Abstract 77: Preclinical evaluation of HDP-101, an anti-BCMA antibody-drug conjugate

Background:

ATACs (antibody-targeted Amanitin conjugates) comprise a new class of antibody-drug conjugates using amanitin as toxic payload. Amanitin binds to the eukaryotic RNA pol II and thereby inhibits the cellular transcription process at very low concentrations. In the current study, in vitro and in vivo data of new ATACs targeting BCMA (B Cell Maturation Antigen, also known as CD269) are presented. BCMA is selectively expressed on malignant plasma cells like in multiple myeloma (MM) and hence considered an ideal target for Amanitin based ADCs.

Material and methods:

MM cell lines: NCI-H929, MM.1S Luc (stable luciferase transfected) and CCRF-CEM (BCMA negative).

Antibody: anti-BCMA Thiomab (Max Delbrück Centrum, Berlin; derivatization and production at Heidelberg Pharma).

Synthesis of HDP-101: Maleimide amanitin compounds were conjugated to substituted cysteine residues of the anti-BCMA Thiomab.

Cell proliferation assay: Quantitative determination of cytotoxicity was performed by CellTiter Glo 2.0 assay (Promega) or WST.1 assay (Roche).

Animal models: Subcutaneous and metastatic mouse xenograft tumor models with MM cell lines NCI-H929 and MM.1S Luc were performed in single-dose and multiple-dosing experiments. Tolerability was assessed in mice and nonhuman primates (NHP).

Results:

HDP-101 showed in vitro cytotoxicity on BCMA+ cell lines in picomolar range, whereas no cytotoxic activity on BCMA- cells was observed.

In mouse xenograft models, HDP-101 caused dose-dependent tumor regression and complete remission after a single i.v. dose of 2.0 mg/kg and 4.0 mg/kg in s.c. xenografts and after single i.v. doses from 0.1 mg/kg to 2.0 mg/kg in disseminating xenografts.

Safety profiling in Cynomolgus monkeys revealed a good tolerability and therapeutic index after sequentially applied doses of 0.3, 1.0, and multiple dose application of 4 x 3.0 mg/kg. Hematology and clinical chemistry parameters were unaffected except liver enzymes and LDH: A mild to moderate and transient increase was observed. The half-life of the ADC in serum was 7-9 days; the free toxin was detectable at levels close to the lower limit of quantification only (LLOQ = 1.2nM).

Conclusions:

Targeted cytotoxic drug delivery to BCMA positive MM cell lines was achieved by using HDP-101, an anti-BCMA-ATAC. The mode of action of the payload Amanitin led to an efficient anti-tumor potential in vitro and in vivo with good tolerability in NHP studies. Using ADCs in the therapy of multiple myeloma is a promising approach, especially by using a cytotoxic agent whose mode of action differs from other commonly used toxins, like ATACs. First-in-human trial is expected to start in 2018.

Citation Format: Torsten Hechler, Aniko Palfi, Christoph Müller, Christian Lutz, Andreas Pahl, Michael Kulke. Preclinical evaluation of HDP-101, an anti-BCMA antibody-drug conjugate [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 77. doi:10.1158/1538-7445.AM2017-77

Abstract 2973: CD269 - A promising target for amanitin based ADCs

Antitumor activity of monoclonal antibodies can be dramatically enhanced by conjugation to toxic small molecules. Beside the recent approval of Kadcyla (T-DM1) and Adcetris (SGN-35) more than 30 antibody-drug conjugates (ADC) have entered clinical trials, promising to strengthen the therapeutic capabilities for cancer treatment in the next decade. Surprisingly most ADCs are based on one of few toxic compounds only and on an even smaller number of toxicity mechanisms: Most antibodies are coupled to the microtubuli-targeting auristatins and maytansines. Toxins that operate through such a mechanism could suffer from limited activity in different cancer indications and in cells expressing resistance mechanisms. Accordingly the use of new drugs that function via alternative toxicity mechanisms could enhance the therapeutic potential of ADCs. Heidelberg Pharma focuses on Amanitin, the most well-known toxin of the amatoxin family. Amanitin binds to the eukaryotic RNA pol II and thereby inhibits the cellular transcription at very low concentrations.

