EZH2 Inhibition Sensitizes IDH1R132H-Mutant Gliomas to Histone Deacetylase Inhibitor

Isocitrate Dehydrogenase-1 (IDH1) is commonly mutated in lower-grade diffuse gliomas. The IDH1R132H mutation is an important diagnostic tool for tumor diagnosis and prognosis; however, its role in glioma development, and its impact on response to therapy, is not fully understood. We developed a murine model of proneural IDH1R132H-mutated glioma that shows elevated production of 2-hydroxyglutarate (2-HG) and increased trimethylation of lysine residue K27 on histone H3 (H3K27me3) compared to IDH1 wild-type tumors. We found that using Tazemetostat to inhibit the methyltransferase for H3K27, Enhancer of Zeste 2 (EZH2), reduced H3K27me3 levels and increased acetylation on H3K27. We also found that, although the histone deacetylase inhibitor (HDACi) Panobinostat was less cytotoxic in IDH1R132H-mutated cells (either isolated from murine glioma or oligodendrocyte progenitor cells infected in vitro with a retrovirus expressing IDH1R132H) compared to IDH1-wild-type cells, combination treatment with Tazemetostat is synergistic in both mutant and wild-type models. These findings indicate a novel therapeutic strategy for IDH1-mutated gliomas that targets the specific epigenetic alteration in these tumors.

Population Pharmacokinetic Analysis of Dexmedetomidine in Children using Real World Data from Electronic Health Records and Remnant Specimens

AIM

Our objectives were to perform a population pharmacokinetic analysis of dexmedetomidine in children using remnant specimens and electronic health records (EHRs) and explore the impact of patient's characteristics and pharmacogenetics on dexmedetomidine clearance.

METHODS

Dexmedetomidine dosing and patient data were gathered from EHRs and combined with opportunistically sampled remnant specimens. Population pharmacokinetic models were developed using nonlinear mixed-effects modeling. Stage one developed a model without genotype variables; Stage two added pharmacogenetic effects.

RESULTS

Our final study population included 354 post-cardiac surgery patients age 0 to 22 years (median 16 months). The data were best described with a two-compartment model with allometric scaling for weight and Hill maturation function for age. Population parameter estimates and 95% confidence intervals were 27.3 L/hr (24.0 - 31.1 L/hr) for total clearance (CL), 161 L (139 - 187 L) for central compartment volume of distribution (V₁ ), 26.0 L/hr (22.5 - 30.0 L/hr) for intercompartmental clearance (Q), and 7903 L (5617 - 11119 L) for peripheral compartment volume of distribution (V₂ ). The estimate for postmenstrual age when 50% of adult clearance is achieved was 42.0 weeks (41.5 - 42.5 weeks) and the Hill coefficient estimate was 7.04 (6.99 - 7.08). Genotype was not statistically or clinically significant.

CONCLUSION

Our study demonstrates the use of real-world EHR data and remnant specimens to perform a population PK analysis and investigate covariate effects in a large pediatric population. Weight and age were important predictors of clearance. We did not find evidence for pharmacogenetic effects of UGT1A4 or UGT2B10 genotype or CYP2A6 risk score.

Combined Src/EGFR Inhibition Targets STAT3 Signaling and Induces Stromal Remodeling to Improve Survival in Pancreatic Cancer

Lack of durable response to cytotoxic chemotherapy is a major contributor to the dismal outcomes seen in pancreatic ductal adenocarcinoma (PDAC). Extensive tumor desmoplasia and poor vascular supply are two predominant characteristics which hinder the delivery of chemotherapeutic drugs into PDAC tumors and mediate resistance to therapy. Previously, we have shown that STAT3 is a key biomarker of therapeutic resistance to gemcitabine treatment in PDAC, which can be overcome by combined inhibition of the Src and EGFR pathways. Although it is well-established that concurrent EGFR and Src inhibition exert these antineoplastic properties through direct inhibition of mitogenic pathways in tumor cells, the influence of this combined therapy on stromal constituents in PDAC tumors remains unknown. In this study, we demonstrate in both orthotopic tumor xenograft and Ptf1a^cre/+;LSL-Kras^G12D/+;Tgfbr2^flox/flox (PKT) mouse models that concurrent EGFR and Src inhibition abrogates STAT3 activation, increases microvessel density, and prevents tissue fibrosis in vivo. Furthermore, the stromal changes induced by parallel EGFR and Src pathway inhibition resulted in improved overall survival in PKT mice when combined with gemcitabine. As a phase I clinical trial utilizing concurrent EGFR and Src inhibition with gemcitabine has recently concluded, these data provide timely translational insight into the novel mechanism of action of this regimen and expand our understanding into the phenomenon of stromal-mediated therapeutic resistance. IMPLICATIONS: These findings demonstrate that Src/EGFR inhibition targets STAT3, remodels the tumor stroma, and results in enhanced delivery of gemcitabine to improve overall survival in a mouse model of PDAC.

Abstract A11: Combined Src and EGFR inhibition targets STAT3 to induce stromal remodeling and increase drug delivery to improve survival in a mouse model of pancreatic cancer

Lack of durable response to cytotoxic chemotherapy is a major contributor to the dismal outcomes seen in pancreatic ductal adenocarcinoma (PDAC). Extensive tumor desmoplasia and poor vascular supply are two predominant characteristics that hinder the delivery of chemotherapeutic drugs into PDAC tumors and mediate resistance to therapy. Previously, we have shown that STAT3 is a key biomarker of therapeutic resistance to gemcitabine treatment in PDAC, which can be overcome by combined inhibition of the Src kinase and epidermal growth factor receptor (EGFR) pathways. Although it is well established that concurrent EGFR and Src inhibition exert these anti-eoplastic properties through inhibiting mitogenic pathways in tumor cells directly, the influence of this combined therapy on stromal constituents in PDAC tumors remains unknown. In the present study, we demonstrate in both orthotopic tumor xenografts and Ptf1acre/+;LSL-KrasG12D/+;Tgfbr2flox/flox (PKT) mouse models that concurrent EGFR and Src inhibition abrogates STAT3 activation, resulting in stromal remodeling through the depletion of tumor collagen content, increasing microvessel density, and preventing tissue fibrosis in vivo. Furthermore, these stromal changes resulting from combined pathway inhibition produce a direct increase in intratumoral gemcitabine levels as determined by MALDI-IMS and improve overall survival in PKT mice treated with combined EGFR and Src inhibition with gemcitabine. As a phase 1 clinical trial utilizing concurrent EGFR and Src inhibition in combination with gemcitabine has recently concluded, these data provide translational insight into the novel mechanism of action of this regimen and expand our understanding into the phenomenon of stromal-mediated therapeutic resistance.

Citation Format: Austin R. Dosch, Xizi Dai, Michelle L. Reyzer, Deukwoo Kwon, Richard Caprioli, Nipun B. Merchant, Nagaraj S. Nagathihalli. Combined Src and EGFR inhibition targets STAT3 to induce stromal remodeling and increase drug delivery to improve survival in a mouse model of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr A11.

