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At least 19 recordsLinked to original sources

Inhibition of thalidomide teratogenicity by acetylsalicylic acid: evidence for prostaglandin H synthase-catalyzed bioactivation of thalidomide to a teratogenic reactive intermediate.

Thalidomide is a teratogenic sedative-hypnotic drug that is structurally similar to phenytoin, which is thought to be bioactivated by prostaglandin H synthase (PHS) and other peroxidases to a teratogenic reactive intermediate. The relevance of this mechanism to thalidomide teratogenicity was evaluated in pregnant New Zealand White rabbits treated with thalidomide at 11:00 A.M. on gestational days 8 to 11, with day 0 indicating the time when sperm were observed in the vaginal fluid. Thalidomide (7.5 mg/kg i.v.) produced mainly fetal limb anomalies analogous to those observed in humans. Thalidomide (25-200 mg/kg i.p.), produced a dose-related increase in a spectrum of fetal anomalies, and in postpartum lethality, but did not produce a reliable incidence of limb anomalies. In subsequent studies, pregnant does received the irreversible PHS inhibitor acetylsalicylic acid (ASA), 75 mg/kg i.p., or its vehicle, followed 2 hr later by thalidomide, 7.5 mg/kg i.v., or its vehicle. ASA pretreatment was remarkably embryoprotective, resulting in respective 61.2 and 61.4% decreases in thalidomide-initiated fetal limb anomalies (P = .002) and postpartum fetal lethality (P < .02), and a small but significant reduction in thalidomide-initiated fetal weight loss. ASA alone did not produce significant embryopathy. These results show that ASA can protect the embryo from thalidomide teratogenicity, suggesting that thalidomide may be bioactivated by PHS to a teratogenic reactive intermediate.

Animals↗

Enantioselective inhibition of TNF-alpha release by thalidomide and thalidomide-analogues.

The question whether the immunomodulating activity of rac-thalidomide resides in either the (-)-(S)- or the (+)-(R)-enantiomer was addressed by synthesis and separation of pure enantiomers of thalidomide analogues which carry a methyl-group at the asymmetric carbon atom and are thus prevented from racemization. The effect of the pure enantiomers of the thalidomide-analogues and also of the enantiomers of thalidomide on release of TNF-alpha was tested in vitro by using stimulated peripheral mononuclear blood cells. Both enantiomers of thalidomide inhibited the release of TNF-alpha equally well at low concentrations (5 and 12.5 micrograms/ml) but at higher concentrations (25 and 50 micrograms 50 micrograms/ml) there was a weak but statistically significant selectivity towards the (-)-(S)-enantiomer. In the case of the configuration-stable thalidomide-analogues there was a very pronounced and statistically significant enantioselectivity towards the (S)-form even at lower concentrations (> or = 5 micrograms/ml). The (S)-enantiomers of the thalidomide-analogues differed in their inhibitory potency from (-)-(S)-thalidomide suggesting that the introduction of the methyl-group increases the TNF-alpha-inhibitory activity while the reduction of one of the carbonyl-functions in the glutarimide-moiety to a methylene-group decreases activity. The effect of these small molecular alterations on activity and the enantioselectivity towards the (S)-enantiomers may indicate that thalidomide and its analogues directly interact with one or several cellular target-proteins.

Cells, Cultured↗

Thalidomide and thalidomide analogs reduce HIV type 1 replication in human macrophages in vitro.

Thalidomide is currently being evaluated for efficacy in alleviating some manifestations of HIV-1 infection. To determine whether thalidomide has any direct effects on HIV-1 infection, we investigated the effect of thalidomide and also of three structural analogs of thalidomide on HIV-1 replication in vitro in human monocyte-derived macrophages. The thalidomide analogs were previously shown to inhibit TNF-alpha production in vitro at much lower concentrations than thalidomide. In HIV-1-infected macrophages treated with thalidomide or thalidomide analogs, viral replication was reduced by 60 to 80% as determined by measuring viral RT activity in the culture supernatants. In all experiments the analogs inhibited HIV-1 replication more efficiently than did thalidomide. The drugs also reduced HIV-1 gag mRNA expression. Furthermore, the drugs caused a decrease in NF-kappaB-binding activity in nuclear extracts of HIV-1-infected macrophages. The role of NF-kappaB in the drug-induced inhibition of HIV-1 replication was confirmed using an NF-kappaB-defective mutant virus to infect macrophages.

