Phase 1/2 study of preoperative docetaxel and mitoxantrone for high-risk prostate cancer

Hematological Changes Following Low Dose Radiation Therapy and Comparison to Current Standard of Care Cancer Treatments

Cancer is the second leading cause of mortality worldwide accounting for almost 10 million deaths in 2020. Current standard of care treatment varies depending on the type and stage of disease, but commonly includes surgery, chemotherapy, and/or radiation therapy. There is evidence that whole- and half-body exposure to low dose ionizing radiation can also be an effective therapeutic due to its stimulation of anti-cancer immunity. One of the limiting factors for past clinical trials using low dose radiation therapy has been adverse hematological events. However, similar hematological changes are also frequently reported following standard of care treatments in oncology. This review summarizes the effects of various cancer therapies on hematologic toxicity through the evaluation of complete blood count reports. The reviewed literature elucidates hematological trends in patients undergoing chemotherapy, and both high and low dose radiation therapy. In general, high dose radiation and chemotherapy can result in widespread changes in blood counts, with the most severe effects related to leukopenia. Overall, compared to standard of care treatments, low dose radiation results in similar, yet more mild hematological changes. Taken together, hematological toxicities should not be a limiting factor in the applicability of low dose radiation as a cancer therapeutic.

Neoadjuvant Approaches Prior To Radical Prostatectomy

Patients with high-risk localized prostate cancer benefit from multimodality therapy of curative intent. Androgen-deprivation therapy (ADT) combined with radiation improves survival in this population. However, prior clinical trials of neoadjuvant ADT and surgery failed to consistently demonstrate a survival advantage. The development of novel, more potent hormonal agents presents an opportunity to revisit the potential for neoadjuvant therapy to improve long-term outcomes for patients with localized prostate cancer. We review recent advances in neoadjuvant approaches for prostate cancer and emerging clinical trials data supporting the use of neoadjuvant therapy prior to radical prostatectomy.

Systemic treatments for high-risk localized prostate cancer

The majority of patients with prostate cancer who later develop lethal metastatic disease have high-risk localized disease at presentation, emphasizing the importance of effective treatment strategies at this stage. Multimodal treatment approaches that combine systemic and local therapies offer a promising strategy for improving the clinical outcomes of patients with high-risk localized prostate cancer. Combinations of neoadjuvant and adjuvant chemotherapy, hormonal therapy, or chemohormonal therapy are considered to be the standard of care in most solid tumours and should be investigated in the future for the treatment of prostate cancer to improve patient outcomes. However, although the combination of androgen deprivation therapy and radiotherapy is a standard of care in high-risk localized or locally advanced prostate cancer, the benefit of chemotherapy or chemohormonal therapy has yet to be demonstrated outside of the metastatic setting. Moreover, the benefit of neoadjuvant and/or adjuvant systemic therapies in combination with radical prostatectomy has not been proved. The development of next-generation hormonal agents, which have been approved for the treatment of castration-resistant prostate cancer, offers further therapeutic possibilities that are being assessed in early-phase clinical trials.

The addition of chemotherapy in the definitive management of high risk prostate cancer

In attempt to improve long-term disease control outcomes for high-risk prostate cancer, numerous clinical trials have tested the addition of chemotherapy (CTX)-either adjuvant or neoadjuvant-to definitive local therapy, either radical prostatectomy (RP) or radiation therapy (RT). Neoadjuvant trials generally confirm safety, feasibility, and pre-RP PSA reduction, but rates of pathologic complete response are rare, and no indications for neoadjuvant CTX have been firmly established. Adjuvant regimens have included CTX alone or in combination with androgen deprivation therapy (ADT). Here we provide a review of the relevant literature, and also quantify utilization of CTX in the definitive management of localized high-risk prostate cancer by querying the National Cancer Data Base. Between 2004 and 2013, 177 patients (of 29,659 total) treated with definitive RT, and 995 (of 367,570 total) treated with RP had CTX incorporated into their treatment regimens. Low numbers of RT + CTX patients precluded further analysis of this population, but we investigated the impact of CTX on overall survival (OS) for patients treated with RP +/- CTX. Disease-free survival or biochemical-recurrence-free survival are not available through the National Cancer Data Base. Propensity-score matching was conducted as patients treated with CTX were a higher-risk group. For nonmatched groups, OS at 5-years was 89.6% for the CTX group vs. 95.6%, for the no-CTX group (P < 0.01). The difference in OS between CTX and no-CTX groups did not persist after propensity-score matching, with 5-year OS 89.6% vs. 90.9%, respectively (Hazard ratio 0.99; P = 0.88). In summary, CTX was not shown to improve OS in this retrospective study. Multimodal regimens-such as RP followed by ADT, RT, and CTX; or RT in conjunction with ADT followed by CTX-have shown promise, but long-term follow-up of randomized data is required.