Novel vacuum stable ketone-based matrices for high spatial resolution MALDI imaging mass spectrometry

We describe the use of aromatic ketones and cinnamyl ketones that have high vacuum stability for analyzing tissue sections using matrix-assisted laser desorption/ionization imaging mass spectrometry. Specifically, the matrix, (E)-4-(2,5-dihydroxyphenyl)but-3-en-2-one (2,5-cDHA) provides high sensitivity and high vacuum stability while producing small size crystals (1-2 μm). A high throughput and highly reproducible sample preparation method was developed for these matrices that first involves using an organic spray solution for small matrix crystal seeding followed by spraying of the matrix in a 30% acetonitrile/70% water solution on the tissue surface to obtain a homogeneous coating of small crystals, suitable for high spatial resolution imaging.

Abstract 3726: INCB52793 JAK1 inhibitor synergizes with ATRA to inhibit expansion of AML

Dysregulated JAK/STAT signaling is known to drive myeloproliferative neoplasms, and targeting JAK1 and JAK2 has led to improvement in morbidity and mortality in these diseases. While dose-dependent anemia and thrombocytopenia limit the use of JAK2 inhibition, selectively targeting JAK1 has been explored as a means to suppress inflammation and STAT-associated neoplastogenesis. Recently, INCB52793 was found to be 100-fold selective for JAK1 over JAK2, and it has recently been explored in the clinic in solid tumors and acute myeloid leukemia (AML). In a large high throughput screen, we detected synergistic effects between INCB52793 and all-trans retinoic acid (ATRA) in several non-promyelocytic AML cell lines. In another in vitro assay, human primary AML blasts exposed to INCB52793 exhibited a marked increase in both CD13 and CD86, two markers indicative of cellular differentiation.

Given these findings, we tested this combination in an in vivo murine model of AML. Human leukemia cells were injected into the tail vein of sublethally irradiated NSGS mice which were then treated days 7-35 post-transplant with ATRA, INCB52793, ATRA/INCB52793, or vehicle. Weekly monitoring for peripheral human CD45+ cells revealed that the INCB52793/ATRA combination effectively decreased the expansion of leukemic cells. At 35-40 days, significant decreases in tumor burden were seen within the bone marrow (BM) and spleens of INCB62793/ATRA treated mice. Bone marrow and splenic cells were also analyzed by mass cytometry, simultaneously measuring 35 signaling, differentiation, and cell death attributes per-cell. The few remaining human cells in the INCB62793/ATRA combo group synergistically displayed 30-fold decreases in CD38, 8-fold increases in CD34, and attained high levels of p-STAT3 and p-STAT5, potentially implying a resistant progenitor population.

Label free proteomics revealed significant fold changes in in vitro INCB52793/ATRA treated cells. Proteins related to cellular differentiation mechanisms, such as SMAD3, BCL11A, RUNX2, HNRNPLL, and SAMHD1, were elevated between 24 to 48 hours post treatment supporting our hypothesis that JAK1 inhibition enhanced ATRA induced differentiation.

Targeting retinoic acid receptor and JAK1 together synergistically resulted in the decreased expansion of multiple AML cell lines, and preferential reduction of AML cells from the blood, spleen and bone marrow of treated mice in vivo. Common CD34-CD38+ tumor cells were eliminated, and rare remaining CD34+ AML cells displayed high p-STAT3 and p-STAT5 levels after INCB52793/ATRA therapy. While ATRA is a critical component in the therapy of acute promyelocytic leukemia (M3), it has not been successfully employed in other AML. These preliminary data represent a potential for INCB52793/ATRA therapy in non-M3 AML.

Citation Format: Haley E. Ramsey, P. Brent Ferrell, Melissa A. Fischer, Agnieszka E. Gorska, Caroline Maier, Jeremy Norris, Melissa Farrow, Danielle Guiterrez, James Pino, Sandra Zinkel, Carlos Lopez, Holly Koblish, Matthew Stubbs, Peggy Scherle, Jonathan M. Irish, Richard Caprioli, Michael R. Savona. INCB52793 JAK1 inhibitor synergizes with ATRA to inhibit expansion of AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3726. doi:10.1158/1538-7445.AM2017-3726

Signal Transducer and Activator of Transcription 3, Mediated Remodeling of the Tumor Microenvironment Results in Enhanced Tumor Drug Delivery in a Mouse Model of Pancreatic Cancer

BACKGROUND & AIMS

A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the presence of a dense desmoplastic reaction (stroma) that impedes drug delivery to the tumor. Attempts to deplete the tumor stroma have resulted in formation of more aggressive tumors. We have identified signal transducer and activator of transcription (STAT) 3 as a biomarker of resistance to cytotoxic and molecularly targeted therapy in PDAC. The purpose of this study is to investigate the effects of targeting STAT3 on the PDAC stroma and on therapeutic resistance.

METHODS

Activated STAT3 protein expression was determined in human pancreatic tissues and tumor cell lines. In vivo effects of AZD1480, a JAK/STAT3 inhibitor, gemcitabine or the combination were determined in Ptf1a(cre/+);LSL-Kras(G12D/+);Tgfbr2(flox/flox) (PKT) mice and in orthotopic tumor xenografts. Drug delivery was analyzed by matrix-assisted laser desorption/ionization imaging mass spectrometry. Collagen second harmonic generation imaging quantified tumor collagen alignment and density.

RESULTS

STAT3 activation correlates with decreased survival and advanced tumor stage in patients with PDAC. STAT3 inhibition combined with gemcitabine significantly inhibits tumor growth in both an orthotopic and the PKT mouse model of PDAC. This combined therapy attenuates in vivo expression of SPARC, increases microvessel density, and enhances drug delivery to the tumor without depletion of stromal collagen or hyaluronan. Instead, the PDAC tumors demonstrate vascular normalization, remodeling of the tumor stroma, and down-regulation of cytidine deaminase.

CONCLUSIONS

Targeted inhibition of STAT3 combined with gemcitabine enhances in vivo drug delivery and therapeutic response in PDAC. These effects occur through tumor stromal remodeling and down-regulation of cytidine deaminase without depletion of tumor stromal content.

Implementation of a Gaussian beam laser and aspheric optics for high spatial resolution MALDI imaging MS

We have investigated the use of a Gaussian beam laser for MALDI Imaging Mass Spectrometry to provide a precisely defined laser spot of 5 μm diameter on target using a commercial MALDI TOF instrument originally designed to produce a 20 μm diameter laser beam spot at its smallest setting. A Gaussian beam laser was installed in the instrument in combination with an aspheric focusing lens. This ion source produced sharp ion images at 5 μm spatial resolution with signals of high intensity as shown for images from thin tissue sections of mouse brain.