In the current study, in vitro and in vivo Data of Amanitin-ADCs targeting CD269 (B cell maturation antigen) are presented. CD269 is expressed on cells of the B cell lineage, predominantly on plasma blasts and plasma cells. It is not expressed on naïve B cells, germinal center B cells and memory B-cells (Darce et al. (2007) J Immunol 179:7276-7286). CD269 is highly expressed on malignant plasma cells like multiple myeloma, a B cell non Hodgkin lymphoma of the bone marrow (Novak et al. (2004) Blood 103:689-94). Since multiple myeloma is a usually incurable malignancy of plasma cells, new therapies are urgently needed. Using ADCs in the cure of multiple myeloma could be a promising approach, especially by using a toxin whose mode of action was not applied before, like amanitin based ADCs.

In vitro data of anti-CD269-amanitin ADC showed cytotoxicity on CD269 positive cell lines in picomolar range, while up to micromolar concentrations, no cytotoxic activity on CD269 negative cells was observed. In mouse xenograft models, anti-CD269-amanitin showed clear anti-tumorigenic potential. A comprehensive data package will be presented.

Citation Format: Aniko Palfi, Torsten Hechler, Christoph Mueller, Andreas Pahl, Michael Kulke. CD269 - A promising target for amanitin based ADCs. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2973.

Abstract A69: A novel mechanism mediates drug resistance in the exocrine-like pancreatic ductal adenocarcinoma (PDAC) subtype

PDAC is a highly aggressive disease with dismal prognosis [1, 2]. Despite extensive research and the discovery of several drug candidates, little progress has been reported since the approval of gemcitabine and erlotinib [1]. Moreover, recent trials with targeted therapies have shown only limited or no benefit [1, 2]. For a number of other carcinomas, tumor subclasses have been uncovered that allow the use of targeted therapies. The mutational landscape of PDAC is complex and heterogeneous, raising the question whether subclasses also exist in PDAC [3]. Collisson et al. described three PDAC subtypes that were identified based on their gene-expression profiles: The classical, the quasi-mesenchymal and the exocrine-like subtype [4]. However, not all subtypes could be identified in the previously available model systems. We have established a novel patient-derived model system that allows the analysis of these three human PDAC subtypes in vitro and in vivo. Hence, we provide a systematic workflow to propagate human PDAC in orthotopic xenografts and to derive tumor-initiating primary cell lines of all three PDAC subtypes. HNF-1 and Keratin 81 were identified as markers for subtype stratification by immunohistochemistry. Application of this two-marker set on a 258 large patient cohort confirmed a predominantly non-overlapping staining and revealed a significant difference in overall survival across the three subtypes. Furthermore, a drug screen uncovered subtype-specific drug sensitivities towards a number of drugs, including gemcitabine and dasatinib. Notably, the exocrine-like subtype was resistant towards all compounds tested. Thus, we aimed to identify the underlying cause of the observed drug resistance. Molecular analysis including gene set enrichment analysis (GSEA) allowed us to identify a putative novel mechanism of drug resistance. Analysis by qRT-PCR and Western blot demonstrated the enhanced expression of several genes mediating this mechanism particularly in the exocrine-like subtype in vitro and in vivo. These findings led to the identification of a novel protein target central to this mechanism. Additionally, retrospective immunohistochemical analysis of a large patient cohort confirmed that this target is predominantly found in those patient tumors classified as exocrine-like. Hence, we hypothesized that the observed strong activation of this mechanism in the exocrine-like PDAC subtype could be responsible for the drug resistance observed in this subclass. In line with this, functional inhibition of this mechanism resulted in increased drug sensitivity in the exocrine-like subtype. Hence, our findings may ultimately advance personalized treatment by applying novel marker-based patient selection strategies in combination with tailored drug use, a strategy which will be presented in more detail at the conference.

