Faculty Bibliography

OBJECTIVES: To determine whether repeat biopsy is necessary when the diagnosis of high-grade prostatic intraepithelial neoplasia (HGPIN) is made with a 12-core biopsy. Repeated biopsy has been recommended for individuals with HGPIN noted on sextant prostate biopsy because of the high likelihood of cancer detection. Recently, we have recommended the routine use of 12 cores, rather than 6, to improve cancer detection. METHODS: The charts of all patients undergoing prostate biopsy during a 2-year period at the Manhattan Veterans Administration Medical Center were reviewed. Patients diagnosed with HGPIN on a 12-core biopsy were identified, and those undergoing a repeat 12-core biopsy within 1 year of the initial biopsy were evaluated to determine the rate of cancer detection. RESULTS: A total of 619 men underwent biopsy during the study period. Of 103 men diagnosed with HGPIN, 43 underwent a repeat biopsy within 1 year at the discretion of the managing urologist. The mean age and median prostate-specific antigen level of those undergoing a repeat biopsy was 65.5 years and 5.37 ng/mL, respectively. At the time of the repeat biopsy, 1 patient was found to have cancer (2.3%), 20 had HGPIN (46.5%), 20 had benign pathologic findings (46.5%), and 1 patient (2.3%) had atypical small acinar proliferation. CONCLUSIONS: A repeat biopsy after the diagnosis of HGPIN on 12-core prostate biopsy rarely results in cancer detection. In the absence of other factors increasing the suspicion of cancer, immediate repeat biopsy for HGPIN diagnosed on a 12-core biopsy is unnecessary

OBJECTIVES: To determine the effect of prostate volume on the specificity of prostate-specific antigen density (PSAD) and PSAD of the transition zone (PSA-TZ) in the detection of prostate cancer. METHODS: Between February 1994 and April 1998, transrectal ultrasound-guided prostate needle biopsies were performed in 235 men with serum prostate-specific antigen (PSA) levels between 4.0 and 10.0 ng/mL. The PSAD and PSA-TZ specificities were calculated at 95% sensitivity cutoff levels generated from the whole group, as well as from cohorts stratified by transition zone index or prostate volume. RESULTS: Statistical significance was noted between the benign (n = 176) and prostate cancer (n = 59) groups for all tested PSA parameters. At 95% sensitivity, PSA-TZ carried a specificity of 37.5% compared with 29.6% for PSAD. When applying a single 95% sensitivity cutoff derived from the entire group to individual volume-stratified cohorts, the specificity decreased to 0% in glands less than 30 g in size. A 95% sensitivity PSA-TZ cutoff generated individually for volume-stratified cohorts of glands less than 30, 30 to 40, and 40 to 60 g resulted in more consistent specificity of 28.2%, 35.2%, and 45.7% for each cohort, respectively. CONCLUSIONS: Unlike whole group-derived cutoffs, the use of volume-specific PSA-TZ cutoffs allows consistently high specificity in all volume-stratified cohorts. The discrepancies in the PSA-TZ and PSAD specificities in published reports are likely due to the application of published cutoffs to populations of differing prostate volumes. The use of volume-specific cutoffs results in reproducible specificity in populations with differing prostate volume distribution, and thereby definitively resolves the differences in PSA-TZ specificity reported in published reports

Replication-competent, attenuated herpes simplex virus-1 (HSV-1) derivatives that contain engineered mutations into the viral gamma34.5 virulence gene have been used as oncolytic agents. However, as attenuated mutants often grow poorly, they may not completely destroy some tumors and surviving cancer cells simply regrow. Thus, although HSV-1 gamma34.5 mutants can reduce the growth of human tumor xenografts in mice and have passed phase I safety studies, their efficacy is limited because they replicate poorly in many human tumor cells. Previously, we selected for a gamma34.5 deletion mutant variant that regained the ability to replicate efficiently in tumor cells. Although this virus contains an extragenic suppressor mutation that confers enhanced growth in tumor cells, it remains attenuated. Here, we demonstrate that the suppressor virus replicates to greater levels in prostate carcinoma cells and, importantly, is a more potent inhibitor of tumor growth in an animal model of human prostate cancer than the gamma34.5 parent virus. Thus, genetic selection in cancer cells can be used as a tool to enhance the antitumor activity of a replication-competent virus. The increased therapeutic potency of this oncolytic virus may be useful in the treatment of a wide variety of cancers

