Thalidomide analogs and PDE4 inhibition

Gene expression profiling in white blood cells reveals new insights into the molecular mechanisms of thalidomide in children with inflammatory bowel disease

Thalidomide has emerged as an effective immunomodulator in the treatment of pediatric patients with inflammatory bowel disease (IBD) refractory to standard therapies. Cereblon (CRBN), a component of E3 protein ligase complex that mediates ubiquitination and proteasomal degradation of target proteins, has been identified as the primary target of thalidomide. CRBN plays a crucial role in thalidomide teratogenicity, however it is unclear whether it is also involved in the therapeutic effects in IBD patients. This study aimed at identifying the molecular mechanisms underpinning thalidomide action in pediatric IBD. In this study, ten IBD pediatric patients responsive to thalidomide were prospectively enrolled. RNA-sequencing (RNA-seq) analysis and functional enrichment analysis were carried out on peripheral blood mononuclear cells (PBMC) obtained before and after twelve weeks of treatment with thalidomide. RNA-seq analysis revealed 378 differentially expressed genes before and after treatment with thalidomide. The most deregulated pathways were cytosolic calcium ion concentration, cAMP-mediated signaling, eicosanoid signaling and inhibition of matrix metalloproteinases. Neuronal signaling mechanisms such as CREB signaling in neurons and axonal guidance signaling also emerged. Connectivity Map analysis revealed that thalidomide gene expression changes were similar to those exposed to MLN4924, an inhibitor of NEDD8 activating enzyme, suggesting that thalidomide exerts its immunomodulatory effects by acting on the ubiquitin-proteasome pathway. In vitro experiments on cell lines confirmed the effect of thalidomide on candidate altered pathways observed in patients. These results represent a unique resource for enhanced understanding of thalidomide mechanism in pediatric patients with IBD, providing novel potential targets associated with drug response.

Anti-emetic effects of thalidomide: Evidence, mechanism of action, and future directions

The rationale for using thalidomide (THD) as a treatment for nausea and vomiting during pregnancy in the late 1950s appears to have been based on its sedative or hypnotic properties. In contrast to contemporaneous studies on the anti-emetic activity of phenothiazines, we were unable to identify publications reporting preclinical or clinical evaluation of THD as an anti-emetic. Our survey of the literature revealed a clinical study in 1965 showing THD reduced vomiting in cancer chemotherapy which was substantiated by similar studies from 2000, particularly showing efficacy in the delayed phase of chemotherapy-induced nausea and vomiting. To identify the mechanism(s) potentially involved in thalidomide's anti-emetic activity we reviewed its pharmacology in the light of nausea and vomiting mechanisms and their pharmacology with a particular emphasis on chemotherapy and pregnancy. The process identified the following potential mechanisms: reduced secretion of Growth Differentiation Factor 15, suppression of inflammation/prostaglandin production, downregulation of cytotoxic drug induced upregulation of iNOS, and modulation of BK (KCa1.1) channels and GABAA/glutamate transmission at critical points in the emetic pathways (nucleus tractus solitarius, area postrema). We propose ways to investigate these hypothesized mechanisms and discuss the associated challenges (e.g., objective quantification of nausea) in addition to some of the more general aspects of developing novel drugs to treat nausea and vomiting.

Antiangiogenic Activity and in Silico Cereblon Binding Analysis of Novel Thalidomide Analogs

Due to its antiangiogenic and anti-immunomodulatory activity, thalidomide continues to be of clinical interest despite its teratogenic actions, and efforts to synthesize safer, clinically active thalidomide analogs are continually underway. In this study, a cohort of 27 chemically diverse thalidomide analogs was evaluated for antiangiogenic activity in an ex vivo rat aorta ring assay. The protein cereblon has been identified as the target for thalidomide, and in silico pharmacophore analysis and molecular docking with a crystal structure of human cereblon were used to investigate the cereblon binding abilities of the thalidomide analogs. The results suggest that not all antiangiogenic thalidomide analogs can bind cereblon, and multiple targets and mechanisms of action may be involved.

Preterm Birth, Inflammation and Infection: New Alternative Strategies for their Prevention

BACKGROUND

Worldwide, the progress in reducing neonatal mortality has been very slow. The rate of preterm birth has increased over the last 20 years in low-income and middle-income countries. Its association with increased mortality and morbidity is based on experimental studies and neonatal outcomes from countries with socioeconomic differences, which have considered implementing alternative healthcare strategies to prevent and reduce preterm births.

METHODS

Currently, there is no widely effective strategy to prevent preterm birth. Pharmacological therapies are directed at inhibiting myometrial contractions to prolong parturition. Some drugs, medicinal plants and microorganisms possess myorelaxant, anti-inflammatory and immunomodulatory properties that have proved useful in preventing preterm birth associated with inflammation and infection.

RESULTS

This review focuses on the existing literature regarding the use of different drugs, medicinal plants, and microorganisms that show promising benefits for the prevention of preterm birth associated with inflammation and infection. New alternative strategies involving the use of PDE-4 inhibitors, medicinal plants and probiotics could have a great impact on improving prenatal and neonatal outcomes and give babies the best start in life, ensuring lifelong health benefits.

CONCLUSION

Despite promising results from well-documented cases, only a small number of these alternative strategies have been studied in clinical trials. The development of new drugs and the use of medicinal plants and probiotics for the treatment and/or prevention of preterm birth is an area of growing interest due to their potential therapeutic benefits in the field of gynecology and obstetrics.

