TGF-β1 potentiates Vγ9Vδ2 T cell adoptive immunotherapy of cancer

Despite its role in cancer surveillance, adoptive immunotherapy using γδ T cells has achieved limited efficacy. To enhance trafficking to bone marrow, circulating Vγ9Vδ2 T cells are expanded in serum-free medium containing TGF-β1 and IL-2 (γδ[T2] cells) or medium containing IL-2 alone (γδ[2] cells, as the control). Unexpectedly, the yield and viability of γδ[T2] cells are also increased by TGF-β1, when compared to γδ[2] controls. γδ[T2] cells are less differentiated and yet display increased cytolytic activity, cytokine release, and antitumor activity in several leukemic and solid tumor models. Efficacy is further enhanced by cancer cell sensitization using aminobisphosphonates or Ara-C. A number of contributory effects of TGF-β are described, including prostaglandin E2 receptor downmodulation, TGF-β insensitivity, and upregulated integrin activity. Biological relevance is supported by the identification of a favorable γδ[T2] signature in acute myeloid leukemia (AML). Given their enhanced therapeutic activity and compatibility with allogeneic use, γδ[T2] cells warrant evaluation in cancer immunotherapy.

Neuropeptide S receptor 1 is a nonhormonal treatment target in endometriosis

Endometriosis is a common chronic inflammatory condition causing pelvic pain and infertility in women, with limited treatment options and 50% heritability. We leveraged genetic analyses in two species with spontaneous endometriosis, humans and the rhesus macaque, to uncover treatment targets. We sequenced DNA from 32 human families contributing to a genetic linkage signal on chromosome 7p13-15 and observed significant overrepresentation of predicted deleterious low-frequency coding variants in NPSR1, the gene encoding neuropeptide S receptor 1, in cases (predominantly stage III/IV) versus controls (P = 7.8 × 10^-4). Significant linkage to the region orthologous to human 7p13-15 was replicated in a pedigree of 849 rhesus macaques (P = 0.0095). Targeted association analyses in 3194 surgically confirmed, unrelated cases and 7060 controls revealed that a common insertion/deletion variant, rs142885915, was significantly associated with stage III/IV endometriosis (P = 5.2 × 10^-5; odds ratio, 1.23; 95% CI, 1.09 to 1.39). Immunohistochemistry, qRT-PCR, and flow cytometry experiments demonstrated that NPSR1 was expressed in glandular epithelium from eutopic and ectopic endometrium, and on monocytes in peritoneal fluid. The NPSR1 inhibitor SHA 68R blocked NPSR1-mediated signaling, proinflammatory TNF-α release, and monocyte chemotaxis in vitro (P < 0.01), and led to a significant reduction of inflammatory cell infiltrate and abdominal pain (P < 0.05) in a mouse model of peritoneal inflammation as well as in a mouse model of endometriosis. We conclude that the NPSR1/NPS system is a genetically validated, nonhormonal target for the treatment of endometriosis with likely increased relevance to stage III/IV disease.

Lethal Poisoning of Cancer Cells by Respiratory Chain Inhibition plus Dimethyl α-Ketoglutarate

Inhibition of oxidative phosphorylation (OXPHOS) by 1-cyclopropyl-4-(4-[(5-methyl-3-(3-[4-(trifluoromethoxy)phenyl]-1,2,4-oxadiazol-5-yl)-1H-pyrazol-1-yl)methyl]pyridin-2-yl)piperazine (BAY87-2243, abbreviated as B87), a complex I inhibitor, fails to kill human cancer cells in vitro. Driven by this consideration, we attempted to identify agents that engage in synthetically lethal interactions with B87. Here, we report that dimethyl α-ketoglutarate (DMKG), a cell-permeable precursor of α-ketoglutarate that lacks toxicity on its own, kills cancer cells when combined with B87 or other inhibitors of OXPHOS. DMKG improved the antineoplastic effect of B87, both in vitro and in vivo. This combination caused MDM2-dependent, tumor suppressor protein p53 (TP53)-independent transcriptional reprogramming and alternative exon usage affecting multiple glycolytic enzymes, completely blocking glycolysis. Simultaneous inhibition of OXPHOS and glycolysis provoked a bioenergetic catastrophe culminating in the activation of a cell death program that involved disruption of the mitochondrial network and activation of PARP1, AIFM1, and APEX1. These results unveil a metabolic liability of human cancer cells that may be harnessed for the development of therapeutic regimens.

Mass cytometry analysis reveals a distinct immune environment in peritoneal fluid in endometriosis: a characterisation study

BACKGROUND

Endometriosis is a gynaecological condition characterised by immune cell infiltration and distinct inflammatory signatures found in the peritoneal cavity. In this study, we aim to characterise the immune microenvironment in samples isolated from the peritoneal cavity in patients with endometriosis.

METHODS

We applied mass cytometry (CyTOF), a recently developed multiparameter single-cell technique, in order to characterise and quantify the immune cells found in peritoneal fluid and peripheral blood from endometriosis and control patients.

RESULTS

Our results demonstrate the presence of more than 40 different distinct immune cell types within the peritoneal cavity. This suggests that there is a complex and highly heterogeneous inflammatory microenvironment underpinning the pathology of endometriosis. Stratification by clinical disease stages reveals a dynamic spectrum of cell signatures suggesting that adaptations in the inflammatory system occur due to the severity of the disease. Notably, among the inflammatory microenvironment in peritoneal fluid (PF), the presence of CD69⁺ T cell subsets is increased in endometriosis when compared to control patient samples. On these CD69⁺ cells, the expression of markers associated with T cell function are reduced in PF samples compared to blood. Comparisons between CD69⁺ and CD69^- populations reveal distinct phenotypes across peritoneal T cell lineages. Taken together, our results suggest that both the innate and the adaptive immune system play roles in endometriosis.