Anti-HIV Agents↗

5'-OH-thalidomide, a metabolite of thalidomide, inhibits angiogenesis.

Despite its known teratogenic effects, thalidomide has been used to treat a variety of diseases ranging from alleviation of autoimmune disorders to prevention of metastasis of cancers. The exact method of action of thalidomide and its derivatives is still under investigation. Thalidomide undergoes very little metabolism by the cytochrome P 450 system in vitro, but at least two hydroxylated metabolites have been found in humans. The two metabolites are 5-hydroxythalidomide, formed by hydroxylation of the phthalimide ring, possibly via arene oxides, and 5'-hydroxythalidomide, formed by hydroxylation of the glutarimide ring, leading to diastereomeric products. These two metabolites, along with another minor metabolite of thalidomide, were tested in a rat aortic ring assay, a human saphenous vein model, and a tube formation assay to assess the metabolite's ability to inhibit angiogenesis. Of the metabolites tested, only 5'-OH-thalidomide showed biologic activity in the rat aortic ring assay, and none of the metabolites showed activity in the human model. The studies with thalidomide and thalidomide metabolites underline the difficulty and complexity of trying to isolate and evaluate a single biologically active agent. These studies, however, do suggest that at least one metabolite, 5'-OH-thalidomide, has moderate antiangiogenic activity at high concentrations. Unfortunately, because of the lack of observed activity of 5'-OH-thalidomide in the human saphenous vein assay, it remains unclear whether there is species specificity for the activity of this metabolite.

Angiogenesis Inhibitors↗

Clinical experience with thalidomide in the management of severe oral and genital ulceration in conditions such as Behçet's disease: use of neurophysiological studies to detect thalidomide neuropathy.

OBJECTIVE: To examine the efficacy, dose, and safety profile, including neurophysiological testing of thalidomide used in 59 patients (including 23 with Behçet's disease) to treat severe oral or genital ulceration (OGU). METHODS: We identified prospectively subjects (including women of childbearing potential) who had persistent OGU over periods lasting one to 40 years and whose active ulceration was not controlled by other therapies. They were treated with thalidomide. Retrospectively, we identified the number of subjects with complete resolution of the ulcers at one and two months of thalidomide therapy, and the dose required to maintain that improvement in those individuals who relapsed after stopping thalidomide. The decrease from the baseline sensory nerve action potential (baseline SNAP) amplitude value (derived from median, radial and sural nerve SNAPs) at which the development of paraesthesiae was likely to occur was also determined. RESULTS: Complete resolution of the ulcers occurred in 81% of patients within one month of thalidomide therapy at doses of 200 mg/day. No further thalidomide was required by 20% of patients responding and in the remainder improvement was maintained with smaller doses (7-200 mg/day). Using an approximate 50% decrease from baseline SNAP as an indication to discontinue thalidomide, the incidence of symptomatic neuropathy was 13.5%. No patients with a decrease of less than 42% developed neuropathy, and a further 13.5% were asymptomatic with a decrease in SNAP between 42 and 69%. Other side effects were seen in 44% of patients. There were no pregnancies and no requirement for urgent pregnancy testing. CONCLUSIONS: Thalidomide provided a useful therapeutic option in severe oral and genital ulceration which had not responded to other therapies. The physician must remain vigilant to the continuing danger of axonal neuropathy and teratogenesis at all times during thalidomide therapy.

Adolescent↗

Thalidomide and a thalidomide analogue inhibit endothelial cell proliferation in vitro.

Angiogenesis is a crucial process in inflammatory reactions as well as in tumor implantation and growth. Tumors with high rates of invasion and recurrence such as gliomas, are specially dependent on neovascularization. This suggests that inhibition of angiogenesis might reduce the growth of these tumors. Thalidomide has been previously shown to inhibit angiogenesis induced by basic fibroblast growth factor in vivo, using the rabbit corneal micropocket assay. Therefore, the effect of thalidomide and a thalidomide analogue (cc-1069) on the proliferation in vitro of endothelial and glioma cells was tested. We observed a decrease in endothelial cell proliferation in cultures treated with thalidomide or the thalidomide analogue cc-1069. The analogue inhibited endothelial cell proliferation more efficiently than thalidomide. The inhibition occurred in association with a marked decrease in the activity of the nuclear factor SP1 and a moderate inhibition of NF-kappaB activation in nuclear extracts of endothelial cells. The drugs did not impair cell viability. There was no effect of thalidomide or the thalidomide analogue on the proliferation of the glioma cell line (U251) in vitro.