Efficient Synthesis of Immunomodulatory Drug Analogues Enables Exploration of Structure-Degradation Relationships

The immunomodulatory drugs (IMiDs) thalidomide, pomalidomide, and lenalidomide have been approved for the treatment of multiple myeloma for many years. Recently, their use as E3 ligase recruiting elements for small-molecule-induced protein degradation has led to a resurgence in interest in IMiD synthesis and functionalization. Traditional IMiD synthesis follows a stepwise route with multiple purification steps. Herein we describe a novel one-pot synthesis without purification that provides rapid access to a multitude of IMiD analogues. Binding studies with the IMiD target protein cereblon (CRBN) reveals a narrow structure-activity relationship with only a few compounds showing sub-micromolar binding affinity in the range of pomalidomide and lenalidomide. However, anti-proliferative activity as well as Aiolos degradation could be identified for two IMiD analogues. This study provides useful insight into the structure-degradation relationships for molecules of this type as well as a rapid and robust method for IMiD synthesis.

Relaxant and anti-inflammatory effect of two thalidomide analogs as PDE-4 inhibitors in pregnant rat uterus

The aim of this study was to evaluate the relaxant and anti-inflammatory effects of two thalidomide analogs as phosphodiesterase-4 (PDE-4) inhibitors in pregnant rat uterus. Uteri from Wistar female rats were isolated at 19 day of pregnancy. Uterine samples were used in functional studies to evaluate the inhibitory effects of the thalidomide analogs, methyl 3-(4-nitrophthalimido)-3-(3,4-dimethoxyphenyl)-propanoate (4NO2PDPMe) and methyl 3-(4-aminophthalimido)-3-(3,4-dimethoxyphenyl)-propanoate (4APDPMe), on prostaglandin-F2α (PGF2α)-induced phasic, K⁺-induced tonic, and Ca²⁺-induced contractions. Accumulation of cAMP was quantified in uterine homogenates by ELISA. Anti-inflammatory effect was assessed by using ELISA for determination of the pro-inflammatory cytokines tumor necrosis factor-α (TNFα) and interleukin (IL)-1β, and anti-inflammatory IL-10, from uterine explants stimulated with lipopolysaccharide (LPS). Nifedipine, forskolin and rolipram were used as positive controls where required. Both thalidomide analogs induced a significant inhibition of the uterine contractions induced by the pharmaco- and electro-mechanic stimuli. Nifedipine and forskolin were more potent than the analogs to inhibit the uterine contractility, but these were more potent than rolipram, and 4APDPMe was equieffective to nifedipine. Thalidomide analogs increased uterine cAMP-levels in a concentration-dependent manner. The LPS-induced TNFα and IL-1β uterine secretion was diminished in a concentration-dependent fashion by both analogs, whereas IL-10 secretion was increased significantly. The thalidomide analogs induced utero-relaxant and anti-inflammatory effects, which were associated with the increased cAMP levels as PDE-4 inhibitors in the pregnant rat uterus. Such properties place these thalidomide analogs as potentially safe and effective tocolytic agents in a field that urgently needs improved pharmacological treatments, as in cases of preterm labor.

Evaluation of US 2016/0115161 A1: isoindoline compounds and methods of their use

INTRODUCTION

Immunomodulatory drugs (IMIDs®) are small orally available molecules that modulate the immune system and other biological targets through multiple mechanisms of action and have been successfully used in the treatment of myelodysplastic syndrome and multiple myeloma. However, recent studies of their complex mechanism of action revealed their potential in autoimmune diseases and solid tumors, which intensified scientific interest in these compounds. Areas covered: This patent application claims new IMIDs for the treatment of cancer and disorders associated with angiogenesis and inflammation. Substitution of isoindolinone ring on position 5 with urea and amide linkers connected to different aromatic rings lead to very potent inhibitors of TNF-α production with antiproliferative activities against Nemalwa cells and against colorectal, pancreatic, prostate and breast cancer cell lines in sub-nano to low-nanomolar concentration range. Expert opinion: Substitution of position 5 on the isoindolinone ring, which is presented in this invention, is currently the hot spot of Celgene's research. Results of biological tests, which are superior over those of presently used IMIDs lenalidomide and pomalidomide, make these compounds viable leads for future development of new anticancer drugs against blood and solid cancers.

Crystal structure of an apremilast ethanol hemisolvate hemihydrate solvatomorph

The title compound represents another solvatomorph of apremilast, containing half of an ethanol and half of a water solvent mol­ecule per formula unit

The title compound, C₂₂H₂₄N₂O₇S·0.5C₂H₅OH·0.5H₂O {systematic name: (S)-4-acetamido-2-[1-(3-eth­oxy-4-meth­oxy­phen­yl)-2-(methyl­sulfon­yl)eth­yl]iso­indo­line-1,3-dione ethanol hemisolvate hemihydrate}, is a novel solvatomorph of apremilast (AP), which is an inhibitor of phosphodiesterase 4 (PDE4) and is indicated for the treatment of adult patients with active psoriatic arthritis. The asymmetric unit contains one mol­ecule of AP and disordered mol­ecules of ethanol and water, both with half occupancy. The dihedral angle between the planes of the phenyl ring and the iso­indole ring is 67.9 (2)°. Extensive intra- and inter­molecular hydrogen bonds help to stabilize the mol­ecular conformation and sustain the crystal packing.

