Biomedical subjects

Samuel Singer

Publications and source records attributed to Samuel Singer.

31 records · Page 2Linked to original sources

PubMed2004

The impact of chemotherapy on the survival of patients with high-grade primary extremity liposarcoma.

OBJECTIVE: To determine if chemotherapy offers a survival benefit to patients with large, high-grade, primary extremity liposarcoma. SUMMARY BACKGROUND DATA: The impact of chemotherapy on the survival of patients with primary extremity soft tissue sarcoma is controversial and its effect on individual histologic subtypes is not defined. PATIENT AND METHODS: Two prospectively collected sarcoma databases were used to identify all patients with >5 cm, high-grade, primary extremity liposarcoma that underwent surgical treatment of cure from 1975 to 2003 (n = 245). Clinical, pathologic and treatment variables were analyzed for disease-specific survival (DSS), distant recurrence-free survival (DRFS) and local recurrence-free survival (LRFS). RESULTS: Sixty-three (26%) patients were treated with ifosfamide based chemotherapy (IF), 83 (34%) with doxorubicin based chemotherapy (DOX) and 99 (40%) received no chemotherapy (NoC). To assess the impact of DOX, a contemporary cohort analysis of patients treated from 1975 to 1990 was performed. The 5 year DSS of the DOX treated patients was 64% (53%-74%) compared with 56% (51%-79%) for the NoC patients (log-rank P value = 0.28). To assess the impact of IF, a contemporary cohort analysis of patients treated from 1990 to 2003 was performed. The 5 year DSS of the IF treated patients was 92% (84%-100%) compared with 65% (51%-79%) for the NoC patients (log-rank P value = 0.0003). Independent prognostic factors for improved DSS were smaller size (HR = 0.7, P = 0.01), myxoid/round cell histologic subtype (HR = 0.3, P = 0.03) and treatment with IF (HR = 0.3, P = 0.01). The five-year DRFS of the IF treated patients was 81% (70%-92%) compared with 63% (50%-76%) for the NoC patients (log-rank P value = 0.02). The 5 year LRFS of the IF treated patients was 86% (76%-96%) compared with 87% (77%-97%) for the NoC patients (log-rank P value = 0.99). CONCLUSIONS: In patients with large, high-grade, primary extremity liposarcoma; DOX is not associated with improved DSS and IF is associated with an improved DSS. Treatment with IF should be considered in patients with high-risk primary extremity liposarcoma.

Adult↗

PubMed2004

Synovial sarcoma: the importance of size and location for survival.

A retrospective analysis was done on 135 consecutive patients with extremity and truncal synovial sarcomas seen at our institutions between 1961 and 1996. Ninety-nine patients (73%) presented with a newly diagnosed localized primary sarcoma, nine patients (7%) presented with a locally recurrent sarcoma previously treated at another institution, and 27 patients (20%) presented with metastatic disease. The median followup for surviving patients was 78 months (range, 20-420 months). The overall survival for patients with localized primary and locally recurrent synovial sarcoma was 51% at 10 years. Patients with localized synovial sarcomas less than 5 cm in longest diameter had a survival at 10 years of 88% compared with a 10-year survival of 38% and 8% for patients with sarcomas 5 to 10 cm and greater than 10 cm in longest diameter, respectively. Distal location (hands and feet) and histologic grade also were statistically significant predictors of patient survival for localized synovial sarcoma on univariate analysis. On multivariate analysis size greater than 10 cm and size 5 to 10 cm were associated with an 18-fold and a 3.1-fold increased risk of death compared with tumors smaller than 5 cm. Grade and location were not found to be independent predictors of survival on multivariate analysis. Primary tumor size and initial status at presentation were prognostic for survival and patients with synovial sarcomas larger than 5 cm or locally recurrent at presentation should be considered for more aggressive surgical and adjunctive radiotherapy or chemotherapy.

Adolescent↗

PubMed2003

Kinase mutations and imatinib response in patients with metastatic gastrointestinal stromal tumor.