BACKGROUND: The maximum tolerated dose (MTD) and efficacy of weekly 1-hour paclitaxel with 3 days of high dose oral estramustine were evaluated in patients with hormone-refractory prostate carcinoma. METHODS: Patients enrolled in cohorts of three received two cycles of six weekly treatments with 1 week of rest: Cohort I received paclitaxel 40 mg/m2 and estramustine 600 mg/m2, and Cohorts II-IV received paclitaxel 60 mg/m2, 75 mg/m2, or 90 mg/m2, respectively, and estramustine 900 mg/m2. Toxicity was assessed weekly, and response was measured by serum prostate specific antigen (PSA), abdominal computed tomography scans, and bone scans at Week 13. RESULTS: Eighteen patients were enrolled, with 12 in Cohorts III and IV. Four patients did not complete treatment. Grade 3 toxicity included one patient with nausea and diarrhea in Cohort III and one patient each with neutropenia and edema followed by Grade 4 thromboembolism in Cohort IV. Grade 1-2 anemia or myelotoxicity were not observed; 3 patients had neuropathy, 5 patients had hair loss, and 8 patients had gastrointestinal symptoms. A decline in the serum PSA level > or = 50% occurred in none of three patients, one of three patients, four of six patients, and four of six patients in Cohorts I-IV, respectively. An intent-to-treat analysis showed responses in 9 of 18 patients (50%) in Cohorts I-IV, with 9 of 15 responders (60%) in Cohorts II-IV. Seven patients achieved declines in serum PSA levels > 75%. The median duration of PSA response was 16.7 weeks. Response was observed in one of three patients with measurable disease. CONCLUSIONS: The MTD for 1-hour weekly paclitaxel was 90 mg/m2 with 3 days of 900 mg/m2 estramustine. Hematologic and neurotoxicity were reduced markedly, and gastrointestinal symptoms were ameliorated, but thromboembolic events were unaffected. PSA response rates were within the expected 60% range for these agents

This article discusses the basic elements of chemoprevention trial designs using cohorts of men following radical prostatectomy who either have prostate-specific antigen (PSA) failure indicative of recurrence or are at high risk for recurrence (positive surgical margins, extracapsular extension, seminal vesicle invasion, positive lymph nodes, Gleason score of greater than or equal to 8, preoperative serum PSA less than 20 ng/mL). Two ongoing randomized, double-blind, placebo-controlled clinical trials with soy protein as intervention in these 2 populations are described. In the trial with men at high risk for recurrence, participants started intervention within 4 months after surgery and were followed for up to 2 years; primary endpoints were PSA failure rate and time-to-PSA failure. In the trial with men with PSA failure (PSA 0.1 to 2.0 ng/mL), participants received treatment for 8 months and the primary endpoint is rise in PSA over time. The strengths and limitations of these designs are discussed and interim experience using studies with soy protein as the intervention agent are summarized

In a multi-institutional Phase II trial, we evaluated the efficacy of a platelet-derived growth factor receptor (PDGF-r) inhibitor, SU101, in patients with hormonerefractory prostate cancer. The patients received a 4-day i.v. loading dose of SU101 at 400 mg/m(2) for 4 consecutive days, followed by 10 weekly infusions at 400 mg/m(2). The primary study end points were a decline in prostate-specific antigen (PSA) and a decrease in measurable tumor. Secondary end points were time to progression and an effect on pain as measured by the Brief Pain Survey. Expression of PDGF-r was examined in both metastatic and archival primary prostate tumor samples. Forty-four patients were enrolled at four centers. The median age was 72 years, the median PSA was 223 ng/ml, and 21 patients had at least one prior chemotherapy. Thirty-nine patients are evaluable for PSA, and three patients demonstrated a PSA decline >50% from baseline (55-99.9% decrease). The median time to progression was 90 days. Of 19 patients evaluable for measurable disease, 1 patient had a partial response. Nine of 35 evaluable patients had significant improvement in pain. The most frequent adverse events were asthenia (75%), nausea (55%), anorexia (50%), and anemia (41%). PDGF-r expression was detected in 80% of the metastases and 88% of primary prostate cancers. The results of this trial may warrant further clinical studies with other PDGF-r inhibitors

To elucidate the mechanism of androgen-dependent cellular proliferation in prostate cancer, androgen-dependent alterations of individual cell cycle regulatory proteins in the androgen-sensitive prostate cancer cell line LNCaP were evaluated. LNCaP cells were deprived of androgens by culture in steroid-depleted media for 5 days, which resulted in the maximal accumulation of cells in G(0)/G(1) phase of the cell cycle. The mitogenic concentration of the synthetic androgen R1881 was established as 0.1 nM using cell proliferation assay. Protein and mRNA levels of particular cyclins, cyclin-dependent kinases (Cdks), cyclin-dependent kinase inhibitors (Ckis), and the retinoblastoma proteins (Rb) were assessed. Androgen stimulation resulted in a post-transcriptional reduction in Rb protein levels, an increase in Rb phosphorylation at serine 780 and an accumulation of high molecular weight Rb protein species. Androgen stimulation also induced the expression of the Cdk2 and Cdk1 as well as their regulatory partners, cyclin A and cyclin B, resulting in a corresponding increase in cyclin A/Cdk2 activity in vitro. Pulse-chase showed decreased Rb protein stability in androgen-treated LNCaP cells. Collectively, our findings suggest a novel mechanism of androgen-dependent prostate cancer growth in which androgen stimulation results in decreased Rb protein expression in LNCaP cells. The observation of decreased Rb protein stability in the setting of increased phosphorylation supports the concept of phosphorylation mediated protein degradation. We propose that the observed reduction in Rb protein level occurs through Rb degradation via the ubiquitin/proteasome pathway, and is preceded by selective Rb phosphorylation by cyclin A/Cdk2 and cyclin B/Cdk1