Old Drug Scaffold, New Activity: Thalidomide-Correlated Compounds Exert Different Effects on Breast Cancer Cell Growth and Progression

Thalidomide was first used for relief of morning sickness in pregnant women and then withdrawn from the market because of its dramatic effects on normal fetal development. Over the last decades, it has been used successfully for the treatment of several pathologies, including cancer. Many analogues with improved activity have been synthesized and tested. Herein we report some effects on the growth and progression of MCF-7 and MDA-MB-231 breast cancer cells by a small series of thalidomide-correlated compounds, which are very effective at inducing cancer cell death by triggering TNFα-mediated apoptosis. The most active compounds are able to drastically reduce the migration of breast cancer cells by regulation of the two major proteins involved in epithelial-mesenchymal transition (EMT): vimentin and E-cadherin. Moreover, these compounds diminish the intracellular biosynthesis of vascular endothelial growth factor (VEGF), which is primarily involved in the promotion of angiogenesis, sustaining tumor progression. The multiple features of these compounds that act on various key points of the tumorigenesis process make them good candidates for preclinical studies.

Synthesis and Antiangiogenic Properties of Tetrafluorophthalimido and Tetrafluorobenzamido Barbituric Acids

The development of novel thalidomide derivatives as immunomodulatory and anti-angiogenic agents has revived over the last two decades. Herein we report the design and synthesis of three chemotypes of barbituric acids derived from the thalidomide structure: phthalimido-, tetrafluorophthalimido-, and tetrafluorobenzamidobarbituric acids. The latter were obtained by a new tandem reaction, including a ring opening and a decarboxylation of the fluorine-activated phthalamic acid intermediates. Thirty compounds of the three chemotypes were evaluated for their anti-angiogenic properties in an ex vivo assay by measuring the decrease in microvessel outgrowth in rat aortic ring explants. Tetrafluorination of the phthalimide moiety in tetrafluorophthalimidobarbituric acids was essential, as all of the nonfluorinated counterparts lost anti-angiogenic activity. An opening of the five-membered ring and the accompanying increased conformational freedom, in case of the corresponding tetrafluorobenzamidobarbituric acids, was well tolerated. Their activity was retained, although their molecular structures differ in torsional flexibility and possible hydrogen-bond networking, as revealed by comparative X-ray crystallographic analyses.

Inhibition of Uterine Contractility by Thalidomide Analogs via Phosphodiesterase-4 Inhibition and Calcium Entry Blockade

Uterine relaxation is crucial during preterm labor. Phosphodiesterase-4 (PDE-4) inhibitors have been proposed as tocolytics. Some thalidomide analogs are PDE-4 inhibitors. The aim of this study was to assess the uterus-relaxant properties of two thalidomide analogs, methyl 3-(4-nitrophthalimido)-3-(3,4-dimethoxyphenyl)-propanoate (4NO2PDPMe) and methyl 3-(4-aminophthalimido)-3-(3,4-dimethoxyphenyl)-propanoate (4APDPMe) and were compared to rolipram in functional studies of spontaneous phasic, K⁺-induced tonic, and Ca²⁺-induced contractions in isolated pregnant human myometrial tissues. The accumulation of cAMP was quantified in HeLa cells. The presence of PDE-4B2 and phosphorylated myosin light-chain (pMLC), in addition to the effect of thalidomide analogs on oxytocin-induced pMLC, were assessed in human uterine myometrial cells (UtSMCs). Thalidomide analogs had concentration-dependent inhibitory effects on spontaneous and tonic contractions and inhibited Ca²⁺-induced responses. Tonic contraction was equipotently inhibited by 4APDPMe and rolipram (IC₅₀ = 125 ± 13.72 and 98.45 ± 8.86 µM, respectively). Rolipram and the thalidomide analogs inhibited spontaneous and tonic contractions equieffectively. Both analogs increased cAMP accumulation in a concentration-dependent manner (p < 0.05) and induced changes in the subcellular localization of oxytocin-induced pMLC in UtSMCs. The inhibitory effects of thalidomide analogs on the contractions of pregnant human myometrium tissue may be due to their PDE-4 inhibitory effect and novel mechanism as calcium-channel blockers.

Thalidomide analogues: Tumor necrosis factor-alpha inhibitors and their evaluation as anti-inflammatory agents

A series of related thalidomide derivatives (2-9) were synthesized by microwave irradiation and evaluated for anti-inflammatory activity. Such activity was assessed in vivo and ex vivo. Compounds 2, 8 and 9 showed the highest levels of inhibition of TNF-α production. On rat paw edema and hyperalgesia assays, compound 9, (1,4-phthalazinedione) demonstrated the highest in vivo anti-inflammatory activity. Thus, compound 9 can be considered as a promising compound to be subjected to further modification to obtain new agents for the treatment of inflammatory diseases.

Apremilast, a novel phosphodiesterase 4 (PDE4) inhibitor, regulates inflammation through multiple cAMP downstream effectors

Introduction

This work was undertaken to delineate intracellular signaling pathways for the PDE4 inhibitor apremilast and to examine interactions between apremilast, methotrexate and adenosine A_2A receptors (A_2AR).

Methods

After apremilast and LPS incubation, intracellular cAMP, TNF-α, IL-10, IL-6 and IL-1α were measured in the Raw264.7 monocytic murine cell line. PKA, Epac1/2 (signaling intermediates for cAMP) and A_2AR knockdowns were performed by shRNA transfection and interactions with A2AR and A2BR, as well as with methotrexate were tested in vitro and in the murine air pouch model. Statistical differences were determined using one or two-way ANOVA or Student’s t test. The alpha nominal level was set at 0.05 in all cases. A P value of < 0.05 was considered significant.