PURPOSE: Most gastrointestinal stromal tumors (GISTs) express constitutively activated mutant isoforms of KIT or kinase platelet-derived growth factor receptor alpha (PDGFRA) that are potential therapeutic targets for imatinib mesylate. The relationship between mutations in these kinases and clinical response to imatinib was examined in a group of patients with advanced GIST. PATIENTS AND METHODS: GISTs from 127 patients enrolled onto a phase II clinical study of imatinib were examined for mutations of KIT or PDGFRA. Mutation types were correlated with clinical outcome. RESULTS: Activating mutations of KIT or PDGFRA were found in 112 (88.2%) and six (4.7%) GISTs, respectively. Most KIT mutations involved exon 9 (n = 23) or exon 11 (n = 85). All KIT mutant isoforms, but only a subset of PDGFRA mutant isoforms, were sensitive to imatinib, in vitro. In patients with GISTs harboring exon 11 KIT mutations, the partial response rate (PR) was 83.5%, whereas patients with tumors containing an exon 9 KIT mutation or no detectable mutation of KIT or PDGFRA had PR rates of 47.8% (P =.0006) and 0.0% (P <.0001), respectively. Patients whose tumors contained exon 11 KIT mutations had a longer event-free and overall survival than those whose tumors expressed either exon 9 KIT mutations or had no detectable kinase mutation. CONCLUSION: Activating mutations of KIT or PDGFRA are found in the vast majority of GISTs, and the mutational status of these oncoproteins is predictive of clinical response to imatinib. PDGFRA mutations can explain response and sensitivity to imatinib in some GISTs lacking KIT mutations.

Animals↗

PubMed2003

Vaccination with irradiated, autologous melanoma cells engineered to secrete granulocyte-macrophage colony-stimulating factor by adenoviral-mediated gene transfer augments antitumor immunity in patients with metastatic melanoma.

PURPOSE: Vaccination with irradiated, autologous melanoma cells engineered to secrete granulocyte-macrophage colony-stimulating factor (GM-CSF) by retroviral-mediated gene transfer generates potent antitumor immunity in patients with metastatic melanoma. Further clinical development of this immunization scheme requires simplification of vaccine manufacture. We conducted a phase I clinical trial testing the biologic activity of vaccination with irradiated, autologous melanoma cells engineered to secrete GM-CSF by adenoviral-mediated gene transfer. PATIENTS AND METHODS: Excised metastases were processed to single cells, transduced with a replication-defective adenoviral vector encoding GM-CSF, irradiated, and cryopreserved. Individual vaccines were composed of 1 x 10(6), 4 x 10(6), or 1 x 10(7) tumor cells, depending on overall yield, and were injected intradermally and subcutaneously at weekly and biweekly intervals. RESULTS: Vaccines were successfully manufactured for 34 (97%) of 35 patients. The average GM-CSF secretion was 745 ng/106 cells/24 hours. Toxicities were restricted to grade 1 to 2 local skin reactions. Eight patients were withdrawn early because of rapid disease progression. Vaccination elicited dense dendritic cell, macrophage, granulocyte, and lymphocyte infiltrates at injection sites in 19 of 26 assessable patients. Immunization stimulated the development of delayed-type hypersensitivity reactions to irradiated, dissociated, autologous, nontransduced tumor cells in 17 of 25 patients. Metastatic lesions that were resected after vaccination showed brisk or focal T-lymphocyte and plasma cell infiltrates with tumor necrosis in 10 of 16 patients. One complete, one partial, and one mixed response were noted. Ten patients (29%) are alive, with a minimum follow-up of 36 months; four of these patients have no evidence of disease. CONCLUSION: Vaccination with irradiated, autologous melanoma cells engineered to secrete GM-CSF by adenoviral-mediated gene transfer augments antitumor immunity in patients with metastatic melanoma.

Adenoviridae↗

PubMed2003

PDGFRA activating mutations in gastrointestinal stromal tumors.

Most gastrointestinal stromal tumors (GISTs) have activating mutations in the KIT receptor tyrosine kinase, and most patients with GISTs respond well to Gleevec, which inhibits KIT kinase activity. Here we show that approximately 35% (14 of 40) of GISTs lacking KIT mutations have intragenic activation mutations in the related receptor tyrosine kinase, platelet-derived growth factor receptor alpha (PDGFRA). Tumors expressing KIT or PDGFRA oncoproteins were indistinguishable with respect to activation of downstream signaling intermediates and cytogenetic changes associated with tumor progression. Thus, KIT and PDGFRA mutations appear to be alternative and mutually exclusive oncogenic mechanisms in GISTs.

Animals↗

PubMed2003

Isotropic susceptibility shift under MAS: the origin of the split water resonances in 1H MAS NMR spectra of cell suspensions.

