Treatment options in hormone-refractory metastatic prostate carcinoma

Prostate cancer represents one of the most important health problems in industrialized countries. It is the second leading cause of cancer-related death in the United States. Therapeutic options are different according to the stage of the disease at the diagnosis. Patients with localized disease may be treated with surgery or radiation, whereas the treatment for patients with a metastatic disease is purely palliative. Hormonal treatment represents the standard therapy for stage IV prostate cancer, but patients ultimately become unresponsive to androgen ablation and are classified as hormone-refractory prostate cancer patients. The molecular mechanisms involved in progression in hormone resistance are characterized by mutations, down and up-regulation in the androgen receptor gene, mutations in p53 and over-expression of Bcl2 and other alterations in genes and in gene expression. The important thing is that we understand these mechanisms to define potential therapeutic agents for the treatment of hormone-refractory prostate cancer patients. Conventional options for patients with hormone-refractory prostate cancer include secondary hormone therapy, radiotherapy and cytotoxic chemotherapy. The commonest antineoplastic agents are mitoxantrone, estramustine and taxanes. Despite an improvement in the palliative benefit, none of these agents has demonstrated a beneficial impact on the overall survival of patients. Therefore, there is no standard therapy for these patients, thus we need new approaches which should be studied in clinical trials. The evaluation and incorporation of new agents into current treatment regimens could have a role in the treatment of hormone-refractory prostate cancer, but their efficacy has not yet been demonstrated.     

Prostate-specific antigen velocity and prostate cancer gleason grade and stage

BACKGROUND: Increased preoperative prostate-specific antigen (PSA) velocity (PSAV) has been associated with increased prostate cancer mortality and higher Gleason scores. The authors evaluated the relation between PSAV, biopsy Gleason score, and pathologic stage in men who were enrolled in a prostate cancer screening trial. METHODS: Data were analyzed from 1441 men who were enrolled in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial who received > or =2 PSA screens and were diagnosed with prostate cancer within 1 year of the last screen. PSAV was estimated by using all screening PSA values within 6 years prediagnosis. RESULTS: Both PSA and PSAV were related to biopsy Gleason score. The multivariable odds ratios (OR), controlling for PSA and demographics, for having a Gleason score of 7 to 10 were 1.3 (95% confidence interval [95% CI], 0.9-1.9), 2.2 (95% CI, 1.5-3.3), and 2.3 (95% CI, 1.4-3.9) for men with PSAV values from 0.5 to 1 ng/mL per year, from 1 to 2 ng/mL per year, and >2 ng/mL per year, respectively, compared with men who had PSAV values <0.5 ng/mL per year. The median PSAV was 0.60 ng/mL per year for men with Gleason scores from 2 to 6 versus 0.84 ng/mL per year for men with Gleason scores from 7 to 10 (P < .0001). Among 658 men who underwent prostatectomy, both PSA and PSAV were associated with advanced pathologic stage in univariate analyses; however, when the analysis controlled for clinical stage and biopsy Gleason score, the associations of PSA and PSAV were no longer statistically significant. CONCLUSIONS: PSAV and PSA levels were associated independently with biopsy Gleason score. Among men who underwent prostatectomy, PSAV and PSA were not predictive of advanced pathologic stage when the analysis was controlled for biopsy Gleason score and clinical stage. It cannot be determined yet whether PSAV is predictive of long-term prostate cancer outcome in this cohort.     

Prognostic model for predicting survival in men with hormone-refractory metastatic prostate cancer.

PURPOSE: To develop and validate a model that can be used to predict the overall survival probability among metastatic hormone-refractory prostate cancer patients (HRPC). PATIENTS AND METHODS: Data from six Cancer and Leukemia Group B protocols that enrolled 1,101 patients with metastatic hormone-refractory adenocarcinoma of the prostate during the study period from 1991 to 2001 were pooled. The proportional hazards model was used to develop a multivariable model on the basis of pretreatment factors and to construct a prognostic model. The area under the receiver operating characteristic curve (ROC) was calculated as a measure of predictive discrimination. Calibration of the model predictions was assessed by comparing the predicted probability with the actual survival probability. An independent data set was used to validate the fitted model. RESULTS: The final model included the following factors: lactate dehydrogenase, prostate-specific antigen, alkaline phosphatase, Gleason sum, Eastern Cooperative Oncology Group performance status, hemoglobin, and the presence of visceral disease. The area under the ROC curve was 0.68. Patients were classified into one of four risk groups. We observed a good agreement between the observed and predicted survival probabilities for the four risk groups. The observed median survival durations were 7.5 (95% confidence interval [CI], 6.2 to 10.9), 13.4 (95% CI, 9.7 to 26.3), 18.9 (95% CI, 16.2 to 26.3), and 27.2 (95% CI, 21.9 to 42.8) months for the first, second, third, and fourth risk groups, respectively. The corresponding median predicted survival times were 8.8, 13.4, 17.4, and 22.80 for the four risk groups. CONCLUSION: This model could be used to predict individual survival probabilities and to stratify metastatic HRPC patients in randomized phase III trials.     