CONCLUSIONS

This study provides a systematic characterisation of the specific immune environment in the peritoneal cavity and identifies cell immune signatures associated with endometriosis. Overall, our results provide novel insights into the specific cell phenotypes governing inflammation in patients with endometriosis. This prospective study offers a useful resource for understanding disease pathology and opportunities for identifying therapeutic targets.

Abstract 2182: Preclincial in vitro and in vivo combination therapies for mutant IDH1R132 tumors with BAY 1436032

Background: Isocitrate dehydrogenase (IDH) mutations are drivers of different tumors. The IDH1R132 mutation is frequently found in glioma (80%), chondrosarcoma (CS, 45%), intrahepatic cholangiocarcinoma (ICC, 20%), acute myeloid leukemia (AML, 7%), and with low incidences in other solid tumors. Although clinical therapies of mutant IDH inhibition were recently approved for the treatment of AML, few patients benefit from a single therapy with a mutant IDH inhibitor and most of them relapse. Here we report preclinical in vitro and in vivo data on combination therapies of the mIDH1R132 inhibitor BAY 1436032 with standard of care chemotherapies.

Methods: in vitro: The sarcoma cell line HT1080 (IDH1R132C), together with two IDH1 wildtype sarcoma cell lines, the SW1353 (IDH2R172S) and SW872 (IDHwt) cell lines, were treated with BAY 1436032 alone and in combination with different standard of care drugs. in vivo: The patient derived xenograft (PDX) ICC model LIXFC2084 (IDH1R132L), the melanoma PDX model MEXF1341 (IDH1R132C) (MEXF1341), the PDX AML model 13PB020 (IDH1R132C) and a sarcoma cell line derived xenograft model HT1080 (IDH1R132C) were included. All models were treated with BAY 1436032 alone and in combination with different standard of care (SOC) drugs.

Results: The in vitro treatment with BAY 1436032 unexpectedly increased growth in HT1080 (IDH1R132C) cells with no effect to the control cell lines SW1353 and SW872. In contrast, in vivo, combination of BAY1436032 with everolimus had additive anti-tumor efficacy and was synergistic with cisplatin or the MEK inhibitor refametinib in the treatment of HT1080 xenografts. The combination of BAY 1436032 and refametinib was also additive in the treatment of a melanoma xenograft with IDH1R132C mutation. Another additive efficacy of BAY 1436032 and gemcitabine or cisplatin could be observed in an ICC xenograft model and further in the combination with everolimus in the same model. The combination of BAY 1436032 together with azacitidine in a PDX AML model was also synergistic.

Conclusion: These results highlight the combinatorial potential of the mIDH1R132 inhibitor BAY 1436032 with standard of care therapy and the importance of microenvironmental factors, which has to be taken into account when dealing with mutant IDH tumors.

Citation Format: Stefan Kaulfuss, Julia Zaman, Anuhar Chaturvedi, Holger Hess-Stumpp, Jennifer Höde, Ricarda Biber, Renan Borowicz, Michael Heuser, Andreas von Deimling, Stefan Pusch. Preclincial in vitro and in vivo combination therapies for mutant IDH1R132 tumors with BAY 1436032 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2182.

Rogaratinib: A potent and selective pan-FGFR inhibitor with broad antitumor activity in FGFR-overexpressing preclinical cancer models

Aberrant activation in fibroblast growth factor signaling has been implicated in the development of various cancers, including squamous cell lung cancer, squamous cell head and neck carcinoma, colorectal and bladder cancer. Thus, fibroblast growth factor receptors (FGFRs) present promising targets for novel cancer therapeutics. Here, we evaluated the activity of a novel pan‐FGFR inhibitor, rogaratinib, in biochemical, cellular and in vivo efficacy studies in a variety of preclinical cancer models. In vitro kinase activity assays demonstrate that rogaratinib potently and selectively inhibits the activity of FGFRs 1, 2, 3 and 4. In line with this, rogaratinib reduced proliferation in FGFR‐addicted cancer cell lines of various cancer types including lung, breast, colon and bladder cancer. FGFR and ERK phosphorylation interruption by rogaratinib treatment in several FGFR‐amplified cell lines suggests that the anti‐proliferative effects are mediated by FGFR/ERK pathway inhibition. Furthermore, rogaratinib exhibited strong in vivo efficacy in several cell line‐ and patient‐derived xenograft models characterized by FGFR overexpression. The observed efficacy of rogaratinib strongly correlated with FGFR mRNA expression levels. These promising results warrant further development of rogaratinib and clinical trials are currently ongoing (ClinicalTrials.gov Identifiers: NCT01976741, NCT03410693, NCT03473756).

What's new?

Deregulated fibroblast growth factor receptor (FGFR) signaling is involved in tumorigenesis and cancer progression. Here, the authors report on a novel pan‐FGFR inhibitor, rogaratinib, that potently and highly selectively prevents the activity of FGFRs 1, 2, 3, and 4. Rogaratinib inhibits cell proliferation in various FGFR‐addicted cancers in vitro, including colon, lung, and bladder cancer. Rogaratinib also exhibits strong in vivo efficacy in several cell line‐ and patient‐derived xenograft models characterized by FGFR mRNA overexpression with good tolerability. Altogether, these data warrant the further development of rogaratinib for treatment of cancers with FGFR alterations, and clinical trials are currently ongoing.