Laser beam filtration for high spatial resolution MALDI imaging mass spectrometry

We describe an easy and inexpensive way to provide a highly defined Gaussian shaped laser spot on target of 5 μm diameter for imaging mass spectrometry using a commercial MALDI TOF instrument that is designed to produce a 20 μm diameter laser beam on target at its lowest setting. A 25 μm pinhole filter on a swivel arm was installed in the laser beam optics outside the vacuum ion source chamber so it is easily flipped into or out of the beam as desired by the operator. The resulting ion images at 5 μm spatial resolution are sharp since the satellite secondary laser beam maxima have been removed by the filter. Ion images are shown to demonstrate the performance and are compared with the method of oversampling to achieve higher spatial resolution when only a larger laser beam spot on target is available.

Cell-autonomous and non-cell-autonomous roles for IRF6 during development of the tongue

Interferon regulatory factor 6 (IRF6) encodes a highly conserved helix-turn-helix DNA binding protein and is a member of the interferon regulatory family of DNA transcription factors. Mutations in IRF6 lead to isolated and syndromic forms of cleft lip and palate, most notably Van der Woude syndrome (VWS) and Popliteal Ptyerigium Syndrome (PPS). Mice lacking both copies of Irf6 have severe limb, skin, palatal and esophageal abnormalities, due to significantly altered and delayed epithelial development. However, a recent report showed that MCS9.7, an enhancer near Irf6, is active in the tongue, suggesting that Irf6 may also be expressed in the tongue. Indeed, we detected Irf6 staining in the mesoderm-derived muscle during development of the tongue. Dual labeling experiments demonstrated that Irf6 was expressed only in the Myf5+ cell lineage, which originates from the segmental paraxial mesoderm and gives rise to the muscles of the tongue. Fate mapping of the segmental paraxial mesoderm cells revealed a cell-autonomous Irf6 function with reduced and poorly organized Myf5+ cell lineage in the tongue. Molecular analyses showed that the Irf6−/− embryos had aberrant cytoskeletal formation of the segmental paraxial mesoderm in the tongue. Fate mapping of the cranial neural crest cells revealed non-cell-autonomous Irf6 function with the loss of the inter-molar eminence. Loss of Irf6 function altered Bmp2, Bmp4, Shh, and Fgf10 signaling suggesting that these genes are involved in Irf6 signaling. Based on these data, Irf6 plays important cell-autonomous and non-cell-autonomous roles in muscular differentiation and cytoskeletal formation in the tongue.

Altered expression of nuclear and cytoplasmic histone H1 in pulmonary artery and pulmonary artery smooth muscle cells in patients with IPAH

The pathogenesis of idiopathic pulmonary hypertension is poorly understood. This paper utilized histology-based Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI MS) to identify as-yet unknown proteins that may be associated with the structural changes in the pulmonary arterial walls of patients with IPAH. The technology identified significant increases in two fragments of histone H1 in the IPAH cases compared to controls. This finding was further examined using immunofluorescence techniques applied to sections from IPAH and control pulmonary arteries. In addition, cultured pulmonary artery smooth muscle cells (PASMCs) were utilized for Western analysis of histone H1 and importin β and importin 7, immunoprecipitation and assessment of nucleosomal repeat length (NRL). Immunofluorescence techniques revealed that nuclear expression of histone H1 was decreased and the chromatin was less compact in the IPAH cases than in the controls; furthermore, some cases showed a marked increase in cytoplasmic histone H1 expression. Using nuclear and cytoplasmic fractions of cultured PASMCs, we confirmed the reduction in histone H1 in the nucleus and an increase in the cytoplasm in IPAH cells compared to controls. Immunoprecipitation demonstrated a decreased association of histone H1 with importin β while importin 7 was unchanged in the IPAH cells compared to controls. The assessment of NRL revealed that the distance between nucleosomes was increased by ~20 bp in IPAH compared to controls. We conclude that at least two factors contribute to the reduction in nuclear histone H1-fragmentation of the protein and decreased import of histone H1 into the nucleus by importins. We further suggest that the decreased nuclear H1 contributes the less compact nucleosomal pattern in IPAH and this, in turn, contributes to the increase in NRL.

Enhanced sensitivity for high spatial resolution lipid analysis by negative ion mode matrix assisted laser desorption ionization imaging mass spectrometry

We have achieved enhanced lipid imaging to a ~10 μm spatial resolution using negative ion mode matrix assisted laser desorption ionization (MALDI) imaging mass spectrometry, sublimation of 2,5-dihydroxybenzoic acid as the MALDI matrix, and a sample preparation protocol that uses aqueous washes. We report on the effect of treating tissue sections by washing with volatile buffers at different pHs prior to negative ion mode lipid imaging. The results show that washing with ammonium formate, pH 6.4, or ammonium acetate, pH 6.7, significantly increases signal intensity and number of analytes recorded from adult mouse brain tissue sections. Major lipid species measured were glycerophosphoinositols, glycerophosphates, glycerolphosphoglycerols, glycerophosphoethanolamines, glycerophospho-serines, sulfatides, and gangliosides. Ion images from adult mouse brain sections that compare washed and unwashed sections are presented and show up to 5-fold increases in ion intensity for washed tissue. The sample preparation protocol has been found to be applicable across numerous organ types and significantly expands the number of lipid species detectable by imaging mass spectrometry at high spatial resolution.

Multiplexed molecular descriptors of pressure ulcers defined by imaging mass spectrometry

The pathogenesis of impaired healing within pressure ulcers remains poorly characterized and rarely examined. We describe the results of a pilot study that applies matrix-assisted laser desorption/ionization imaging mass spectrometry technology for direct tissue analysis to evaluate proteomic signatures ranging from 2 to 20 kDa and phospholipids from 300-1,200 Da in focal regions within the wound microenvironment. Distinguishing molecular differences were apparent between upper vs. lower regions of ulcers and further contrasted against adjacent dermis and epidermal margins using protein profiles, ion density maps, principal component analysis and significant analysis of microarrays. Several proteins previously uncharacterized in pressure ulcers, the α-defensins (human neutrophil peptide [HNP]-1, -2, -3), are potential markers indicating whether the wound status is improving or being prolonged in a deleterious, chronic state. Thymosin β4 appears to be a favorable protein marker showing higher relative levels in adjacent dermis and maturing areas of the wound bed. Lipidomic examination revealed the presence of major lipid classes: glycerophosphocholines, glycerophosphoglycerols, glycerophosphoinositols, and triacylglycerols. Our pilot data examined from either a global perspective using proteomic or lipidomic signatures or as individual distributions reveal that imaging mass spectrometry technology can be effectively used for discovery and spatial mapping of molecular disturbances within the microenvironment of chronic wounds.

