Thalidomide increases the synthesis of IL-2 in cultures of human mononuclear cells stimulated with Concanavalin-A, Staphylococcal enterotoxin A, and purified protein derivative

Role of innate immunity in chemotherapy-induced peripheral neuropathy

It has become increasingly clear that the innate immune system plays an essential role in the generation of many types of neuropathic pain including that which accompanies cancer treatment. In this article we review current findings of the role of the innate immune system in contributing to cancer treatment pain at the distal endings of peripheral nerve, in the nerve trunk, in the dorsal root ganglion and in the spinal dorsal horn.

Thalidomide does not interfere with graft-versus-leukemia reactivity in mice

Objective. To determine whether thalidomide is an effective prophylactic agent against acute graft-versus-host disease (GVHD) and whether it exerts an effect on graft-versus-leukemia (GVL) reactivity, the drug was administered to leukemic mice that were exposed to allogeneic bone marrow transplantation.

Methods. Mice (BALB/c 3 C57BL/6) F1 were inoculated with 107 B cell leukemia cells (BCL1) and conditioned with total body irradiation followed by reconstitution with bone marrow plus splenic cells harvested from C57BL/6 mice. After transplant, mice were treated with oral thalidomide (20 mg/kg/day) for a period of 10 days.

Results. Stable chimerism was documented in all recipients with $73% (mean) donor-type C57 cells. In this semi-allogeneic murine model, thalidomide failed to prevent or alleviate the acute GVHD symptoms; however, the drug did not impair GVL reactivity. The antileukemia allogeneic effect was similar in the thalidomide and non-thalidomide-treated animals. Comparison of the GVL reactivity occurring in the allogeneically transplanted groups with that in the syngeneic recipients revealed a significant difference ( P 5 0.001).

Conclusions. Although thalidomide did not exert any effect against acute GVHD, the fact that the GVL reactivity was spared holds promise for its use as a treatment modality in chronic GVHD.

Lenalidomide alone or lenalidomide plus dexamethasone significantly inhibit IgG and IgM in vitro... A possible explanation for their mechanism of action in treating multiple myeloma

Lenalidomide (len) is an analog of thalidomide (thal), and both are used in the treatment of a diverse group of medical conditions. A common finding in this group is the detection of immunoglobulin in skin lesions, or high levels of immunoglobulin or myeloma protein in serum and urine. While their mechanism(s) of action is not known, the drugs are noted for their ability to modulate monocyte, lymphocyte, and natural killer cell functions; suppression of immunoglobulin synthesis could offer an explanation for their effectiveness in treating multiple myeloma (MM). Our objective was to determine if, on an equimolar basis, thal, len or dexamethasone (dex) could affect pokeweed (PWM)-induced synthesis of IgG, IgM and IL-2. When peripheral blood mononuclear cells were stimulated with PWM, len surpassed thal in suppressing IgM and IgG, and enhancing IL-2. Dex enhanced IgG, and suppressed IL-2. When the stimulated cells were treated with len (an effective promoter of IL-2 and suppressor of IgM and IgG) plus dex (an effective suppressor of IL-2 and enhancer of IgG), the net result was suppression of IgM and IgG. The synthesis of IgM and IgG by putative PWM-stimulated B cell blasts is significantly blocked by len. This suggest that the B-lymphocyte is a targeted cell for len, and that suppression of the synthesis of IgG and IgM could provide an explanation for the mechanism by which len effectively treats MM.

Thalidomide inhibited the synthesis of IgM and IgG whereas Thalidomide+Dexamethasone and Dexamethasone alone acted as co-stimulants with pokeweed and enhanced their synthesis

Thalidomide (Thal) provides effective treatment for erythema nodosum leprosum (ENL). In combination with Dexamethasome (Dex) it is an effective treatment for multiple myeloma (MM) and Waldenström's macroglobulinemia (WM). Thal's mechanism(s) of action in the treatment of these diverse medical conditions is not known, but it could be suppression of immunoglobulin (Ig) synthesis. Mononuclear cells were stimulated with pokeweed (PWM), and treated with Thal, Thal+Dex or Dex. The cultures were assayed for IgM and IgG. The maximum synthesis was expected to occur in cultures stimulated with PWM at 0.5, 5.0 or 10 microg/ml. The test agents at 15 microM each were expected to alter the response. Compared to cultures stimulated with PWM alone, there was significantly less Ig in the cultures containing Thal+PWM, and significantly more Ig in the cultures containing Thal+Dex+PWM or Dex+PWM (Wilcoxon). The median % of maximum was 57 for cultures treated with Thal+PWM; 184 for cultures treated with Thal+Dex+PWM, and 139 for cultures treated with Dex+PWM. Thal also acted as a co-stimulant with PWM and enhanced the synthesis of IL-2, IL-6 and DNA; whereas, Thal+Dex or Dex enhanced Ig synthesis, but suppressed IL-2, IL-6 and cell proliferation. Thal's ability to suppress Ig may explain its activity in ENL, MM and WM. The enhancement of Ig by Dex does not help to explain a role for Dex alone or in combination with Thal for the treatment of MM and WM.

Design, synthesis and antitumor evaluation of novel thalidomide dithiocarbamate and dithioate analogs against Ehrlich ascites carcinoma-induced solid tumor in Swiss albino mice

A series of 16 novel thalidomide sulfur analogs containing one and two sulfur atoms 2 and 4-18, respectively, were designed and synthesized. These compounds were screened for in vitro antitumor activity against Ehrlich ascites carcinoma (EAC) cell line and exhibited potent cytotoxic activity. On the bases of the obtained results for in vitro cytotoxic activity, thalidomide sulfur analogs containing two sulfur atoms 8, 9, 13 and 14 were selected and tested in vivo against EAC-induced solid tumor in female mice compared to thalidomide 1 as well as its analog 2 and exhibited a highly significant reduction in tumor volume (TV). Results illustrated the antioxidative activity of these compounds as the level of hepatic lipid peroxidation decreased and levels of antioxidant enzymes like superoxide dismutase (SOD) and catalase were elevated. The histopathological investigations revealed that thalidomide sulfur analogs 2, 8, 9, 13 and 14 have antimitotic, apoptotic and necrotic activities against solid tumor. These compounds lead to increase of Fas-L expression. The immunohistochemical studies showed a decrease in Ki67 and vascular endothelial growth factor (VEGF) staining in tumor cells from treated-animals when compared with non-treated groups, which suggests an inhibition of tumor proliferation rate and angiogenic process associated with tumor growth. Compounds 9 and 13 were the most potent compounds in tumor necrosis without liver necrosis. At the same time, treatment with compound 9 resulted in liver degeneration.