[1] Hidalgo, M. Pancreatic cancer. The New England journal of medicine. 362, 1605-1617, doi:10.1056/NEJMra0901557 (2010).

[2] Vincent, A., Herman, J., Schulick, R., Hruban, R. H. & Goggins, M. Pancreatic cancer. Lancet. 378, 607-620, doi:10.1016/S0140-6736(10)62307-0 (2011).

[3] Jones, S. et al. Core signalling pathways in human pancreatic cancers revealed by global genomic analyses. Science. 321, 1801-1806, doi:10.1126/science.1164368 (2008).

[4] Collisson, E. A. et al. Subtypes of pancreatic ductal adenocarcinoma and their differing responses to therapy. Nature medicine. 17, 500-503, doi:10.1038/nm.2344 (2011).

Citation Format: Elisa M. Noll, Christian Eisen, Elisa Espinet, Vanessa Vogel, Corinna Klein, Albrecht Stenzinger, Franziska Zickgraf, Peter Neuhaus, Marcus Bahra, Bruno V. Sinn, Christian Lutz, Michael Kulke, Andreas Pahl, Nathalia A. Giese, Oliver Strobel, Jens Werner, Wilko Weichert, Andreas Trumpp, Martin R. Sprick. A novel mechanism mediates drug resistance in the exocrine-like pancreatic ductal adenocarcinoma (PDAC) subtype. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A69.

TP53 loss creates therapeutic vulnerability in colorectal cancer

TP53, a well-known tumour suppressor gene that encodes p53, is frequently inactivated by mutation or deletion in most human tumours. A tremendous effort has been made to restore p53 activity in cancer therapies. However, no effective p53-based therapy has been successfully translated into clinical cancer treatment owing to the complexity of p53 signalling. Here we demonstrate that genomic deletion of TP53 frequently encompasses essential neighbouring genes, rendering cancer cells with hemizygous TP53 deletion vulnerable to further suppression of such genes. POLR2A is identified as such a gene that is almost always co-deleted with TP53 in human cancers. It encodes the largest and catalytic subunit of the RNA polymerase II complex, which is specifically inhibited by α-amanitin. Our analysis of The Cancer Genome Atlas (TCGA) and Cancer Cell Line Encyclopedia (CCLE) databases reveals that POLR2A expression levels are tightly correlated with its gene copy numbers in human colorectal cancer. Suppression of POLR2A with α-amanitin or small interfering RNAs selectively inhibits the proliferation, survival and tumorigenic potential of colorectal cancer cells with hemizygous TP53 loss in a p53-independent manner. Previous clinical applications of α-amanitin have been limited owing to its liver toxicity. However, we found that α-amanitin-based antibody-drug conjugates are highly effective therapeutic agents with reduced toxicity. Here we show that low doses of α-amanitin-conjugated anti-epithelial cell adhesion molecule (EpCAM) antibody lead to complete tumour regression in mouse models of human colorectal cancer with hemizygous deletion of POLR2A. We anticipate that inhibiting POLR2A will be a new therapeutic approach for human cancers containing such common genomic alterations.

Efficacy of drugs used in the treatment of IBD and combinations thereof in acute DSS-induced colitis in mice

AIMS

Although acute dextran sodium sulphate (DSS)-induced colitis in mice is frequently used as a preclinical model for testing drugs involved in inflammatory bowel disease (IBD), only limited data is available that compares the efficacy of established drug treatments and combinations employed in IBD. We have therefore compared the efficacy of aminosalicylates (mesalazine, olsalazine), corticosteroids (budesonide), thiopurines (6-thioguanine (6-TG)) and cyclosporine A (CsA) and combinations thereof as well as the EP4 agonist AGN205203 in the acute DSS-colitis model.

MAIN METHODS

Female BALB/c mice were challenged with 4% DSS in drinking water for 7 days to induce colitis and treated daily with different drugs/combinations orally. Disease scores (diarrhoea, bleeding, disease activity index), systemic (body weight loss, serum amyloid A levels) and colonic (myeloperoxidase activity, length and histopathology) inflammation parameters were analysed.

