The Evolving Role of Chemotherapy and Other Systemic Therapies for Managing Localized Prostate Cancer

Rh2 or its aglycone aPPD in combination with docetaxel for treatment of prostate cancer

BACKGROUND

Docetaxel is one of the few chemotherapeutic drugs that are considered highly effective when used to treat prostate cancer patients that have relapsed and/or metastatic disease, it is therefore reasonable to expect further improvements in treatment outcomes when it is combined with other therapeutic agents active in prostate cancer. This study assesses the combination of well tolerated and orally bioavailable formulations of ginsenoside Rh2 or its aglycone aPPD with docetaxel.

METHODS

The in vitro activity of Rh2, aPPD, and docetaxel was determined in four prostate cancer cell lines: PC-3, LNCaP, DU145, and C4-2. Combinations of Rh2 or aPPD with docetaxel were assessed using the constant ratio combination design. Combination Indices (CI) and Dose Reduction Indices (DRI) were subsequently estimated using Calcusyn. In vivo efficacy studies and Immunohistochemical analyses (PC-3 model) were also evaluated.

RESULTS

In PC-3, DU145 and C4-2 prostate cancer cells combinations of Rh2 or aPPD with docetaxel were predominantly additive or synergistic. Combinations of Rh2 + docetaxel and aPPD + docetaxel caused established PC-3 tumors to regress from their initial size by 15% and 27%, respectively. Tumor cell proliferation rate (measured by Ki-67 positive cells) was significantly lower for combinations of Rh2 + docetaxel and aPPD + docetaxel, compared to animals treated with docetaxel alone.

CONCLUSIONS

Rh2 and aPPD can be combined with docetaxel to yield additive or synergistic activity in vitro and in vivo. Pending further assessment of toxicity and pharmacodynamic behavior, this study supports testing of combinations of ginsenoside Rh2 or its aglycone aPPD with docetaxel in a clinical setting.

Morphologic characterization of preoperatively treated prostate cancer: toward a post-therapy histologic classification

BACKGROUND

Preoperative treatment of prostate cancer (PCa) changes morphology of residual tumors so that the Gleason score is no longer valid.

OBJECTIVE

To codify morphologic features of preoperatively treated PCa and identify potential classifiers predictive of outcome.

DESIGN, SETTING, AND PARTICIPANTS

We performed a detailed morphologic evaluation of specimens obtained from 115 patients with high-risk PCa who had preoperative androgen ablation, alone or in combination with chemotherapy.

MEASUREMENTS

Included hierarchical clustering analysis of morphologic characteristics, associations with other pathologic parameters, and univariate and multivariate analyses in search for associations with disease outcome.

RESULTS AND LIMITATIONS

Based on hierarchical clustering analysis, we categorized pretreated prostate cancer in three morphologically distinct groups: group A, characterized by a predominance of cell clusters, cell cords, and isolated cells; group B tumors, by intact and fused small glands; and group C tumors by any degree of cribriform growth pattern or intraductal tumor spread. Univariate analysis identified associations between this grouping, pathologic tumor stage (p<0.01) and residual tumor volume (p<0.001). Presence of intraductal spread or cribriform pattern in biopsies was associated with group C tumors. The presence of cribriform or intraductal spread morphology and positive surgical margins were stronger predictors of biochemical relapse than pathologic stage on multivariate analysis. The number of specimens evaluated in this study was limited, and a prospective validation is warranted along with molecular studies to validate the proposed morphologic classifier.

CONCLUSIONS

If validated, this classification will introduce uniformity in the selection of tissue samples for biomarker studies, facilitate the comparison of trials among different institutions, and may provide a new prognostic tool for preoperatively treated PCa.

Adjunctive therapy for men with high risk localized and locally advanced prostate cancer: targeting disseminated tumor cells

PURPOSE

Our research into the pathophysiology of micrometastatic dissemination and cancer recurrence has resulted in the initiation of a clinical trial for men with clinically localized and locally advanced disease.

MATERIALS AND METHODS

We describe the development of this trial, which exploits anti-angiogenesis therapy, and delineate how our understanding of prostate cancer metastasis influenced its design.

RESULTS

Prostate cancer is a heterogeneous disease. Although many men can be cured with local therapy, a large majority with clinically localized disease will experience a relapse usually at a distant site. This result is most likely due to micrometastatic dissemination early in the disease process. Therefore, successful contemporary treatment of many men with prostate cancer should include a combination of local and systemic therapies. Fortunately, cellular, molecular and genetic features that may predict which men are most in need of this therapeutic approach are being identified and characterized. This insight not only supports the rationale for a combination therapeutic approach to prostate cancer management, but will help identify the pathways and agents that provide the most promising targets for intervention.