Thalidomide suppressed IL-1beta while enhancing TNF-alpha and IL-10, when cells in whole blood were stimulated with lipopolysaccharide

Thalidomide is used to treat erythema nodosum leprosum (ENL). The events that precipitate this inflammatory reaction, which may occur in multibacillary leprosy patients, and the mechanism by which thalidomide arrest ENL, are not known. Thalidomide's ability to inhibit tumor necrosis factor alpha (TNF-alpha) in vitro has been proposed as a partial explanation of its effective treatment of ENL. In in vitro assays, thalidomide can enhance or suppress TNF-alpha. This is dependent on the stimulant used to evoke TNF-alpha; the procedure used to isolate the mononuclear cells from blood, and the predominant mononuclear cell type in the culture. To avoid artifacts that may occur during isolation of mononuclear cells from blood, we stimulated normal human blood with LPS and evaluated the effect of thalidomide and dexamethasone on TNF-alpha, and other inflammatory cytokines and biomarkers. Thalidomide suppressed interleukin 1 beta (IL-1beta) (p = 0.007), and it enhanced TNF-alpha (p = 0.007) and interleukin 10 (IL-10) (p = 0.031). Dexamethasone enhanced IL-10 (p = 0.013) and suppressed IL-1beta, TNF-alpha, interleukin 6 (IL-6), and interleukin 8 (IL-8) (p = 0.013). The two drugs did not suppress: C-reactive protein (CRP), Ig-superfamily cell-adhesion molecule 1 (ICAM 1), tumor necrosis factor receptor 1 (TNFR1), tumor necrosis factor receptor 2 (TNFR2), or amyloid A. In vitro and in vivo evidence is accumulating that TNF-alpha is not the primary cytokine targeted by thalidomide in ENL and other inflammatory conditions.

Thalidomide: mechanisms of action

The classification of thalidomide as an orphan drug with anti-inflammatory actions has led to its off-label use in conditions refractory to other medications. Although the observed clinical effects of thalidomide suggest it to have immunomodulatory capabilities, the mechanism of action is unclear. Here we review both the positive and negative studies of thalidomide at the bench in order to improve our understanding of the possible mechanisms of this drug in treating a variety of diseases at the bedside. Studies on the effects of thalidomide on the innate and adaptive immune system as well as tumorigenesis and angiogenesis are discussed.

Thalidomide suppressed interleukin-6 but not tumor necrosis factor-alpha in volunteers with experimental endotoxemia

An early rationale for using thalidomide to treat erythema nodosum leprosum had been based on some reports that it suppresses tumor necrosis factor-alpha (TNF-alpha). However, in vivo and in vitro studies have yielded variable results, having shown that thalidomide can either enhance or suppress TNF-alpha. Since the course of circulating cytokines like TNF-alpha after infusion of endotoxin into volunteers is reproducible and characteristic, we investigated the effect of thalidomide on endotoxin-induced synthesis of TNF-alpha, interleukin (IL)-6, and IL-8. The cytokine response from 18 placebo-treated subjects who had undergone the endotoxin challenge were pooled with a placebo-treated subject from the current study and were compared with 4 subjects who received thalidomide (100 mg) every 6 h for 5 doses before endotoxin challenge. Thirty minutes after the last dose of thalidomide or placebo, volunteers were infused with 4-ng/kg endotoxin. Plasma was collected and assayed for cytokines by enzyme-linked immunosorbent assay. Endotoxin evoked the synthesis of the cytokines in all volunteers. The peak response for TNF-alpha was 1.5 h, 2.5 h for IL-8, and 3.0 h for IL-6. Thalidomide did not significantly delay the release of cytokines into the circulating blood. At the peak response, thalidomide reduced the concentration of the cytokines in the plasma. Using the area under the dose response curve (AUC(0 to 24) h), thalidomide reduced the AUC for IL-6 by 56%, for IL-8 by 30%, and TNF-alpha by 32%. In this model, thalidomide did not suppress TNF-alpha or IL-8, but it did suppress IL-6 at 4-h postinfusion with lipopolysaccharide (P=0.004), at 6 h (P=0.014), at 12 h (P=0.001), and at 16 h (P=0.012).

Effect of thalidomide on the expression of TNF-alpha m-RNA and synthesis of TNF-alpha in cells from leprosy patients with reversal reaction

Hypersensitivity reactions called reversal reaction (RR) and erythema nodosum leprosum (ENL) occur in leprosy. They are characterized by an increase in tumor necrosis factor-alpha (TNF-alpha). Thalidomide is an effective treatment for ENL but not RR. Its effectiveness in ENL is attributed to inhibition of TNF-alpha, and this does not explain its failure to treat RR. We assessed thalidomide's effect on TNF-alpha in RR. Mononuclear cells from RR and non-RR patients and healthy individuals were treated with thalidomide and M.leprae (AFB), a cytosol fraction of M. leprae or Dharmendra lepromin. Thalidomide suppressed TNF-alpha, but when some RR patients' cells were stimulated with AFB, it enhanced TNF-alpha.

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.

Immune parameters in multiple myeloma patients: influence of treatment and correlation with opportunistic infections

The present study evaluated cellular and humoral immune parameters in myeloma patients, focusing on the effect of treatment and the risk of opportunistic infections. Peripheral blood lymphocyte subsets and serum levels of nonmyeloma immunoglobulins (Ig) were analysed in 480 blood samples from 77 myeloma patients. Untreated myeloma patients exhibited significantly reduced CD4+/45RO+, CD19+, CD3+/HLA-DR+, and natural killer (NK) cells, as well as nonmyeloma IgA, IgG and IgM. Conventional-dose chemotherapy resulted in significantly reduced CD4+ and even further decline of CD4+/CD45RO+ and CD19+ cells, most notably in relapsed patients. Additional thalidomide treatment had no significant effects on these parameters. Following high-dose chemotherapy (HD-CTX), prolonged immunosuppression was observed. Although CD8+, NK, CD19+ and CD+/CD45RO+ cells recovered to normal values within 60, 90, 360 and 720 days, respectively, CD4+ counts remained reduced even thereafter. Nine opportunistic infections were observed, including five cytomegalovirus (CMV) diseases, one Pneumocystis carinii pneumonia (PCP) and three varicella zoster virus infections with CMV diseases and PCP occurring exclusively after HD-CTX. Opportunistic infections were correlated with severely reduced CD4+, as well as CD4+/CD45RO+ and CD19+ counts. Thus, myeloma patients display cellular and humoral immunodeficiencies, which increase following conventional as well as HD-CTX, and constitute an important predisposing factor for opportunistic infections.

Selective leukemic-cell killing by a novel functional class of thalidomide analogs

Using a novel cell-based assay to profile transcriptional pathway targeting, we have identified a new functional class of thalidomide analogs with distinct and selective antileukemic activity. These agents activate nuclear factor of activated T cells (NFAT) transcriptional pathways while simultaneously repressing nuclear factor-kappaB (NF-kappaB) via a rapid intracellular amplification of reactive oxygen species (ROS). The elevated ROS is associated with increased intracellular free calcium, rapid dissipation of the mitochondrial membrane potential, disrupted mitochondrial structure, and caspase-independent cell death. This cytotoxicity is highly selective for transformed lymphoid cells, is reversed by free radical scavengers, synergizes with the antileukemic activity of other redox-directed compounds, and preferentially targets cells in the S phase of the cell cycle. Live-cell imaging reveals a rapid drug-induced burst of ROS originating in the endoplasmic reticulum and associated mitochondria just prior to spreading throughout the cell. As members of a novel functional class of "redoxreactive" thalidomides, these compounds provide a new tool through which selective cellular properties of redox status and intracellular bioactivation can be leveraged by rational combinatorial therapeutic strategies and appropriate drug design to exploit cell-specific vulnerabilities for maximum drug efficacy.