Bulk susceptibility variations in a multiphase system such as cultured cells and tissue have two manifestations: a dipolar field component outside the regular heterogenous region which introduces linebroadening, and an isotropic field part which results in a frequency shift. Previous NMR studies have emphasized the utility of magic angle spinning for averaging the dipolar component, particularly if the spins of interest are limited to one phase of a multiphase system such as a sample of liquid with air pockets or glass beads. However, in analyzing spectra from complex multiphase systems, such as cell suspensions and tissues, etc., the isotropic part is often neglected, leading to questionable interpretation of experimental results. The present study demonstrates that under magic angle spinning, the water resonance in NMR experiments of cell suspensions is split into two resolved peaks due to the isotropic susceptibility shift. These two peaks are assigned to a central core of cell free water and an outer cylindrical ring of tightly packed cells in close association with water. A comprehensive theory for this splitting is provided based on a coaxis cylinder model with different susceptibilities. The frequency difference is shown to be dependent on the susceptibility difference and also on the angle of the rotor in the magnetic field. The splitting distance of the two water peaks can be used to measure the susceptibility difference of water in these two phases. The susceptibility difference was measured for three different cell types: 3T3 F442A preadipocyte cells, mouse embryonic stem cells, and human red blood cells.

3T3 Cells↗

PubMed2003

Histologic subtype and margin of resection predict pattern of recurrence and survival for retroperitoneal liposarcoma.

OBJECTIVE: The aim of this study was to determine the pattern of recurrence and prognostic significance of histologic subtype in a large series of patients with primary retroperitoneal liposarcoma. SUMMARY BACKGROUND DATA: Classification of liposarcoma into subtypes, based on morphologic features and cytogenetic aberrations, is now widely accepted. Previous studies have shown that high histologic grade and incomplete gross resection are the most important prognostic factors for survival in patients with retroperitoneal sarcoma and suggest that patients with liposarcoma have a 3-fold higher risk of local recurrence compared with other histologies. METHODS: A prospective database was used to identify 177 patients with primary retroperitoneal liposarcoma treated between July 1982 and June 2002. Histology at primary presentation was reviewed by a sarcoma pathologist and subtyped into 4 distinct groups according to strict criteria. The influence of clinicopathological factors on local recurrence, distant recurrence, and disease-specific survival was analyzed. RESULTS: Of 177 patients with primary retroperitoneal liposarcoma operated on for curative intent, 99 (56%) presented with well-differentiated, 65 (37%) with dedifferentiated, 9 (5%) with myxoid, and 4 (2%) with round cell morphology. The tumor burden was determined by the sum of the maximum tumor diameters. The median tumor burden was 26 cm (5-139). Median follow-up time for 92 (52%) surviving patients was 37 (mean, 0.5-192) months. Multivariate analysis showed that dedifferentiated liposarcoma subtype was associated with a 6-fold increased risk of death compared with well-differentiated histology (P < 0.0001). In addition to histologic subtype, incomplete resection (P < 0.0001), contiguous organ resection (excluding nephrectomy; P = 0.05), and age (P = 0.03) were important independent prognostic factors for survival in retroperitoneal liposarcoma. Retroperitoneal dedifferentiated liposarcoma was associated with an 83% local recurrence rate and 30% distant recurrence rate at 3 years. CONCLUSIONS: The histologic subtype and margin of resection are prognostic for survival in primary retroperitoneal liposarcoma. Dedifferentiated histologic subtype and the need for contiguous organ resection (excluding nephrectomy) was associated with an increase risk of local and distant recurrence. Nephrectomy may be needed to achieve complete resection, but has no measurable influence on disease specific survival.

Databases, Factual↗

PubMed2003

Soft tissue sarcomas of adults: state of the translational science.

Sarcomas--like leukemias, which are also mesodermal malignancies--carry biological significance disproportionate to their clinical frequency. Identification of mutations and translocations associated with these tumors has illuminated aberrant signaling pathways that cause these diseases, determine their behavior, and are therapeutic targets. Activated receptor-associated tyrosine kinase c-kit, mutated in most gastrointestinal stromal tumors, has proven a clinically effective target for enzyme inhibition. A translocation involving a single gene family, consisting of EWS and related genes, has been identified in five different sarcomas, and its chimeric protein products could prove similarly amenable to inhibitors. Resolution of the histopathological complexity is being aided by data from molecular and chromosomal characterization. Improvements in imaging, definition of prognostic factors, and surgical and radiotherapeutic treatment have resulted in improved local control. Continued progress will depend on further adapting the rapidly evolving technologies of genomics and proteomics. It will also depend upon accurate histopathological diagnosis based on validated reagents and consistent methodologies applied to adequate tissue samples derived from patients with complete clinical data. Finally, multicenter, coordinated trials, such as those that occurred with assessment of imatinib mesylate in metastatic gastrointestinal stromal tumors, will assure the most rapid reductions in morbidity and mortality.