Weekly administration of docetaxel for symptomatic metastatic hormone-refractory prostate carcinoma

BACKGROUND: The current Phase II study investigated the clinical benefit, impact on quality of life (QOL), and tolerability of weekly docetaxel in symptomatic patients with metastatic hormone-refractory prostate carcinoma (HRPC). METHODS: Patients received weekly docetaxel 35 mg/m(2) intravenously for 6 consecutive weeks followed by a 2-week rest repeatedly for a maximum of 24 weeks of treatment. Clinical benefit evaluations, based on Karnofsky performance status (KPS) and pain, were assessed weekly during therapy. A clinical benefit response was defined as a sustained (> or = 4-week) improvement in at least one of these parameters without worsening in the other. Patient-assessed QOL (using the European Organization for Research and Treatment of Cancer QLQ-C30), changes in prostate-specific antigen (PSA) levels, tumoral response, and toxicity also were evaluated. RESULTS: Thirty men (median age, 67 years), 15 of whom had received previous chemotherapy, were treated. Overall, 46% of patients achieved a positive pain response and 48% achieved a 50%-or-greater reduction in PSA. KPS was high at baseline (80%), and no significant changes in this parameter were observed. Compared with baseline, all scores improved after the first cycle of therapy, particularly emotional (P = 0.015), pain (P = 0.001), constipation (P = 0.001), and global QOL (P = 0.011) scores. After the second cycle, dyspnea scores decreased (P = 0.010). At the last QOL assessment, there also was deterioration in terms of fatigue (P = 0.013), dyspnea (P = 0.010), and physical functioning (P = 0.017). Toxicity was mild and included neutropenia (Grade 3-4, n = 2). CONCLUSIONS: Of these elderly symptomatic patients with HRPC, half had received previous chemotherapy. Weekly docetaxel was found to be associated with improvements in clinical benefit response and in QOL and was well tolerated.     

A randomized,placebo-controlled trial of zoledronic acid in patients with hormone-refractory metastatic prostate carcinoma

BACKGROUND: Bone metastases are a common cause of morbidity in patients with prostate carcinoma. We studied the effect of a new bisphosphonate, zoledronic acid, which blocks bone destruction, on skeletal complications in prostate cancer patients with bone metastases. METHODS: Patients with hormone-refractory prostate cancer and a history of bone metastases were randomly assigned to a double-blind treatment regimen of intravenous zoledronic acid at 4 mg (N = 214), zoledronic acid at 8 mg (subsequently reduced to 4 mg; 8/4) (N = 221), or placebo (N = 208) every 3 weeks for 15 months. Proportions of patients with skeletal-related events, time to the first skeletal-related event, skeletal morbidity rate, pain and analgesic scores, disease progression, and safety were assessed. All statistical tests were two-sided. RESULTS: Approximately 38% of patients who received zoledronic acid at 4 mg, 28% who received zoledronic acid at 8/4 mg, and 31% who received placebo completed the study. A greater proportion of patients who received placebo had skeletal-related events than those who received zoledronic acid at 4 mg (44.2% versus 33.2%; difference = -11.0%, 95% confidence interval [CI] = -20.3% to -1.8%; P =.021) or those who received zoledronic acid at 8/4 mg (38.5%; difference versus placebo = -5.8%, 95% CI = -15.1% to 3.6%; P =.222). Median time to first skeletal-related event was 321 days for patients who received placebo, was not reached for patients who received zoledronic acid at 4 mg (P =.011 versus placebo), and was 363 days for those who received zoledronic acid at 8/4 mg (P =.491 versus placebo). Compared with urinary markers in patients who received placebo, urinary markers of bone resorption were statistically significantly decreased in patients who received zoledronic acid at either dose (P =.001). Pain and analgesic scores increased more in patients who received placebo than in patients who received zoledronic acid, but there were no differences in disease progression, performance status, or quality-of-life scores among the groups. Zoledronic acid at 4 mg given as a 15-minute infusion was well tolerated, but the 8-mg dose was associated with renal function deterioration. CONCLUSION: Zoledronic acid at 4 mg reduced skeletal-related events in prostate cancer patients with bone metastases.     