Animals↗

Thalidomide for the treatment of refractory multiple myeloma: association of plasma concentrations of thalidomide and angiogenic growth factors with clinical outcome.

Recent reports showed that thalidomide has anti-angiogenic activity and is effective for the treatment of refractory multiple myeloma (MM). We examined the relationship between the clinical efficacy and adverse effects of thalidomide and the plasma concentrations of this drug as well as angiogenic growth factors in refractory MM. Ten out of twenty-four evaluable patients (42%) showed more than 25% reduction of M-protein, and eight (33%) achieved more than 50% reduction. These changes were associated with restoration of anemia and recovery of normal immunoglobulin level. Somnolence and headache, constipation, peripheral neuropathy and skin rash were frequently observed, but were well tolerated. However, grade 2 - 4 severe neutropenia was also observed in nine cases. These adverse effects other than neutropenia occurred more frequently in the patients with higher plasma concentrations of thalidomide (2.0 microg/ml at 12 h after the last administration) and were readily alleviated by dose reduction. In contrast, neutropenia developed regardless of the plasma concentration. Plasma concentrations of angiogenic growth factors were frequently elevated before treatment. After thalidomide treatment, these growth factor levels tend to decrease to near-normal ranges in responders but were still high in most non-responders. After thalidomide treatment, plasma vascular endothelial growth factor (VEGF) level was significantly reduced in responders (P = 0.025), but not in non-responders (P = 0.37). Reduction of plasma VEGF level might be an important indicator for anti-myeloma effect of thalidomide.

Adult↗

Teratogen metabolism: activation of thalidomide and thalidomide analogues to products that inhibit the attachment of cells to concanavalin A coated plastic surfaces.

Thalidomide metabolites inhibited the attachment of tumor cells to concanavalin A coated polyethylene surfaces. Thalidomide, itself, was non-inhibitory. Thalidomide activation to inhibitory products required hepatic microsomes, an NADPH-generating system, and molecular oxygen. Production of inhibitory metabolites was unaffected by either epoxide hydrolase or 1,2-epoxy-3,3,3-trichloropropane (TCPO), an inhibitor of epoxide hydrolase endogenous to hepatic S9 fraction. Therefore, the attachment inhibitor was probably not an arene oxide. Inhibition was not accompanied by cytotoxicity, as judged by trypan blue exclusion. Although uninduced hepatic microsomes from mice, rats and dogs had similar abilities to activate thalidomide, microsomes from Aroclor 1254 induced rats were relatively inactive in the system. Inhibitory metabolites were generated from the thalidomide analogues EM8 , EM12 , EM16 , EM87 , EM136 , EM255 , E350 , phthalimide, phthalimido-phthalimide, indan, 1- indanone and 1,3- indandione . Glutarimide , glutamic acid and phthalic acid did not activate to inhibitory products.

Animals↗

Stimulation of gap junctional intercellular communication by thalidomide and thalidomide analogs in human skin fibroblasts.

It has been speculated that gap junctional intercellular communication (GJIC), an intercellular signalling pathway, is involved in embryogenesis by coupling compartments of the same developmental potential. We found that thalidomide induces GJIC in human fibroblasts after activation by liver microsomes in concentrations as low as 10(-7) M. Treatment of cells with the thalidomide analog EM-12 increased GJIC without prior activation. No alteration of GJIC was detected with phthalimide and glutamate, the components of thalidomide. However, 2-phthalimido glutaric acid (PGA), a hydrolysis product of thalidomide, stimulated GJIC without activation at concentrations between 10(-10) M and 10(-5) M. We suggest modification of GJIC as a biochemical mechanism responsible for pharmacological and toxicological properties of thalidomide and related compounds.

Cell Communication↗

Interaction of thalidomide, phthalimide analogues of thalidomide and pentoxifylline with the anti-tumour agent 5,6-dimethylxanthenone-4-acetic acid: concomitant reduction of serum tumour necrosis factor-alpha and enhancement of anti-tumour activity.