KEY FINDINGS

Mesalazine, olsalazine (100mg/kg) and budesonide (0.5mg/kg) were only weakly active or even worsened colitis. 6-TG dose-dependently reduced systemic and colonic inflammation parameters with estimated ED50 values between 0.5-4 mg/kg. CsA (10, 25 and 50mg/kg) dose-dependently reduced colitis with high efficacy on systemic inflammation. A combination of CsA 25mg/kg+olsalazine 100mg/kg produced a more pronounced anti-inflammatory effect than the compounds given alone. AGN205203 (3, 10 and 30 mg/kg BID) was the most efficacious compound and almost completely inhibited colitis.

SIGNIFICANCE

6-TG and CsA are suitable reference compounds in the DSS mouse model. CsA+olsalazine, as a combination, was more efficacious than the compounds given alone, supporting combination treatments in IBD.

Regulation of MMP-9 by a WIN-binding site in the monocyte-macrophage system independent from cannabinoid receptors

The cannabinoid system is known to be involved in the regulation of inflammatory processes. Therefore, drugs targeting cannabinoid receptors are considered as candidates for anti-inflammatory and tissue protective therapy. We demonstrated that the prototypical cannabinoid agonist R(+)WIN55,212-2 (WIN) reduced the secretion of matrix metalloproteinase-9 (MMP-9) in a murine model of cigarette-smoke induced lung inflammation. In experiments using primary cells and cell lines of the monocyte-macrophage-system we found that binding of the cannabinoid-receptor agonist WIN to a stereo-selective, specific binding site in cells of the monocyte-macrophage-system induced a significant down-regulation of MMP-9 secretion and disturbance of intracellular processing, which subsequently down-regulated MMP-9 mRNA expression via a ERK1/2-phosphorylation-dependent pathway. Surprisingly, the anti-inflammatory effect was independent from classical cannabinoid receptors. Our experiments supposed an involvement of TRPV1, but other yet unidentified sites are also possible. We conclude that cannabinoid-induced control of MMP-9 in the monocyte-macrophage system via a cannabinoid-receptor independent pathway represents a general option for tissue protection during inflammation, such as during lung inflammation and other diseases associated with inflammatory tissue damage.

Desmoglein 3-specific T regulatory 1 cells consist of two subpopulations with differential expression of the transcription factor Foxp3

Pemphigus vulgaris (PV) is an autoimmune bullous skin disorder associated with autoantibodies against desmoglein (Dsg) 3. An imbalance of type 1 regulatory T (Tr1) cells and T helper type 2 (Th2) cells specific for Dsg3 may be critical for the loss of tolerance against Dsg3 in PV. Within the population of Dsg3-responsive, interleukin (IL)-10-secreting Tr1 cell clones, two major subpopulations were identified and sorted by fluorescence-activated cell sorting (FACS) based on their size and granularity. Upon in vitro culture, the larger subpopulation differentiated back into the two former subpopulations of the Tr1 cell clones, while the smaller subpopulation died within 2 weeks. The smaller subpopulation of the Tr1 cell clones was characterized by the expression of Foxp3, the secretion of IL-10, transforming growth factor (TGF)-beta and IL-5 upon stimulation with Dsg3, a proliferative response to IL-2 but not to Dsg3 or mitogenic stimuli, and an inhibitory effect on the proliferative response of Dsg3-responsive Th clones in a Dsg3-specific manner. In contrast, the larger subpopulation showed a Th-like phenotype, lacking Foxp3, cytotoxic T-lymphocyte antigen 4 (CTLA4) and glucocorticoid-induced tumour necrosis factor receptor (GITR) expression and IL-2 secretion, and did not mount a proliferative response to Dsg3 and mitogenic stimuli. The two Tr1 subpopulations showed expression of identical T-cell receptor (TCR) V beta chains which varied among the PV patients studied. Upon inhibition of Foxp3, the smaller Tr1 subpopulation developed a proliferate response to Dsg3 and mitogenic stimuli, no longer suppressed Dsg3-specific Th cells, lost expression of GITR and CTLA4 and secreted IL-2. Thus, our observations suggest a distinct relationship between Dsg3-specific Tr1 and Th-like cells which may be critical for the continuous generation and survival of Dsg3-specific Tr1 cells.