Suppression of antitumor T cell immunity by the oncometabolite (R)-2-hydroxyglutarate

The oncometabolite (R)-2-hydroxyglutarate (R-2-HG) produced by isocitrate dehydrogenase (IDH) mutations promotes gliomagenesis via DNA and histone methylation. Here, we identify an additional activity of R-2-HG: tumor cell-derived R-2-HG is taken up by T cells where it induces a perturbation of nuclear factor of activated T cells transcriptional activity and polyamine biosynthesis, resulting in suppression of T cell activity. IDH1-mutant gliomas display reduced T cell abundance and altered calcium signaling. Antitumor immunity to experimental syngeneic IDH1-mutant tumors induced by IDH1-specific vaccine or checkpoint inhibition is improved by inhibition of the neomorphic enzymatic function of mutant IDH1. These data attribute a novel, non-tumor cell-autonomous role to an oncometabolite in shaping the tumor immune microenvironment.

Acetyl-CoA Carboxylase 1-Dependent Protein Acetylation Controls Breast Cancer Metastasis and Recurrence

Breast tumor recurrence and metastasis represent the main causes of cancer-related death in women, and treatments are still lacking. Here, we define the lipogenic enzyme acetyl-CoA carboxylase (ACC) 1 as a key player in breast cancer metastasis. ACC1 phosphorylation was increased in invading cells both in murine and human breast cancer, serving as a point of convergence for leptin and transforming growth factor (TGF) β signaling. ACC1 phosphorylation was mediated by TGFβ-activated kinase (TAK) 1, and ACC1 inhibition was indispensable for the elevation of cellular acetyl-CoA, the subsequent increase in Smad2 transcription factor acetylation and activation, and ultimately epithelial-mesenchymal transition and metastasis induction. ACC1 deficiency worsened tumor recurrence upon primary tumor resection in mice, and ACC1 phosphorylation levels correlated with metastatic potential in breast and lung cancer patients. Given the demonstrated effectiveness of anti-leptin receptor antibody treatment in halting ACC1-dependent tumor invasiveness, our work defines a "metabolocentric" approach in metastatic breast cancer therapy.

Pan-mutant IDH1 inhibitor BAY 1436032 for effective treatment of IDH1 mutant astrocytoma in vivo

Mutations in codon 132 of isocitrate dehydrogenase (IDH) 1 are frequent in diffuse glioma, acute myeloid leukemia, chondrosarcoma and intrahepatic cholangiocarcinoma. These mutations result in a neomorphic enzyme specificity which leads to a dramatic increase of intracellular D-2-hydroxyglutarate (2-HG) in tumor cells. Therefore, mutant IDH1 protein is a highly attractive target for inhibitory drugs. Here, we describe the development and properties of BAY 1436032, a pan-inhibitor of IDH1 protein with different codon 132 mutations. BAY 1436032 strongly reduces 2-HG levels in cells carrying IDH1-R132H, -R132C, -R132G, -R132S and -R132L mutations. Cells not carrying IDH mutations were unaffected. BAY 1436032 did not exhibit toxicity in vitro or in vivo. The pharmacokinetic properties of BAY 1436032 allow for oral administration. In two independent experiments, BAY 1436032 has been shown to significantly prolong survival of mice intracerebrally transplanted with human astrocytoma carrying the IDH1R132H mutation. In conclusion, we developed a pan-inhibitor targeting tumors with different IDH1R132 mutations.

The branched-chain amino acid transaminase 1 sustains growth of antiestrogen-resistant and ERα-negative breast cancer

Antiestrogen-resistant and triple-negative breast tumors pose a serious clinical challenge because of limited treatment options. We assessed global gene expression changes in antiestrogen-sensitive compared with antiestrogen-resistant (two tamoxifen resistant and two fulvestrant resistant) MCF-7 breast cancer cell lines. The branched-chain amino acid transaminase 1 (BCAT1), which catalyzes the first step in the breakdown of branched-chain amino acids, was among the most upregulated transcripts in antiestrogen-resistant cells. Elevated BCAT1 expression was confirmed in relapsed tamoxifen-resistant breast tumor specimens. High intratumoral BCAT1 levels were associated with a reduced relapse-free survival in adjuvant tamoxifen-treated patients and overall survival in unselected patients. On a tissue microarray (n=1421), BCAT1 expression was detectable in 58% of unselected primary breast carcinomas and linked to a higher Ki-67 proliferation index, as well as histological grade. Interestingly, BCAT1 was predominantly expressed in estrogen receptor-α-negative/human epidermal growth factor receptor-2-positive (ERα-negative/HER-2-positive) and triple-negative breast cancers in independent patient cohorts. The inverse relationship between BCAT1 and ERα was corroborated in various breast cancer cell lines and pharmacological long-term depletion of ERα induced BCAT1 expression in vitro. Mechanistically, BCAT1 indirectly controlled expression of the cell cycle inhibitor p27^Kip1 thereby affecting pRB. Correspondingly, phenotypic analyses using a lentiviral-mediated BCAT1 short hairpin RNA knockdown revealed that BCAT1 sustains proliferation in addition to migration and invasion and that its overexpression enhanced the capacity of antiestrogen-sensitive cells to grow in the presence of antiestrogens. Importantly, silencing of BCAT1 in an orthotopic triple-negative xenograft model resulted in a massive reduction of tumor volume in vivo, supporting our findings that BCAT1 is necessary for the growth of hormone-independent breast tumors.

