Biomedical subjects

Howard Scher

Publications and source records attributed to Howard Scher.

13 recordsLinked to original sources

PubMed2004

Gene expression analysis of human prostate carcinoma during hormonal therapy identifies androgen-responsive genes and mechanisms of therapy resistance.

The androgen-signaling pathway is critical to the development and progression of prostate cancer and androgen ablation is a mainstay of therapy for this disease. We performed a genome-wide expression analysis of human prostate cancer during androgen ablation therapy to identify genes regulated by androgen and genes differentially expressed after the development of resistance. Six hundred and fifty-four of 63,175 probe sets detected significant expression changes after 3 months of treatment with goserelin and flutamide. This included 149 genes that were also differentially expressed 36 hours after androgen withdrawal in LNCaP cells. These genes reflect the physiological changes that occur in treated tumors and include potential direct targets of the androgen receptor. Expression profiles of androgen ablation-resistant tumors demonstrated that many of the gene expression changes detected during therapy were no longer present suggesting a reactivation of the androgen response pathway in the absence of exogenous hormone. Therapy resistance was associated with differential expression of a unique set of genes that reflect potential mechanisms of reactivation. Specifically an up-regulation of the androgen receptor and key enzymes for steroid biosynthesis suggest that resistant tumors have increased sensitivity to and endogenous synthesis of androgenic hormones. The specific pathways of reactivation provide opportunities for classification of resistant tumors and targeted therapies.

Algorithms↗

PubMed2004

Feasibility of radical prostatectomy after neoadjuvant chemohormonal therapy for patients with high risk or locally advanced prostate cancer: results of a phase I/II study.

PURPOSE: We determined the feasibility of radical prostatectomy after neoadjuvant chemohormonal therapy in locally advanced (stage T3 or greater) and/or high risk tumors (Gleason 8 to 10 and/or serum prostate specific antigen (PSA) greater than 20 ng/ml). MATERIALS AND METHODS: Enrollment criteria included clinical stage T1 to 2 with any Gleason grade and PSA greater than 20 ng/ml, clinical stage T3 to 4 with any serum PSA or Gleason grade, or any clinical stage with biopsy Gleason grade of 8 to 10 and any serum PSA. All patients received neoadjuvant hormonal therapy during chemotherapy (4 cycles of paclitaxel and carboplatin and estramustine) followed by radical prostatectomy. Nerve sparing was decided on an individual basis and a nerve graft was offered to those who underwent unilateral or bilateral nerve resection. Perioperative morbidity, mortality and delayed complications were assessed. RESULTS: A total of 36 patients were enrolled. After chemohormonal therapy clinical stage was less in 39% of patients and greater in 36%. Bilateral nerve sparing was performed in 3 patients and the remaining 33 underwent either unilateral or bilateral neurovascular bundle resection with nerve grafts performed in 17 (52%). Deep vein thrombosis (22%) was the most frequent complication of chemotherapy. Minor postoperative complications occurred in 6 patients. At a median followup of 29 months (range 5 to 51) after radical prostatectomy 32 (89%) were continent and 5 (15%) preoperatively potent men remained potent. The positive surgical margin rate was 22%. Of all subjects 45% remain free from biochemical recurrence. CONCLUSIONS: Neoadjuvant chemohormonal therapy followed by radical prostatectomy can be performed with low morbidity. Positive surgical margin rates are low. This approach yielded good local control of disease, however impact on tumor recurrence and survival is not known.

Adult↗

PubMed2004

Tumor localization of 16beta-18F-fluoro-5alpha-dihydrotestosterone versus 18F-FDG in patients with progressive, metastatic prostate cancer.

UNLABELLED: This trial was an initial assessment of the feasibility, in vivo targeting, and biokinetics of 16beta-(18)F-fluoro-5alpha-dihydrotestosterone ((18)F-FDHT) PET in patients with metastatic prostate cancer to assess androgen receptor expression. METHODS: Seven patients with progressive clinically metastatic prostate cancer underwent (18)F-FDG and (18)F-FDHT PET scans in addition to conventional imaging methods. Three patients had their studies repeated 1 mo later, 2 while on testosterone therapy, and the third after treatment with 17-allylamino-17-demethoxygeldanamycin (17-AAG). High-pressure liquid radiochromatography was used to separate (18)F-FDHT from radiolabeled metabolites. Lesion-by-lesion comparisons between the (18)F-FDHT, (18)F-FDG, and conventional imaging methods were performed. RESULTS: Metabolism of (18)F-FDHT was rapid, with 80% conversion within 10 min to radiolabeled metabolites that circulated bound to plasma proteins. Tumor uptake was rapid and tumor retention was prolonged. Fifty-nine lesions were identified by conventional imaging methods. (18)F-FDG PET was positive in 57 of 59 lesions (97%), with an average lesion maximum standardized uptake value (SUV(max)) = 5.22. (18)F-FDHT PET was positive in 46 of 59 lesions (78%), with the average positive lesion SUV(max) = 5.28. Treatment with testosterone resulted in diminished (18)F-FDHT uptake at the tumor site. CONCLUSION: (18)F-FDHT localizes to tumor sites in patients with progressive clinically metastatic prostate cancer and may be a promising agent to analyze antigen receptors and their impact on the clinical management of prostate cancer.