The continuing challenges of leprosy

Leprosy is best understood as two conjoined diseases. The first is a chronic mycobacterial infection that elicits an extraordinary range of cellular immune responses in humans. The second is a peripheral neuropathy that is initiated by the infection and the accompanying immunological events. The infection is curable but not preventable, and leprosy remains a major global health problem, especially in the developing world, publicity to the contrary notwithstanding. Mycobacterium leprae remains noncultivable, and for over a century leprosy has presented major challenges in the fields of microbiology, pathology, immunology, and genetics; it continues to do so today. This review focuses on recent advances in our understanding of M. leprae and the host response to it, especially concerning molecular identification of M. leprae, knowledge of its genome, transcriptome, and proteome, its mechanisms of microbial resistance, and recognition of strains by variable-number tandem repeat analysis. Advances in experimental models include studies in gene knockout mice and the development of molecular techniques to explore the armadillo model. In clinical studies, notable progress has been made concerning the immunology and immunopathology of leprosy, the genetics of human resistance, mechanisms of nerve injury, and chemotherapy. In nearly all of these areas, however, leprosy remains poorly understood compared to other major bacterial diseases.

Thalidomide in multiple myeloma

Multiple myeloma is an incurable bone marrow cancer, the treatment of which is notoriously difficult. Only modest advances have been achieved using complex polychemotherapeutic regimens, transplant strategies and supportive therapy. In 1999, when new drugs for myeloma were urgently needed, thalidomide was introduced and opened up a completely new line of therapy for the disease. Although the mechanism of action is not yet completely understood, thalidomide has demonstrated efficacy in patients with refractory, relapsed myeloma, even in late-stage cases. This article reviews the current knowledge of thalidomide in myeloma treatment, focusing especially on the possible mechanisms of action, clinical results and adverse events of this drug.

Thalidomide therapy for myelofibrosis with myeloid metaplasia

BACKGROUND

Thalidomide is a putative antiangiogenesis agent with activity in several hematologic malignancies.

METHODS

Forty-four patients who had myelofibrosis with myeloid metaplasia received treatment with thalidomide in a Phase II clinical trial at a dose of 200 mg daily with escalation by 200 mg weekly until the best tolerated dose (maximum, 800 mg) was reached.

RESULTS

Seventeen of 41 evaluable patients (41%) who received treatment for at least 15 days had a response. A complete response (without reversal of bone marrow fibrosis) was achieved in 4 patients (10%), a partial response was achieved in 4 patients (10%), and hematologic improvements in anemia, thrombopenia, and/or splenomegaly were observed in 9 patients (21%). Improvements in anemia occurred in 7 of 35 patients (20%) with hemoglobin levels <10.0 g/dL, and improvements in thrombopenia occurred in 5 of 24 patients (21%) with platelet counts <100 x 10(9)/L. Five of 24 patients (21%) became transfusion-independent. Major or minor regression of splenomegaly was noted in 9 of 29 evaluable patients (31%), and complete regression was noted in 5 patients. Responders had a lower baseline median vascular endothelial growth factor levels (77.9 pg/mL vs. 97.7 pg/mL; P <.01) and higher median basis fibroblast growth factor levels (60.8 pg/mL vs. 37.4 pg/mL; P <.01) compared with nonresponders. Nine patients (22%) had deterioration that was attributed to thalidomide (resolved after withdrawal) with either progressive cytopenias or excessive proliferation. Two patients developed Grade 3 neutropenia with recovery and resumed therapy with dose reductions, and both later achieved a complete response. Dose-related toxicities included fatigue (50%), constipation (48%), rash or pruritus (37%), sedation (35%), peripheral edema (29%), tremors (23%), peripheral neuropathy (22%), and orthostasis (16%).

CONCLUSIONS

Thalidomide warrants further evaluation in patients with MMM, particularly in combination regimens, along with the investigation of newer analogs.

Phase I/II study of thalidomide in combination with interleukin-2 in patients with metastatic renal cell carcinoma

BACKGROUND

The purpose of the study was to determine, in a Phase I/II study, the efficacy and safety profile of thalidomide with interleukin-2 (IL-2) in patients with metastatic renal cell carcinoma (MRCC).

METHODS

Fifteen patients (8 of whom were previously treated) enrolled in Phase I were treated with escalating doses of oral thalidomide (200-600 mg) and a fixed dose of IL-2 (7 mIU/m(2)) by subcutaneous injection. A course was 6 weeks, with the exception of Course 1, which was 7 weeks. Thirty-seven Phase II patients who had not received prior chemotherapy or immunotherapy for renal cell carcinoma (RCC) received an initial thalidomide dose of 200 mg at Week 0, which was escalated to 400 mg after 48 hours. Subcutaneous IL-2 was administered at the same fixed daily dose used in Phase I.

RESULTS

Fifty-one of 52 Phase I/II patients were evaluable. Twenty-seven patients (52%) experienced disease control, including 4 (8%) complete responses, 15 (29%) partial responses, and 8 (15%) cases of stable disease. Disease progression was observed in 24 patients (47%). Survival in the 2 phases ranged from 4 weeks to 45.2+ months. At the time of last follow-up, 2 of 51 patients (4%) remained on maintenance thalidomide therapy and continue to be followed. Three of the 51 patients with CRs (6%) ceased thalidomide therapy at 23-25 months and have maintained their responses to date. One complete responder was lost to follow-up. As of January 2005, 14 of 51 patients (27%) remained alive. Toxicities were mild to moderate, including Grade 1 to 2 somnolence, constipation, neuropathy, rash, flu-like symptoms, fluid retention, hypotension, and hypothyroidism (according to version 2.0 of National Cancer Institute Common Toxicity Criteria). In addition, two patients experienced deep venous thrombosis.

CONCLUSIONS

Thalidomide in combination with IL-2 is tolerable and can produce durable, active responses in patients with MRCC. To evaluate the merits of thalidomide as a valuable agent against MRCC and to more fully determine the efficacy of thalidomide/IL-2 combination therapy, the scrutiny of Phase III testing is required. Further development of thalidomide/IL-2 combination therapy will be the focus of this group.

Therapeutic renaissance of thalidomide in the treatment of haematological malignancies

Very few drugs had a history similar to that of thalidomide (alpha-N-[phthalimido] gluramide). First introduced in the late 1950s in Germany, in 1961 thalidomide was withdrawn due to its teratogenic effects. More than three decades after, it is attracting growing interest because of its reported immunomodulatory and anti-inflammatory properties. The discovery that thalidomide inhibits angiogenesis led to preclinical and clinical trials as an anticancer agent in the treatment of solid tumours and haematological malignancies, as summarized in this review article. More recently, structural analogues of thalidomide have been synthesized in order to explore potential molecular targets of thalidomide, as well as to identify new agents with improved therapeutic efficacy.