Role of chemotherapy in prostate cancer

Chemotherapy in prostate cancer (PCa) has undergone dramatic landscape changes. While earlier studies utilized varying chemotherapy regimens which were found to be largely palliative in nature and hardly resulted in durable or meaningful responses, docetaxel resulted in the first chemotherapy agent that showed improvement in overall survival in metastatic castration-resistant prostate cancer (mCRPC). However, combination chemotherapy or any agents added to docetaxel have failed to yield incremental benefits. The improvement in overall survival as well as secondary endpoints of prostate-specific antigen (PSA) and time to recurrence when using docetaxel in the metastatic hormone-sensitive state has changed the standard of care for treatment of newly diagnosed de novo metastatic PCa. There are also promising results in locally advanced PCa and high-risk PCa in both the neoadjuvant and adjuvant settings. This review summarizes the historical as well as the more contemporary use of chemotherapeutic agents in PCa in varying states and phases of disease.

Radical Prostatectomy for High-risk Localized or Node-Positive Prostate Cancer: Removing the Primary

PURPOSE OF REVIEW

We reviewed the literature to determine what role, if any, radical prostatectomy should play in the treatment of high-risk and/or node-positive prostate cancer.

RECENT FINDINGS

The AUA, NCCN, and EAU all include radical prostatectomy as a treatment option for high-risk prostate cancer based on evidence that has shown improvements in biochemical-free and disease-specific survival. Lymph node-positive patients may also derive benefit from radical prostatectomy with lymph node dissection, however, only retrospective studies with high risk of selection bias have been published to date. High-risk prostate cancer is a heterogeneous disease representing a wide range of disease characteristics. Radical surgery, historically avoided in such patients, may now be considered a valid treatment option for select cases. The adverse effects of surgery using modern techniques lead to similar quality of life outcomes as radiation therapy, and treatment of the primary tumor is likely beneficial when compared to ADT alone.

Docetaxel and mitoxantrone before radical prostatectomy in men with high-risk prostate cancer: 10-year follow-up and immune correlates

The aims of this study were to report the clinical outcomes in a cohort of men with high-risk prostate cancer treated with neoadjuvant docetaxel and mitoxantrone 10 years after treatment, identify pretreatment clinical parameters that may be predictors of recurrence, and describe tumor-infiltrating leukocytes present in radical prostatectomy specimens. We conducted a phase I/II study of neoadjuvant docetaxel and mitoxantrone before radical prostatectomy in high-risk localized prostate cancer to determine the feasibility of this combination and predictors of prostate cancer recurrence after cytotoxic chemotherapy. After 10 years of follow-up, 34 (63%) of 54 participants experience a recurrence. In univariate analysis, prostate-specific antigen (PSA) density (P=0.01), pathological stage (P=0.03), lymph node status (P<0.0001), seminal vesicle invasion (P=0.003), and tissue vascular endothelial growth factor (VEGF) expression (P=0.016) were significantly associated with recurrence. In multivariate analysis, only lymph node status, PSA density, and VEGF expression were significant predictors of disease recurrence. We used a tissue microarray for the first 50 participants to characterize the tumor-infiltrating lymphocytes and evaluate them for association with recurrence. We measured CD3, CD4, CD8, FoxP3, CD20, CD15, CD68, and CD163 by immunohistochemistry in both tumor and normal prostate specimens, but did not find an association between immunophenotype and recurrence. There was a significantly different density of CD68 and CD163 cells between normal and tumor tissue. Lymph node status, PSA density, and tissue VEGF expression predict recurrence after chemotherapy for high-risk prostate cancer. Additional studies are needed to determine the potential benefit of chemotherapy in the neoadjuvant setting.