Adult↗

PubMed2002

Prognostic value of KIT mutation type, mitotic activity, and histologic subtype in gastrointestinal stromal tumors.

PURPOSE: Previous studies have reported clinical correlates for KIT mutations in GISTs, but in most of those studies the KIT mutations were found in less than 50% of the GISTs. The aim of this study was to evaluate the prognostic relevance for KIT mutations in a series of GISTs in which the mutations were evaluated intensively by genomic and cDNA sequencing. PATIENTS AND METHODS: A comprehensive clinical and pathologic analysis of 48 patients with GISTs who had snap-frozen tissue was performed. The median tumor size was 10 cm (range, 2 to 30 cm). Median follow-up for disease-free patients was 48 months. KIT genomic and cDNA was sequenced by using nucleic acid templates isolated from frozen tumors. RESULTS: The overall 5-year recurrence-free survival was 41% +/- 6%. Five-year recurrence-free survival for patients with tumors that had mitotic counts of three mitoses or fewer per 30 high-power fields (HPF), more than three to <or= 15 mitoses per 30 HPF, and more than 15 mitoses per 30 HPF were 89% +/- 7%, 49% +/- 12%, and 16% +/- 6%, respectively (P =.0001). The 32 patients with spindle-cell histology had a 49% +/- 7% 5-year recurrence-free survival; in contrast, the 16 patients with epithelioid or mixed histology had a 23% +/- 11% 5-year recurrence-free survival (P =.01). Five-year recurrence-free survival for patients with tumors less than 5 cm, 5 to 10 cm, and more than 10 cm were 82% +/- 12%, 45% +/- 9%, and 27% +/- 8%, respectively (P =.03). Prognostic associations were found with particular KIT mutation types, and patients with missense exon 11 mutations had a 5-year recurrence-free survival of 89% +/- 11% compared with 40% +/- 8% for GISTs with other mutation types (P =.03). The independent predictors for disease-free survival were the presence of deletion/insertion exon 11 mutations (hazard ratio [HR] = 4; P =.006), more than 15 mitoses per 30 HPF (HR = 18; P =.0001), mixed histology (HR = 21; P =.0001), and male sex (HR = 3; P =.05). CONCLUSION: In this series of KIT-expressing GISTs, tumor mitotic activity and histologic subtype were the most important prognostic features. The majority of GISTs contain KIT-activating mutations with the type/location of mutation serving as an independent predictor for disease-free survival. These results suggest that KIT mutation and activation are important in GIST pathogenesis and also may provide important prognostic information.

Adult↗

PubMed2002

Efficacy and safety of imatinib mesylate in advanced gastrointestinal stromal tumors.

BACKGROUND: Constitutive activation of KIT receptor tyrosine kinase is critical in the pathogenesis of gastrointestinal stromal tumors. Imatinib mesylate, a selective tyrosine kinase inhibitor, has been shown in preclinical models and preliminary clinical studies to have activity against such tumors. METHODS: We conducted an open-label, randomized, multicenter trial to evaluate the activity of imatinib in patients with advanced gastrointestinal stromal tumor. We assessed antitumor response and the safety and tolerability of the drug. Pharmacokinetics were assessed in a subgroup of patients. RESULTS: A total of 147 patients were randomly assigned to receive 400 mg or 600 mg of imatinib daily. Overall, 79 patients (53.7 percent) had a partial response, 41 patients (27.9 percent) had stable disease, and for technical reasons, response could not be evaluated in 7 patients (4.8 percent). No patient had a complete response to the treatment. The median duration of response had not been reached after a median follow-up of 24 weeks after the onset of response. Early resistance to imatinib was noted in 20 patients (13.6 percent). Therapy was well tolerated, although mild-to-moderate edema, diarrhea, and fatigue were common. Gastrointestinal or intraabdominal hemorrhage occurred in approximately 5 percent of patients. There were no significant differences in toxic effects or response between the two doses. Imatinib was well absorbed, with pharmacokinetics similar to those reported in patients with chronic myeloid leukemia. CONCLUSIONS: Imatinib induced a sustained objective response in more than half of patients with an advanced unresectable or metastatic gastrointestinal stromal tumor. Inhibition of the KIT signal-transduction pathway is a promising treatment for advanced gastrointestinal stromal tumors, which resist conventional chemotherapy.

Adolescent↗

PubMed2002

Biochemical correlates of thiazolidinedione-induced adipocyte differentiation by high-resolution magic angle spinning NMR spectroscopy.