Results

In vitro, apremilast increased intracellular cAMP and inhibited TNF-α release (IC₅₀=104nM) and the specific A_2AR-agonist CGS21680 (1μM) increased apremilast potency (IC₅₀=25nM). In this cell line, apremilast increased IL-10 production. PKA, Epac1 and Epac2 knockdowns prevented TNF-α inhibition and IL-10 stimulation by apremilast. In the murine air pouch model, both apremilast and MTX significantly inhibited leukocyte infiltration, while apremilast, but not MTX, significantly inhibited TNF-α release. The addition of MTX (1 mg/kg) to apremilast (5 mg/kg) yielded no more inhibition of leukocyte infiltration or TNF-α release than with apremilast alone.

Conclusions

The immunoregulatory effects of apremilast appear to be mediated by cAMP through the downstream effectors PKA, Epac1, and Epac2. A2AR agonism potentiated TNF-α inhibition by apremilast, consistent with the cAMP-elevating effects of that receptor. Because the A2AR is also involved in the anti-inflammatory effects of MTX, the mechanism of action of both drugs involves cAMP-dependent pathways and is therefore partially overlapping in nature.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0771-6) contains supplementary material, which is available to authorized users.

Apremilast is a selective PDE4 inhibitor with regulatory effects on innate immunity

Apremilast, an oral small molecule inhibitor of phosphodiesterase 4 (PDE4), is in development for chronic inflammatory disorders, and has shown efficacy in psoriasis, psoriatic arthropathies, and Behçet's syndrome. In March 2014, the US Food and Drug Administration approved apremilast for the treatment of adult patients with active psoriatic arthritis. The properties of apremilast were evaluated to determine its specificity, effects on intracellular signaling, gene and protein expression, and in vivo pharmacology using models of innate and adaptive immunity. Apremilast inhibited PDE4 isoforms from all four sub-families (A1A, B1, B2, C1, and D2), with IC50 values in the range of 10 to 100 nM. Apremilast did not significantly inhibit other PDEs, kinases, enzymes, or receptors. While both apremilast and thalidomide share a phthalimide ring structure, apremilast lacks the glutarimide ring and thus fails to bind to cereblon, the target of thalidomide action. In monocytes and T cells, apremilast elevated intracellular cAMP and induced phosphorylation of the protein kinase A substrates CREB and activating transcription factor-1 while inhibiting NF-κB transcriptional activity, resulting in both up- and down-regulation of several genes induced via TLR4. Apremilast reduced interferon-α production by plasmacytoid dendritic cells and inhibited T-cell cytokine production, but had little effect on B-cell immunoglobulin secretion. In a transgenic T-cell and B-cell transfer murine model, apremilast (5mg/kg/day p.o.) did not affect clonal expansion of either T or B cells and had little or no effect on their expression of activation markers. The effect of apremilast on innate immunity was tested in the ferret lung neutrophilia model, which allows monitoring of the known PDE4 inhibitor gastrointestinal side effects (nausea and vomiting). Apremilast significantly inhibited lung neutrophilia at 1mg/kg, but did not induce significant emetic reflexes at doses <30 mg/kg. Overall, the pharmacological effects of apremilast are consistent with those of a targeted PDE4 inhibitor, with selective effects on innate immune responses and a wide therapeutic index compared to its gastrointestinal side effects.

Novel thieno[2,3-d]pyrimidines: their design, synthesis, crystal structure analysis and pharmacological evaluation

Novel thieno[2,3-d]pyrimidines containing a cyclohexane ring fused with a six- or five-membered heterocyclic moiety along with a benzylic nitrile were designed as potential inhibitors of PDE4. Expeditious synthesis of these compounds was carried out via a multi-step sequence consisting of a few key steps such as Gewald reaction, Dieckmann type cyclisation and Krapcho decarboxylation. This newly developed strategy involved construction of the thienopyrimidine ring followed by the cyclohexanone moiety and subsequently the fused heterocyclic ring. A number of thieno[2,3-d]pyrimidine based derivatives were synthesized using this method some of which showed promising PDE4B inhibitory properties. One of them was tested for PDE4D inhibition in vitro and dose dependent inhibition of TNF-α. A few selected molecules were docked into the PE4B protein the results of which showed good overall correlations to their observed PDE4B inhibitory properties in vitro. The crystal structure analysis of representative compounds along with hydrogen bonding patterns and molecular arrangement present within the molecule is described.

Therapeutic approaches for tumor necrosis factor inhibition

Tumor necrosis factor (TNF) consists of an inflammatory cytokine essential for homeostasis and organism defense. Despite its physiological relevance, both increased biosynthesis and release of TNF lead to the exacerbation of inflammatory and oxidative responses, which are related to the pathogenesis of a host of diseases of an inflammatory, autoimmune and/or infectious nature. In this context, effective therapeutic approaches for the modulation of TNF have been the focus of research efforts. Approximately one million individuals worldwide have been treated with biotechnological inhibitors of this cytokine, the so-called anti-TNF biopharmaceuticals. However, given the high risk of infection and the limitations related to cost and administration routes, new therapeutic approaches aimed at biological targets that directly or indirectly modulate the production and/or activation of TNF appear promising alternatives for the discovery of new anti-inflammatory and immunomodulatory orally active drugs and are therefore discussed in this paper.

