IPSS), or quality of life (QoL) between the two groups (p>0.05). We also observed no differences in the transfusion rate, mean catheterization time, or positive margin rate (p>0.05). However, the mean operative time was significantly higher in the RRP with preoperative NHT group than in the other group (p=0.034). There was no significant difference in the biochemical recurrence rate during the last follow-up according to NHT (p=0.102) or positive surgical margin (p=0.473).

Conclusions

These results suggest that there were no clinical benefits to the administration of NHT before RRP from the viewpoint of biochemical recurrence.

Phase II trial of short-term neoadjuvant docetaxel and complete androgen blockade in high-risk prostate cancer

BACKGROUND

The low probability of curing high-risk prostate cancer (PC) with local therapy suggests the need to study modality of therapeutic approaches. To this end, a prospective phase II trial of neoadjuvant docetaxel (D) and complete androgen blockade (CAB) was carried out in high-risk PC patients. The primary end point was to detect at least 10% of pCRs after chemohormonal treatment.

METHODS

Patients with T1c-T2 clinical stage with prostate-specific antigen (PSA) >20 ng ml(-1) and/or Gleason score >or=7 (4+3) and T3 were included. Treatment consisted of three cycles of D 36 mg m(-2) on days 1, 8 and 15 every 28 days concomitant with CAB, followed by radical prostatectomy (RP).

RESULTS

A total of 57 patients were included. Clinical stage was T1c, 11 patients (19.3%); T2, 30 (52.6%) and T3, 16 (28%) patients. Gleason score was >or=7 (4+3) in 44 (77%) patients and PSA >20 ng ml(-1) in 15 (26%) patients. Treatment was well tolerated with 51 (89.9%) patients completing neoadjuvant therapy together with RP. The rate of pCR was 6% (three patients). Three (6%) additional patients had microscopic residual tumour (near pCR) in prostate specimen. With a median follow-up of 35 months, 18 (31.6%) patients presented PSA relapse.

CONCLUSION

Short-term neoadjuvant D and CAB induced a 6% pCR rate, which is close to what would be expected with ADT alone. The combination was generally well tolerated.

Pathological effects of prostate cancer correlate with neuroendocrine differentiation and PTEN expression after bicalutamide monotherapy

PURPOSE

Androgen deprivation therapy is the primary treatment for advanced prostate cancer but many patients eventually experience progression to hormone refractory status. Understanding the molecular changes after androgen deprivation therapy would help evaluate the efficacy or failure of second line therapies. Therefore, we analyzed the expression of the tumor suppressor phosphatase and tensin homologue deleted on chromosome 10 (PTEN), the human epidermal receptor-2 and neuroendocrine differentiation after bicalutamide monotherapy, which is emerging as an alternative treatment for locally advanced prostate cancer.

MATERIALS AND METHODS

Molecular arrangements were evaluated in 107 radical prostatectomy specimens from patients given 150 mg bicalutamide before surgery. Pathological regressive changes, and the correlation of postoperative biochemical failure with the extent of molecular arrangements and pathological effects were analyzed.

RESULTS

Patients with minimal regression effects after bicalutamide therapy had advanced pathological stage disease, and tended to have positive chromogranin A expression and PTEN inactivation. Only 4 (3.7%) prostatectomy specimens showed human epidermal receptor-2 immunostaining. The probability of positive chromogranin A expression in the PTEN inactivation group was 2.5-fold (OR 2.5, 95% CI 1.1-5.6, p = 0.023) higher than in the nonPTEN inactivation group. Cox regression analysis revealed that seminal vesicle invasion, PTEN/chromogranin A expression and lymph node invasion were significant variables for time to biochemical recurrence.

CONCLUSIONS

PTEN inactivation and neuroendocrine differentiation were related to refractoriness to bicalutamide therapy. These results support the hypothesis that neuroendocrine differentiation is caused by activation of the serine threonine kinase Akt pathway, which results from PTEN inactivation.

Neoadjuvant platelet derived growth factor receptor inhibitor therapy combined with docetaxel and androgen ablation for high risk localized prostate cancer

PURPOSE

Platelet derived growth factor receptor inhibitor therapy improves the efficacy of taxane chemotherapy in preclinical models of prostate cancer. Men with high risk localized prostate cancer were treated with platelet derived growth factor receptor inhibitor therapy, docetaxel and hormone ablation in the preoperative setting, and clinicopathological outcomes were evaluated.

MATERIALS AND METHODS

A total of 36 men with cT2 or greater disease, Gleason grade 8-10, serum prostate specific antigen more than 20 ng/ml or cT2b and prostate specific antigen more than 10 ng/ml and Gleason 7 disease, without radiological evidence of metastases, were scheduled to receive intramuscular leuprolide, 600 mg daily oral imatinib and 30 mg/m(2) weekly docetaxel x 4 every 42 days for 3 cycles before radical prostatectomy (beta [0.02, 1.98] prior on the possibility of pathological complete remission). Unresectable disease, postoperative prostate specific antigen 0.2 ng/ml or greater, or administration of postoperative radiation or hormones were defined as treatment failure.