Thiazolidinediones, a class of synthetic ligands to the peroxisome proliferator-activated receptor-gamma, induce terminal adipocyte differentiation of 3T3 F442A cells, and have already been used as alternative therapeutic agents for the treatment of liposarcoma in clinical trials. The biochemical changes occurring in the 3T3 F442A cell line and well-differentiated liposarcoma following induction of adipocyte differentiation with the thiazolidinedione troglitazone were measured using high-resolution magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. 3T3 F442A cell differentiation was characterized by a large accumulation of intracellular triglyceride and withdrawal from the cell cycle. Phosphatidylcholine (PTC), phosphocholine (PC), myo-inositol, and glycerol were found to be possible biochemical markers for adipocyte differentiation induced by thiazolidenediones. The molar ratio of PTC to PC increased fourfold in differentiated 3T3 F442A cells compared to undifferentiated cells, suggesting a substantial increase in CTP:phosphocholine cytidylyltransferase activity with differentiation. A 2.8-fold increase in the PTC:PC ratio was observed in the lipoma-like well-differentiated liposarcoma of three patients who were treated with troglitazone when compared to liposarcoma from patients not treated with this drug. Thus, this ratio may be an NMR-detectable marker of troglitazone efficacy and response to differentiation therapy for liposarcoma.

3T3 Cells↗

PubMed2002

Coronary bypass surgery in women: a long-term comparative study of quality of life after bilateral internal mammary artery grafting in men and women.

BACKGROUND: Coronary bypass surgery carries a higher operative mortality and less favorable long-term clinical benefits for women than men. The impact of arterial revascularization on long-term results, including quality of life (QOL) in women, compared with men, has not been clearly defined. METHODS: A retrospective analysis was performed comparing 261 consecutive women patients from a single surgical practice receiving bilateral internal mammary artery (IMA) and supplemental vein grafts between January 1972 and October 1994 with a computer-matched cohort of 261 men undergoing bilateral IMA surgery during the same time period. Univariate analysis confirmed the homogeneity of the two groups based on multiple preoperative variables. The SF-36 QOL assessment tool was completed for all patients at follow-up, which ranged from 1 month to 25 years, with a mean follow-up of 9.1 years for women and 8.6 years for men. RESULTS: There was no significant difference in operative mortality, nor in the incidence of any of 10 postoperative complications evaluated. The actuarial survival at 15 years was 53.7% +/- 4.8% for women and 50.9% +/- 5.6% for men (p = 0.218). At follow-up, 97.0% of women and 94.3% of men were free of angina and in Canadian Cardiovascular Society (CCS) class I or II. The need for reoperation (1.8% vs 1.9%) and PTCA (4.8% vs. 3.2%) was comparable in both groups. However, a higher rate of late myocardial infarction was found in women than men (1.8% vs 0.6, p = 0.021). The long-term event-free survival was found to be no different in men than women (p = 0.084). QOL as measured by the SF-36 was compared with the general population corrected for age and gender. Men and women scored as well or better than the general population in a majority of the eight health scales. Moreover, with regard to the health summary scores, men scored significantly higher (p = 0.001) in physical health, whereas women scored significantly higher (p = 0.011) in mental health when compared with age-adjusted norms. CONCLUSIONS: Men and women undergoing coronary revascularization using bilateral internal mammary artery conduits experience comparable outcomes, excellent long-term results, and enjoy a QOL comparable to or better than the general population as measured by the SF-36.

Actuarial Analysis↗

PubMed2002

PPARgamma ligands inhibit primary tumor growth and metastasis by inhibiting angiogenesis.

Several drugs approved for a variety of indications have been shown to exhibit antiangiogenic effects. Our study focuses on the PPARgamma ligand rosiglitazone, a compound widely used in the treatment of type 2 diabetes. We demonstrate, for the first time to our knowledge, that PPARgamma is highly expressed in tumor endothelium and is activated by rosiglitazone in cultured endothelial cells. Furthermore, we show that rosiglitazone suppresses primary tumor growth and metastasis by both direct and indirect antiangiogenic effects. Rosiglitazone inhibits bovine capillary endothelial cell but not tumor cell proliferation at low doses in vitro and decreases VEGF production by tumor cells. In our in vivo studies, rosiglitazone suppresses angiogenesis in the chick chorioallantoic membrane, in the avascular cornea, and in a variety of primary tumors. These results suggest that PPARgamma ligands may be useful in treating angiogenic diseases such as cancer by inhibiting angiogenesis.

Angiogenesis Inhibitors↗