SIAH ubiquitin ligases regulate breast cancer cell migration and invasion independent of the oxygen status

Seven-in-absentia homolog (SIAH) proteins are evolutionary conserved RING type E3 ubiquitin ligases responsible for the degradation of key molecules regulating DNA damage response, hypoxic adaptation, apoptosis, angiogenesis, and cell proliferation. Many studies suggest a tumorigenic role for SIAH2. In breast cancer patients SIAH2 expression levels correlate with cancer aggressiveness and overall patient survival. In addition, SIAH inhibition reduced metastasis in melanoma. The role of SIAH1 in breast cancer is still ambiguous; both tumorigenic and tumor suppressive functions have been reported. Other studies categorized SIAH ligases as either pro- or antimigratory, while the significance for metastasis is largely unknown. Here, we re-evaluated the effects of SIAH1 and SIAH2 depletion in breast cancer cell lines, focusing on migration and invasion. We successfully knocked down SIAH1 and SIAH2 in several breast cancer cell lines. In luminal type MCF7 cells, this led to stabilization of the SIAH substrate Prolyl Hydroxylase Domain protein 3 (PHD3) and reduced Hypoxia-Inducible Factor 1α (HIF1α) protein levels. Both the knockdown of SIAH1 or SIAH2 led to increased apoptosis and reduced proliferation, with comparable effects. These results point to a tumor promoting role for SIAH1 in breast cancer similar to SIAH2. In addition, depletion of SIAH1 or SIAH2 also led to decreased cell migration and invasion in breast cancer cells. SIAH knockdown also controlled microtubule dynamics by markedly decreasing the protein levels of stathmin, most likely via p27(Kip1). Collectively, these results suggest that both SIAH ligases promote a migratory cancer cell phenotype and could contribute to metastasis in breast cancer.

BAY 87-2243, a highly potent and selective inhibitor of hypoxia-induced gene activation has antitumor activities by inhibition of mitochondrial complex I

The activation of the transcription factor hypoxia-inducible factor-1 (HIF-1) plays an essential role in tumor development, tumor progression, and resistance to chemo- and radiotherapy. In order to identify compounds targeting the HIF pathway, a small molecule library was screened using a luciferase-driven HIF-1 reporter cell line under hypoxia. The high-throughput screening led to the identification of a class of aminoalkyl-substituted compounds that inhibited hypoxia-induced HIF-1 target gene expression in human lung cancer cell lines at low nanomolar concentrations. Lead structure BAY 87-2243 was found to inhibit HIF-1α and HIF-2α protein accumulation under hypoxic conditions in non-small cell lung cancer (NSCLC) cell line H460 but had no effect on HIF-1α protein levels induced by the hypoxia mimetics desferrioxamine or cobalt chloride. BAY 87-2243 had no effect on HIF target gene expression levels in RCC4 cells lacking Von Hippel–Lindau (VHL) activity nor did the compound affect the activity of HIF prolyl hydroxylase-2. Antitumor activity of BAY 87-2243, suppression of HIF-1α protein levels, and reduction of HIF-1 target gene expression in vivo were demonstrated in a H460 xenograft model. BAY 87-2243 did not inhibit cell proliferation under standard conditions. However under glucose depletion, a condition favoring mitochondrial ATP generation as energy source, BAY 87-2243 inhibited cell proliferation in the nanomolar range. Further experiments revealed that BAY 87-2243 inhibits mitochondrial complex I activity but has no effect on complex III activity. Interference with mitochondrial function to reduce hypoxia-induced HIF-1 activity in tumors might be an interesting therapeutic approach to overcome chemo- and radiotherapy-resistance of hypoxic tumors.

Abstract 4953: Stromal endosialin modulates the proinflammatory tumor microenvironment and is crucial for the growth of orthotopic pancreatic tumors

Endosialin (CD248), a transmembrane protein expressed in stromal fibroblasts and activated pericytes during embryonic development, is expressed in human carcinomas. Although its function is unknown, due to its highly specific expression pattern endosialin represents a promising anti-tumor target. To unravel the role of endosialin during tumor progression and metastasis, we employed systematic loss-of-function approaches in stromal fibroblasts in vitro as well as in subcutaneous and orthotopic tumors in vivo. These experiments revealed an important role of endosialin in regulating fibroblast proliferation and in orchestrating an inflammatory response by modulating the secretion of inflammatory cytokines (IL6) in stromal fibroblasts. The proinflammatory environment created by activated fibroblasts is thought to support tumor growth and metastasis in vivo. Experiments in endosialin-deficient mice confirmed an important role of endosialin in tumor progression in highly stroma-recruiting orthotopic pancreatic tumor models. Finally, lung metastases were dramatically decreased in endosialin-deficient mice supporting a role of a proinflammatory tumor stroma in tumor dissemination. Taken together, our experiments identify endosialin as an important modulator of stromal responses that are crucial for tumor progression and metastasis. Endosialin may therefore represent a novel target for development of anticancer therapies for solid tumors.