In vitro dendritic cell generation and lymphocyte subsets in myeloma patients: influence of thalidomide and high-dose chemotherapy treatment

While vaccination with antigen-pulsed dendritic cells (DCs) represents a promising therapeutic strategy in multiple myeloma (MM), clinical benefit, so far, has been limited to individual patients. To identify potential problems with this approach, we have analyzed the influence of treatment parameters, in particular high-dose chemotherapy (HD-CTX) and thalidomide, on in vitro DC generation and peripheral blood lymphocyte subsets in MM patients. From a total of 25 MM patients, including 14 patients on thalidomide treatment and 11 after HD-CTX, in vitro DC generation from peripheral blood monocytes under serum-free condition was investigated. In addition, peripheral blood lymphocyte subsets were assessed in 17 patients including 10 patients on thalidomide treatment and 9 patients after HD-CTX. Efficient in vitro generation of DCs (median 7.1x10(6)/100 ml peripheral blood; range 0.1-42.5x10(6)/100 ml peripheral blood) expressing DC-typical surface markers was observed in 23 MM patients (92%), although reduced expression of CD1a, CD40, CD83, and HLA-DR was observed in patients treated with thalidomide. With respect to lymphocyte subsets, MM patients showed significantly (p<0.05) reduced B and CD4+ lymphocytes in the peripheral blood. This effect was most prominent within 6 months of HD-CTX and in patients receiving thalidomide (usually in combination with CTX). CD8+ lymphocytes were significantly increased in MM patients. Thus, despite the well-known deficiencies in their immune system, adequate numbers of DCs can be generated in most myeloma patients. In patients treated with thalidomide, however, it remains to be seen whether the reduced expression of co-stimulatory molecules has functional relevance.

Thalidomide Is Inactive in Heavily Pretreated Patients with Metastatic Breast Cancer

Experimental studies have demonstrated that thalidomide has anti-tumor activity mediated by blockage of angiogenesis, with clinical efficacy in multiple myeloma, glioblastoma multiforme, and renal cell cancer. We investigated the therapeutic activity and toxicity of thalidomide in patients with progressive metastatic breast cancer pretreated with chemotherapy. Inclusion criteria were metastatic breast cancer in progression of disease after at least two lines of chemotherapy, age > or = 18 years, performance status < or = 2, and adequate hematologic, renal, and hepatic functions. Twelve patients entered the study, eight of whom were pretreated with three or more lines of chemotherapy (66.7%). Thalidomide was well tolerated: the most common side effects were constipation and somnolence (58.3% of patients). No objective response or durable stable disease was observed. Median time to progression and median overall survival were 8 weeks (range, 4-10 weeks) and 16 weeks (range, 8-54 weeks), respectively. In conclusion, thalidomide is an ineffective treatment in patients with progressive metastatic breast cancer heavily pretreated with chemotherapy.

Thalidomide in combination with dexamethasone for pretreated patients with multiple myeloma: serum level of soluble interleukin-2 receptor as a predictive factor for response rate and for survival

The aim of this study was to assess the side effects and the efficacy of thalidomide alone or in combination with dexamethasone in relapsed multiple myeloma (MM) and to evaluate possible predictive factors for response rate and survival. Twenty-nine pretreated patients were enrolled, including 13 patients with a relapse after high-dose chemotherapy. The median number of relapses was 3 (range: 1-7). Twenty-two patients received thalidomide in combination with dexamethasone and seven patients thalidomide alone. The dosage of thalidomide was 400 mg/day and the dosage of dexamethasone 20 mg/m2 daily for 4 consecutive days every 3 weeks. Cycles of dexamethasone were given until maximal decline of myeloma protein was achieved, whereas therapy with thalidomide was maintained until disease progression. Responses occurred in 62% of patients, including 5 (17%) complete remissions and 13 (45%) partial remissions. The median event-free survival (EFS) was 7.2 months and the median overall survival (OS) 26.1 months. In multivariate analysis, pretreatment serum levels of soluble interleukin-2 receptor (sIL-2R) were a significant prognostic factor for EFS, and those of beta2-microglobulin (beta2M) and sIL-2R for OS. Serum levels of sIL-2R significantly increased after 3 weeks of treatment in 89% of patients, possibly representing lymphocyte activation induced by thalidomide. Two patients died of septic complications within 3 months after starting treatment with thalidomide and dexamethasone and one patient of herpes encephalitis after 26 months of treatment with thalidomide alone. Also, one case of pneumonia and one case of deep venous thrombosis of the lower limb occurred. Other side effects were somnolence, peripheral neuropathy, and bradycardia occurring in 35, 55, 38 and 55% of patients, respectively. The combination of thalidomide and dexamethasone is an effective therapy in heavily pretreated myeloma patients with a high response rate and acceptable toxicities. A powerful predictive factor both for EFS and OS was the pretreatment serum level of sIL-2R.

Tumor angiogenesis in the bone marrow of multiple myeloma patients and its alteration by thalidomide treatment

Angiogenesis in solid tumors is important to tumor growth, invasion and metastasis. Recently, it has been suggested that angiogenesis plays a certain role in the development of hematopoietic malignancies, including leukemia and multiple myeloma. We evaluated tumor angiogenesis in the bone marrow (BM) of multiple myeloma (MM) patients by calculating microvessel density (MVD) in needle-biopsy specimens obtained from 51 cases of untreated MM or monoclonal gammopathy of undetermined significance (MGUS). The MVD in the BM of donors for transplantation and patients with non-hematological diseases was calculated as a control. There was an obvious increase in MVD in the BM of MM patients, and the MVD correlated with the grade of myeloma cell invasion of the BM in the untreated MM cases. It was recently reported that thalidomide might be effective for the treatment of MM. We assessed the effect of thalidomide on angiogenesis in BM treatment of 11 patients with refractory MM. The concentration of M-protein in the serum or urine of seven of the 11 patients was reduced by at least 30% after thalidomide treatment, and MVD in the BM decreased in three of these seven cases in response to thalidomide. Increased plasma concentrations of basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF) were observed in all 11 cases before thalidomide administration and both levels were reduced after treatment with thalidomide. Augmented angiogenesis in the bone marrow of MM patients was confirmed in the present study. It seems that thalidomide is effective in the treatment of MM through the impairment of angiogenesis by decreasing FGF-2 and VEGF production. This is the first report on pathological evidence in the bone marrow of MM before and after thalidomide treatment, in Japan.

Thalidomide: a new anticancer drug?

Experimental studies have demonstrated that thalidomide (Thal), a drug developed as a sedative, has antitumoural properties. The possible antitumour mechanisms of action involve: inhibition of angiogenesis, cytokine-mediated pathways, modulation of adhesion molecules, inhibition of cyclooxygenase-2 and stimulation of immuno response. Therefore, Thal is under clinical evaluation in oncology. This paper provides an overview of the data currently available in literature regarding, in terms of activity and toxicity, the use of Thal in cancer patients. Multiple myeloma is so far the most responsive malignancy. A moderate activity has been documented in certain solid tumours: glioblastoma multiforme, renal cell carcinoma and malignant melanoma. Tolerability is generally satisfactory with peripheral neuropathy being the most relevant dose-dependent toxicity. The more frequent, but moderate side effects are: somnolence, constipation, dizziness and fatigue. More studies are needed to properly evaluate the anticancer activity of Thal alone or in combination with other anticancer treatments. Preliminary studies suggest promising results of Thal in combinations with corticosteroids and cytotoxic drugs as front-line therapy of multiple myeloma. Regarding therapy of solid tumours in the adult, combination with chemotherapy, radiation therapy and molecular-targeting compounds are under investigation.