DMXAA (5,6-dimethylxanthenone-4-acetic acid), a novel anti-tumour agent currently undergoing clinical evaluation, appears to mediate its anti-tumour effects through immune modulation and the production of the cytokine tumour necrosis factor-alpha (TNF). Our previous studies have shown that thalidomide, a potent inhibitor of TNF biosynthesis that has numerous biological effects, including inhibition of tumour angiogenesis, unexpectedly augments the anti-tumour response in mice to DMXAA. We show here that thalidomide (100 mg kg(-1)) has no effect when administered with inactive doses of DMXAA, and that it must be given simultaneously with an active dose of DMXAA to have its maximum potentiating effect on the growth of the murine Colon 38 adenocarcinoma. To address the issue of whether inhibition of serum TNF production is important for potentiation of anti-tumour activity, we have tested three potent analogues of thalidomide. All three analogues, when co-administered with DMXAA to mice at doses lower than those used with thalidomide, inhibited TNF production and were effective in potentiating the anti-tumour activity of DMXAA against transplanted Colon 38 tumours. One of the analogues, N-phenethyltetrafluorophthalimide, was 1000-fold more potent than thalidomide and at a dose of 0.1 mg kg(-1) in combination with DMXAA (30 mg kg(-1)) cured 100% of mice, compared with 67% for the group treated with DMXAA alone. We also tested pentoxifylline and found it to suppress TNF production in response to DMXAA and to potentiate the anti-tumour effect of DMXAA. The results are compatible with the hypothesis that pharmacological reduction of serum TNF levels might benefit the anti-tumour effects of DMXAA and suggest new strategies for therapy using this agent.

Animals↗

Thalidomide and a thalidomide analogue drug costimulate virus-specific CD8+ T cells in vitro.

CD8(+) T cell immunity is critical for protection from viral disease, such as that caused by the human immunodeficiency virus (HIV) or cytomegalovirus (CMV). It is therefore important to identify therapies that can boost antiviral immunity. The recent finding that thalidomide acts as a T cell costimulator suggested that this drug may boost antiviral CD8(+) T cell responses. In this in vitro study, in a human autologous CD8(+) T cell/dendritic cell (DC) coculture system, thalidomide and a potent thalidomide analogue were shown to enhance virus-specific CD8(+) T cell cytokine production and cytotoxic activity. The drug-enhanced antiviral activity was noted in cells from both healthy donors and persons chronically coinfected with HIV and CMV. This stimulatory effect was directed at CD8(+) T cells, and not DCs. These results suggest an application for thalidomide and the thalidomide analogue as a novel immune-adjuvant therapy in chronic viral infections.

Adjuvants, Immunologic↗

Stimulation of gap junctional intercellular communication by thalidomide and thalidomide analogs in human fetal skin fibroblasts (HFFF2) and in rat liver epithelial cells (WB-F344).

Gap junction channels maintain cell-cell communication and are essential for the coordination of tissues, playing a pivotal role in embryonal development. Gap junctional intercellular communication (GJIC), studied here in human fetal skin fibroblasts (HFFF2) and in rat liver epithelial cells (WB-F344), was almost doubled upon exposure to thalidomide (10 microM) in the presence of NADH or NADPH (20 microM). Neither in HFFF2 nor in WB-F344 cells did any detectable alteration in GJIC occur with the thalidomide analog EM 16 (10 microM), known as a non-teratogenic compound. The thalidomide analog EM 364 (10 microM) increased GJIC without prior metabolic activation. It is suggested that GJIC modification may be related to the pharmacological and toxicological properties of thalidomide.

Angiogenesis Inhibitors↗

Management of erythema nodosum leprosum by thalidomide: thalidomide analogues inhibit M. leprae-induced TNFalpha production in vitro.

Thalidomide is being successfully used for the treatment of erythema nodosum leprosum (ENL), among other disorders with inflammatory and immunological bases. Although the active molecules responsible for the diverse therapeutic activities of the drug and the sequence of reactions triggered inside the cells remain unclear, it was demonstrated that thalidomide (THAL) inhibits TNFalpha mRNA expression and protein production by stimulated monocytes and activated T lymphocytes. Patients treated with THAL experienced a reduction in serum TNFalpha levels and it diminished cytokine gene expression at the lesion site, with a concomitant abrogation of clinical symptoms. It has been reported that thalidomide as well as some its analogues decrease M. leprae-induced TNFalpha and IL-12 mRNA in vitro. THAL also reduced monocyte apoptosis in the cultures. The present data further support thalidomide's effects on TNFa synthesis and the growing need to search for new specific TNFalpha inhibitors (non-teratogenic compounds) that might be potentially used in clinical disorders such as leprosy.