CONCLUSIONS

Despite advances in prevention and early detection, refinements in surgical technique, and improvements in radiation and systemic therapies, the ability to cure all men with prostate cancer remains unattainable. The continuing challenge is the successful eradication of recurrent and metastatic disease.

High‐Risk Localized Prostate Cancer: Integrating Chemotherapy

Docetaxel (Taxotere); Aventis Pharmaceuticals Inc., Bridgewater, NJ, http://www.aventispharma-us.com) is the first agent to significantly extend survival in hormone-refractory prostate cancer. Because agents active in advanced cancers tend to be beneficial in earlier stage disease, docetaxel is now to be assessed, along with hormonal therapy, in the adjuvant setting among patients whose localized prostate cancer has features that put them at particular risk for recurrence and cancer-specific mortality. Data from a pilot study suggest that neo-adjuvant treatment with docetaxel may be appropriate for selected high-risk patients and that such treatment can be undertaken without increasing surgical morbidity. Gene-expression profiling of tissue before and after docetaxel treatment is providing further insight into its effects. A randomized trial, conducted by the Cancer and Leukemia Group B, will evaluate neoadjuvant docetaxel in high-risk patients, whereby patients will be randomized to either immediate radical prostatectomy or surgery preceded by hormonal therapy plus docetaxel. Another large randomized trial will be evaluating the effect of adjuvant hormonal therapy with or without docetaxel in high-risk men after radical prostatectomy.

Adenoviral infection of survivin antisense sensitizes prostate cancer cells to etoposide in vivo

BACKGROUND

We aimed to investigate whether use of a survivin antisense fragment carried by an adenovirus vector (Ad.survivin-AS) could enhance the therapeutic efficacy of chemotherapy for androgen-independent prostate cancer.

METHODS

We used Ad.survivin-AS to promote apoptosis through inhibition of survivin expression. Recombinant adenoviruses alone or in combination with chemotherapeutic agents were tested for anti-cancer activity both in vitro and in vivo.

RESULTS

Infection with Ad.survivin-AS strongly inhibited survivin expression in a dose- and time-dependent manner, resulting in significant antitumor activity in vitro and in vivo. Downregulation of survivin expression potentiated induction of apoptosis by the chemotherapeutic agents docetaxel and etoposide in DU145 cells. In particular, the combination of etoposide and Ad.survivin-AS demonstrated dramatic growth inhibition with no tumor regrowth being observed during the experimental period.

CONCLUSIONS

The prominent synergy of this combination may provide a basis for clinical application of Ad.survivin-AS as a chemosensitizer of etoposide.

Racial Disparity of Epidermal Growth Factor Receptor Expression in Prostate Cancer

Purpose

The epidermal growth factor receptor (EGFR) plays a critical role in prostate cancer (PC) signal transduction and is the target of a novel class of anticancer agents. Despite recent reports of interethnic variation in response to EGFR inhibitors, limited information exists regarding differences in expression of EGFR in PC patients. This has therapeutic relevance because a better understanding of the molecular basis underlying the ethnic variability will help in the design of individualized treatment regimens using EGFR inhibitors.

Patients and Methods

We investigated EGFR expression in a well-characterized cohort of PC patients to determine the association between EGFR expression and race. Tumor tissues from 202 radical prostatectomies performed between 1990 and 2000 at the Veterans Administration Medical Center (New York, NY) were studied (142 African Americans, 60 whites; median age, 67 years; stage T2, n = 130; stage ≥ T3, n = 72; Gleason score < 7, n = 110; Gleason score ≥ 7, n = 92). Membrane-specific EGFR expression was evaluated immunohistochemically.

Results

EGFR overexpression, defined as complete membrane staining in more than 10% of tumor cells, was observed in 75 of 202 patients (37%). There was a significant association between EGFR overexpression and African American race (P = .0006), higher pretreatment prostate-specific antigen (PSA; P = .02), and stage (P = .02), but not Gleason score (P = .33). The association between African American race and EGFR overexpression remained significant in a multivariate model after controlling for grade, stage, and pretreatment PSA simultaneously (P = .003).

Conclusion

Our data demonstrate that race contributes significantly to variability of EGFR expression in prostate cancer. Racial background may have an impact on the design of clinical trials to test the efficacy of anti-EGFR agents.