[Multimodal therapy of locally advanced prostate cancer]

Locally advanced prostate cancer (LAPCA) comprises about 5-10 % of all newly diagnosed prostate cancers and is associated with the highest prostate cancer specific mortality (approximately 8-20 %). LAPCA is defined by the presence of extraprostatic extension, seminal vesicle invasion, and bladder neck infiltration of pelvic lymph node metastases. It is evident that prognosis can only be improved by interdisciplinary multimodality treatment strategies. Adequate local staging by multiparametric MRI is one of the cornerstones for an individualized, risk-adapted treatment approach. This might consist of extended radical prostatectomy with an extended pelvic lymphadenectomy or intensity-modulated radiation therapy with androgen deprivation as the primary local therapeutic approach. Both treatment strategies may be combined with neoadjuvant or adjuvant radiation therapy or salvage surgery. Combination with neoadjuvant or adjuvant chemotherapy and new androgen receptor pathway inhibitors might also be possible. This article summarizes the current treatment strategies for LAPCA.

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.

Long-term oncological outcomes of a phase II trial of neoadjuvant chemohormonal therapy followed by radical prostatectomy for patients with clinically localised, high-risk prostate cancer

OBJECTIVE

To determine long-term oncological outcomes of radical prostatectomy (RP) after neoadjuvant chemohormonal therapy (CHT) for clinically localised, high-risk prostate cancer.

PATIENTS AND METHODS

In this phase II multicentre trial of patients with high-risk prostate cancer (PSA level >20 ng/mL, Gleason ≥8, or clinical stage ≥T3), androgen-deprivation therapy (goserelin acetate depot) and paclitaxel, carboplatin and estramustine were administered before RP. We report the long-term oncological outcomes of these patients and compared them to a contemporary cohort who met oncological inclusion criteria but received RP only.

RESULTS

In all, 34 patients were enrolled and followed for a median of 13.1 years. Within 10 years most patients had biochemical recurrence (BCR-free probability 22%; 95% confidence interval [CI] 10-37%). However, the probability of disease-specific survival at 10 years was 84% (95% CI 66-93%) and overall survival was 78% (95% CI 60-89%). The CHT group had higher-risk features than the comparison group (123 patients), with an almost doubled risk of calculated preoperative 5-year BCR (69% vs 36%, P < 0.01). After adjusting for these imbalances the CHT group had trends toward improvement in BCR (hazard ratio [HR] 0.76, 95% CI 0.43-1.34; P = 0.3) and metastasis-free survival (HR 0.55, 95% CI 0.24-1.29; P = 0.2) although these were not statistically significant.

CONCLUSIONS

Neoadjuvant CHT followed by RP was associated with lower rates of BCR and metastasis compared with the RP-only group; however, these results were not statistically significant. Because this treatment strategy has known harms and unproven benefit, this strategy should only be instituted in the setting of a clinical trial.

Chemotherapy and novel therapeutics before radical prostatectomy for high-risk clinically localized prostate cancer

Although both surgery and radiation are potential curative options for men with clinically localized prostate cancer, a significant proportion of men with high-risk and locally advanced disease will demonstrate biochemical and potentially clinical progression of their disease. Neoadjuvant systemic therapy before radical prostatectomy (RP) is a logical strategy to improve treatment outcomes for men with clinically localized high-risk prostate cancer. Furthermore, delivery of chemotherapy and other systemic agents before RP affords an opportunity to explore the efficacy of these agents with pathologic end points. Neoadjuvant chemotherapy, primarily with docetaxel (with or without androgen deprivation therapy), has demonstrated feasibility and safety in men undergoing RP, but no study to date has established the efficacy of neoadjuvant chemotherapy or neoadjuvant chemohormonal therapies. Other novel agents, such as those targeting the vascular endothelial growth factor receptor, epidermal growth factor receptor, platelet-derived growth factor receptor, clusterin, and immunomodulatory therapeutics, are currently under investigation.