Novel therapies in multiple myeloma

The discovery of the activity of thalidomide in myeloma in the late 1990s transformed the therapy of myeloma dramatically. Apart from providing a useful treatment option for patients with myeloma, it has spurred clinical investigation of several other nonchemotherapeutic agents for this disease. These active, promising agents include CC-5013 (a thalidomide analog) and bortezomib (a proteasome inhibitor), as well as other agents, such as arsenic trioxide, ENMD 0995 and 2-methoxyestradiol. Preliminary data show that a number of these agents are active in treating disease that has relapsed after conventional chemotherapy as well as after high-dose therapy and transplantation, and some agents are active even after other novel agents have failed. The only novel drug that is commercially available currently is thalidomide, which has a therapeutically relevant benefit at all stages of the disease. A therapeutic trial of thalidomide is essential for all patients with myeloma. There are in vitro and in vivo data showing synergy between some of the novel agents. Although these novel drugs are typically used for treating disease that is refractory to or has relapsed after cytotoxic therapy, it is likely that they will start being used as part of frontline therapy, either by themselves or in combination with chemotherapy.

A pilot study of thalidomide in patients with progressive metastatic renal cell carcinoma

BACKGROUND

The highly vascular nature of renal cell carcinoma (RCC) suggests that angiogenesis inhibition may be therapeutic for patients with this disease. Thalidomide inhibits basic fibroblast growth factor and vascular endothelial growth factor (VEGF)-induced angiogenesis.

METHODS

In a pilot study, we evaluated the safety and efficacy of escalating doses of thalidomide in patients with progressive metastatic RCC (mRCC), measurable disease, and good organ function. Patients received oral thalidomide starting at 200 mg per day and increasing by 100-200 mg per day weekly until a target dose of 1200 mg per day was reached. Study endpoints were objective tumor response and toxicity.

RESULTS

Of the 20 patients enrolled, 19 were evaluable for response. Eighteen achieved the target dose. The most common, but reversible, toxicities were constipation, somnolence, and fatigue. Peripheral neuropathy was seen after prolonged therapy, necessitating dose reduction. Two patients achieved a partial response and nine had stable disease for a median of 14 months (range, 3-17 months). Median time to progression was 4.7 months (range, 0.7-31.3 months). Fifteen patients died (median survival, 18.1 months; 95% lower confidence bound 10.7). Survival was significantly longer in patients with higher hemoglobin level and longer time from first metastasis to start of thalidomide, but significantly shorter in patients with multiple organ involvement and previous treatments.

CONCLUSIONS

Thalidomide at this dose is associated with manageable acute toxicities but long-term dose-limiting neuropathy. Objective responses are rare in patients with mRCC and are characterized by delay in achieving maximum tumor reduction. Prolonged stable disease is seen in some patients, but the benefit of thalidomide, as well as other angiogenesis inhibitors, in that setting needs to be studied in controlled, randomized trials.

Thalidomide can costimulate or suppress CD4+ cells' ability to incorporate [H3]-thymidine--dependence on the primary stimulant

Thalidomide is a drug that can enhance mitogen- and antigen-stimulated cells' ability to synthesize IL-2. To assess if thalidomide could concomitantly enhance the synthesis of IFN-gamma and incorporation of [H3]-thymidine, peripheral blood mononuclear cells (PBMC) were incubated in the presence or absence of thalidomide and staphylococcal enterotoxin A (SEA), anti-CD3, Con-A or PHA. After 18 h, the cultures were sampled for IL-2. At the termination of the 3-day cultures, they were assayed for IFN-gamma and incorporation of [H3]-thymidine. Regardless of the mitogen used to stimulate the PBMC, the thalidomide-treated PBMC produced more IL-2 than controls. Thalidomide enhanced IFN-gamma synthesis in the Con-A and anti-CD3-stimulated PBMC. It suppressed the ability of SEA and PHA-stimulated PBMC to incorporate [H3]-thymidine, whereas it enhanced incorporation of [H3]-thymidine in PBMCs stimulated with anti-CD3. When the PBMC were enriched for CD4+ or CD8+ cells, the SEA- and anti-CD3-stimulated CD4+ cells responded far better than the CD8+ cells in the synthesis of IL-2 and incorporation of [H3]-thymidine. In the thalidomide-treated SEA-stimulated CD4+ and CD8+ cells, thalidomide acted as a costimulant to enhance the synthesis of IL-2. In the anti-CD3-stimulated thalidomide-treated cultures of PBMC enriched for CD4+ cells, thalidomide acted as a costimulant to enhance the incorporation [H3]-thymidine. Thalidomide cooperated with all of the mitogens to enhance T-cell synthesis of IL-2. However, depending on the stimulant, thalidomide could suppress or enhance PBMC incorporation of [H3]-thymidine. The SEA-stimulated cells targeted by thalidomide to suppress incorporation of [H3]-thymidine were CD4+. CD4+ cells stimulated with anti-CD3 were enhanced by thalidomide in their ability to synthesize IL-2 and to incorporate [H3]-thymidine. Increased production of IL-2 by activated T cells may be a mechanism through which thalidomide exerts its immunomodulatory effects.

Thalidomide in cancer treatment: a potential role in the elderly?

There is increased interest in the treatment of cancer with thalidomide because of its antiangiogenic, immunomodulating and sedative effects. In animal models, the antitumour activity of thalidomide is dependent on the species, route of administration and coadministration of other drugs. For example, thalidomide has shown antitumour effects as a single agent in rabbits, but not in mice. In addition, the antitumour effects of the conventional cytotoxic drug cyclophosphamide and the tumour necrosis factor inducer 5,6-dimethylxanthenone-4-acetic acid (DMXAA) were found to be potentiated by thalidomide in mice bearing colon 38 adenocarcinoma tumours. Further studies have revealed that thalidomide upregulates intratumoral production of tumour necrosis factor-alpha 10-fold over that induced by DMXAA alone. Coadministration of thalidomide also significantly reduced the plasma clearance of DMXAA and cyclophosphamide. All these effects of thalidomide may contribute to the enhanced antitumour activity. Recent clinical trials of thalidomide have indicated that it has minimal anticancer activity for most patients with solid tumours when used as a single agent, although it was well tolerated. However, improved responses have been reported in patients with multiple myeloma. Palliative effects of thalidomide on cancer-related symptoms have also been observed, especially for geriatric patients with prostate cancer. Thalidomide also eliminates the dose-limiting gastrointestinal toxic effects of irinotecan. There is preliminary evidence indicating that the clearance of thalidomide may be reduced in the elderly. The exact role of thalidomide in the treatment of cancer and cancer cachexia in the elderly remains to be elucidated. However, it may have some value as part of a multimodality anticancer therapy, rather than as a single agent.