Citation Format: Sven Christian, Vijaysahankar Sivanandam, Michael Strerath, Heiner Apeler, Holger Hess-Stumpp, Hellmut G. Augustin. Stromal endosialin modulates the proinflammatory tumor microenvironment and is crucial for the growth of orthotopic pancreatic tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4953. doi:10.1158/1538-7445.AM2013-4953

Abstract 4509: BAY 87-2243 targets hypoxia-induced activation and stabilization of HIF-1α: A novel approach to overcome resistance mechanisms in cancer therapy

The development of resistance against radio- or chemotherapy is one of the main causes for relapse after treatment and ultimately cancer progression. Local hypoxia within tumors is associated with radio- and chemoresistance as well as aggressive tumor growth and invasion (Vaupel et al., 2004). The transcription factor HIF-1α (hypoxia-inducible factor) is stabilized under low oxygen tension and heterodimerizes with HIF-1ß to regulate the expression of a plethora of genes involved in cellular energy metabolism, neoangiogenesis, anti-apoptotic and pro-proliferative mechanisms promoting tumor progression and metastasis (Calzada et al. 2007). Because hypoxia-induced upregulation of HIF-1α appears to be of pivotal importance in tumor resistance mechanisms during cancer treatment, we screened for inhibitors of hypoxia-induced HIF-1 activation.

A HCT116 cell line containing 4X-hypoxia response element-luciferase reporter was used in high-throughput screening of small molecule inhibitors under hypoxic condition (1% O2). Lead optimization resulted in the identification of BAY 87-2243, a highly selective and potent inhibitor of hypoxia-induced HIF-1α stabilization and activation. In vitro characterization showed that BAY 87-2243 specifically suppressed HIF-1 regulated target genes as assayed by qPCR. Analyses addressing the mode of action revealed that BAY 87-2243 acts upstream of VHL and PHD because the compound did not suppress HIF-1α protein stabilization and HIF target gene expression either in the presence of a PHD inhibitor in H460 cells or in VHL-null RCC4 cells. In preclinical animal models, BAY 87-2243 dosed orally was well tolerated at therapeutic doses up to 15 mg/kg and showed moderate to high anti-tumor growth inhibitory activity as monotherapy in various subcutaneous and orthotopic xenograft models. Analysis of tumor samples demonstrated a decrease of nuclear HIF-1α protein level by immunohistochemistry as well as a specific suppression of HIF-1 target genes. These data indicate that specific inhibition of hypoxia-induced HIF-1 activation is achievable with small molecule inhibitors and is a novel approach to cancer therapy.

Vaupel P, Mayer A, Hockel M (2004) Tumor hypoxia and malignant progression. Methods Enzymol 381:335-354

M. J. Calzada, L. del Peso, Hypoxia inducible factors and cancer. Clin. Transl. Oncol. 2007, 9(5), 278-289:

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4509. doi:10.1158/1538-7445.AM2011-4509

Efficacy of MS-275, a selective inhibitor of class I histone deacetylases, in human colon cancer models

N-(2-aminophenyl)-4-[N-(pyridine-3yl-methoxy-carbonyl) aminomethyl] benzamide (MS-275) is a second generation histone deacetylase (HDAC) inhibitor with significant anti-tumor efficacy currently in clinical development. We investigated the effect of MS-275 treatment on various colon cancer cell lines, as well as on mouse xenograft models derived from human colorectal cancer. MS-275 exerted strong anti-proliferative effects in five cell lines and increased the acetylation of histones 3 and 4. In vivo testing of the compound in eight different models of human colon cancer derived from primary colorectal cancers or from established cell lines revealed that five models were responders, two non-responders and one an anti-responder. Gene expression profiles were determined in order to identify genes and pathways differentially regulated upon MS-275 treatment in responder versus non-responder models. Principle component analysis revealed a correlation of the anti-tumor efficacy with the sub-clustering of the MS-275 treatment groups in 7 out of 8 models. Although the overall gene expression pattern was rather unique for each individual model, 129 genes were significantly up- and 58 genes significantly down-regulated in at least 2 out of 5 responder models in response to MS-275 treatment. We identified potential biomarkers for response to MS-275, such as PRA1, MYADM and PALM2-AKAP2 which were up-regulated in all responder models and down-regulated or unchanged in all non-responder models. Our results provide a starting point for the development of clinically relevant biomarkers for predicting a response to MS-275 and the understanding of the mode of action of this HDAC inhibitor.

Sagopilone crosses the blood-brain barrier in vivo to inhibit brain tumor growth and metastases

The aim of this study was to determine the efficacy of sagopilone (ZK-EPO), a novel epothilone, compared with other anticancer agents in orthotopic models of human primary and secondary brain tumors. Autoradiography and pharmacokinetic analyses were performed on rats and mice to determine passage across the blood-brain barrier and organ distribution of sagopilone. Mice bearing intracerebral human tumors (U373 or U87 glioblastoma, MDA-MB-435 melanoma, or patient-derived non-small-cell lung cancer [NSCLC]) were treated with sagopilone 5-10 mg/kg, paclitaxel 8-12.5 mg/kg (or temozolomide, 100 mg/kg) or control (vehicle only). Tumor volume was measured to assess antitumor activity. Sagopilone crossed the blood-brain barrier in both rat and mouse models, leading to therapeutically relevant concentrations in the brain with a long half-life. Sagopilone exhibited significant antitumor activity in both the U373 and U87 models of human glioblastoma, while paclitaxel showed a limited effect in the U373 model. Sagopilone significantly inhibited the growth of tumors from CNS metastasis models (MDA-MB-435 melanoma and patient-derived Lu7187 and Lu7466 NSCLC) implanted in the brains of nude mice, in contrast to paclitaxel or temozolomide. Sagopilone has free access to the brain. Sagopilone demonstrated significant antitumor activity in orthotopic models of both glioblastoma and CNS metastases compared with paclitaxel or temozolomide, underlining the value of further research evaluating sagopilone in the treatment of brain tumors. Sagopilone is currently being investigated in a broad phase II clinical trial program, including patients with glioblastoma, NSCLC, breast cancer, and melanoma.