Surgical management of prostate cancer

Surgery remains a mainstay in the management of localized prostate cancer. This article addresses surgical aspects germane to the management of men with prostate cancer, including patient selection for surgery, nerve-sparing approaches, minimization of positive surgical margins, and indications for pelvic lymph node dissection. Outcomes for men with high-risk prostate cancer following surgery are reviewed, and the present role of neoadjuvant therapy before radical prostatectomy is discussed. In addition, there is a review of the published literature on surgical ablative therapies for prostate cancer.

[Neoadjuvant before surgery treatments: state of the art in prostate cancer]

GOAL

To study the impact of systemic treatment in neoadjuvant strategy before surgery in prostate cancer.

MATERIALS

Literature reviews with data analysis from PubMed search using the keywords "neoadjuvant", "chemotherapy", "hormonal therapy", "prostate surgery", "radical prostatectomy", but also reports from ASCO and ESMO conferences. The articles on neoadjuvant treatment before radiotherapy were excluded.

RESULTS

First studies with former therapy are more than 15-years-old and with questionable methodology: lack of power to have a clear idea of the impact on survival criteria such as overall survival or relapse-free survival. However, the impact of neoadjuvant hormone therapy on the classic risk factors for relapse (positive margins, intraprostatic disease, positive lymph nodes) was demonstrated by these studies and a Cochrane meta-analysis. The association with hormone therapy seems mandatory in comparison to treatment based solely on chemotherapy and/or targeted therapy. Promising data on the use of new drugs and their combinations arise: abiraterone acetate combined with LHRH analogue showed a fast PSA decrease and higher rates of pathologic complete response. Other results are promising with hormonal blockages at various key points.

CONCLUSION

Studies with 2nd generation anti-androgene agents or enzyme inhibitors seem to show very promising results. To provide answers about the effectiveness of current neoadjuvant strategy in terms of survival, other studies are needed: randomized phase III or phase II exploring predictive biomarkers. The design of such trials requires a multidisciplinary approach with urologists, oncologists, radiologists and methodologists.

Genetic profiling to determine risk of relapse-free survival in high-risk localized prostate cancer

PURPOSE

The characterization of actionable mutations in human tumors is a prerequisite for the development of individualized, targeted therapy. We examined the prevalence of potentially therapeutically actionable mutations in patients with high-risk clinically localized prostate cancer.

EXPERIMENTAL DESIGN

Forty-eight samples of formalin-fixed paraffin-embedded prostatectomy tissue from a neoadjuvant chemotherapy trial were analyzed. DNA extracted from microdissected tumor was analyzed for 643 common solid tumor mutations in 53 genes using mass spectroscopy-based sequencing. In addition, PTEN loss and erythroblast transformation-specific-related gene (ERC) translocations were examined using immunohistochemistry (IHC) in associated tissue microarrays. Association with relapse during 5 years of follow-up was examined in exploratory analyses of the potential clinical relevance of the genetic alterations.

RESULTS

Of the 40 tumors evaluable for mutations, 10% had point mutations in potentially actionable cancer genes. Of the 47 tumors evaluable for IHC, 36% had PTEN loss and 40% had ERG rearrangement. Individual mutations were not frequent enough to determine associations with relapse. Using Kaplan-Meier analysis with a log-rank test, the 16 patients who had PTEN loss had a significantly shorter median relapse-free survival, 19 versus 106 months (P = 0.01).

CONCLUSIONS

This study confirms that point mutations in the most common cancer regulatory genes in prostate cancer are rare. However, the PIK3CA/AKT pathway was mutated in 10% of our samples. Although point mutations alone did not have a statistically significant association with relapse, PTEN loss was associated with an increased relapse in high-risk prostate cancer treated with chemotherapy followed by surgery.