Spatial mapping by imaging mass spectrometry offers advancements for rapid definition of human skin proteomic signatures

Investigations into the human skin proteome by classical analytical procedures have not addressed spatial molecular distributions in whole-skin biopsies. The aim of this study was to develop methods for the detection of protein signatures and their spatial disposition in human skin using advanced molecular imaging technology based on mass spectrometry technologies. This technology allows for the generation of protein images at specific molecular weight values without the use of antibody while maintaining tissue architecture. Two experimental approaches were employed: MALDI-MS profiling, where mass spectra were taken from discrete locations based on histology, and MALDI-IMS imaging, where complete molecular images were obtained at various MW values. In addition, proteins were identified by in situ tryptic digestion, sequence analysis of the fragment peptides and protein database searching. We have detected patterns of protein differences that exist between epidermis and dermis as well as subtle regional differences between the papillary and reticular dermis. Furthermore, we were able to detect proteins that are constitutive features of human skin as well as those associated with unique markers of individual variability.

Proteomic Discrimination of Well- from Poorly-Differentiated Breast Carcinomas

Background: Pathological grade is a useful prognostic factor for stratifying breast cancer patients into favorable (well-differentiated tumors) and less favorable (poorly-differentiated tumors) outcome groups. The current system of tumor grading, however, is highly subjective and a large proportion of tumors are characterized as intermediate-grade, making determination of optimal treatments difficult.Methods: Primary breast tumor specimens from patients diagnosed with well- (n=27) and poorly-differentiated (n=51) invasive ductal carcinoma were obtained from patients enrolled in the Clinical Breast Care Project. Frozen tissues were sectioned and mounted on gold coated MALDI target plates for protein expression profiling. Hematoxylin and eosin (H&E) stained slides were prepared from serial sections for histological characterization. MALDI matrix was deposited as individual spots on the tissue sections in a histology directed manner to assay specific areas and tissue types of interest. Mass spectral data were then acquired from multiple sites across each tissue section.Results: 129 features were observed in well-differentiated and 132 in poorly-differentiated tumors. While the majority of features detected were similar between the two groups, 6 protein features were expressed at significantly lower and 12 at significantly higher levels in the poorly-differentiated tumors, including increased expression of Calgranulin A and Calgizzarin.Conclusions: Protein expression differences detected here suggest that well- and poorly-differentiated invasive breast tumors are molecularly distinct diseases and that these protein changes may contribute to the structural integrity of the tumor cell. In particular, calgranulin A and calgizzarin are members of the S100 protein family, and function in processes such as cell proliferation and differentiation. Further refinement of this differentiation protein signature may not only improve our understanding of the biological processes involved with tumor grade but provide pathologists with new molecular tools to classify breast tumors and reduce the subjectivity associated with current grading criteria.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6126.

Total parathyroidectomy without autotransplantation for the treatment of secondary hyperparathyroidism associated with chronic kidney disease: clinical and laboratory long-term follow-up

Forty-six consecutive patients who underwent total parathyroidectomy (tPTX) for hyperparathyroidism associated with end-stage kidney disease (CKD5) in a University Hospital from 1990 to 1999 were included in a long-term observational study. Outcome parameters included symptoms (bone pain, pruritus and muscle weakness evaluated by visual analog scales [VAS]) and laboratory data (intact parathyroid hormone [iPTH], total calcium, and alkaline phosphatase) assessed before, shortly postoperatively and then at a later time point: 40 patients were on maintenance hemodialysis and six on conservative medical therapy. Forty-four patients had four glands removed, while only three glands were found in the remaining two. Perioperative complications consisted of acute symptomatic hypocalcemia in 10 (22%) patients and non-specific complaints in three (7%). No laryngeal nerve palsies occurred. After a median follow-up of eight years, 43 subjects were evaluated: 37 (86%) were cured, three (7%) had persistent and three (7%) recurrent disease. Eleven patients underwent successful renal transplantation and 23 died during the period of observation. iPTH decreased from a mean of 1084+/-505 pg/ml to 120+/-381 pg/ml (p < 0.0001). No subsequent bone fractures, persistent bone pain or disability were reported; this includes patients who later received a functioning renal graft. tPTX was able to correct hyperparathyroidism in most of the patients and was associated with a low long-term relapse rate. iPTH levels remained low in 17 cases without symptoms and no clinically significant side effects. The beneficial effects of tPTX occurred in the majority of patients while renal transplantation was performed in a minority of patients. tPTX should be considered a safe and successful procedure for the treatment of severe secondary hyperparathyroidism associated with chronic kidney disease.

Mass spectrometry profile as a predictor of overall survival benefit after treatment with epidermal growth factor receptor inhibitors in head and neck squamous cell carcinoma

6000

Background: Our previous study has shown that a matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) profile in serum or plasma can predict lung cancer patient survival after treatment with epidermal growth factor receptor inhibitors (EGFRI). We examined the ability of this same MALDI-MS profile in plasma or sera to predict for survival benefit of EGFRIs in patients with head and neck squamous cell carcinoma (HNSCC). Methods: Spectra were obtained in triplicate using MALDI-MS from 314 samples obtained from five HNSCC cohorts treated with 1) gefitinib (G, n = 100); 2) erlotinib and bevacizumab (E/B, n = 81); 3) cetuximab (C, n = 21); 4) surgery (S, n = 78); and 5) palliative chemotherapy (PC, n = 34). Each sample was classified into “good” or “poor” outcome groups and overall survival was examined using this MALDI-MS classifier (VeriStrat, Biodesix, Steamboat Springs, CO). Results: Successful classification could be achieved in 311/314 (98%) of the samples. In all EGFRI-treated cohorts, the classifier predicted survival benefit while the cohorts without EGFRI-treatment showed no survival difference by log-rank testing (G: p = 0.007, HR 0.41, 95%-CI 0.22–0.79; E/B: p = 0.02, HR 0.20, 95%-CI 0.05–0.78; C: p=0.06, HR 0.26, 95%-CI 0.06–1.06; and PC: p = 0.76, HR 0.88, 95%-CI 0.4–1.97), independent of performance status, age, gender and smoking history. Conclusions: This study suggests that the same predictive algorithm for MALDI-MS generated from patients with lung cancer treated with EGFRIs is also predictive of survival outcome in HNSCC patients treated with both TKIs and cetuximab, and may allow rational selection of patients most likely to benefit from an EGFRI monotherapy.

[Table: see text]

Differential efficacy of combined therapy with radiation and AEE788 in high and low EGFR-expressing androgen-independent prostate tumor models

PURPOSE

To determine the efficacy of combining radiation (XRT) with a dual epidermal growth factor receptor (EGFR)/vascular endothelial growth factor receptor inhibitor, AEE788, in prostate cancer models with different levels of EGFR expression.

METHODS AND MATERIALS

Immunoblotting was performed for EGFR, phosphorylated-EGFR, and phosphorylated-AKT in prostate cancer cells. Clonogenic assays were performed on DU145, PC-3, and human umbilical vein endothelial cells treated with XRT +/- AEE788. Tumor xenografts were established for DU145 and PC-3 on hind limbs of athymic nude mice assigned to four treatment groups: (1) control, (2) AEE788, (3) XRT, and (4) AEE788 + XRT. Tumor blood flow and growth measurements were performed using immunohistochemistry and imaging.