RESULTS

A total of 39 men were registered over 15 months. Median patient age was 57 years (range 44 to 71). Risk factors included T3 disease (22 of 39), Gleason 8-10 disease (31 of 39) and prostate specific antigen more than 20 ng/ml (12 of 39). Three men were ineligible or declined therapy, 29 of 36 (81%) received 3 cycles of therapy and 7 of 36 (19%) discontinued therapy related to toxicity. Grades 3-4 toxicity included rash (4), diarrhea (4), fatigue (6) and neutropenia (1). The surgical approach was feasible, without excessive or unusual complications such as wound dehiscence. No pathological complete remissions were defined. At a median followup of 39 months 53% were free from progression.

CONCLUSIONS

Evidence for a favorable impact of platelet derived growth factor receptor inhibitor therapy on the efficacy of neoadjuvant docetaxel and hormonal ablation in high risk localized prostate cancer was not obtained.

Neoadjuvant hormonal deprivation for patients undergoing radical prostatectomy

The purpose of this study is to evaluate the therapeutic effect of radical prostatectomy combined with preoperative neoadjuvant hormonal ablation therapy for prostate cancer (PCa). In this study, a total of 31 patients with local PCa underwent radical prostatectomy; of these, 12 patients underwent preoperative hormonal deprivation with a combination of goserelin and flutamide for a period of 5.6 months. Data regarding clinical characteristics were compared between the neoadjuvant therapy and radical prostatectomy groups. A total of 31 patients received pelvic lymph node clearance, and the rate of positive lymph nodes was 12.9% (4/31). Serum prostate-specific antigen (PSA) was 8.9 +/- 1.2 microg L(-1) after the neoadjuvant therapy and 0.4 +/- 0.3 microg L(-1) one month after the radical prostatectomy. There were significant differences in the positive surgical margins, seminal vesicle invasion and lymph node metastasis between the neoadjuvant therapy group (n = 12) and the radical prostatectomy group (n = 19, P < 0.01). The resulsts indicates that preoperative hormonal deprivation induced by goserelin and flutamide can decrease clinical and pathological staging, but assessment of its influence on long-term prognosis requires further study.

[Chemotherapy for prostate cancer]

For many years the benefit of chemotherapy in patients with prostate cancer was thought to be limited to palliation of late-stage disease, and thus this treatment option only became involved in patient care towards the end of the disease process, if at all. However, two landmark phase-III trials with docetaxel-based therapy (TAX 327 and Southwest Oncology Group, SWOG, 9916) have shown a survival benefit for patients with hormone refractory prostate cancer (HRPC) thus prompting a change in patterns of care. With raising interest for chemotherapeutic options and clinical trials for new drugs and new indications (neoadjuvant therapy, adjuvant therapy, increasing PSA levels after local treatment, and hormone sensitive cancer) under way our goal was to review within the context of a multidisciplinary team the available evidence and explore the standard for the medical treatment of prostate cancer outside of clinical trials. We are carefully evaluating the current treatment recommendations based on the available evidence and highlight potential future treatment options but also discuss important clinical topics (treatment until progression versus the advantage of chemo holidays, definition of particular patient subgroups and potential second line options) for which there are no clear cut answers to date. The role and importance of radiotherapy, biphosphonate treatment and the medical management of pain and side effects is also discussed. The multitude of treatment options for patients with advanced prostate cancer clearly asks for a close collaboration between urologists, medical oncologists and radiation therapists.

Neoadjuvant therapy and prostate cancer: what a urologist should know

PURPOSE OF REVIEW

Prostate cancer is curable only when treated at an early stage, when the tumor is still localized to the prostate gland. However, even in apparent cases of clinically localized disease, unsuspected extracapsular disease may significantly increase the risk of primary treatment failure. This risk is especially high if the patient has one or more of the following risk factors: a serum prostate-specific antigen level >20 ng/ml, a Gleason score >7, locally advanced disease (clinical stage T3/T4), and extensive disease on prostate biopsy.

RECENT FINDINGS

Various regimens of neoadjuvant hormonal therapy and/or chemotherapy have produced mixed results and generally have not influenced the rate of disease relapse (defined by prostate-specific antigen level) in high-risk patients with localized prostate cancer. In addition, antiangiogenic agents, gene therapy, molecular targeting agents, and other promising new therapies have been investigated in a neoadjuvant setting with limited results.

SUMMARY

Despite considerable advances, high-risk localized prostate cancer remains an extremely refractory disease. In patients with high-risk prostate cancer, single-modality treatment in the form of surgery offers a 5-year biochemical disease-free survival rate of no better than 50%. To further elucidate optimal treatment regimens for these patients we must actively enrol patients in clinical trials.