Rationale for and review of neoadjuvant therapy prior to radical prostatectomy for patients with high-risk prostate cancer

Despite state of the art local therapy, a significant portion of men with high-risk prostate cancer develop progressive disease. Neoadjuvant systemic therapy prior to radical prostatectomy (RP) is an approach that can potentially maximize survival outcomes in patients with localized disease. This approach is under investigation with a wide array of agents and provides an opportunity to assess pathologic and biologic activity of novel treatments. The aim of this review is to explore the past and present role of neoadjuvant therapy prior to definitive therapy with RP in patients with high-risk localized or locally advanced disease. The results of neoadjuvant androgen-deprivation therapy (ADT), including use of newer agents such as abiraterone, are promising. Neoadjuvant chemotherapy, primarily with docetaxel, with or without ADT has also demonstrated efficacy in men with high-risk disease. Other novel agents targeting the vascular endothelial growth factor receptor (VEGFR), epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), clusterin, and the immune system are currently under investigation and have led to variable results in early clinical trials. Despite optimistic data, approval of neoadjuvant therapy prior to RP in patients with high-risk prostate cancer will depend on positive results from well designed phase III trials.

Malate dehydrogenase 2 confers docetaxel resistance via regulations of JNK signaling and oxidative metabolism

BACKGROUND

Resistance to chemotherapy represents a significant obstacle in prostate cancer therapeutics. Novel mechanistic understandings in cancer cell chemotherapeutic sensitivity and resistance can optimize treatment and improve patient outcome. Molecular alterations in the metabolic pathways are associated with cancer development; however, the role of these alterations in chemotherapy efficacy is largely unknown.

METHODS

In a bed-side to bench-side reverse translational approach, we used cDNA microarray and qRT-PCR to identify genes that are associated with biochemical relapse after chemotherapy. Further, we tested the function of these genes in cell proliferation, metabolism, and chemosensitivity in prostate cancer cell lines.

RESULTS

We report that the gene encoding mitochondrial malate dehydrogenase 2 (MDH2) is overexpressed in clinical prostate cancer specimens. Patients with MDH2 overexpression had a significantly shorter period of relapse-free survival (RFS) after undergoing neoadjuvant chemotherapy. To understand the molecular mechanism underlying this clinical observation, we observed that MDH2 expression was elevated in prostate cancer cell lines compared to benign prostate epithelial cells. Stable knockdown of MDH2 via shRNA in prostate cancer cell lines decreased cell proliferation and increased docetaxel sensitivity. Further, MDH2 shRNA enhanced docetaxel-induced activations of JNK signaling and induced metabolic inefficiency.

CONCLUSION

Taken together, these data suggest a novel function for MDH2 in prostate cancer development and chemotherapy resistance, in which MDH2 regulates chemotherapy-induced signal transduction and oxidative metabolism.

Neoadjuvant Chemotherapy prior to Radical Prostatectomy for Patients with High-Risk Prostate Cancer: A Systematic Review

High-risk prostate cancer represents a pretentious clinical problem since a significant number of its patients will relapse and progress after radical prostatectomy. Neoadjuvant chemotherapy may be valuable since its efficacy in hormone-resistant prostate cancer has been established. In this paper, we report studies of neoadjuvant chemotherapies that have been used in high-risk patients prior to radical prostatectomy. Even though the results regarding the prognostic surrogates are not significant, the effects on clinical and pathological outcomes are promising, while toxicity in most of the studies is in the expected field.

Preoperative therapy for localized prostate cancer: a comprehensive overview

At the 2012 American Society of Clinical Oncology (ASCO) Annual Meeting, two studies of preoperative systemic therapy for localized prostate cancer garnered significant attention. In the first, investigators evaluated various permutations of conventional hormonal therapies prior to prostatectomy, with detailed biomarker studies focused on tissue androgens. In the second, investigators assessed the novel CYP17 lyase inhibitor abiraterone prior to prostatectomy. Both studies provide a wealth of biological information, but the question remains - will preoperative systemic therapy ultimately be incorporated into clinical algorithms for prostate cancer? Herein, the existing literature for both preoperative hormonal and chemotherapeutic approaches is reviewed. We performed a MEDLINE search of published prospective and retrospective clinical studies assessing preoperative systemic therapy for prostate cancer from 1982 onwards, revealing a total of 75 publications meeting these criteria. Of these, 55 possessed a number of patients (i.e., greater than 10) deemed worth of the current analysis. Beyond outlining these datasets, we discuss the relevance of clinical and pathologic endpoints in assessing preoperative therapy.