RESULTS

AEE788 effectively decreased phosphorylated-EGFR and phosphorylated-AKT levels in DU145 and PC-3 cells. Clonogenic assays showed no radiosensitization for DU145 and PC-3 colonies treated with AEE788 + XRT. However, AEE788 caused decreased proliferation in DU145 cells. AEE788 showed a radiosensitization effect in human umbilical vein endothelial cells and increased apoptosis susceptibility. Concurrent AEE788 + XRT compared with either alone led to significant tumor growth delay in DU145 tumors. Conversely, PC-3 tumors derived no added benefit from combined-modality therapy. In DU145 tumors, a significant decrease in tumor blood flow with combination therapy was shown by using power Doppler sonography and tumor blood vessel destruction on immunohistochemistry. Maldi-spectrometry (MS) imaging showed that AEE788 is bioavailable and heterogeneously distributed in DU145 tumors undergoing therapy.

CONCLUSIONS

AEE788 + XRT showed efficacy in vitro/in vivo with DU145-based cell models, whereas PC-3-based models were adequately treated with XRT alone without added benefit from combination therapy. These findings correlated with differences in EGFR expression and showed effects on both tumor cell proliferation and vascular destruction.

Mass spectrometry to classify non-small-cell lung cancer patients for clinical outcome after treatment with epidermal growth factor receptor tyrosine kinase inhibitors: a multicohort cross-institutional study

BACKGROUND

Some but not all patients with non-small-cell lung cancer (NSCLC) respond to treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). We developed and tested the ability of a predictive algorithm based on matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) analysis of pretreatment serum to identify patients who are likely to benefit from treatment with EGFR TKIs.

METHODS

Serum collected from NSCLC patients before treatment with gefitinib or erlotinib were analyzed by MALDI MS. Spectra were acquired independently at two institutions. An algorithm to predict outcomes after treatment with EGFR TKIs was developed from a training set of 139 patients from three cohorts. The algorithm was then tested in two independent validation cohorts of 67 and 96 patients who were treated with gefitinib and erlotinib, respectively, and in three control cohorts of patients who were not treated with EGFR TKIs. The clinical outcomes of survival and time to progression were analyzed.

RESULTS

An algorithm based on eight distinct m/z features was developed based on outcomes after EGFR TKI therapy in training set patients. Classifications based on spectra acquired at the two institutions had a concordance of 97.1%. For both validation cohorts, the classifier identified patients who showed improved outcomes after EGFR TKI treatment. In one cohort, median survival of patients in the predicted "good" and "poor" groups was 207 and 92 days, respectively (hazard ratio [HR] of death in the good versus poor groups = 0.50, 95% confidence interval [CI] = 0.24 to 0.78). In the other cohort, median survivals were 306 versus 107 days (HR = 0.41, 95% CI = 0.17 to 0.63). The classifier did not predict outcomes in patients who did not receive EGFR TKI treatment.

CONCLUSION

This MALDI MS algorithm was not merely prognostic but could classify NSCLC patients for good or poor outcomes after treatment with EGFR TKIs. This algorithm may thus assist in the pretreatment selection of appropriate subgroups of NSCLC patients for treatment with EGFR TKIs.

Identification of proteins promoting development of metastatic breast tumors

1041

Background: Primary breast tumors are constantly shedding tumor cells into the circulatory and lymphatic systems. Although detection of occult tumor cells is a risk factor for recurrence and progression, tumor cells remain detectable years after initial diagnosis in patients without clinical or histological detection of metastasis. Thus the question remains as to why some women with circulating tumor cells develop metastatic breast cancer while others do not. Methods: Negative lymph nodes from women with node negative (n=22) and node positive disease (n=36) were obtained from patients enrolled in the Clinical Breast Care Project. Negative lymph node status was confirmed by IHC analysis. Frozen tissues were sectioned and mounted on gold coated MALDI target plates for protein expression profiling. Hematoxylin and eosin (H&E) stained slides were prepared from serial sections for histological characterization. MALDI matrix was deposited as individual spots on the tissue sections in a histology directed manner to assay specific areas and tissue types of interest. Mass spectral data were then acquired from multiple sites across each tissue section. Results: 131 features were observed in negative nodes from patients without metastatic disease and 129 in negative nodes from patients with lymph node metastases. While the majority of features detected were similar between the two groups, 8.5% were differentially expressed. Two of the features which were expressed at significantly higher levels in nodes from patients with metastatic disease have been putatively identified as thymosin β4 and thymosin β10. Conclusions: Thymosin β4 and 10 have been associated with disease progression and metastatic capacity in a number of tumor types. The overexpression of these proteins in tumor-negative nodes from patients with metastatic disease in other regional nodes suggests lymph nodes do not play a passive role in metastasis, rather, expression of a specific subset of proteins creates an hospitable environment to facilitate colonization. These markers of metastasis may permit molecular discrimination of those patients with indolent disease from those at risk for metastasis and will thus allow for the design of customized treatment regimens to more effectively treat, or prevent, metastatic spread.

No significant financial relationships to disclose.

Biochemical evidence of tumor response and measurable levels of the drug in glioblastoma tissue from patients treated with imatinib

2023

Background: Glioblastoma multiforme (GBM) carries a grave prognosis. There are phase I-II studies indicating that imatinib is active in GBM in pre-treated patients. To better understand the molecular basis of imatinib’s activity in this disease we performed a pharmacodynamic neoadjuvant study with imatinib in GBM. Methods: Patients underwent CT guided biopsy of their brain tumors. If diagnosed with GBM they were immediately treated with 7 days of imatinib 400mg po BID followed by either definitive surgery or, if that was not feasible, followed by re-biopsy. Corticosteroid dose was stable during this period and valproic acid was the only anti-epileptic drug allowed in order to avoid pharmacokinetic interaction with imatinib. Treatment after recovery was as per usual institutional policy. Pre and post treatment tissue specimens were analyzed by immunohistochemistry, proteomic technology and molecular biological methods. Pharmacokinetic studies were also performed. Results: Twenty patients were enrolled in 2 institutions with a median age of 64, of which 14 were male and 6 female. PS was 0 in 2, 1 in 9 and 2 in 9. Seventeen patients had pure GBM, 2 had mixed GBM with astrocytoma and one had anaplastic astrocytoma. Eighteen patients had stable disease on pre and post treatment MRI, one had progressed and one was not evaluable. Median survival was 6.2 months (1.1–18mo). Intact imatinib was quantified in the post treatment tissue specimens and correlations were made with serum imatinib levels per patient. No correlation was seen. Tissue specimens were analyzed by in situ MALDI mass spectroscopy and differential protein expression profiles were detected, when pre and post treatment specimens were compared. The identification of candidate proteins is ongoing. In 11 patients with evaluable, high-quality, matched pre and post imatinib biopsies, 4 had biochemical evidence of tumor response (decreased AKT or MAPK, or increased p27). In addition, 2 patients showed high-level EGFR activation, and one patient had high-level PDGFR activation. Conclusions: Treatment of GBM patients with imatinib results in measurable levels of the drug in the tumor. Potential indicators of biochemical response in a subset of patients were identified.