Apremilast, a cAMP phosphodiesterase-4 inhibitor, demonstrates anti-inflammatory activity in vitro and in a model of psoriasis

BACKGROUND AND PURPOSE

Apremilast is an orally administered phosphodiesterase-4 inhibitor, currently in phase 2 clinical studies of psoriasis and other chronic inflammatory diseases. The inhibitory effects of apremilast on pro-inflammatory responses of human primary peripheral blood mononuclear cells (PBMC), polymorphonuclear cells, natural killer (NK) cells and epidermal keratinocytes were explored in vitro, and in a preclinical model of psoriasis.

EXPERIMENTAL APPROACH

Apremilast was tested in vitro against endotoxin- and superantigen-stimulated PBMC, bacterial peptide and zymosan-stimulated polymorphonuclear cells, immunonoglobulin and cytokine-stimulated NK cells, and ultraviolet B light-activated keratinocytes. Apremilast was orally administered to beige-severe combined immunodeficient mice, xenotransplanted with normal human skin and triggered with human psoriatic NK cells. Epidermal skin thickness, proliferation index and inflammation markers were analysed.

KEY RESULTS

Apremilast inhibited PBMC production of the chemokines CXCL9 and CXCL10, cytokines interferon-gamma and tumour necrosis factor (TNF)-alpha, and interleukins (IL)-2, IL-12 and IL-23. Production of TNF-alpha by NK cells and keratinocytes was also inhibited. In vivo, apremilast significantly reduced epidermal thickness and proliferation, decreased the general histopathological appearance of psoriasiform features and reduced expression of TNF-alpha, human leukocyte antigen-DR and intercellular adhesion molecule-1 in the lesioned skin.

CONCLUSIONS AND IMPLICATIONS

Apremilast displayed a broad pattern of anti-inflammatory activity in a variety of cell types and decreased the incidence and severity of a psoriasiform response in vivo. Inhibition of TNF-alpha, IL-12 and IL-23 production, as well as NK and keratinocyte responses by this phosphodiesterase-4 inhibitor suggests a novel approach to the treatment of psoriasis.

Discovery of (S)-N-[2-[1-(3-ethoxy-4-methoxyphenyl)-2-methanesulfonylethyl]-1,3-dioxo-2,3-dihydro-1H-isoindol-4-yl] acetamide (apremilast), a potent and orally active phosphodiesterase 4 and tumor necrosis factor-alpha inhibitor

In this communication, we report the discovery of 1S (apremilast), a novel potent and orally active phosphodiesterase 4 (PDE4) and tumor necrosis factor-alpha inhibitor. The optimization of previously reported 3-(1,3-dioxo-1,3-dihydroisoindol-2-yl)-3-(3,4-dimethoxyphenyl)propionic acid PDE4 inhibitors led to this series of sulfone analogues. Evaluation of the structure-activity relationship of substitutions on the phthalimide group led to the discovery of an acetylamino analogue 1S, which is currently in clinical trials.

Thalidomide Analogs from Diamines: Synthesis and Evaluation as Inhibitors of TNF-.ALPHA. Production

Fourteen thalidomide analogs bearing two phthalimido units were prepared in high yields (83-94%) by condensation of different diamines with phthalic or 3-nitrophthalic anhydride. An in vitro investigation of the compounds as inhibitors of the TNF-alpha production was performed. The inhibition was higher for compounds bearing amino and nitro groups and was modulated by increasing the size of the spacers between the phthalimide groups.

Development of new CoMFA and CoMSIA 3D-QSAR models for anti-inflammatory phthalimide-containing TNFα modulators

In the present study, we describe a new 3D-QSAR analysis of 42 previously reported thalidomide analogues, with the ability to modulate the pro-inflammatory cytokine TNFalpha, by using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Three statistically significant models were obtained. The best resulting CoMFA and CoMSIA models have conventional r(2) values of 0.996 and 0.983, respectively. The cross-validated q(2) values are 0.869 and 0.868, respectively. The analysis of CoMFA and CoMSIA contour maps provided insight into the possible sites for structural modification of the thalidomide analogues for better activity and reduced toxicity.

Immunomodulatory drugs in myelodysplastic syndromes

This review summarises the mechanism of action of immunomodulatory analogues of thalidomide and their use in myelodysplastic syndromes. Thalidomide was found to have a response rate of approximately 20% in these patients. Lenalidomide--which is more potent and less toxic than thalidomide--has been used in three clinical trials and produced the best responses (60 - > 90%) in low- and intermediate-1-risk transfusion-dependent patients with del(5q). The responses are purely erythroid in nature, and are associated with major cytogenetic responses in > 50% of the del(5q) patients. Non-del(5q) low- and intermediate-1-risk transfusion-dependent patients also had a approximately 25% incidence of transfusion independence following therapy with lenalidomide. Median time to response is approximately 4 weeks and 90% of patients respond within 12 weeks. The precise mechanism of action remains unknown but anticytokine, antiangiogenic and immunomodulatory properties are thought to play a role.