MS-275, a potent orally available inhibitor of histone deacetylases--the development of an anticancer agent

In the last few years it was found that beside genetic aberrations, epigenetic changes also play an important role in tumorigenesis. Acetylation and deacetylation of histones have been found to contribute to a significant extent to epigenetic regulation of gene expression. Analyses of various tumor models and patient samples revealed that the enzyme class of histone deacetylases is associated with many types of cancer and that, for example, over-expression of these enzymes leads to a disturbed balance between acetylation and deacetylation of histones, resulting in differences in the gene expression patterns between normal and cancer cells. Consequently, this class of enzymes has been considered as a potential target for cancer therapy. Numerous inhibitors have been identified and several are in clinical development. Although, with SAHA, one inhibitor has been approved by the FDA for a tumor indication, many open questions remain regarding the mode of action of these inhibitors. In this review, various aspects of preclinical and clinical research of the HDAC inhibitor MS-275 are described, to provide insight into the development of such a compound.

Chronic progesterone antagonist-estradiol therapy suppresses breakthrough bleeding and endometrial proliferation in a menopausal macaque model

BACKGROUND

Clinicians routinely prescribe progestins along with estrogens during menopausal hormone therapy (HT) to block estrogen-dependent endometrial proliferation. Breakthrough bleeding (BTB) can negate the utility of this treatment. Because progestin antagonists also inhibit estrogen-dependent endometrial proliferation in women and macaques, we used a menopausal macaque model to determine whether a potent progestin antagonist (ZK 230 211, Schering AG; ZK) combined with estrogen would provide a novel mode of HT.

METHOD

Ovariectomized rhesus macaques were treated for 5 months with either estradiol (E(2)) alone, E(2) + progesterone (two doses) or E(2) + ZK (0.01, 0.05 or 0.25 mg/kg).

RESULTS

In the E(2) + progesterone groups, progesterone suppressed endometrial proliferation and induced a thick decidualized endometrium. In the E(2) + ZK 230 211 groups, all doses of ZK blocked endometrial proliferation and induced endometrial atrophy. In all ZK-treated groups, the atrophied endometrium contained some dilated glands lined by an inactive, flattened, non-mitotic epithelium. BTB was much lower in the E(2) + ZK groups (17 days of spotting, all groups) than in the E(2) and E(2) + progesterone groups (155 bleeding days, all groups). ZK suppressed E(2) effects in the cervix, but not in the vagina, oviduct or mammary glands. All serum chemistry and lipid profiles were normal.

CONCLUSION

The ability of ZK to block estrogen-dependent endometrial proliferation, induce endometrial atrophy and suppress BTB in a menopausal macaque model indicates that progestin antagonists may provide a novel mode of HT.

Histone deacetylase inhibitors and cancer: from cell biology to the clinic

Aberrant gene regulation plays an important role in tumor initiation and progression, and the acetylation of histones is a well understood key component of gene regulation. Histone acetylation involves the opposing activities of the histone acetyltransferases (HATs) and histone deacetylases (HDACs)--histone acetylation is associated with increased transcriptional activity while histone deacetylation is associated with repression of gene expression. In addition, the modification of non-histone proteins by HATs and HDACs is also an important process in regulating gene expression. Several lines of evidence suggest that inappropriate transcriptional activation and repression mediated by HATs and HDACs is a common occurrence in the formation of many different types of cancer. These enzymes thus represent novel molecular targets for which inhibitors are sought that could reprogram transcription and inhibit tumor cell growth and progression. Much of the research has focused on HDAC inhibitors, where several agents have demonstrated in vitro and in vivo activity against different tumor cell models and have entered Phase I clinical trials. HDAC inhibitors are believed to exert their antiproliferative effects by inducing a small set of genes involved in regulating cellular activities such as proliferation and differentiation. Future research is expected to lead to a better understanding of the molecular targets of HDACs and facilitate the development of more potent inhibitors of these enzymes. First results from clinical trials will help to determine the optimal strategy for utilizing these agents for the treatment of cancer patients.