No significant financial relationships to disclose.

Proteomic analysis of lung cancer tumors

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Background: In this study we assess the utility of direct tumor tissue MALDI-MS in a large prospective collection of surgically resected lung cancers to distinguish cancer from non-cancer, histology, occult lymph node involvement, and survival. Methods: 175 non-small cell lung cancer specimens and 62 histologically normal lung tissues obtained at the time of surgery were used in this analysis. Twelve micron thick frozen sections were placed on conductive glass slides. Sections were stained with Cresyl Violet and matrix applied to areas identified by a pathologist under microscopic guidance as containing greater than 80% tumor before three separate areas involved with tumor was analyzed by MALDI MS. Relative intensities of selected peaks were used for class comparison. A class prediction model was built based on the weighted flexible compound covariate method of analysis (WFCCM). Results: We created a prediction model from a training cohort consisting 81 tumors and 19 histologically normal tissue samples. A total of 221 peaks were used for statistical analysis. In tumor/normal discrimination, 46 peaks were used for the prediction model (p<0.0001), while, 22 were used (p<0.005) to predict histology, 11 (p<0.05) to predict nodal involvement, and 14 (p<0.005) in survival prediction. Using these prediction models, classification accuracy was 90% in normal/tumor discrimination, 81.8% in histology and 61.7% in nodal involvement prediction. In the survival prediction model, patients with longer than median survival could be distinguished from those with shorter than median survival (p<0.0001, Log-rank test). We then validated the same features in a blind test set from the remaining 93 tumors and 43 normals. For tumor/normal discrimination, prediction accuracy in test cohort was 94.3%. Histology prediction accuracy was 93.9% in predicting squamous cell carcinoma. Nodal involvement prediction accuracy was 49.3%. Longer or shorter median survival was also predicted in this set with statistical significance p<0.08. (Log rank test). Conclusion: We report the analysis of a large set of tumor and normal samples by MALDI MS and confirm similar accuracy in tumor/normal, histology and survival discrimination to previous our report. This project was supported by the Lung SPORE P50 CA90949 (DPC) and NCI 5R33CA86243 (RMC).

No significant financial relationships to disclose.

[Natriuretic peptides in heart failure]

The recent discovery of cardiac endocrine function, together with the development of accurate and feasible assay methods for cardiac natriuretic hormone evaluation, i.e. for B-type natriuretic peptide (BNP) and inactive peptide NT-proBNP have confirmed their pathophysiological and clinical significance for cardiovascular disease assessment. Concerning heart failure, their value is for diagnostic screening in selected/unselected populations, for differential diagnosis of dyspnea and for prognostic stratification, and as a guide for follow-up and treatment of patients. Recent Italian recommendations pointed out that BNP/NT-proBNP has a role in ruling-out the diagnosis of heart failure in patients with dubious signs/symptoms: plasma BNP/NT-proBNP concentrations help in the clinical evaluation of chronic heart failure patients when risk stratification is needed, whereas the routine BNP/NT-proBNP assay is still not recommended to guide therapeutic decision-making.

Perspective: a program to improve protein biomarker discovery for cancer

Biomarkers for cancer risk, early detection, prognosis, and therapeutic response promise to revolutionize cancer management. Protein biomarkers offer tremendous potential in this regard due to their great diversity and intimate involvement in physiology. An effective program to discover protein biomarkers using existing technology will require team science, an integrated informatics platform, identification and quantitation of candidate biomarkers in disease tissue, mouse models of disease, standardized reagents for analyzing candidate biomarkers in bodily fluids, and implementation of automation. Technology improvements for better fractionation of the proteome, selection of specific biomarkers from complex mixtures, and multiplexed assay of biomarkers would greatly enhance progress.

Proteomic exploration of pancreatic islets in mice null for the alpha2A adrenergic receptor

The present studies extend recent findings that mice null for the alpha(2A) adrenergic receptor (alpha(2A) AR KO mice) lack suppression of exogenous secretagogue-stimulated insulin secretion in response to alpha(2) AR agonists by evaluating the endogenous secretagogue, glucose, ex vivo, and providing in vivo data that baseline insulin levels are elevated and baseline glucose levels are decreased in alpha(2A) AR KO mice. These latter findings reveal that the alpha(2A) AR subtype regulates glucose-stimulated insulin release in response to endogenous catecholamines in vivo. The changes in alpha(2A) AR responsiveness and resultant changes in insulin/glucose homeostasis encouraged us to utilize proteomics strategies to identify possible alpha(2A) AR downstream signaling molecules or other resultant changes due to perturbation of alpha(2A) AR expression. Although agonist stimulation of islets from wild type (WT) mice did not significantly alter islet protein profiles, several proteins were enriched in islets from alpha(2A) AR KO mice when compared with those from WT mice, including an enzyme participating in insulin protein processing. The present studies document the important role of the alpha(2A) AR subtype in tonic suppression of insulin release in response to endogenous catecholamines as well as exogenous alpha(2) agonists and provide insights into pleiotropic changes that result from loss of alpha(2A) AR expression and tonic suppression of insulin release.

Changes in heart rate variability in chronic uremic patients during ultrafiltration and hemodialysis

BACKGROUND

The analysis of heart rate variability (HRV) is a useful tool to evaluate cardiac autonomic modulation, which is frequently impaired in chronic uremia.

AIMS

The aim of this study was to evaluate HRV in chronic uremics and to separately investigate the acute changes induced by volume depletion and solute removal during a hemodialysis session.

METHODS

Fourteen uremic patients (8 males and 6 females, aged 50 +/- 15 years) on maintenance hemodialysis and 14 sex- and age-matched healthy controls were studied. Both groups underwent ambulatory electrocardiogram monitoring to evaluate the HRV time and frequency domain indices. The hemodialysis session was performed by 1 h of high-rate isolated ultrafiltration followed by 3 h of bicarbonate diffusive procedure.

RESULTS

In uremic patients, the overall variability in the frequency [low-frequency power (LF): 505 +/- 473, vs. 1,446 +/- 654; high-frequency power (HF): 133 +/- 162 vs. 512 +/- 417; p < 0.001] and time domain indices (standard deviation of normal R-R intervals: 101.9 +/- 33.3 vs. 181.7 +/- 44.1 ms; p < 0.001) was markedly reduced compared to controls, whereas mean heart rate (83 +/- 12.4 vs. 60.9 +/- 8.8 bpm; p < 0.001) and LF/HF ratio (5.8 +/- 3.5 vs. 2.2 +/- 0.8; p < 0.001) were increased. Isolated ultrafiltration produced a marked further decrease in HRV indices, but the subsequent diffusive hemodialysis procedure, with a low ultrafiltration rate, made HRV increase again.