Immunomodulatory effects of thalidomide analogs on LPS-induced plasma and hepatic cytokines in the rat

Thalidomide has shown to inhibit, selectively and mainly the cytokine tumor necrosis factor-alpha (TNF-alpha), thus, thalidomide has inhibitory consequences on other cytokines; this is ascribed as an immunomodulatory effect. Novel thalidomide analogs are reported with immunomodulatory activity. The aim of this work was to synthesize some of these analogs and to assess them as immunomodulatory agents in an acute model of LPS-induced septic challenge in rat. Animal groups received orally twice a day vehicle carboxymethylcellulose (0.9%), or thalidomide in suspension (100mg/kg), or analogs in an equimolar dose. Two hours after last dose, rats were injected with saline (NaCl, 0.9%, i.p.) or LPS (5mg/kg, i.p.). Groups were sacrificed 2h after injection and samples of blood and liver were obtained. TNF-alpha, interleukin-6, -1beta, and -10 (IL-6, IL-1beta, IL-10) were quantified by enzyme linked immunosorbent assay (ELISA) and studied in plasma and liver. After 2h of LPS-induction, different patterns of measured cytokines were observed with thalidomide analogs administration evidencing their immunomodulatory effects. Interestingly, some analogs decreased significantly plasma and hepatic levels of LPS-induced proinflammatory TNF-alpha and others increased plasma concentration of anti-inflammatory IL-10. Thalidomide analogs also showed slight effects on the remaining proinflammatory cytokines. Differences among immunomodulatory effects of analogs can be related to potency, mechanism of action, and half lives. Thalidomide analogs could be used as a pharmacological tool and in therapeutics in the future.

Thalidomide analogs as emerging anti-cancer drugs

Recently, it has been demonstrated that a number of novel thalidomide analogs possess anti-cancer properties due to their T cell co-stimulatory, anti-angiogenic and/or anti-inflammatory effects. Based on such effects, a class of thalidomide analogs known as Immunomodulatory Drugs (IMiDs) have recently entered into phase I clinical trials for the treatment of a number of cancers. The lead IMiD CC-5013 (referred to clinically as REVIMID) is now entering phase III clinical trials for multiple myeloma and metastatic melanoma, while CC-4047 (ACTIMID) is currently under investigation in phase I/II and II trials for multiple myeloma and prostate cancer, respectively. The other group of compounds, classified as Selective Cytokine Inhibitory Drugs (SelCIDs), do not co-stimulate T cells, but have anti-inflammatory and anti-angiogenic properties. Moreover, a subset of SelCIDs has been found to possess direct anti-tumor activity both in vitro and in vivo. This minireview highlights the various mechanisms of action associated with these compounds and their subsequent clinical development. The enhanced efficacy and lower side-effect profiles of the analogs in comparison to thalidomide make the use of these agents very attractive as novel anti-cancer agents.

Thalidomide treatment in multiple myeloma

Thalidomide was first evaluated in patients with refractory multiple myeloma in the mid-90s. Based on the promising results achieved in these patients, the drug was subsequently used in earlier stages of the disease. Meanwhile, numerous phase II studies have been published using different doses and treatment schedules of thalidomide. In order to enhance efficacy, combinations of thalidomide with dexamethasone, chemotherapy and interferon were tried in different settings. In these trials important data regarding the toxicity profile of thalidomide have also been collected. Several trials in newly diagnosed myeloma patients are still ongoing. In the future, the optimal dose of thalidomide and the best schedule in combination with dexamethasone or chemotherapy have to be defined.Thalidomide's mechanism of action is still unclear. There are, however, several hypotheses regarding its mode of action. Recently, several analogues of thalidomide-the so-called ImiDs, have been developed. Preclinical data indicate that they might be more effective and less toxic than thalidomide. Trials evaluating the ImiDs in the clinical setting are still ongoing. In this paper, we will review the available clinical data regarding efficacy and toxicity of thalidomide, discuss its possible mechanism of action and point to future directions of research and clinical development of the ImiDs.

Thalidomide and its analogues have distinct and opposing effects on TNF-alpha and TNFR2 during co-stimulation of both CD4(+) and CD8(+) T cells

Thalidomide (Thd) is clinically useful in a number of conditions where its efficacy is probably related to its anti-TNF-alpha activity. More recently, Thd has also been shown to co-stimulate T cells and second generation co-stimulatory (IMiD trade mark ) analogues are currently being assessed in the treatment of cancer patients. However, in contrast to their known suppressive effects during inflammatory stimuli, the effects of Thd/IMiDs on TNF-alpha and TNF receptors (TNFRs) during T cell co-stimulation are not known. We sought to determine the effect of Thd, two clinically relevant IMiDs (CC-4047, ACTIMID trade mark and CC-5013, REVIMID trade mark ) and a non-stimulatory SelCID analogue (CC-3052) on TNF-alpha production and on the expression and shedding of TNFRs during co-stimulation. We found that co-stimulation of PBMC with Thd/IMiDs, but not CC-3052, prevented alphaCD3-induced T cell surface expression of TNFR2 and thereby reduced soluble TNFR2 (sTNFR2) levels. However, there was no effect on total (surface/intracellular) TNFR2 protein expression, suggesting inhibition of trafficking to the cell membrane. The extent of co-stimulation by Thd/IMiDs (assessed by CD69/CD25 expression and IL-2/sIL-2Ralpha production) was similar for CD4+ and CD8+ T lymphocytes and correlated with TNFR2 inhibition. Co-stimulation, but not the early inhibitory effect on TNFR2, was IL-2-dependent and led to increased TNF-alpha production by both CD4+ and CD8+ T lymphocytes. The clinical relevance of this observation was confirmed by the elevation of serum TNF-alpha during REVIMID trade mark treatment of patients with advanced cancer. Together, these results suggest a possible role for TNF-mediated events during co-stimulation and contrast with the TNF inhibitory effects of Thd and its analogues during inflammatory stimuli.