Cytochrome P450 2C19 681G>A polymorphism and high on-clopidogrel platelet reactivity associated with adverse 1-year clinical outcome of elective percutaneous coronary intervention with drug-eluting or bare-metal stents

OBJECTIVES

We investigated whether the loss of function CYP2C19 681G>A *2 polymorphism is associated with high (>14%) residual platelet aggregation (RPA) on clopidogrel and whether high on-clopidogrel RPA impacts clinical outcome after elective coronary stent placement.

BACKGROUND

The cytochrome P450 (CYP)-dependent conversion of clopidogrel to its active metabolite may contribute to the variability in antiplatelet effect of clopidogrel.

METHODS

The study included 797 consecutive patients undergoing percutaneous coronary intervention, who were followed-up for 1 year. Adenosine-diphosphate-induced (5 mumol/l) RPA was assessed after a 600-mg loading dose and after the first 75-mg maintenance dose of clopidogrel before discharge. CYP2C19 genotype was analyzed by real-time polymerase chain reaction.

RESULTS

Of the patients included, 552 (69.3%) were CYP2C19 wild-type homozygotes (*1/*1) and 245 (30.7%) carried at least one *2 allele. Residual platelet aggregation at baseline did not differ significantly between genotypes. On clopidogrel, RPA was significantly (p < 0.001) higher in *2 carriers than in wild-type homozygotes (23.0% [interquartile range (IQR) 8.0% to 38.0%] vs. 11.0% [IQR 3.0% to 28.0%] after loading; 11.0% [IQR 5.0% to 22.0%] vs. 7.0% [IQR 3.0% to 14.0%] at pre-discharge). Between *2 carriers and wild-type homozygotes, we found significant (p < 0.001) differences in the proportion of patients with RPA >14%, both after loading (62.4% vs. 43.4%) and at pre-discharge (41.3% vs. 22.5%). Residual platelet aggregation >14% at pre-discharge incurred a 3.0-fold increase (95% confidence interval 1.4 to 6.8; p = 0.004) in the 1-year incidence of death and myocardial infarction.

CONCLUSIONS

Patients carrying at least one CYP2C19*2 allele are more prone to high-on clopidogrel platelet reactivity, which is associated with poor clinical outcome after coronary stent placement (Effect of Clopidogrel Loading and Risk of PCI [EXCELSIOR]; NCT00457236).

Preclinical modelling using nasal epithelial cells for the evaluation of herbal extracts for the treatment of upper airway diseases

The epithelium constitutes the interface between the internal milieu and the external environment, and the nasal epithelium is the initial point of contact for respiratory viruses, airborne allergens and environmental pollutants. The major function of the nasal epithelium was regarded to be primarily that of a physical barrier, but recent studies clearly indicate that its cells are metabolically very active with the capacity to modulate a variety of inflammatory processes through the action of an array of receptor-mediated events. This review summarizes the current view of the active role of the nasal epithelium in the inflammation of the upper airways and its possible modulation by herbal extracts to treat diseases of the upper airways such as common cold and sinusitis.

Prospective use of CYP pharmacogenetics and medication analysis to facilitate improved therapy - a pilot study

OBJECTIVES

To assess the efficacy of cytochrome P450 (CYP) pharmacogenetic testing and medication interaction analysis in a controlled environment for reduction of events, stays in hospital, extra care and required extra doctors visits to the patients.

METHODS

A prospective cohort study of 28 patients in a geriatric care facility with multimedication and at least one report of an event was performed over a period of 7 months. In the first phase of the study the patients were closely monitored twice a day by the care staff, recording all potential events, regardless of association with the indication or not, requirement for extra care, requirement for an unplanned site visit from a physician and days in hospital. In a 1-month period, the patients were genotyped for the cytochromes CYP2C9, CYP2C19 and CYP2D6, and their medication analyzed for interactions, using a proprietary computer program. Recommendations for medication change based upon genetics and/or medication interaction analysis were made to the care physicians. In a second 3-month phase the patients were monitored as in Phase I. The data comparing Phase I with Phase II was analyzed using two way ANOVA.