CONCLUSIONS

Chronic uremics showed abnormal autonomic modulation with sympathetic-vagal imbalance. The unbalanced hypersympathetic response to body fluid depletion is related to the ultrafiltration rate. Low interdialytic weight gain and a low ultrafiltration rate, associated with adequate hemodialysis, should be the preferable strategy for uremic patients with autonomic dysfunction.

Responses of the skin microcirculation to acetylcholine and to sodium nitroprusside in chronic uremic patients

The aim of the present study was to assess the endothelial function of the microcirculation in chronic renal failure. We investigated the responses of the cutaneous blood flow to locally delivered acetylcholine and sodium nitroprusside in uremic patients. The study included 60 chronic uremic patients: 40 patients with a creatinine clearance of 4-25 ml/min were on conservative treatment and 20 patients were on maintenance hemodialysis. The changes in skin blood flow following iontophoretic delivery of acetylcholine (an endothelium-dependent vasodilator) and sodium nitroprusside (an endothelium-independent vasodilator) were measured by laser Doppler flowmetry. Acetylcholine induced a progressive increase in blood flow in both groups, reaching approximately 100% of the maximal hyperemic response obtained by sodium nitroprusside delivery. The percent increase in blood flow from baseline was lower in hemodialysis patients than in patients on conservative treatment, after both acetylcholine (550 +/- 44 vs. 718 +/- 61%, P < 0.05) and sodium nitroprusside (553 +/- 46 vs. 735 +/- 69%, P < 0.05) delivery. In the hemodialysis group, the hyperemic responses to acetylcholine and sodium nitroprusside did not improve after the hemodialysis session. Hence, the hyperemic responses of the skin microcirculation are lower in hemodialysis patients than in patients on conservative treatment, and did not ameliorate after hemodialysis. It seems to be independent of endothelial dysfunction, and associated with the severity of uremia and with the maintenance hemodialysis treatment. This microcirculatory abnormality is in keeping with the arterial stiffness and vascular wall damages described in dialysis patients, which contribute to the cardiovascular morbidity of chronic uremia.

Clinical relevance of cardiac natriuretic peptides measured by means of competitive and non-competitive immunoassay methods in patients with renal failure on chronic hemodialysis

Increased levels of cardiac natriuretic peptides in patients undergoing hemodialysis may be a marker of cardiomyopathy and in consequence may be suitable prognostic indicators for the risk of development of cardiac disease. We measured plasma levels of ANP, BNP, proANP(1-98) and proBNP(1-76)-related peptides with some competitive and non-competitive immunoassay methods in patients with renal failure on chronic hemodialysis in order to compare the analytical performances of these methods and to evaluate the clinical usefulness of each assay for patients with chronic renal failure. ANP and BNP values significantly decreased after hemodialysis (on average, ANP by 36% and BNP by 16%); while all proANP and proBNP values tended to increase, but only proANP(1-30) (by 14.4%) and Nt-proBNP (by 9.5%) significantly. Although significant correlations were found among all the circulating levels of cardiac peptides studied, N-terminal pro-peptides correlated better among themselves than with ANP and BNP; ANP was only slightly correlated with all the other peptides, the only exception being BNP. Only BNP levels significantly increased according to the degree of ventricular hypertrophy and/or ventricular function in patients with chronic renal failure. The ANP assay is preferable in physiological and clinical studies for the rapid changes in atrial pre-load. BNP would be more useful in the follow-up of cardiac complications in patients with end-stage renal disease on regular hemodialysis. The assays of N-terminal proANP(1-98)-and proBNP(1-76)-related peptides proved to be of limited use, because they were not able to detect acute changes in pre-load during hemodialysis and were less useful than BNP levels as markers of ventricular hypertrophy and/or functional cardiac impairment.

Measurement of brain natriuretic peptide in plasma samples and cardiac tissue extracts by means of an immunoradiometric assay method

We evaluated the analytical characteristics and clinical usefulness of a commercial immunoradiometric assay (IRMA) kit for brain natriuretic peptide (BNP). Mean (+/-SD) plasma BNP concentrations measured in 129 normal subjects were 2.9+/-2.7 pmol/l (median 2.2 pmol/l; range 0.1-12.4 pmol/l). The mean (+/- SD) value observed in healthy men (2.1 +/- 2.0 pmol/l, n = 49) was significantly (p=0.0009) different to that found in women (3.4 +/- 2.9 pmol/l, n=80). A positive relationship (R=0.214, p=0.0174) was found between BNP values and age. In 65 patients with cardiac diseases, BNP levels increased with the progression of clinical severity of disease; patients with more severe disease [NYHA functional class III-IV, mean (+/- SD) BNP +/- 254 +/- 408 pmol/l, n=22] showed significantly (p<0.0001) increased values compared to patients with mild symptoms of disease (NYHA functional class I-II, mean (+/- SD) BNP=19.6 +/- 17.2 pmol/l, n=43). Furthermore, in 32 patients with chronic renal failure, greatly increased (p<0.0001) BNP values were found both before (mean +/- SD=88. 1+/- 111.1 pmol/l) and after haemodialysis (mean +/- SD=65.6 +/- 76.7 pmol/l), with a significant reduction after haemodialysis (p=0.0004) compared to pre-haemodialysis. The mean (+/- SD) BNP value found in atrial extracts collected during aorto-coronary bypass operations in 15 patients was 14.5 +/- 51.9 pmol/g of cardiac tissue. Moreover, the mean (+/- SD) tissue levels of BNP in 7 heart transplant recipients were 128.4 +/- 117.2 pmol/g of cardiac tissue in atrium, 68.4 +/- 76.7 pmol/g in ventricle, and 10.9 +/- 8.5 pmol/g in interventricular septum. Finally, BNP values found in cardiac tissues of two subjects collected at autopsy were considerably lower (on average 1/1000) than those observed in cardiac tissues of patients with cardiac diseases. The IRMA method for BNP determination evaluated in this study showed a good degree of sensitivity, precision and practicability. Therefore, this method should be a reliable tool for the measurement of plasma BNP levels for both experimental studies and routine assay.

Potassium removal increases the QTc interval dispersion during hemodialysis

This study was planned to clarify the mechanism(s) by which hemodialysis increases the QTc dispersion, a marker of risk of ventricular arrhythmias. To this aim, 10 uremic patients, without any relevant heart diseases, underwent two different types of hemodialysis schedules. In the first, 1 h of isolated high rate ultrafiltration preceded the standard diffusive procedure. In the second, during the first hour of standard bicarbonate hemodialysis, the decrease of plasma potassium concentration was prevented by increasing K+ concentration in the dialysate, according to its pre dialysis plasma levels. During the high rate ultrafiltration period, together with ECG signs of increased sympathetic nervous system activity and catecholamines secretion, the QTc dispersion did not change significantly. Instead, an evident increment was observed 1 h after the start of the diffusive hemodialysis, then slowly progressing until the end of the dialysis and finally returning to the pre dialysis values within 2 h after the end of the session. To the contrary, the increase of the QTc dispersion was totally blunted during a standard hemodialysis procedure in absence of plasma K+ decrease, but appeared again when the K+ dialysate fluid concentration was restored to 2 mmol/l. This study provides evidence that the increase of QTc dispersion occurring on hemodialysis is mainly related to the diffusive process, more precisely to the K+ removal. This is one more reason to focus attention on K+ removal rate especially when hemodialysis treatment is given in uremics affected by cardiac diseases with high risk of arrhythmias.