Novel thalidomide analogues display anti-angiogenic activity independently of immunomodulatory effects

The anti-tumour effects of thalidomide have been associated with its anti-angiogenic properties. Second generation thalidomide analogues are distinct compounds with enhanced therapeutic potential. Although these compounds are beginning to enter trials for the treatment of cancer there is very little information regarding the anti-angiogenic activity of these clinically relevant compounds. Furthermore, it is not known how the various immunomodulatory activities of these compounds relate to anti-angiogenic activity. In this study we assessed the anti-angiogenic activity of compounds from both IMiD and SelCID classes of analogues using a novel in vitro multicellular human assay system and the established rat aorta assay. Our results show that both the IMiDs and SelCIDs tested are significantly more potent than thalidomide. The anti-angiogenic potency of the analogues was not related to inhibition of endothelial cell proliferation, nor their TNF-alpha/PDE type 4 inhibitory properties. However, anti-migratory effects in vitro and inhibition of tumour growth in vivo was observed with the analogue IMiD-1 (clinically known as REVIMID). Our results show that anti-angiogenic activity spans both currently defined classes of thalidomide analogue and is not related to their previously described immunomodulatory properties. Identification of the differential effects of these compounds will enable targeting of such compounds into the appropriate clinical setting.

Cytokine modulation and suppression of liver injury by a novel analogue of thalidomide

Thalidomide has been shown to reduce the production of tumor necrosis factor-alpha (TNF-alpha), a cytokine with deleterious pathophysiologic effects in various diseases. In search of thalidomide analogues with improved TNF-alpha inhibiting properties, 5-ethyl-1-phenyl-5-(3,4,5,6-tetrafluorophthalimido)barbituric acid (TFBA) was found to be superior to thalidomide. Besides TNF-alpha, TFBA also suppressed interleukin-6 and interleukin-10 production of isolated monocytes. The possibility that TFBA exerts its action by increasing levels of cAMP via inhibition of phosphodiesterase-4 activity was excluded. TFBA had no influence on T cell proliferation; neither did it inhibit TNF-alpha production in peripheral blood mononuclear cells stimulated by anti-CD3 monoclonal antibody. When applied to mice treated with D-galactosamine and lipopolysaccharide, TFBA prevented a rise in serum TNF-alpha, had no effect on interleukin-6 levels and led to an increase in interleukin-10 production. The changes in cytokine production observed in vitro and in vivo were reflected by similar changes in the mRNA expression. Moreover, TFBA significantly reduced liver transaminase levels in D-galactosamine/lipopolysaccharide-treated mice and thus efficiently protected the animals from liver injury. Thus, according to its properties, TFBA has the potential of modulating an immune response by acting as an anti-inflammatory agent.

Protective antitumor immunity induced by a costimulatory thalidomide analog in conjunction with whole tumor cell vaccination is mediated by increased Th1-type immunity

Thalidomide and its novel T cell costimulatory analogs (immunomodulatory drugs) are currently being assessed in the treatment of patients with advanced cancer. However, neither tumor-specific T cell costimulation nor effective antitumor activity has been demonstrated in vivo. In this study, we assessed the ability of an immunomodulatory drug (CC-4047/ACTIMID) to prime a tumor-specific immune response following tumor cell vaccination. We found that the presence of CC-4047 during the priming phase strongly enhanced antitumor immunity in the vaccinated group, and this correlated with protection from subsequent live tumor challenge. Protection was associated with tumor-specific production of IFN-gamma and was still observed following a second challenge with live tumor cells 60 days later. Furthermore, CD8(+) and CD4(+) splenocyte fractions from treated groups secreted increased IFN-gamma and IL-2 in response to tumor cells in vitro. Coculture of naive splenocytes with anti-CD3 mAb in the presence of CC-4047 directly costimulated T cells and increased Th1-type cytokines. Our results are the first to demonstrate that a costimulatory thalidomide analog can prime protective, long-lasting, tumor-specific, Th1-type responses in vivo and further support their ongoing clinical development as novel anti-cancer agents.

Aza analogues of thalidomide: synthesis and evaluation as inhibitors of tumor necrosis factor-alpha production in vitro

A synthetic entry to derivatives of the new classes of 5-phthalimidouracils and 5-phthalimidobarbituric acids is reported. These 5-phthalimidopyrimidines as well as phthalimido-2,4-difluorobenzenes were designed as analogues of thalidomide, a well known inhibitor of TNF-alpha production. A preliminary in vitro investigation of the compounds as inhibitors of the TNF-alpha production was performed. Among the compounds of the present series, 5-ethyl-1-phenyl-5-(tetrafluorophthalimido)barbituric acid and 2-(2,4-difluorophenyl)-4,5,6,7-tetrafluoro-1H-isoindole-1,3(2H)-dione were proved to be potent inhibitors. Both compounds showed inhibitory activity in the lower micromolar range on the LPS-induced TNF-alpha production in human monocytes.

Potent inhibition of cytokine production from intestinal lamina propria T cells by phosphodiesterase-4 inhibitory thalidomide analogues

In Crohn's disease, intestinal lamina propria (LP) T cells overproduce TNF-alpha and IFN-gamma, and clinical and animal studies indicate that this is pathogenic. Thalidomide influences cytokine production by leukocytes, inhibiting macrophage TNF-alpha, and is beneficial in treating Crohn's disease. Chemical analogues have been synthesized that may lack teratogenic and other side effects of thalidomide. We tested three analogues [selective cytokine inhibitory drugs (SelCIDs) A, B, and C, all potent PDE4 inhibitors] for effect on TNF-alpha, IFN-gamma, and IL-10 production by and on proliferation of intestinal LP mononuclear cells after T-cell stimulation and results were compared with those for peripheral blood leukocytes (PBL). While thalidomide itself had little effect, the SelCIDs were potent inhibitors, with relative inhibitory potencies: A> or =B>>C. The LP T cells were less sensitive to inhibition by the SelCIDs than were PBL. Since highly pre-activated PBL were even less sensitive, activation state alone can account for the responsiveness of intestinal LP T cells. Thalidomide analogues could play a role in treating Crohn's disease and other inflammatory disorders.

