Structural modifications of thalidomide produce analogs with enhanced tumor necrosis factor inhibitory activity

Chemical stabilities and biological activities of thalidomide and its N-alkyl analogs

PURPOSE. To determine whether the N-alkyl analogs of the thalidomide are active and stable, their stabilities in buffer and their abilities to inhibit tumor necrosis factor alpha (TNF-alpha) in vitro in human peripheral blood mononuclear cell cultures were investigated.

METHODS

TNF-alpha concentrations were determined with the aid of ELISA kits. Chemical stabilities of the compounds were determined in three phosphate buffer solutions (pH 6, 6.4, and 7.4) at 25 and 32 degrees C by high-pressure liquid chromatography, and half-lives were calculated.

RESULTS

The addition of N-alkyl groups to the glutarimide ring of the thalidomide molecule had little effect on the ability such compounds have to inhibit TNF-alpha production. There was no statistical difference between the activity of thalidomide and its N-alkyl analogs at a 95% confidence level. Like thalidomide, the N-alkyl analogs in this series inhibit an average of 60% of the TNF-alpha synthesis in lipopolysaccharide-stimulated peripheral blood mononuclear cell cultures. Thalidomide and its N-alkyl analogs are hydrolyzed at very similar rates, with half-lives ranging from 25 to 35 h at 32 degrees C at pH 6.4 and an average rate constant of 2.35 x 10(-2)/h.

CONCLUSION

Alkylating thalidomide had little effect on its ability to inhibit the production of TNF-alpha in these cell cultures. All of the compounds tested seem to have some, perhaps comparable, therapeutic potential.

Thalidomide treatment for refractory Crohn's disease: a review of the history, pharmacological mechanisms and clinical literature

Several recent case reports and clinical trials have demonstrated that thalidomide is emerging as an efficacious alternative in the treatment of selected patients with refractory Crohn's disease. The effects of thalidomide are at least partly mediated by down-regulation of tumour necrosis factor (TNF)-alpha, a potent proinflammatory cytokine. However, thalidomide is also known to inhibit angiogenesis, and it has several other well-described immunomodulatory properties. Clinical studies have confirmed that previously refractory Crohn's disease patients respond to thalidomide, and many enter clinical remission. Efficacy usually occurs within 4 weeks. Thalidomide also has steroid-sparing properties, and it is particularly useful in treating oral and fistulous complications of Crohn's disease. Although it is usually tolerable, careful monitoring is recommended to prevent toxicities, such as birth defects and peripheral neuropathy. This review provides a detailed summary of the literature to date on the use of thalidomide treatment for Crohn's disease. Special attention is directed towards its history, mechanisms, and proposed role. The recent development of thalidomide analogues is also discussed briefly.

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.

Immunotherapeutic and antitumour potential of thalidomide analogues

The immunomodulatory drug thalidomide has been shown to be clinically useful in a number of conditions including various immunological disorders and cancers. Clinical activity in vivo is attributed to the wide ranging immunological and non-immunological properties possessed by this drug; these include anti-TNF-alpha, T-cell co-stimulatory, anti-angiogenic activities and also direct antitumour activity. Recently, the design of compounds based on the thalidomide structure has led to the synthesis of analogues with greatly enhanced immunological activity and with similarly decreased toxicity. These derivatives fail into at least two categories; selective cytokine inhibitory drugs (SelCID), which are phosphodiesterase Type 4 (PDE4) inhibitors and immunomodulatory drugs (IMiD), similar to thalidomide which act via unknown mechanism(s). These compounds are in the process of being characterised in laboratory studies and are also now being assessed in Phase I and Phase I/II clinical studies. In this review we will highlight the properties of these two novel classes of compound in terms of their effects on both immunological and non-immunological systems in vitro. We will also describe how these studies are enabling the characterisation and development of these compounds into clinically relevant drugs in widely varying diseases. To this end we will describe the various clinical studies of lead compounds that are in progress and speculate as to the potential and future development of these exciting compounds.