Omega-3 fatty acid supplementation and lipoprotein(a) concentrations in patients with chronic glomerular diseases

Renal disease patients often exhibit alterations in the lipid profile which may become an important risk of accelerated atherosclerosis and contribute to disease progression. Among such alterations, increased levels of lipoprotein(a) [Lp(a)] are common and may be related, in part, to the degree of proteinuria. Omega-3 polyunsaturated fatty acids (omega-3 FA) have been reported to decrease Lp(a) concentrations in nonrenal subjects. In addition, they have recently been shown to reduce proteinuria in patients with chronic glomerular disease. We therefore tested the hypothesis that omega-3 FA treatment in patients with chronic glomerular disease may reduce Lp(a) concentrations. Eight patients (2 with membranous glomerulonephritis, 6 with focal glomerular sclerosis) were submitted to a total of 13 six-week courses of treatment with omega-3 FA, at a dose of 3 g/day with a triglyceride preparation (n = 4) and of 7.7 g/day with an ethyl-ester preparation (n = 9). Both treatments significantly increased the proportions of omega-3 to omega-6 FA in total serum lipids, documenting compliance to treatment. Both treatments were also effective in decreasing serum thromboxane (from mean 490 +/- (SEM) 70 to 325 +/- 49 ng/ml, p < 0.05, in the high-dose group) and prolonging the bleeding time (from 5.8 +/- 0.4 to 7.7 +/- 0.5 min, p < 0.05, in the high-dose group), thus documenting the biological efficacy of treatment. However, despite a significant reduction in serum triglyceride levels (from 137 +/- 20 to 104 +/- 19 mg/dl in the high-dose group), Lp(a) concentrations did not change (292 +/- 120 U/l before, 315 +/- 130 U/l after the high-dose therapy). Treatment-related changes in proteinuria (from 2.9 +/- 0.5 to 2.1 +/- 0.7 g/24 h) were not related at all to changes in Lp(a) levels. We conclude that omega-3 FA do not decrease Lp(a) concentrations in renal patients with chronic glomerular diseases and that Lp(a) levels are unlikely to be related to the degree of proteinuria within the short-term modifications induced by omega-3 FA.

Recombinant human erythropoietin and high flux haemodiafiltration

Since 1982, 32 uraemic patients were treated in our institution by high flux haemodiafiltration (H-HDF) in order to shorten significantly the dialytic treatment session. H-HDF used a high surface area filter (1.4-1.9 m2) with high hydraulic permeability (polyacrylonitrile and polysulfone), at high blood flow (450 ml/min) and high rates of reinfusion of substitution fluid (22 l/session). In this way the dialytic session was shortened to 140 +/- 19 min, maintaining a good cardiovascular stability and high dialytic efficiency (Kt/V > 1.1). Human recombinant erythropoietin rHuEpo introduced in the therapy of this group in 1987 has resulted in an improvement of renal anaemia, but also a prolongation of the time of dialytic treatment due to a decrease in the efficiency of filters. During the period of the study, the treatment time increased from 140 +/- 19 min to 168 +/- 25 min with a concomitant increase of haematocrit and haemoglobin (from 24% to 36% and from 7.9 to 10.5 g/dl, respectively). H-HDF maintains a noticeable increase in dialytic efficacy with good cardiovascular stability, but the goal of a significant reduction in the time of treatment can no longer be obtained.

n-3 fatty acids reduce proteinuria in patients with chronic glomerular disease

Dietary supplementation with n-3 polyunsaturated fatty acids (n-3 PUFA) has been shown to reduce proteinuria in experimental models of renal diseases, but their potential role in the treatment of human renal disease is unknown. We administered n-3 PUFA in the form of triglycerides [with eicosapentaenoic (EPA)+docosahexaenoic (DHA) = 3 g/day into 4 patients] and of ethyl esters (EPA+DHA = 7.7 g/day) into 10 patients (one patient twice) with chronic glomerular disease (membranous glomerulonephritis and focal glomerular sclerosis), all diagnosed histologically. Serum albumin was > 2.4 g/dl and serum creatinine < 2.5 mg/dl in all patients. Treatment was given for periods of six weeks, followed by a prolonged follow-up for 27 weeks in 10 cases. Dietary supplementation with n-3 PUFA caused the expected reduction in platelet generation of thromboxane B2 (mean +/- SEM, from 490 +/- 70 ng/ml at baseline, to 342 +/- 147 ng/ml at 6 weeks, P < 0.05) of serum triglycerides (from 236 +/- 60 to 170 +/- 43, P < 0.01), and a prolongation of the bleeding time (from 5.8 +/- 0.4 min to 7.7 +/- 0.4 min, P < 0.01) in patients treated with ethyl esters. A modest but significant reduction in serum total cholesterol was noticed (from 275 +/- 27 to 252 +/- 24 mg/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Automatic continuous venovenous hemodiafiltration in cardiosurgical patients

Intermittent substitutive treatments in severely ill patients with acute renal failure are difficult or not suitable because of technical problems and/or hemodynamic instability. Continuous venovenous hemodiafiltration allows an adequate, slow removal of fluid, electrolytes, and waste products by combining diffusive and convective solute transport. Eight patients with acute renal failure, after cardiovascular surgery and cardiogenic shock, were treated by continuous venovenous hemodiafiltration. An automatic system (Equaline System, Amicon Division, USA) was employed. Venous accesses (femoral or subclavian) were used with double lumen catheters. A polysulfone filter (0.4 m2) was used in the study. Blood flow was 30 ml/min and dialysate flow rate 16.6 ml/min. Sterile pyrogen-free hemofiltration substitution fluid was used as dialysate. Mean duration of treatment was 10.3 +/- 3.2 days. After 72 hours blood urea nitrogen levels dropped from 136 +/- 46.13 to 53.5 +/- 12.3 mg/dl and creatinine levels dropped from 6.9 +/- 1.7 to 2.6 +/- 0.9 mg/dl. A controlled steady-state was then maintained. Mean urea clearance was 21 +/- 5.3 ml/min; mean ultrafiltration rate was 20.3 +/- 4.1 L/day. Continuous venovenous hemodiafiltration, with the Equaline System, is effective for the clearance of waste products and is able to maintain perfect fluid balance in catabolic patients with acute renal failure and multiple organ failure.