General aspects of anti-angiogenesis and cancer therapy

Angiogenesis is the outgrowth of new vessels from pre-existing ones. Tumour growth and metastasis is dependent on angiogenesis and many stimulatory and inhibitory factors have been described which play an active role in this process. Inhibition of tumour neovasculature may be one strategy to inhibit tumour growth. Naturally occurring inhibitors of angiogenesis have been discovered and synthetic agents have been designed. Many of these inhibitors are currently being evaluated in clinical trials for the treatment of cancer. This review discusses the mechanism of action of these anti-angiogenics as well as a description of the clinical trials in which they are being evaluated.

Synthesis and structure-activity relationships of novel compounds for the inhibition of TNF-alpha production

This study describes the synthesis, in vitro evaluation and molecular modeling study of novel compounds for the inhibition of TNF-alpha production. Among these compounds, 2-[3-(cyclopentyloxy)-4-methoxyphenyl]-1-isoindolinone (9) was selected as a lead compound and its pyridine derivative 10 was more potent in activity and safer than rolipram.

Thalidomide analogue CC1069 inhibits development of rat adjuvant arthritis

The cytokine tumour necrosis factor-alpha (TNF-alpha) has been implicated in the aetiology of rheumatoid arthritis in humans as well as of experimental arthritis in rodents. Thalidomide, and to a greater extent the new thalidomide analogue CC1069, inhibit monocyte TNF-alpha production both in vitro and in vivo. The aim of the present study is to establish whether these drugs block production of TNF-alpha as well as IL-2 by rat leucocytes and whether this inhibition affects the development of rat adjuvant arthritis (AA). Cultured splenocytes were stimulated with either lipopolysaccharide (LPS) or concanavalin A (Con A) in the presence of thalidomide, CC1069, or solvent, and the production of TNF-alpha and IL-2 were compared. Next, adjuvant was injected into the base of the tail of rats without or with daily intraperitoneal injections with 100-200 mg/kg per day thalidomide or 50-200 mg/kg per day CC1069. Disease activity, including ankle swelling, hind limb radiographic and histological changes, weight gain, and ankle joint cytokine mRNA levels, were monitored. CC1069, but not the parent drug thalidomide, inhibited in vitro production of TNF-alpha and IL-2 by stimulated splenocytes in a dose-dependent manner. In vivo, a dose-dependent suppression of AA disease activity occurred in the CC1069-treated animals. In contrast, thalidomide-treated rats experienced comparable arthritis severity to placebo-treated animals. There was also a reduction in TNF-alpha and IL-2 mRNA levels in the ankle joints of CC1069-treated rats compared with thalidomide- and placebo-treated arthritic rats. Early initiation of CC1069 treatment suppressed AA inflammation more efficiently than delayed treatment. We conclude that thalidomide, which did not suppress TNF-alpha or IL-2 production in vitro by Lewis rat cells, did not suppress development of rat AA. However, the development of rat AA can be blocked by the thalidomide analogue CC1069, which is an efficient inhibitor of TNF-alpha production and IL-2 in vitro.

Differential Cytokine Modulation and T Cell Activation by Two Distinct Classes of Thalidomide Analogues That Are Potent Inhibitors of TNF-α

TNF-α mediates both protective and detrimental manifestations of the host immune response. Our previous work has shown thalidomide to be a relatively selective inhibitor of TNF-α production in vivo and in vitro. Additionally, we have recently reported that thalidomide exerts a costimulatory effect on T cell responses. To develop thalidomide analogues with increased anti-TNF-α activity and reduced or absent toxicities, novel TNF-α inhibitors were designed and synthesized. When a selected group of these compounds was examined for their immunomodulatory activities, different patterns of cytokine modulation were revealed. The tested compounds segregated into two distinct classes: one class of compounds, shown to be potent phosphodiesterase 4 inhibitors, inhibited TNF-α production, increased IL-10 production by LPS-induced PBMC, and had little effect on T cell activation; the other class of compounds, similar to thalidomide, were not phosphodiesterase 4 inhibitors and markedly stimulated T cell proliferation and IL-2 and IFN-γ production. These compounds inhibited TNF-α, IL-1β, and IL-6 and greatly increased IL-10 production by LPS-induced PBMC. Similar to thalidomide, the effect of these agents on IL-12 production was dichotomous; IL-12 was inhibited when PBMC were stimulated with LPS but increased when cells were stimulated by cross-linking the TCR. The latter effect was associated with increased T cell CD40 ligand expression. The distinct immunomodulatory activities of these classes of thalidomide analogues may potentially allow them to be used in the clinic for the treatment of different immunopathological disorders.

Amino-substituted thalidomide analogs: potent inhibitors of TNF-alpha production

Thalidomide, (1), is a known inhibitor of TNF-alpha release in LPS stimulated human PBMC. Herein we describe the TNF-alpha inhibitory activity of amino substituted analogs of thalidomide (1) and its isoindolin-1-one analog, EM-12 (2). The 4-amino substituted analogs were found to be potent inhibitors of TNF-alpha release in LPS stimulated human PBMC.