Predictive factors for skeletal complications in hormone-refractory prostate cancer patients with metastatic bone disease

Factors predictive of skeletal-related events (SREs) in bone metastatic prostate cancer patients with hormone-refractory disease were investigated. We evaluated the frequency of SREs in 200 hormone-refractory patients consecutively observed at our Institution and followed until death or the last follow-up. Baseline parameters were evaluated in univariate and multivariate analysis as potential predictive factors of SREs. Skeletal-related events were observed in 86 patients (43.0%), 10 of which (5.0%) occurred before the onset of hormone-refractory disease. In univariate analysis, patient performance status (P=0.002), disease extent (DE) in bone (P=0.0001), bone pain (P=0.0001), serum alkaline phosphatase (P=0.0001) and urinary N-telopeptide of type one collagen (P=0.0001) directly correlated with a greater risk to develop SREs, whereas Gleason score at diagnosis, serum PSA, Hb, serum albumin, serum calcium, types of bone lesions and duration of androgen deprivation therapy did not. Both DE in bone (hazard ratio (HR): 1.16, 95% confidence interval (CI): 1.07-1.25, P=0.000) and pain score (HR: 1.13, 95% CI: 1.06-1.20, P=0.000) were independent variables predicting for the onset of SREs in multivariate analysis. In patients with heavy tumour load in bone and great bone pain, the percentage of SREs was almost twice as high as (26 vs 52%, P<0.02) and occurred significantly earlier (P=0.000) than SREs in patients with limited DE in bone and low pain. Bone pain and DE in bone independently predict the occurrence of SREs in bone metastatic prostate cancer patients with hormone-refractory disease. These findings could help physicians in tailoring the skeletal follow-up most appropriate to individual patients and may prove useful for stratifying patients enrolled in bisphosphonate clinical trials.     

Ten-year survival in patients with metastatic prostate cancer

The objective of this analysis is to identify baseline covariates that predict which patients will be long-term survivors with metastatic prostate cancer. We analyzed data from Southwest Oncology Group (SWOG) S8894, a clinical trial in men with newly diagnosed metastatic prostate cancer, to evaluate pretreatment characteristics associated with 10-year survival. There were 1286 eligible patients randomized to this study. Of these, 794 have been followed for > or = 10.5 years and are included in the analyses. Proportional odds models were used to predict 3 survival categories (survival for < 5 years, 5 up to 10 years, and > or = 10 years). Baseline patient and disease characteristics investigated were protocol treatment (flutamide vs. placebo), severity of disease, SWOG performance status (PS), bone pain, Gleason score, race, age, and prostate-specific antigen (PSA) level at study entry. Of the 794 evaluable patients, 77% lived < 5 years, 16% lived 5 up to 10 years, and 7% lived > or = 10 years. Factors predicting a statistical significant association with longer survival (P < 0.05) included minimal disease, better PS, no bone pain, lower Gleason score, and lower PSA level. All but PS were also significant in multivariate analyses. However, only 13% of patients (5 of 38) who lived > or = 10 years were correctly predicted in their survival category based on the model, whereas 98% (405 of 414) who died within the first 5 years were correctly predicted. Although statistically significant baseline characteristics were identified in this clinical trial, they did not accurately predict the survival interval to which a patient belonged.     

Prostate-specific antigen doubling time predicts clinical outcome and survival in prostate cancer patients treated with combined radiation and hormone therapy