RESULTS

Of the 28 patients in the study in both phases, 16 (55%) had genetic and/or medication interaction problems that required change of medication. A total of 11 out of 16 (69%) of the patients did have their medication altered by the care physician. Of the 11 patients, five (45%) demonstrated some betterment in the number of reported events after alteration of their medication. Of these five patients, three had improvements when their medication was altered for their genetics. A further three (one patient had improvements due to both effects) had improvements when their medication was altered after a medication interaction analysis.

CONCLUSION

Although an exploratory pilot study, this cohort study shows the possibilities and potential of pharmacogenetic testing for CYP alterations combined with medication interaction analysis of patients in a geriatric care facility.

The association of ABCB1 polymorphisms and elevated serum digitoxin concentrations in geriatric patients

OBJECTIVE

Digitoxin is a known substrate of the efflux pump P-glycoprotein (gene name: ABCB1). P-glycoprotein expression was shown to be modulated by single nucleotide polymorphisms in the ABCB1 gene, but it remains unclear whether these polymorphisms influence digitoxin blood levels. Our objective was to examine the association of ABCB1 C3435T genotype and elevated serum digitoxin concentrations (SDC) in a cohort of 77 geriatric patients consecutively admitted to a geriatric department over a 12-month period.

METHODS

The impact of ABCB1 3435 CC, CT, and TT genotypes on SDC and SDC normalized for daily digitoxin dosage and body weight was assessed by multivariate regression analysis.

RESULTS

Among participants, 18 (23%) had the CC, 36 (47%) the CT, and 23 (30%) the TT genotype. Adjusting for relevant covariates, no significant association of ABCB1 C3435T genotype and SDC or normalized SDC was detected. Mean SDC was 22.4 ng/ml (95% CI 18.9-25.9) for the TT, 21.8 ng/ml (95% CI 18.1-25.5) for the CT, and 25.7 ng/ml (95% CI 20.6-30.8) for the CC genotype. The means for normalized SDC were 5.2 kg.l(-1) (95% CI 4.3-6.1) for the TT, 6.1 kg.l(-1) (95% CI 4.7-7.5) for the CT, and 6.2 kg.l(-1) (95% CI 4.6-7.7) for the CC genotype.

CONCLUSION

In this sample of frail geriatric patients, the impact of ABCB1 C3435T genotype on serum digitoxin concentration was not of major relevance. Regular monitoring of digitoxin blood levels and surveillance of appropriate drug use remain the best ways to prevent digitoxin intoxications in the elderly.

Cytokine profiles of cord and adult blood leukocytes: differences in expression are due to differences in expression and activation of transcription factors

BACKGROUND

Stem cell transplantation as therapy for hematological disorders is often hampered by severe graft-versus-host-disease. This may be reduced by umbilical cord blood transplantation, an effect that has been attributed to qualitative differences between neonatal and adult T cells. We compared levels of secreted proteins and cytokine mRNA induced in cord blood leukocytes (CBL) and adult blood leukocytes (ABL) by various stimuli.

RESULTS

While interleukin-2 (IL-2) levels were similar in CBL and ABL, there was less induction of the Th1 cytokine interferon-gamma in CBL. Production of the Th2 cytokines IL-4, IL-5, and IL-13 and the hematopoietic cytokine IL-3 was much lower in CBL versus ABL after T-cell receptor-mediated stimulation, whereas production of GM-CSF was comparable in the 2 cell types. The lower levels of Th1 and Th2 cytokines were maintained in CBL during a 4-day time-course study, while after 12 hours IL-3 and GM-CSF reached in CBL levels similar to those in ABL. For all cytokines except IFN gamma, the IC50 values for inhibition by cyclosporin A were similar in ABL and CBL. In contrast, there was less expression and activation of transcription factors in CBL. Activation of NF-kappaB by TPA/ionomycin was detected in ABL but not CBL. Furthermore, there was less expression of the Th subset-specific transcription factors T-bet and c-maf in CBL versus ABL, whereas GATA-3 expression was similar. Expression of T-bet and c-maf correlated with expression of the Th1 and Th2 cytokines, respectively. Time course experiments revealed that T-bet expression was stimulated in both cell types, whereas c-maf and GATA-3 were induced only in ABL.