PTK 787/ZK 222584, a tyrosine kinase inhibitor of all known VEGF receptors, represses tumor growth with high efficacy

The angiogenesis inhibitor PTK 787/ZK 222584 (PTK/ZK) blocks all known VEGF receptor (VEGFR) tyrosine kinases, including the lymphangiogenic VEGFR3, in the lower nanomolar range. From a panel of 100 kinases only PDGFR, c-kit, and c-fms are inhibited beyond those in the nanomolar range. PTK/ZK functions as a competitive inhibitor at the ATP-binding site of the receptor kinase as shown here in kinetic experiments. The VEGF signal blockade in microvascular endothelial cells (MVEC) results in a blockade of MVEC proliferation (IC50=30 nM), without affecting the proliferation of normal tissue cells and tumor cells. The efficacy of PTK/ZK depends on its continuous presence within the endothelial target cells. Early removal attenuates its antiproliferative activity in vitro. Growth inhibition of endothelial cells is fully reversible as demonstrated by "washout" experiments. Without inhibiting tumor cell proliferation directly, PTK/ZK results in a significant retardation of tumor growth in a number of experimental tumor models of different tissue origin. Combination of PTK/ZK with an antiandrogen revealed additive effects on tumor-growth inhibition. Treatment efficacy was monitored both by tumor weight and by the determination of serum concentrations of the surrogate marker PSA. PTK/ZK is currently being investigated in patients with different solid tumor types for its therapeutic utility. Preliminary data from phase I/II clinical trials of PTK/ZK as a monotherapy suggested a positive safety and tolerability profile, which we interpret to be a consequence of the high selectivity of the drug for a limited number of kinases. Preliminary response, time to progression, and overall survival data were promising.1 Based on these encouraging results, PTK/ZK is currently in Phase III clinical trials for metastatic colorectal cancer.

Cycle-dependent endometrial expression and hormonal regulation of thefibulin-1gene

Fibulin-1 is a secreted protein associated with elastic matrix fibres and basement membranes. It plays a role in stabilizing blood vessels and can also regulate cell motility and invasiveness. We studied the regulation of the fibulin-1 gene in the rat and human endometrium, an organ where cyclic tissue remodeling and angiogenesis take place. The rat fibulin-1C and -1D-specific DNA sequences were first identified and a comparison of the deduced amino acid sequence with the mouse and human counterparts showed a very strong conservation. The exon-intron structure was also maintained. Primers were derived for RT-PCR analysis of fibulin-1 expression in rat endometrium. The highest levels of fibulin-1C and -1D transcripts were measured at metestrous and diestrous, and in early pregnancy at day 3 post-coitum. In vivo studies showed stimulation of endometrial fibulin-1D expression after estrogen application, an effect prevented by parallel treatment with progesterone. Analysis of human endometrial tissues indicated that the fibulin-1D transcript levels were higher during the mid-secretory phase than during the proliferative and early secretory phases. Cultured human endometrial stromal cells treated with progesterone responded with a dramatic increase of fibulin-1 protein expression. This was enhanced by parallel treatment with epidermal growth factor and prevented by application of the antiprogestin RU486. Altogether the results show a cycle-dependent regulation of endometrial fibulin-1 expression controlled by both progesterone and estrogen. Based on its implication in tissue remodeling and angiogenesis, fibulin-1 may play an important role in endometrial receptivity for embryo implantation.

Cyr61, a deregulated gene in endometriosis

Gene expression profiling was performed to identify genes involved in the development of endometriosis. In the secretory phase of the menstrual cycle, several estrogen-regulated genes were up-regulated in endometria of women with endometriosis. The most consistent regulation with one of the highest factors was observed for the Cyr61 gene, which codes for a secreted, cysteine-rich, heparin-binding protein that promotes cell adhesion, migration, and neovascularization. Estrogen responsiveness of endometrial Cyr61 expression was suggested by the higher expression during the proliferative phase and the reduction observed in human endometrial fragments grafted into nude mice subsequently treated with an anti-estrogen. The expression level of Cyr61 was found to be further increased in ectopic endometriotic lesions, as compared to eutopic endometria. In these lesions, an imbalance in expression of the estrogen-converting enzymes 17beta-hydroxysteroid dehydrogenase type 1 and 2 was found, which might explain the elevated Cyr61 level. However, Cyr61 expression was not altered in endometriotic lesions of women treated with a GnRH agonist. These results suggest that Cyr61 may represent a gene characteristic for endometriosis and also play an important role in the development and persistence of endometriotic lesions.

Asoprisnil (J867): a selective progesterone receptor modulator for gynecological therapy

Asoprisnil is a novel selective steroid receptor modulator that shows unique pharmacodynamic effects in animal models and humans. Asoprisnil, its major metabolite J912, and structurally related compounds represent a new class of progesterone receptor (PR) ligands that exhibit partial agonist and antagonist activities in vivo. Asoprisnil demonstrates a high degree of receptor and tissue selectivity, with high-binding affinity for PR, moderate affinity for glucocorticoid receptor (GR), low affinity for androgen receptor (AR), and no binding affinity for estrogen or mineralocorticoid receptors. In the rabbit endometrium, both asoprisnil and J912 induce partial agonist and antagonist effects. Asoprisnil induces mucification of the guinea pig vagina and has pronounced anti-uterotrophic effects in normal and ovariectomized guinea pigs. Unlike antiprogestins, asoprisnil shows only marginal labor-inducing activity during mid-pregnancy and is completely ineffective in inducing preterm parturition in the guinea pig. Asoprisnil exhibits only marginal antiglucocorticoid activity in transactivation in vitro assays and animal models. In male rats, asoprisnil showed weak androgenic and anti-androgenic properties. In toxicological studies in female cynomolgus monkeys, asoprisnil treatment abolished menstrual cyclicity and endometrial atrophy. Early clinical studies of asoprisnil in normal volunteers demonstrated a dose-dependent suppression of menstruation irrespective of the effects on ovulation, with no change in basal estrogen concentrations and no antiglucocorticoid effects. Unlike progestins, asoprisnil does not induce breakthrough bleeding. With favorable safety and tolerability profiles thus far, asoprisnil appears promising as a novel treatment of gynecological disorders, such as uterine fibroids and endometriosis.