Apoptosis↗

Thalidomide metabolites and analogues. 3. Synthesis and antiangiogenic activity of the teratogenic and TNFalpha-modulatory thalidomide analogue 2-(2,6-dioxopiperidine-3-yl)phthalimidine.

Versatile synthesis of the teratogenic, TNFalpha-modulatory, and antiangiogenic thalidomide analogue 2-(2,6-dioxopiperidine-3-yl)phthalimidine (1) and its direct antiangiogenic properties are described. With thalidomide or thalidomide derivatives as precursors, the synthesis involved either carbonyl reduction/thiation-desulfurization or carbonyl reduction/acyliminium ion reduction protocols. Compared to earlier studies with thalidomide, which was only active with microsomal treatment, 1 exhibited marginal inhibitory activity in the rat aortic ring assay, thereby demonstrating the requirement for metabolic activation.

Angiogenesis Inhibitors↗

Treatment of Waldenstrom's macroglobulinemia with single-agent thalidomide or with the combination of clarithromycin, thalidomide and dexamethasone.

To evaluate the activity of thalidomide in Waldenstrom's macroglobulinemia (WM), 20 patients were treated on a dose schedule that escalated from 200 mg/d to 600 mg/d. On an intention-to-treat basis, five (25%) patients achieved a partial response, which was noted within 3 months of treatment. Adverse effects were common and prevented dose escalation of thalidomide in 75% of patients and led to premature discontinuation of treatment in 35%. We subsequently evaluated the oral combination of clarithromycin (500 mg twice per day), low-dose thalidomide (200 mg once daily), and dexamethasone (40 mg once per week). Our preliminary analysis on 12 previously treated patients indicate activity of this regimen in WM: three patients achieved a partial response and two patients demonstrated monoclonal protein reduction of greater than 25%. This combination was associated with a variety of side effects due not only to thalidomide, but also to corticosteroids and to clarithromycin. Our preliminary data indicate that this combination may be a useful salvage regimen for some patients with heavily pretreated macroglobulinemia.

Angiogenesis Inhibitors↗

Teratogen metabolism: spontaneous decay products of thalidomide and thalidomide analogues are not bioactivated by liver microsomes.

Thalidomide and two analogues, EM87 and EM12, inhibited the attachment of tumor cells to concanavalin A-coated surfaces only if the drugs were first incubated with hepatic microsomes and cofactors. Most agents that inhibit attachment are demonstrated teratogens. Thalidomide undergoes spontaneous hydrolysis to at least 12 products in saline buffered to a pH of greater than 7. These hydrolysis products did not inhibit attachment nor could they be activated to inhibitory products with hepatic microsomes. Similarly EM12 and EM 87 hydrolysis products were neither inhibitory nor substrates for activation. If the three drugs were incubated in buffered saline, there was a progressive decline in their ability to act as substrates for activation to an inhibitory product. It was possible to remove microsomes from the incubation mixture following drug activation by centrifugation. This microsome-free mixture inhibited cell attachment. When mouse ovarian tumor (MOT) cells were added to the microsome-free mixture, attachment was inhibited. However, if the activated drugs were incubated in saline, there was a progressive decline in their ability to inhibit attachment. Decay rates differed for the three compounds. At a pH of 7.4, thalidomide, EM87, and EM12 required 3 h, 1h and 6h, respectively, to decay to control levels. These relative rates of decay are consistent with the relative teratogenicity of the three drugs.

Animals↗

Evidence for the intercalation of thalidomide into DNA: clue to the molecular mechanism of thalidomide teratogenicity?

The intercalation of thalidomide (alpha-phthalimidoglutarimide) into nucleic acids was studied by spectrophotometric titrations, displacement of known intercalators, viscosity changes of DNA solutions, and by phase partition analysis. Specific binding of thalidomide was found to DNA of various specimens (human placenta, calf thymus, salmon sperm), but not to RNA (from bakers yeast, torula yeast).

Animals↗