CONCLUSION

The diminished capability of CBL to synthesize cytokines is probably due to decreased activation of NF-kappaB, whereas differences in Th subsets are due to differences in regulation of Th lineage-specific transcriptions factors. We propose that the reduced incidence and severity of GvHD after allogeneic transplantation of umbilical CB cells is due to lesser activation of specific transcription factors and a subsequent reduction in production of certain cytokines.

MDR1 genotype-dependent regulation of the aldosterone system in humans

OBJECTIVE

Aldosterone plays a major role in the development of both hypertension and heart failure. As aldosterone is a substrate of the ABCB1 (P-glycoprotein) efflux transporter, whose expression and activity has been shown to be linked to the ABCB1 3435C-->T polymorphism, we tested the impact of the ABCB1 3435C-->T polymorphism on aldosterone disposition, blood pressure, cardiac structure, and kidney function.

METHODS

A homogenous group of 116 young, white male Caucasian individuals with normal or mildlyto moderately elevated, but never treated blood pressure was included. Blood pressure was compared between individuals with ABCB1 3435 CC, CT, and TT genotypes. Moreover, genotype-dependent differences in basal and angiotensin II-stimulated serum aldosterone, cardiac structure, and kidney function were evaluated.

RESULTS

Of the 116 volunteers, 35 had the CC, 51 the CT and 30 the TT genotype. At baseline, no significant genotype-dependent differences in serum aldosterone were observed. After infusion of angiotensin II, the increase in aldosterone serum concentration was significantly higher in the TT group than that in the CT and CC groups (CC +11+/-35, CT +18+/-48, TT +45+/-50 pg/ml, P=0.012). Systolic and diastolic blood pressure, left ventricular structure, and function and baseline renal function were not significantly different. After additional oral sodium load (5 g/day over 1 week) urinary sodium excretion was found to be increased in individuals with the CC or CT genotype only but not in those with the TT genotype (CC +71+/-83, CT +52+/-114, TT -11+/-98 mmol/day, P=0.005).

CONCLUSION

The present study demonstrates that the ABCB1 3435 genotype affects angiotensin II-stimulated serum aldosterone levels and salt-stimulated urinary sodium excretion. Although blood pressure and cardiac structure were unchanged in this young study population, our findings indicate a new link between MDR1 genotype and the aldosterone system in humans.

Pharmacogenomics of asthma

Patient response to asthma therapy is consistently observed to be heterogeneous. Pharmacogenomics is the study of inherited differences in interindividual drug disposition and effects, with the goal of selecting the optimal drug therapy and dosage for each patient. This review will cover selected examples of gene polymorphisms that influence the outcome of asthma therapy, and whole-genome expression studies using microarray technology that have shown tremendous potential for benefiting asthma pharmacogenomics. The utility of the mouse as an experimental system for pharmacogenomic discovery will also be discussed in the context of asthma therapy.

Lipopolysaccharide-induced lung inflammation is inhibited by neutralization of GM-CSF