In vivo properties of an anti-GnRH Spiegelmer: an example of an oligonucleotide-based therapeutic substance class

Spiegelmers are high-affinity l-enantiomeric oligonucleotide ligands that display high resistance to enzymatic degradation compared with d-oligonucleotides. The target binding properties of Spiegelmers can be designed by an in vitro-selection process starting from a random pool of oligonucleotides. Applying this method, a Spiegelmer with high affinity (K(D) = 20 nM) for the peptide hormone, gonadotropin-releasing hormone (GnRH) was isolated. The Spiegelmer acts as an antagonist to GnRH in Chinese hamster ovary cells stably expressing the human GnRH receptor, and its activity is unchanged by linking to 40-kDa polyethylene glycol. In a castrated rat model the Spiegelmer further demonstrated strong GnRH antagonist activity, which is more pronounced and persists longer with the polyethylene glycol-linked derivative. Furthermore, in rabbits the anti-GnRH Spiegelmer was shown to have a very low, possibly negligible immunogenic potential. These studies suggest that Spiegelmers could be of substantial interest in the development of new pharmaceutical approaches against GnRH and other targets.

Peritoneal endometriosis: validation of an in-vivo model

BACKGROUND

The current medical treatment of endometriosis, a common gynaecological disease, is still associated with a high recurrence rate. To establish an appropriate in-vivo model to evaluate new therapeutic strategies we validated the nude mouse model for the intraperitoneal cultivation of human endometrial tissue.

METHODS

Human endometrium of the proliferative phase was implanted into the peritoneal cavity of normal cycling and ovariectomized athymic mice and of cycling non-obese diabetic (NOD)-severe combined immuno-deficiency (SCID) mice. Morphology, proliferation, differentiation, and angiogenesis in the ectopic endometrium at different time points after implantation was investigated.

RESULTS

Adhesion of endometrial fragments was observed from day 2 onwards. The lesions persisted for up to 28 days revealing a well preserved glandular morphology. The glandular epithelium maintained cytokeratin expression even after 14 days of culture. With progressing culture, glands exhibited vimentin staining in combination with a decrease of surrounding stromal cells. Proliferation of glandular epithelium could be demonstrated throughout the investigated period of 28 days, whereas expression of oestrogen and progesterone receptors was maintained only in endometriotic lesions grown in cycling but not in ovariectomized mice. Neoangiogenesis occurred from day 4 onwards, independent from the intraperitoneal localization of the ectopic lesions.

CONCLUSIONS

This in-vivo model is a promising tool to test the effect of compounds such as different hormone agonists/antagonists or anti-angiogenic factors to develop new therapeutic concepts in endometriosis.

Synthesis and biological activity of a novel, highly potent progesterone receptor antagonist

Herein we describe the chemical synthesis and pharmacological characterization of a novel, highly potent progesterone receptor (PR) antagonist, ZK 230211. The introduction of a 17alpha-pentafluorethyl side chain in the D-ring of the steroid skeleton allowed the combination of high antiprogestagenic activity with little or no other endocrinological effects. In contrast to many other antiprogestins, ZK 230211 did not convert to an agonist in the presence of protein kinase A (PKA) activators and showed high antiprogestagenic activity on both PR isoforms PR-A and PR-B. This high antiprogestagenic activity could also be demonstrated in several in vivo models. Furthermore, this compound displayed only marginal antiglucocorticoid effects. In tumor models ZK 230211 exhibited strong antiproliferative action. The pharmacological properties of ZK 230211 may prove useful in the treatment of endometriosis, leiomyomas, breast cancer, and in hormone replacement therapy.

Antiproliferative effects of progesterone antagonists and progesterone receptor modulators on the endometrium

Progesterone antagonists (PAs, antiprogestins) can modulate estrogenic effects in various estrogen-dependent tissues. These modulatory effects are complex and depend on species, tissue, type of compound, dose, and duration of treatment. In non-human primates, PAs, including mifepristone, ZK 137 316 and ZK 230 211, inhibit endometrial proliferation and induce amenorrhea. When administered chronically at relatively low doses, these compounds block the mitotic activity of endometrial epithelium and induce stromal compaction in a dose-dependent manner in both spayed and intact monkeys at high estradiol concentrations. These effects were accompanied by an atrophy of spiral arteries. The antiproliferative effects were endometrium-specific, since the estrogenic effects in the oviduct and vagina were not inhibited by PAs. Similar endometrial antiproliferative effects were also found after treatment with the progesterone receptor modulator (PRM), mesoprogestin J1042. The endometrial antiproliferative effects of PAs, particularly within the endometrial glands, were also observed in spayed rabbits. In spayed rats, however, the PAs did not inhibit, but rather enhanced, various estrogen responses, including endometrial proliferation, pointing to species-specific differences. In conclusion, our studies indicate that both pure PAs and PRMs selectively inhibit estrogen-dependent endometrial proliferation in the primate endometrium without affecting estrogenic response in other estrogen-dependent tissues or inducing unscheduled bleeding. Our studies indicate that the spiral arteries, which are unique to the primate endometrium, are the primary targets that are damaged or inhibited by PAs and PRMs. The damage to these unique vessels may underlay the paradoxical, endometrium-specific, antiproliferative effects of these compounds. Hence, the properties of PAs and PRMs (mesoprogestins) open up new applications in gynecological therapy and hormone replacement therapy.