Thalidomide analogue CC-3052 reduces HIV+ neutrophil apoptosis in vitro

Thalidomide has significant immunomodulatory properties and has been used successfully in the treatment of oral ulcers and wasting in HIV patients. However, its use is limited by its poor bioavailability due to low solubility and short half life in solution, and teratogenic and neurotoxic side-effects. Recently, water-soluble analogues of thalidomide with significantly greater immunomodulatory activity and reduced side-effects have become available. We examined the effect of thalidomide and one analogue, CC-3052, on neutrophil apoptosis following culture for 20 h in vitro. Apoptosis was assessed by reduced CD16 expression and Annexin V binding using flow cytometry. Thalidomide or CC-3052 alone had no effect on neutrophil apoptosis when used at physiological levels. However, when used together with prostaglandin E2 (10-7 M), a potent adenylate cyclase activator, CC-3052 but not thalidomide (both 10-5 M) reduced apoptosis in neutrophils from normal and HIV+ donors. The reduced apoptosis could not be attributed to the ability of CC-3052 to reduce tumour necrosis factor-alpha (TNF-alpha) production, but may be due to its PDE4 inhibitor properties, as it increased [cAMP]i, and mimicked the effect of increasing [cAMP]i using dibutryl cAMP, a membrane-permeable analogue of cAMP. The results suggest a role for thalidomide analogue CC-3052 in reducing persistent activation of the TNF-alpha system in HIV without markedly impairing neutrophil viability.

[Anti-angiogenesis: a new approach to tumor therapy?]

BACKGROUND

The overall mortality due to metastatic cancer has not or only minimally been reduced in spite of intensive research and many innovations in the field of conventional antineoplastic therapy in the past decade. In the last years it has become a fact that tumor growth is angiogenesis-dependent. Therefore, inhibitors of angiogenesis are a new class of antineoplastic substances with a novel mechanism of action that might be a powerful complement to conventional cytostatic therapy. SUBSTANCES AND CLINICAL TRIALS: Inhibitors of tumor-angiogenesis which have entered clinical trials, with their results published until December 1998 are discussed here. Most results originate from phase-I or phase-II clinical trials. They are discussed and compared in respect to toxicity and response. Also some substances with high therapeutic potential which are still in preclinical testing are discussed.

RESULTS

Many of the investigated angiogenesis inhibitors demonstrated anti-tumor effects in phase-I or phase-II clinical trials. The commonest manifestation was stable disease, followed by partial remissions. In a few cases, complete remissions were observed. The toxicities of these substances differ both in type and degree of side effects.

CONCLUSION

Some antiangiogenic drugs appear to be promising candidates for a clinical use in the therapy of solid tumors. Further conclusions can only be drawn after evaluation of the results of ongoing phase-III clinical trials.

Pharmacokinetics and hemodynamic effects of single oral doses of thalidomide in asymptomatic human immunodeficiency virus-infected subjects

Thalidomide (alpha-N-phthalimidoglutarimide), a potent inhibitor of tumor necrosis factor alpha (TNF-alpha), is proving to be a promising drug in the treatment of a number of inflammatory, autoimmune, and HIV-associated disorders. The pharmacokinetics and hemodynamic effects of two single oral doses of thalidomide (100 and 200 mg) were investigated, using a randomized, two-period crossover design, in a group of asymptomatic, male HIV-seropositive subjects. Thalidomide pharmacokinetics were linear at the doses studied, and were best described by a one-compartment model with first-order absorption and elimination processes. The drug was rapidly absorbed, with a mean absorption half-life of 0.95 hr (range, 0.16-2.49 hr) and 1.19 hr (range, 0.33-3.53 hr) after 100- and 200-mg doses, respectively. The corresponding mean Cmax values were 1.15+/-0.24 microg/ml (100 mg) and 1.92+/-0.47 microg/ml (200 mg; p<0.001), which were achieved (Tmax) at 2.5+/-1.5 h and 3.3+/-1.4 hr, respectively. Plasma concentrations of thalidomide declined thereafter, in a log-linear manner, with elimination half-lives of 4.6+/-1.2 hr (100 mg) and 5.3+/-2.2 hr (200 mg). The apparent volumes of distribution (Vdss/F) were 69.9+/-15.6 liters (100 mg) and 82.7+/-34.9 liters (200 mg) while total body clearances (Cl/F) were 10.4+/-2.1 and 10.8+/-1.7 liters/hr, respectively. Significant dose-dependent decreases in supine systolic and diastolic blood pressures were seen for up to 2 hr postdosing; somnolence, headache, dizziness, and confusion were also reported more frequently at the higher dose of thalidomide.