Aged↗

PubMed2003

Phase I clinical trial of histone deacetylase inhibitor: suberoylanilide hydroxamic acid administered intravenously.

PURPOSE: To evaluate the safety, pharmacokinetics, and biological activity of suberoylanilide hydroxamic acid (SAHA) administered by 2-h i.v. infusion in patients with advanced cancer. EXPERIMENTAL DESIGN: SAHA was administered for 3 days every 21 days in part A and 5 days for 1-3 weeks in part B. Dose escalation proceeded independently in patients with solid tumor and hematological malignancies (part B only). Pharmacokinetic studies were performed along with assessment of acetylated histones in peripheral blood mononuclear cells and tumor tissues. RESULTS: No dose-limiting toxicities were observed in 8 patients enrolled in part A (75, 150, 300, 600, and 900 mg/m(2)/day). Among 12 hematological and 17 solid tumor patients enrolled in part B (300, 600, and 900 mg/m(2)/day), therapy was delayed > or = 1 week for grade 3/4 leukopenia and/or thrombocytopenia in 2 of 5 hematological patients at 600 mg/m(2)/day x 5 days for 3 weeks. The maximal-tolerated dose was 300 mg/m(2)/day x 5 days for 3 weeks for hematological patients. One solid patient on 900 mg/m(2)/day x 5 days for 3 weeks developed acute respiratory distress and grade 3 hypotension. The cohort was expanded to 6 patients, and no additional dose-limiting toxicities were observed. Mean terminal half-life ranged from 21 to 58 min, and there was dose-proportional increase in area under the curve. An accumulation of acetylated histones in peripheral blood mononuclear cells up to 4 h postinfusion was observed at higher dose levels. Posttherapy tumor biopsies showed an accumulation of acetylated histones by immunohistochemistry. Four (2 lymphoma and 2 bladder) patients had objective tumor regression with clinical improvement in tumor related symptoms. CONCLUSIONS: Daily i.v. SAHA is well tolerated, inhibits the biological target in vivo, and has antitumor activity in solid and hematological tumors.

Acetylation↗

PubMed2003

Dose escalation study of intravenous estramustine phosphate in combination with Paclitaxel and Carboplatin in patients with advanced prostate cancer.

PURPOSE: The purpose is to determine a safe weekly dose of i.v. estramustine phosphate (EMP) to combine with weekly paclitaxel and monthly carboplatin in patients with advanced prostate cancer. EXPERIMENTAL DESIGN: Patients with advanced prostate cancer (castrate and noncastrate) were administered escalating doses of weekly 1-h infusion of i.v. EMP (500-1000-1500 mg/m(2)) in combination with weekly paclitaxel (100 mg/m(2) over 1 h) and i.v. carboplatin (area under the curve 6 mg/ml-min every 4 weeks). Four weeks of therapy were considered one cycle. In the first three cohorts, EMP was given i.v. 3 h before paclitaxel. Cohorts 4 and 5 reversed the administration order: EMP (doses 1000-1500 mg/m(2)) was given immediately after the end of paclitaxel infusion. Plasma levels of EMP and its metabolites, estramustine and estromustine, were monitored at time 0, at 120 min, and approximately at 20, 21, and 168 h from the start of EMP infusion. Paclitaxel concentrations were determined at basal (0), 30, 60, 90, and 120 min and 18 h after the start of paclitaxel infusion, and a concentration-time curve was estimated. Pharmacokinetic evaluation was performed in cycles 1 and 2 during the first week of therapy. RESULTS: Nineteen patients were entered on the initial three dose levels (cohorts 1-3). Dose-limiting transient hepatic toxicity was encountered in cohort 3 (EMP = 1500 mg/m(2)). An additional 13 patients were treated with paclitaxel (100 mg/m(2)) first, followed by i.v. EMP at 1000 mg/m(2) (cohort 4), and 1500 mg/m(2) (cohort 5). No dose-limiting toxicities were seen, and cohort 5 was determined safe for Phase II studies. Thromboembolic events were observed in 9% of patients (no prophylactic coumadin was used). Plasma concentrations of EMP and metabolites increased proportionally with dose. In all cohorts, there was a slight decrease in EMP and estramustine plasma concentrations between cycles 1 and 2. Although not significant, higher levels of estromustine at cycle 2 were observed in comparison to cycle 1. Decreased clearance of paclitaxel leading to higher than expected paclitaxel plasma concentrations was observed during the first cycle of therapy. Paclitaxel plasma concentrations were lower during cycle 2. In 17 patients with androgen-independent disease, 59% had >/=50% posttherapy decline in PSA and 22% showed measurable disease regression. CONCLUSIONS: The regimen of weekly i.v. EMP in combination with paclitaxel and carboplatin can be safely administered with hepatic toxicity being transient and reversible. Pharmacokinetic results suggest that EMP competitively inhibits the biotransformation of paclitaxel after the first administration. This effect is counterbalanced, after repeated administrations, by a possible induction of the metabolic system caused by EMP. Phase II testing is ongoing to evaluate the efficacy of this combination.