Safety and effectiveness of neoadjuvant luteinizing hormone-releasing hormone agonist plus low-dose estramustine phosphate in high-risk prostate cancer: a prospective single-arm study

BACKGROUND

Radical prostatectomy (RP) has limited cancer control potential for the patient with high-risk prostate cancer (Pca). We prospectively examined the efficacy and safety of neoadjuvant therapy with luteinizing hormone-releasing hormone (LHRH) agonist + low-dose estramustine phosphate (EMP) (LHRH+EMP) followed by RP.

METHODS

High-risk Pca was defined by the D'Amico stratification system. A total of 142 patients with high-risk Pca were enrolled in this trial from September 2005 to March 2011. The LHRH+EMP therapy included administration of LHRH agonist and 280 mg day(-1) EMP for 6 months before RP. Pathological cancer-free (pT0) rate on the surgical specimen was the primary end point. Secondary end points were PSA-free survival and toxicity.

RESULTS

The average patient age was 67.4 years (interquartile range (IQR) 72, 65) and the median initial PSA level was 14.80 ng ml(-1) (IQR 26.22, 7.13). The median Gleason score was 9 (IQR 9, 7) and 97 patients (68.3%) had clinical stage T2c or T3. All patients completed 6 months of LHRH+EMP neoadjuvant therapy with no delays in RP. Seven patients (4.9%) achieved pT0. Surgical margins were negative in 125 patients (87.0%). At a median follow-up period of 34.9 months, PSA-free survival was 84.3%. No serious adverse events were reported during the study and there were no toxicity-related deaths.

CONCLUSIONS

Six months of LHRH+EMP neoadjuvant therapy followed by RP is safe and oncological outcomes are acceptable. Although this study was a single-arm trial with a relatively short follow-up, this treatment may have a potential to improve PSA-free survival in high-risk Pca patients. Further clinical trials are warranted.

A systematic review of the role of adjuvant and neoadjuvant pharmacotherapy in patients undergoing radical prostatectomy

INTRODUCTION

Between 25 and 30% of patients with newly diagnosed prostate cancer are classified as high risk for an adverse prognosis. A significant number of these will progress to biochemical or clinical relapse. As there is no consensus regarding the optimal treatment of these cases, a multimodal therapeutic approach, including radical prostatectomy, remains an option.

AREAS COVERED

The Pubmed/Medline database was searched to identify trials that have evaluated adjuvant and neoadjuvant pharmaceutical protocols combined with radical prostatectomy and provided information regarding efficacy and safety.

EXPERT OPINION

Improvements in adverse pathological findings, following operations in patients who received neoadjuvant treatment, have been reported in the majority of the reviewed studies. Furthermore, the addition of pharmacotherapy to radical prostatectomy has produced beneficial results in survival surrogates. However, no benefits in overall survival were observed with adjuvant or neoadjuvant protocols and toxicity was a concern, especially in combination regimens. New studies on the effects of current pharmacotherapy and of new agents on overall survival and quality of life, after defining well-established criteria for patient stratification and inclusion, are required urgently.

Phase 2 study of neoadjuvant docetaxel plus bevacizumab in patients with high-risk localized prostate cancer: a Prostate Cancer Clinical Trials Consortium trial

BACKGROUND

Treatment of high-risk localized prostate cancer remains inadequate. The authors performed a phase 2 multicenter trial of neoadjuvant docetaxel plus bevacizumab before radical prostatectomy.