PURPOSE: To determine whether prostate-specific antigen (PSA) doubling time predicts clinical outcomes in patients with prostate cancer that has been treated with combined radiation and hormone therapy. METHODS AND MATERIALS: We reviewed the medical records of 621 men with nonmetastatic prostate cancer treated with radiation therapy and hormone therapy between 1989 and 2003. "Any" clinical failure was defined as any distant, nodal, or local failure, or the use of salvage therapy. "True" clinical failure was defined as any distant, nodal, or local failure. PSA doubling time was calculated by using the log PSA values from patients with a PSA failure as defined by the American Society of Therapeutic Radiology Oncology consensus statement. One hundred thirty-seven men were at intermediate risk for PSA failure (as determined by T2b, Gleason score of 7, or PSA 10.1-0 ng/mL) and 484 men were at high risk for failure (T2c-4; Gleason 8-10; or PSA >20 ng/mL). Pretreatment PSA value, Gleason score, tumor stage, timing and duration of hormone therapy, radiation therapy dose, and PSA doubling time were analyzed for any associations with time to clinical failure by using Cox regression analysis. Estimates of survival were calculated by using the Kaplan-Meier method. Pairwise comparisons were made by using the log-rank test. RESULTS: Sixty-two men experienced any clinical failure, and 22 men experienced true clinical failure. Multivariate analysis revealed that pretreatment PSA (p = 0.013), Gleason score (p = 0.0019), and a PSA doubling time (PSADT) < or =8 months (p < 0.001) were independently associated with time to any clinical failure. Tumor stage, hormone therapy timing, hormone therapy duration, and radiation therapy dose were not statistically significant on multivariate or univariate analysis. Only hormone therapy duration (p = 0.008) and PSADT < or =8 months (<0.001) were significantly associated with time to true clinical failure. The estimated 5-year rate of any clinical failure was 9.4% for men with a PSADT >8 months and 60.4% for men with a PSA doubling time < or =8 months (p < 0.001). The estimated 5-year rate of true clinical failure was 6.5% for men with a PSADT >8 months and 68.5% for men with a PSADT < or =8 months (p < 0.001). Lower radiation dose was the only significant predictor of PSADT < or =8 months on multivariate regression analysis. The estimated 6-year overall survival rate after PSA failure was 79.1% for men with a PSADT >8 months and 29.7% for men with a PSADT < or =8 months. The median overall survival time for patients with a PSADT >8 months was not reached in this study. The median overall survival time for patients with a PSADT < or =8 months was 61.8 months (p = 0.015). CONCLUSION: In men with prostate cancer that has been treated with combined hormone and radiation therapy, a posttreatment PSADT of < or =8 months is associated with worse clinical outcomes and may be an early surrogate marker for decreased survival. These patients should be considered for more aggressive salvage therapy protocols.     

Suramin in combination with weekly epirubicin for patients with advanced hormone-refractory prostate carcinoma.

BACKGROUND: Suramin and epirubicin are both active agents in the treatment of patients with hormone-refractory advanced prostate carcinoma, with demonstrated antitumor synergism in vitro on human prostate carcinoma cells and different dose-limiting toxicities. The authors conducted this Phase II study to determine the feasibility, toxicity, and antitumor activity of suramin in combination with epirubicin. METHODS: Only patients with hormone-independent advanced prostate carcinoma who had progressive disease after the last therapeutic maneuver they had undergone, including antiandrogen withdrawal, entered the study. Suramin was administered initially as a 6-day continuous infusion for 10 consecutive weeks and then for 6 days every 28 days for a maximum of 6 months. Doses were determined by a computer-assisted dosing system that used Bayesian pharmacokinetics to maintain suramin plasma concentrations of 200-250 microg/mL. Cortisone acetate 25 mg, administered at 8 a.m. and 8 p.m. daily, was begun 4 weeks after the initiation of suramin therapy. Epirubicin 25 mg/m2 was given as a weekly intravenous bolus beginning on Day 1 and was continued for a maximum of 6 months. RESULTS: Twenty-six patients entered the study. Toxicities mainly included World Health Organization Grade 1-2 nausea, fatigue, anorexia, neutropenia, peripheral neuropathy, creatinine elevation, proteinuria, and prolonged prothrombin time, whereas Grade 3 toxicities were uncommon. Among 11 patients with measurable disease, 3 (27%) demonstrated an objective response. Among 24 patients evaluated for prostate specific antigen (PSA) response, 8 (33%; 95% confidence interval 16-55%) had a > or =50% decrease in PSA levels, which lasted a median of 32 (range, 8-52) weeks. Median progression free and overall survival were both 8 months. CONCLUSIONS: The combination of suramin and epirubicin used in the current study is feasible, is associated with moderate toxicities, and has antitumor activity in advanced hormone-refractory prostate carcinoma. However, the results obtained with this combination do not represent major improvements in the treatment of patients with this disease, compared with suramin or epirubicin alone or other available treatments.     

State-of-the-art treatment of metastatic hormone-refractory prostate cancer

Initial therapy for advanced prostate cancer includes androgen ablation by surgical or medical castration. Still, nearly all men with metastases will progress to hormone-refractory prostate cancer (HRPC). Current U.S. Food and Drug Administration-approved agents for the treatment of HRPC include mitoxantrone and estramustine, although the vinca alkaloids and the taxanes have shown promising activity in single-agent phase II trials. Combinations of these agents induce a biochemical response in greater than 50% of patients, but the median duration of response is approximately 6 months. Overall survival of patients treated with these combinations is approximately 18-24 months. Studies are ongoing to develop novel therapies that target specific molecular pathways or mechanisms of chemotherapy resistance. Novel agents under development include growth factor receptor inhibitors, antisense oligonucleotides, bisphosphonates, and cell differentiating agents. Evaluation and incorporation of these agents into existing treatment regimens will guide us in the development of more active regimens in the treatment of HRPC.     