Thalidomide, an antiangiogenic agent with clinical activity in cancer

Despite the teratogenic past of thalidomide, there is recent evidence indicating the drug's efficacy in the management of various diseases from immune disorders to cancers. The history, pharmacodynamic and pharmacokinetic properties of thalidomide in the clinic are discussed in this review article.

Thalidomide in multiple myeloma

Thalidomide--removed from widespread clinical use by 1962 because of severe teratogenicity--has anti-angiogenic and immunomodulatory effects, including the inhibition of TNF alpha. It has returned to practice as an effective oral agent in the management of various disease states including erythema nodosum leprosum, for which it was FDA-approved in 1998, and more recently certain malignancies, including multiple myeloma. Whilst the mechanism of action of thalidomide remains incompletely understood, considerable insight has been generated by extensive preclinical studies in multiple myeloma. Moreover, clinical trials both as a single agent and in combination have confirmed benefit in relapsed and refractory disease. Thalidomide's role in treating newly diagnosed patients is currently under study and it is now established as an important therapeutic option in the treatment of multiple myeloma.

Thalidomide: emerging role in cancer medicine

Thalidomide--removed from widespread clinical use by 1962 because of severe teratogenicity--has antiangiogenic and immunomodulatory effects, including the inhibition of tumor necrosis alpha factor. It has now returned to practice as an effective oral agent in the management of various disease states including erythema nodosum leprosum, for which it was approved by the U.S. Food and Drug Administration in 1998, and more recently certain malignancies, including multiple myeloma. Although thalidomide's mechanism of action remains incompletely understood, considerable insight has been generated by extensive preclinical studies in multiple myeloma. Moreover, clinical trials have confirmed benefit in relapsed disease, and the role of thalidomide in treating newly diagnosed patients is currently under study. Its use in other tumors is under evaluation, with promise in renal cell carcinoma, prostate cancer, glioma, and Kaposi's sarcoma. Activity has also been demonstrated in chronic graft-versus-host disease and in symptom relief as part of palliative care.

Thalidomide in cancer

Thalidomide has immunomodulatory and anti-angiogenic properties which may underlie its activity in cancer. After its success in myeloma, it has been investigated in other plasma cell dyscrasias, myelodysplastic syndromes, gliomas, Kaposi's sarcoma, renal cell carcinoma, advanced breast cancer, and colon cancer. Thalidomide causes responses in 30-50% of myeloma patients as a single agent, and acts synergistically with corticosteroids and chemotherapy. Thalidomide results in the reduction or elimination of transfusion-dependence in some patients with myelodysplastic syndrome. Responses have also been seen in one-third of patients with Kaposi's sarcoma, in a small proportion of patients with renal cell carcinoma and high-grade glioma, and in some patients with colon cancer in combination with irinotecan. The drug is being investigated currently in a number of clinical trials for cancer. Drowsiness, constipation, and fatigue are common side effects, whereas peripheral neuropathy and skin rash are seen in one-third. A minority of patients experience bradycardia. Thrombotic phenomena are especially common when thalidomide is combined with chemotherapy. Adverse effects severe enough to necessitate cessation of therapy are seen in around 20% of patients. A therapeutic trial of thalidomide is essential in all patients with relapsed or refractory myeloma. In other cancers, the best way to use the drug is in the setting of clinical trials. In the absence of access to studies or alternative therapeutic options, thalidomide could be considered singly or in combination with standard therapy.

Theoretical basis for the activity of thalidomide

The revival of thalidomide began shortly after the drug was withdrawn from the market because of its teratogenic properties. Therapeutic effects of thalidomide were found accidentally in leprosy patients with erythema nodosum leprosum (ENL). Subsequent research widened the understanding of the activity of thalidomide, and with improved methodology and the augmented background knowledge of immunology it was possible to interpret the properties of thalidomide more coherently. Effects on tumour necrosis factor-alpha (TNFalpha) release play an important role in the ability of thalidomide to affect the immune system. Alteration of synthesis and release of cytokines such as interleukin (IL)-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12 and interferon-gamma is involved in the complex mechanisms of thalidomide. Thalidomide targets leucocytes, endothelial cells and keratinocytes, affecting them in a different manner and at different cellular levels. Changes in the density of adhesion molecules alter leucocyte extravasation and the inflammatory response in the tissue involved. Several mechanisms for the teratogenic action of thalidomide are currently under review, but this mode of action of the drug still remains unclear and we review evidence-based hypotheses for the teratogenicity of thalidomide. Thalidomide shows significant clinical impact in several diseases such as ENL in lepromatous leprosy, chronic graft-versus-host disease, systemic lupus erythematosus, sarcoidosis, aphthous lesions in HIV infection, wasting syndrome in chronic illness, inflammatory bowel disease, multiple myeloma and some solid tumours. In 1998 the US Food and Drug Administration approved thalidomide exclusively for the treatment of ENL, and strict conditions were stipulated for its use in order to prevent teratogenic adverse effects. However, despite the promising findings of thalidomide at the molecular level, namely its anti-TNFalpha properties and its intercalation with DNA, and activity in clinical trials, there is still a great need for more intensive research.

Thalidomide in gastrointestinal disorders

Thalidomide was originally marketed as a sedative, but was removed from the market in 1961 after it was associated with an epidemic of severe birth defects. Subsequently, it has been shown to have therapeutic efficacy in a number of the gastrointestinal tract conditions characterised by immune dysregulation. The exact mechanism of the immunosuppressive effects of thalidomide is unknown; proposed mechanisms include inhibition of tumour necrosis factor alpha release and inhibition of angiogenesis. In chronic graft versus host disease, use of high dose thalidomide (1200 mg/day) may bring about a response in 20% of patients with refractory disease. Thalidomide 200 mg/day helps eradicate ulcers in 50% of patients with HIV-associated oral aphthous ulceration. In Behçet's disease, thalidomide 100 to 300 mg/day can decrease the number of mucocutaneous ulcers, although full remission occurs in less than 20% of patients. In Crohn's disease, thalidomide 50 to 300 mg/day may decrease the severity of mucosal disease and prompt closure of fistulae. Patients to be placed on thalidomide therapy must practice either abstinence or strict birth control; women must undergo regular pregnancy testing and utilise 2 forms of contraception. Other adverse effects include sedation (present in nearly all patients), symptomatic neuropathy (present in approximately 20%), and skin rashes. Given the potential toxicity, thalidomide use should generally be limited to clinical protocols with institutional review board oversight.