AN OVERVIEW OF CHEMOTHERAPY TRIALS IN LOCALIZED AND RECURRENT NONMETASTATIC PROSTATE CANCER

PURPOSE

High risk localized and recurrent prostate cancers remain difficult problems for clinicians. Definitive local treatments such as surgery and radiation therapy cure only a minority of these patients. As a result, efforts are being made to decrease the risk of recurrence and delay progression to symptomatic hormone refractory disease using chemotherapy prior to, during or after definitive local therapy.

MATERIALS AND METHODS

A MEDLINE literature review was performed of studies evaluating chemotherapy and other systemic therapies for localized prostate cancer. In addition, ongoing randomized clinical trials were reviewed.

RESULTS

Chemotherapy in the management of localized and recurrent disease is evolving. Early studies demonstrated the feasibility of administering chemotherapy to patients prior to and immediately after local therapy, and in the setting of an increasing prostate specific antigen state. Although chemotherapy has established activity and acceptable toxicity in patients with hormone refractory prostate cancer, more extensive use in patients with androgen dependent disease will require data from randomized studies to determine its efficacy. At least 5 ongoing, randomized, phase III trials currently are evaluating the role of chemotherapy in various prostate cancer disease states, including nonmetastatic, hormone refractory disease, the increasing prostate specific antigen state, and adjuvant and neoadjuvant settings in patients at high risk.

CONCLUSIONS

Chemotherapy is being investigated actively in randomized trials of earlier states of prostate cancer. Enrollment onto clinical trials should be the highest priority for investigators and clinicians.

Neoadjuvant and adjuvant chemotherapy for high-risk localized prostate cancer

The optimal treatment strategy for patients with high-risk localized prostate cancer remains unknown. Definitive local treatments such as radical prostatectomy and external beam radiotherapy cure only a minority of these patients. Recent efforts have been made to reduce the risk of recurrence and delay progression to symptomatic hormone-refractory disease by using chemotherapy before, during, or after definitive local therapy. Chemotherapy is an effective modality in the treatment of hormone- refractory prostate cancer. Studies have established its role in the palliation of symptoms in patients with hormone-refractory disease, though a survival benefit remains to be demonstrated. Prospective randomized trials are underway to test the hypothesis that neoadjuvant and adjuvant chemotherapy may improve survival rate in patients with high-risk localized prostate cancer. The data currently available from nonrandomized trials have not yet established the exact role of neoadjuvant and adjuvant chemotherapy and its potential impact on survival. However, preliminary data suggest that chemotherapy, when administered in concert with definitive local therapy, may be promising in patients with locally advanced prostate cancer. Randomized clinical trials are ongoing to see if neoadjuvant and adjuvant chemotherapy will translate into an improved clinical benefit for the patient, and participation by patients is paramount. We review the recent literature regarding the use of neoadjuvant and adjuvant chemotherapy in patients with locally advanced prostate cancer.

CpG Hypermethylation ofMDR1Gene Contributes to the Pathogenesis and Progression of Human Prostate Cancer

Multidrug resistance 1 (MDR1) gene encodes for P-glycoprotein (P-gp), a Mr 170,000 transmembrane calcium-dependent efflux pump that is inactivated in prostate cancer. We hypothesize that inactivation of the MDR1 gene through CpG methylation contributes to the pathogenesis and progression of prostate cancer. To test this hypothesis, CpG methylation status of the MDR1 promoter and its correlation with clinicopathological findings were evaluated in 177 prostate cancer samples and 69 benign prostate hypertrophy (BPH) samples. Cellular proliferation index and apoptotic index were determined by proliferating cell nuclear antigen (PCNA) and single-strand DNA immunostaining, respectively. After 5-aza-2'-deoxycytidine treatment, increased expression of MDR1 mRNA transcript was found in prostate cancer cell lines (DU145, DuPro, and ND1). MDR1 methylation frequency was significantly higher in prostate cancer samples compared with BPH samples (54.8 versus 11.6%, respectively, P < 0.001). Logistic regression analysis revealed that PC patients are 11.5 times more likely to have MDR1 methylation than BPH patients (95% confidence interval 4.87-27.0) and that MDR1 methylation is independent of the age. Significant correlation of MDR1 methylation was observed with high pT category (P < 0.001), high Gleason sum (P = 0.008), high preoperative prostate-specific antigen (P = 0.01), and advancing pathological features. In addition, PCNA-labeling index were significantly higher in methylation-specific PCR (MSP)-positive than in MSP-negative prostate cancer samples (P = 0.048). In contrast, no significant difference in apoptotic index was found between MSP-positive and -negative prostate cancer samples. These findings suggest that CpG hypermethylation of MDR1 promoter is a frequent event in prostate cancer and is related to disease progression via increased cell proliferation in prostate cancer cells.