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.

Thalidomide and its impact in dermatology

Thalidomide, originally marketed as a sedative, was introduced in West Germany in 1956 and in numerous other countries soon thereafter. In part because it did not impair coordination or respiratory function, the drug rapidly became extremely popular. By 1961, however, there were mounting reports of phocomelia and other severe congenital abnormalities associated with maternal use of thalidomide, and the drug was withdrawn from the market and its availability highly restricted. A few years later, thalidomide would find use in dermatology after it was reported that leprosy patients with erythema nodosum leprosum (ENL) experienced rapid and dramatic improvement after taking the drug as a sedative. Additional data quickly confirmed thalidomide's efficacy in ENL, and today it is the drug of choice in the condition. In subsequent decades, the drug has been successfully tried in treatment of a variety of apparently unrelated dermatologic disorders. Meanwhile, thalidomide has been shown to possess a range of biologic actions, including inhibition of tumor necrosis factor alpha, possibly relevant to its clinical efficacy. Dermatologic disorders in addition to ENL in which thalidomide's effectiveness is well documented include aphthous stomatitis, discoid lupus erythematosus, actinic prurigo, Behçet's disease, and prurigo nodularis. More recently, the drug has been employed in dermatologic conditions associated with HIV infection. When used with safeguards to prevent teratogenicity and the drug's other major adverse effect, peripheral neuropathy, thalidomide may offer a good therapeutic option for many patients in whom other drug therapies have proven inadequate.

CC-3052: A Water-Soluble Analog of Thalidomide and Potent Inhibitor of Activation-Induced TNF-α Production

The immunomodulatory drug thalidomide has been shown to be clinically useful in a number of situations due to its ability to inhibit TNF-α synthesis. However, its use is restricted by potentially serious side effects, including teratogenicity and neuorotoxicity; furthermore, insolubility may present problems in terms of systemic bioavailability. Recently, structural modifications of thalidomide have been designed enabling greatly enhanced anti-TNF-α activity in LPS-treated mice. In contrast to thalidomide (LPS-induced TNF-α IC50 ∼200 μM in DMSO) and other analogs tested, one of these compounds, CC-3052 (IC50 ∼1 μM in water), is water soluble. Furthermore, this analog exhibits increased stability in human plasma (t1/2 ∼17.5 vs 1.5 h for thalidomide) and appears to be nontoxic, nonmutagenic, and nonteratogenic. At pharmacologically active levels, cellular proliferation and LPS-induced IL-6 mRNA and IL-12p40 mRNA (as well as IL-1β and IL-6 protein levels) in whole blood cultures were not affected; apparent inhibition of NK activity by CC-3052 was reversed upon addition of exogenous rTNF-α. In addition, IL-10 mRNA and protein levels were increased. These properties are consistent with results indicating inhibition of phosphodiesterase type IV activity by CC-3052. Furthermore, CC-3052 did not increase the degradation rate of macrophage TNF-α transcripts nor inhibit LPS-induced primary macrophage NF-κB activation. Taken together, the potency of selective TNF-α inhibition, water solubility, and increased plasma stability make CC-3052 an excellent candidate for further development and clinical evaluation for the treatment of TNF-α-mediated disease.

Thalidomide analogs and PDE4 inhibition

N-Phthaloyl 3-amino-3-arylpropionic acid analogs of thalidomide that are potent inhibitors of tumor necrosis factor-alpha are reported. These compounds were found to be potent inhibitors of phosphodiesterase 4.

Enhanced potency of perfluorinated thalidomide derivatives for inhibition of LPS-induced tumor necrosis factor-alpha production is associated with a change of mechanism of action

Perfluorination of phthalimides leads to dramatically increased potency as inhibitors of TNF-alpha production. We examined the enantiodependence for several tetrafluorophthalimides and alpha-methylthalidomide, 3. Only 3 exhibited strikingly enantiodependent activity. The key structural determinant for the enhanced activity is the tetrafluorophthaloyl group, which confers enhanced potency and a change in the mechanism of inhibition.

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.