Thalidomide in cancer: potential uses and limitations

In addition to immunomodulatory and cytokine-modulatory properties, thalidomide has antiangiogenic activity. It has been investigated in a number of cancers including multiple myeloma, myelodysplastic syndromes, gliomas, Kaposi's sarcoma, renal cell carcinoma, advanced breast cancer, and colon cancer. Its role has been best explored in myeloma, where, at daily doses of 100 to 800 mg, it is remarkably active, causing clinically meaningful responses in one-third of extensively pretreated patients and in over half of patients treated early in the course of the disease. It also acts synergistically with corticosteroids and chemotherapy in myeloma. Thalidomide produces improvement of cytopenias characteristic of myelodysplastic syndrome, resulting in the reduction or elimination of transfusion dependence in some patients. Responses have also been seen in one-third of patients with Kaposi's sarcoma, in a small proportion of patients with renal cell carcinoma and high grade glioma and, in combination with irinotecan, in some patients with colon cancer. Thalidomide is being investigated currently in a number of clinical trials for cancer. Drowsiness, constipation and fatigue are common adverse effects seen in 75% of patients. Symptoms of peripheral neuropathy and skin rash are seen in 30%. A minority of patients experience bradycardia and thrombotic phenomena. Despite the high frequency of adverse effects, those severe enough to necessitate cessation of therapy are seen in only 10 to 15% of patients. A therapeutic trial of thalidomide should be considered in all patients with myeloma who are unresponsive to or relapse after standard therapy. In other malignant diseases, the most appropriate way to use the drug is in the setting of well designed clinical trials. In the absence of access to such studies, thalidomide could be considered singly or in combination with standard therapy in patients with no meaningful therapeutic options.

Current role of thalidomide in cancer treatment

Thalidomide (Thalidomid, Celgene, Warren, NJ) is a putative anti-angiogenesis and immunomodulatory agent that has demonstrated activity in various dermatologic and rheumatologic conditions in addition to Crohn's disease. The biologic effects of thalidomide and the clinical trials conducted in solid tumors, hematologic malignancies, chronic graft-versus-host disease (GVHD), and cancer-related cachexia are reviewed. A summary of the preliminary results of ongoing clinical trials is presented, and the future directions of thalidomide research in the oncology are discussed.

Potential novel uses of thalidomide: focus on palliative care

Thalidomide, after being banned from the market in the early 1960s because of the worldwide teratogenesis disaster, is currently being rediscovered because of its multiple therapeutic effects in various serious diseases and symptoms. Original studies examined the anxiolytic, mild hypnotic, anti-emetic and adjuvant analgesic properties of this drug. Subsequently, thalidomide was found to be highly effective in managing the cutaneous manifestations of leprosy (erythema nodosum leprosum) and even to be superior to aspirin (acetylsalicylic acid) in controlling leprosy-associated fever. Recent research shows promising results with thalidomide in patients with progressive bodyweight loss related to advanced cancer and HIV infection. Thalidomide therapy of diseases such as tuberculosis, sarcoidosis, aphthous ulcers in HIV syndrome and Behcet's disease, rheumatoid arthritis, multiple myeloma, graft-versus-host disease, pyoderma gangrenosum, inflammatory bowel disease, Sjögren's syndrome, lupus erythematosus and a variety of solid tumours is currently being explored. Furthermore, in preliminary studies, thalidomide has been found to be effective in several syndromes related to advanced cancer, such as the cancer cachexia syndrome, chronic nausea, insomnia, profuse sweating and pain. Whether thalidomide has a therapeutic effect on neoplastic fever has yet to be elucidated. These intriguing features make the use of the drug potentially attractive for palliative care. In addition, by a distinct mechanism of action compared with most other drugs, thalidomide offers the possibility of combined treatment with other agents with non-overlapping toxicities. The mechanism of action of thalidomide is probably based on the suppression of tumour necrosis factor-alpha and the modulation of interleukins. However, it is not possible to identify a single dominant mechanism, since the action of cytokines and the effect of thalidomide appear to be complex. This review article discusses the original uses and teratogenic effects of thalidomide within its historical context and, linking recent research at the molecular level with clinical findings, aims to provide the reader with insight into the current understanding of its biological actions, toxicities and potential benefits.

Thalidomide: a remarkable comeback

The thalidomide product is a racemic mixture of the L- and D-enantiomeric forms of a synthetic glutamic acid derivative that contains a phthalimide ring and a glutarimide ring. Initially marketed as a sedative, it was withdrawan from the world market after it was found to be associated with severe birth defects. Recently, the compound has generated renewed interest because of its immunomodulatory and anti-angiogenic properties. The nature of its immunologic effects is under active investigation. It is orally bioavailable and can be administered in once daily dosing. Its primary route of metabolism is spontaneous hydrolysis. In controlled clinical trials, thalidomide has proven effective in the treatment of erythema nodosum leprosum, oral and oesophageal aphthous ulceration associated with advanced HIV infection and oral ulceration associated with Behcet's syndrome. Promising results have been obtained in preliminary studies of other immunologic and neoplastic disorders, but controlled clinical studies are still lacking for these entities. Adverse effects include teratogenicity, peripheral neuropathy and sedation. In the US, thalidomide can be prescribed only through a restricted drug distribution program.

Thalidomide: current and potential clinical applications

More than three decades after its withdrawal from the world marketplace, thalidomide is attracting growing interest because of its reported immunomodulatory and anti-inflammatory properties. Current evidence indicates that thalidomide reduces the activity of the inflammatory cytokine tumor necrosis factor (TNF)-alpha by accelerating the degradation of its messenger RNA. Thalidomide also inhibits angiogenesis. Recently, the drug was approved for sale in the United States for the treatment of erythema nodosum leprosum, an inflammatory complication of Hansen's disease. However, it has long been used successfully in several other dermatologic disorders, including aphthous stomatitis, Behçet's syndrome, chronic cutaneous systemic lupus erythematosus, and graft-versus-host disease, the apparent shared characteristic of which is immune dysregulation. Many recent studies have evaluated thalidomide in patients with human immunodeficiency virus (HIV) infection; the drug is efficacious against oral aphthous ulcers, HIV-associated wasting syndrome, HIV-related diarrhea, and Kaposi's sarcoma. To prevent teratogenicity, a comprehensive program has been established to control access to the drug, including registration of prescribing physicians, dispensing pharmacies, and patients; mandatory informed consent and education procedures; and limitation of the quantity of drug dispensed. Clinical and, in some patients, electrophysiologic monitoring for peripheral neuropathy is indicated with thalidomide therapy. Other adverse effects include sedation and constipation. With appropriate safeguards, thalidomide may benefit patients with a broad variety of disorders for which existing treatments are inadequate.

Thalidomide's ability to augment the synthesis of IL-2 in vitro in HIV-infected patients is associated with the percentage of CD4+ cells in their blood

Thalidomide is used for treating erythema nodosum leprosum. It is also used to treat aphthous ulcers in HIV-infected patients. The mechanism of action of this drug is yet to be fully understood, but modulation of inflammatory cytokines like IL-2 and TNF-alpha may play a role. We investigated the effect of thalidomide on the production of IL-2 and TNF-alpha by staphylococcal enterotoxin A (SEA) stimulated peripheral blood mononuclear cells (PBMC) from HIV-infected patients. The PBMC from 20 patients was incubated in the presence of 4.0 microg/ml of thalidomide and 50 ng/ml of SEA. After 18 h, the culture supernatant was assayed for IL-2 and TNF-alpha. The PBMC incubated with thalidomide and SEA produced significantly more IL-2 than those incubated with SEA alone. The TNF-alpha secreted by the same cells incubated with thalidomide and SEA was not significantly different from that secreted by the cells incubated with SEA alone. The amount of IL-2 produced in the thalidomide and SEA treated cultures was directly correlated with the percentage of CD4+ cells in blood, and inversely correlated with the percentage of CD8+ cells in blood. No statistically significant correlations were found when comparing the amount of TNF-alpha produced in the thalidomide and SEA treated cultures with the percentage of CD4+ or CD8+ cells in the blood. Thalidomide can act, in vitro, as an additional stimulant to augment the synthesis of IL-2 in HIV-infected patients. Increased production of IL-2 by activated T-cells may be a mechanism through which it exerts its immunomodulatory effects.