Plasma osteopontin: associations with survival and metastasis to bone in men with hormone-refractory prostate carcinoma

BACKGROUND: Osteopontin (OPN) is a secreted glycoprotein that is detectable in human body fluids. Its increased expression has been found in many malignancies, and a stimulatory effect on human prostate carcinoma cells in vitro has been demonstrated. Plasma OPN levels have been associated with tumor burden and survival in patients with metastatic breast carcinoma. The authors explored these associations in men with hormone-refractory prostate carcinoma (HRPC). METHODS: Plasma samples from 100 men with HRPC were collected. OPN was measured using an antigen-capture enzyme-linked immunosorbent assay technique. Multivariable analyses were performed to identify predictors of OPN and survival. RESULTS: At the time of OPN sampling, the median patient age was 73 years (range, 50-86 years), and 92% of patients had metastases. The median plasma OPN level was 198.5 ng/mL (range, 15.0-2363.0 ng/mL), the median prostate specific antigen level was 67.8 microg/L (range, 0.1-7550.0 microg/L), and the median survival was 13.7 months. OPN plasma levels were higher in patients with versus patients without bone metastases (P = 0.024). Multivariable modeling demonstrated an independent association of the OPN level with alkaline phosphatase, hemoglobin, and creatinine levels. The log-transformed OPN level (hazard ratio [HR], 2.38; P < 0.0001), performance status (HR, 2.43; P = 0.007), and a history of prior radiotherapy for localized prostate carcinoma (HR, 0.48; P = 0.0229) were independent predictors of survival in a Cox multivariate model. CONCLUSIONS: In this study, in men with established HRPC, the plasma OPN level was associated with the presence of metastases to bone and with other measures of tumor burden, and it was correlated independently and negatively with survival.     

Prostate-specific antigen spikes after permanent prostate brachytherapy

PURPOSE: To evaluate whether any clinical, treatment, or dosimetric parameters correlated with the development of a prostate-specific antigen (PSA) spike after permanent prostate brachytherapy. METHODS AND MATERIALS: The evaluated population consisted of 218 hormone-naive patients free of biochemical or clinical failure who underwent permanent prostate brachytherapy with or without supplemental external beam radiotherapy for clinical Stage T1b-T3a adenocarcinoma of the prostate gland (1997 AJCC) between August 1995 and November 1999. No patient underwent pre- or postimplant hormonal manipulation, pretreatment seminal vesicle biopsy, or pathologic lymph node staging. In addition, none of the 218 patients possessed equivocal biochemical results (one or two consecutive PSA rises or a declining PSA >1.0 ng/mL). The median patient follow-up was 46.2 months. A PSA spike was defined as a rise of >or=0.2 ng/mL, followed by a durable decline. The clinical parameters evaluated included patient age, clinical T stage, Gleason score, pretreatment PSA level, prostate volume, brachytherapy planning volume, and patient follow-up in months. The evaluated treatment parameters included isotope and use of supplemental external beam radiotherapy. The dosimetric parameters evaluated included the minimal dose received by 90% of the prostate gland (D(90)), the percentage of the prostate volume receiving 100% (V(100)), 150%, and 200% (V(200)) of the prescribed minimal peripheral dose, and the mean, median, maximal, and minimal urethral doses. Biochemical disease-free survival was defined by the American Society for Therapeutic Radiology and Oncology consensus definition with the additional constraint that the most recent PSA level was 0.2 to 0.5 to 1.0 ng/mL (20%, 50%, and 80%, respectively, p <0.001). In Cox multivariate regression analysis, patient age, clinical stage, first postimplant PSA level, and V(150) were predictive for the development of a PSA spike. A postimplant dosimetric threshold of either <115% of the minimal peripheral dose for D(90) or <55% of the prostate volume for V(150) was strongly predictive of a spike. When the variables only determinable after the occurrence of the PSA spike were included in the multivariate analysis, V(150), preimplant PSA level, and nadir PSA were the significant predictors. CONCLUSION: Of the patients, 23.9% developed a PSA spike with a median time to development of 16.3 months and a median prespike and median postspike PSA of 0.50 ng/mL and 0.90 ng/mL, respectively. In multivariate analysis, patient age, clinical stage, first postimplant PSA level, and V(150) were predictive for the development of a PSA spike. At approximately 66 months after implantation, the PSA curves converged for spike and nonspike patients, with a median PSA level <0.1 ng/mL.