METHODS

Eligibility included any of the following: prostate-specific antigen (PSA) >20 ng/mL or PSA velocity >2 ng/mL/y, cT3 disease, any biopsy Gleason score 8 to 10, and Gleason score 7 with T3 disease by endorectal magnetic resonance imaging (MRI) at 1.5 T. Also, those with ≥50% biopsy cores involved and either Gleason score 7, PSA >10, or cT2 disease were eligible. Patients were treated with docetaxel 70 mg/m(2) every 3 weeks for 6 cycles and bevacizumab 15 mg/m(2) every 3 weeks for 5 cycles. The primary endpoint was partial response by endorectal MRI.

RESULTS

Forty-one patients were treated. Median age was 55 years (range, 40-66 years). Baseline characteristics included: median PSA, 10.1 ng/mL; cT2, 49%, cT3, 32%; and Gleason score 8 to 10, 73%. Thirty-eight of 41 (93%) patients completed all 6 cycles. Grade ≥3 adverse events were rare, although 3 of 41 (7%) experienced febrile neutropenia. Twelve patients (29%; 95% confidence interval [CI], 16%-45%) achieved a >50% reduction in tumor volume, and 9 patients (22%; 95% CI, 11%-38%) achieved a >50% post-treatment decline in PSA. Thirty-seven of the 41 patients underwent radical prostatectomy; there were no complete pathologic responses.

CONCLUSIONS

Neoadjuvant docetaxel and bevacizumab is safe, and results in reductions in both tumor volume and serum PSA, in men with high-risk localized prostate cancer. The role of neoadjuvant chemotherapy in prostate cancer, and perioperative antiangiogenic therapy in general, requires further elucidation through ongoing and planned trials.

Chemotherapy sensitivity recovery of prostate cancer cells by functional inhibition and knock down of multidrug resistance proteins

BACKGROUND

In several cancer types, expression of multidrug resistance (MDR) proteins has been associated with lack of chemotherapy response. In advanced prostate cancer (PCa) the use of chemotherapy is mainly palliative due to its high resistance. Previously, we described that MDR phenotype in PCa could be related with high basal and drug-induced expression of MDR proteins P-Glycoprotein (P-Gp), MRP1, and LRP.

METHODS

Using primary cell cultures from PCa patients, we evaluated the effect of function and expression inhibition of P-Gp, MRP1, and LRP, on cell survival after chemotherapy exposure. Cells were treated with specific MDR protein substrates (docetaxel and mitoxantrone for P-Gp, methotrexate for MRP1 and cisplatin for LRP) and pharmacological inhibitors (cyclosporine A, genistein and 3-aminobenzamide), and cell survival was evaluated trough 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and cell cycle analysis. MRP1 activity was evaluated by FACS using the specific inhibitor MK571. Cells were transfected with MDR proteins siRNAs and treated with the corresponding substrates.

RESULTS

PCa cell resistance to MDR protein substrates was partially reversed, decreasing cell survival in around 20%, by treating primary cell cultures with specific pharmacological inhibitors. PCa cells transfected with siRNAs against MDR proteins decreased cell survival when treated with the corresponding drugs. Docetaxel was the most effective chemotherapeutic drug to induce cell death and decrease survival.

CONCLUSION

Low chemotherapy response in PCa could be explained, in part, by over-expression of functional MDR proteins. Expression and function of these proteins should be evaluated to enhance efficacy of docetaxel-based therapies of patients with hormone-resistant PCa.

Contemporary management of high-risk localized prostate cancer

The management of high-risk, localized prostate cancer remains a formidable challenge despite significant technical advances in surgery and radiation therapy. Treatment outcomes of radiation therapy are improved by the addition of adjuvant androgen deprivation therapy, whereas, with surgery, oncologic results are enhanced with either postoperative radiation therapy or androgen deprivation therapy in select cases. In high-risk prostate cancer, disease recurrence after primary therapy may occur at either distant or local sites. Ongoing studies are in the process of evaluating systemic therapy for the eradication of local and micrometastatic disease. Neoadjuvant therapies offer the opportunity to maximize local control as a path to improved outcomes and critically evaluate agent effectiveness in the target tissue. The treatment for high-risk localized prostate cancer is in evolution. It is likely that the development of effective strategies based on understanding prostate tumor biology will lead to significant advances in the treatment of this disease.