Tuberculosis I: a conceptual frame for the immunopathology of the disease

An analysis of the cellular and humoral immune responses after bacille Calmette-Guerin (BCG) vaccination and during tuberculosis treatment favors the hypothesis of an immune defence developed in four overlapping successive stages. The initial immune response is innate. The following two intermingle innate and specific responses against low molecular weight oligopeptidic and nonpeptidic antigens, as muramyldipeptide and trehalose dimycolate, and large molecular weight nonpeptidic antigens such as lipoarabinomannan. The ultimate specific response is directed against protein antigens as Antigen 60. BCG and primary tuberculosis (TB) infections induce cellular and humoral immune responses essentially against oligopeptidic and small and large molecular weight nonpeptidic antigens. Immune responses against non-peptidic substances contribute to the immunoprotection of the infected person who develops a primary infection. Some infected people allow the expression of the immunosuppressive activity of the pathogen. This results in the synthesis of interleukin-10 (IL-10), which suppresses the formation of interferon-gamma (INF-gamma) and IL-2, and of IL-6, which suppresses T-cell responses. These patients have a skewed immune response against non-peptidic antigens and present with symptoms. They will not recover unless responses directed against proteinic antigens occur, which restore INF-gamma and IL-2 production. The formation of immumoglobulin-G (IgG)-type antibodies and of a cellular immunity against mycobacterial peptidic antigens is essential for a good protection against a post-primary infection.

Examining a paradox in the pathogenesis of human pulmonary tuberculosis: immune activation and suppression/anergy

Protective immunity against Mycobacterium tuberculosis (MTB) in animal models is based on cell-mediated immunity (CMI), involving bi-directional interactions between T cells and cells of the monocyte/macrophage (MO/MA) lineage. Key factors include MO-derived interleukin (IL)-12 and tumor necrosis factor (TNF)-alpha as well as T cell derived IL-2 and interferon (IFN)-gamma. These cytokines appear particularly crucial in the induction of MA-mediated elimination of mycobacteria. Several lines of evidence indicate that similar mechanisms are operating in humans. During active pulmonary tuberculosis (PTB), signs of both immune depression and immune activation are concomitantly present. Decreased tuberculin skin test reactivity in vivo and deficient IFN-gamma production by MTB-stimulated mononuclear cells in vitro are observed. On the other hand, the serum levels of several cytokines, including TNF, and other inflammatory mediators are increased and circulating MO and T cell show phenotypic and functional evidence of in vivo activation. In this review, we will discuss the evidence for three models, which could explain this apparent paradox: 1. Stimulation of the T cell-suppressive function from MO/MA; 2. Intrinsic T cell refractoriness, possibly associated with tendency to apoptosis (programmed cell death), and 3. Compartmentalization and redistribution of immune responses to the site of disease. The opportunistic behavior of MTB during human immunodeficiency virus (HIV) infection can be explained by suppression of type-1 responses at the level of antigen-presenting cells, CD4 T cells and effector macrophages. The ominous prognostic significance of intercurrent PTB during HIV infection seems primarily due to prolonged activation of HIV replication in macrophages. Supportive immune therapy during PTB could aim at correcting the type-1 deficiency either by IFN-gamma inducers (e.g. IL-12, IL-18) or by neutralizing the suppressive cytokines transforming growth factor beta (TGF-beta) and IL-10. Alternatively, inflammatory over-activity could be reduced by neutralizing TNF. Finally, anti-apoptotic therapies (e.g. IL-15) might be considered.

Differential regulation by thalidomide and dexamethasone of cytokine expression in human peripheral blood mononuclear cells

Immunosuppressive drugs are used routinely to reduce the inappropriate production of cytokines in an immune response. Recent attention has focused on drugs that selectively inhibit specific cytokines. Both thalidomide and dexamethasone have been reported to exhibit immunomodulatory effects on cytokines in vitro. We wished to examine the effects of thalidomide and dexamethasone on the production of cytokines by peripheral blood mononuclear cells (PBMC), following mitogenic stimulation, at the level of both secreted product and mRNA production. PBMC from healthy human volunteers were stimulated optimally with phytohaemagglutinin (PHA) in the presence of varying concentrations of thalidomide and dexamethasone using dimethyl sulphoxide (DMSO) as the solvent. Analysis of supernatants by enzyme-linked immunosorbent assay (ELISA) showed that thalidomide caused a dose-dependent inhibition of the pro-inflammatory cytokines interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-alpha), maximally reducing production by 20 (P < 0.05) and 30% (P < 0.01), respectively, compared with controls. However, thalidomide did not affect either proliferation or the production of interleukin 2 (IL-2), interleukin 4 (IL-4) or interleukin 10 (IL-10). A slight bell shaped inhibition of interferon gamma (IFN-gamma) was seen which was statistically significant (P < 0.05). In contrast, dexamethasone inhibited markedly the expression of all cytokines tested (IL-2, IL-4, IL-6, IL-10, IFN-gamma and TNF-alpha) in dose-dependent fashion, reducing levels to near to background. Reverse transcription-polymerase chain reaction (RT-PCR) analyses showed that thalidomide inhibited selectively the expression of TNF-alpha and IL-6 mRNA, whereas dexamethasone inhibited mRNA levels of all cytokines examined. The data indicate that dexamethasone is a broad range immunosuppressant inhibiting all cytokines tested in a dose-dependent manner at the level of both secreted product and mRNA. Conversely, thalidomide selectively inhibits the production of IL-6 and TNF-alpha. Due to their markedly different effects on cytokine production, and the fact that both drugs act at the level of transcription, we believe they influence separate pathways involved in cytokine gene regulation.

Thalidomide costimulates primary human T lymphocytes, preferentially inducing proliferation, cytokine production, and cytotoxic responses in the CD8+ subset

The efficacy of thalidomide (alpha-phthalimido-glutarimide) therapy in leprosy patients with erythema nodosum leprosum is thought to be due to inhibition of tumor necrosis factor alpha. In other diseases reported to respond to thalidomide, the mechanism of action of the drug is unclear. We show that thalidomide is a potent costimulator of primary human T cells in vitro, synergizing with stimulation via the T cell receptor complex to increase interleukin 2-mediated T cell proliferation and interferon gamma production. The costimulatory effect is greater on the CD8+ than the CD4+ T cell subset. The drug also increases the primary CD8+ cytotoxic T cell response induced by allogeneic dendritic cells in the absence of CD4+ T cells. Therefore, human T cell costimulation can be achieved pharmacologically with thalidomide, and preferentially in the CD8+ T cell subset.