Granulocyte-macrophage colony-stimulating factor (GM-CSF) plays an important role in the pathogenesis of acute and chronic lung disease as a major regulator governing the functions of granulocyte and macrophage lineage populations. Chronic obstructive pulmonary disease (COPD) is a disease characterized by lung inflammation with accumulation of neutrophils and increased levels of pro-inflammatory cytokines including GM-CSF in the patient's lungs. We used intranasal administration of lipopolysaccharide (LPS) to mice to induce a disease that resembles COPD with pulmonary inflammation, neutrophil recruitment and release of pro-inflammatory mediators in the bronchoalveolar lavage fluid of the diseased mice. 2 h prior to LPS administration, mice were systemically treated with the murine GM-CSF neutralizing antibody mAb 22E9 per intraperitoneal injection. Intranasal challenge with LPS-induced an increase of total cell number and of neutrophils in the bronchoalveolar lavage fluid. Elevated levels of tumor necrosis factor alpha (TNF-alpha), keratinocyte cytokine and macrophage inflammatory protein-2 (MIP-2) were also observed at this time point. GM-CSF was no longer detectable in bronchoalveolar lavage fluid at 24 h due to its early expression with a peak reached 6 h after LPS challenge. Pretreatment of mice with GM-CSF neutralizing antibody dose-dependently inhibited the accumulation of neutrophils and reduced TNF-alpha and MIP-2 protein levels in bronchoalveolar lavage fluid. These data suggest that neutralization of GM-CSF may represent a novel treatment modality for lung inflammation and in particular for COPD.

Are there any realistic chances to develop new drugs for asthma?

Asthma bronchiale, an inflammatory airway disease, imposes a significant health care problem worldwide. It is characterized by three critical phenotypic traits: intermittent and reversible bronchoconstriction, bronchial hyperresponsiveness and airway inflammation. Conventional therapy basically consists of beta(2)-adrenoceptor agonists in combination with glucocorticoids. Nevertheless, there is an urgent need for novel therapies, both for patients with uncontrollable disease symptoms and for those suffering from glucocorticoid-insensitive asthma. Monotherapy seems to be relatively ineffective against this complex and multifaceted disease, which is evident by the variety of disappointing treatment strategies. Thus, we should instead concentrate on multiple target strategies, such as novel and more potent glucocorticoids or phosphodiesterase type 4 (PDE4) inhibitors with isozyme selectivity. In addition, an examination of the application method should not be neglected, with emphasis on inhalative approaches. To summarize, research into asthma's pathophysiology is of critical importance, concentrating on human-relevant targets and conducting preliminary studies. With these imperatives in mind, we can hope to better manage this multifactor disease in the near future.

Synergistic effects of the anti-cholinergic R,R-glycopyrrolate with anti-inflammatory drugs

Currently, much effort is geared towards developing therapies that impact on the inflammation in respiratory diseases such as asthma and COPD, assuming that this will improve disease pathology. R,R-Glycopyrrolate, a quaternary ammonium compound, is a muscarinic receptor antagonist with the potential to be used as a long-acting bronchodilator in patients with asthma and COPD. In this study we evaluated whether the combination of R,R-glycopyrrolate with known anti-inflammatory drugs results in synergistic effects. Human primary monocytes were used as an in vitro model system. M3, M4, M1 and M2 receptors were expressed in these cells in descending order. The combinatory effects of the drugs on the release of TNF-alpha after lipopolysaccharide stimulation were analyzed. R,R-Glycopyrrolate alone did not affect LPS induced TNF-alpha release. The PDE4 inhibitor rolipram dose dependently inhibited the TNF-alpha release. Maximum inhibition was around 70%. The IC(35) for rolipram was 68.9+/-15.2 nM. The simultaneous administration of 10 microM R,R-glycopyrrolate reduced the IC(35) to 1.70+/-1.18 nM. The anti-histamine azelastine inhibited TNF-alpha release dose dependently. The simultaneous administration of R,R-glycopyrrolate did not influence the action of azelastine. The corticosteroid budesonide inhibited the TNF-alpha release dose dependently with an IC(50) of 0.55+/-0.13 nM. The simultaneous administration of 10 microM R,R-glycopyrrolate reduced the IC(50) to 0.13+/-0.03 nM. Finally, R,R-glycopyrrolate was most effective in the triple combination with budesonide and rolipram in the reduction of TNF-alpha release. In conclusion, R,R-glycopyrrolate acts synergistically with the PDE4 inhibitor rolipram and the steroid budesonide in inhibiting inflammatory mediators.