Aged↗

PubMed2002

Comprehensive gene expression analysis of prostate cancer reveals distinct transcriptional programs associated with metastatic disease.

The identification of genes that contribute to the biological basis for clinical heterogeneity and progression of prostate cancer is critical to accurate classification and appropriate therapy. We performed a comprehensive gene expression analysis of prostate cancer using oligonucleotide arrays with 63,175 probe sets to identify genes and expressed sequences with strong and uniform differential expression between nonrecurrent primary prostate cancers and metastatic prostate cancers. The mean expression value for >3,000 tumor-intrinsic genes differed by at least 3-fold between the two groups. This includes many novel ESTs not previously implicated in prostate cancer progression. Many differentially expressed genes participate in biological processes that may contribute to the clinical phenotype. One example was a strong correlation between high proliferation rates in metastatic cancers and overexpression of genes that participate in cell cycle regulation, DNA replication, and DNA repair. Other functional categories of differentially expressed genes included transcriptional regulation, signaling, signal transduction, cell structure, and motility. These differentially expressed genes reflect critical cellular activities that contribute to clinical heterogeneity and provide diagnostic and therapeutic targets.

Adult↗

PubMed2002

Alteration of p53 pathway in squamous cell carcinoma of the head and neck: impact on treatment outcome in patients treated with larynx preservation intent.

PURPOSE: To identify the role of p53 pathway alteration(s) as predictors of treatment outcome in patients with advanced, resectable, squamous cell carcinoma (SCC) of the larynx and pharynx treated with larynx preservation (LP) intent. PATIENTS AND METHODS: Seventy-one patients treated on two consecutive LP protocols were studied based on availability of representative tissues. We analyzed the expression pattern of p53, its upstream regulator mdm2, and downstream transcriptional target p21/WAF1 by immunohistochemistry. Positive phenotype was defined as >or= 20% of tumor cells showing nuclear immunoreactivity. Results were correlated with treatment outcomes. RESULTS: Positive phenotype was observed in 35 (49%) of 71 cases for p53, in 52 (74%) of 70 for mdm2, and in 37 (54%) of 68 for p21. There was no correlation between p53 phenotype and p21 nuclear accumulation. The mdm2-negative phenotype was most predictive of major response at the primary tumor site (P =.088). p53-positive phenotype was associated with worse local control with LP (LCLP; 49% v 23%, P =.053) and inferior overall survival (OS; 51% v 29%, P =.017) at 5 years. On Cox regression analysis, p53-positive phenotype predicted inferior OS (P =.033) and showed a trend for worse LCLP (P =.102). When analyzed in a multivariate model as continuous variables, p53 showed a stronger correlation with inferior OS (P <.01), and mdm2 was associated with worse OS (P <.01). CONCLUSION: Among the three markers studied, our data support p53 phenotype as the most informative predictor of unfavorable outcomes in the LP setting, and suggest a role for mdm2 phenotype that requires further exploration. Our analysis does not support a p53-dependent mechanism for p21 expression. Prospective and larger studies are necessary before integration of these molecular markers as part of molecular staging and predictors for organ preservation or other outcomes.

Adult↗

PubMed2002

Fatal respiratory failure associated with treatment of prostate cancer using docetaxel and estramustine.

Chemotherapy that targets microtubular trafficking induces responses in most patients with prostate cancer. One regimen under investigation is the combination of docetaxel and estramustine. We report on 2 patients with androgen-independent disease who received continuous weekly docetaxel and estramustine and who died of irreversible respiratory failure. The clinical, pathologic, and radiographic data support drug toxicity as the likely etiology. Inclusive of these patients, only 17 cases (10 fatal) of acute pulmonary toxicity using docetaxel have been reported, despite its wide use. We recommend that patients receiving weekly docetaxel, with or without estramustine, have frequent treatment breaks and be evaluated with computed tomography of the chest every 8 weeks.

Aged↗

PubMed1999