CLINICAL EXPERIENCES WITH THALIDOMIDE IN PATIENTS WITH CANCER

What's Old is New: The Past, Present and Future Role of Thalidomide in the Modern-Day Management of Multiple Myeloma

Immunomodulatory drugs (IMiDs) have become an integral part of therapy for both newly diagnosed and relapsed/refractory multiple myeloma (RRMM). IMiDs bind to cereblon, leading to the degradation of proteins involved in B-cell survival and proliferation. Thalidomide, a first-generation IMiD, has little to no myelosuppressive potential, negligible renal clearance, and long-proven anti-myeloma activity. However, thalidomide's adverse effects (e.g., somnolence, constipation, and peripheral neuropathy) and the advent of more potent therapeutic options has led to the drug being less frequently used in many countries, including the US and Canada. Newer-generation IMiDs, such as lenalidomide and pomalidomide, are utilized far more frequently. In numerous previous trials, salvage therapy with thalidomide (50-200 mg/day) plus corticosteroids (with or without selected cytotoxic or targeted agents) has been shown to be effective and well-tolerated in the RRMM setting. Hence, thalidomide-based regimens remain important alternatives for heavily pretreated patients, especially for those who have no access to novel therapies and/or are not eligible for their use (due to renal failure, high-grade myelosuppression, or significant comorbidities). Ongoing and future trials may provide further insights into the current role of thalidomide, especially by comparing thalidomide-containing regimens with protocols based on newer-generation IMiDs and by investigating thalidomide's association with novel therapies (e.g., antibody-drug conjugates, bispecific antibodies, and chimeric antigen receptor T cells).

The evolving role and utility of off-label drug use in multiple myeloma

The treatment landscape for multiple myeloma (MM) has dramatically changed over the last three decades, moving from no US Food and Drug Administration approvals and two active drug classes to over 19 drug approvals and at least eight different active classes. The advances seen in MM therapy have relied on both a structured approach to obtaining new labels and cautious off-label drug use. Although there are country and regional differences in drug approval processes, many of the basic principles behind off-label drug use in MM can be summarized into four main categories: 1) use of a therapy prior to the current approval regulations; 2) widespread use of a therapy following the release of promising clinical trial results but prior to drug approval; 3) use of a cheap therapy supported by clinical safety and efficacy data but without commercial backing; and 4) niche therapies for small well-defined patient populations where large clinical trials with sufficient power may be difficult to perform. This review takes a historical approach to discuss how off-label drug use has helped to shape the current treatment approach for MM.

Thalidomide in dermatology: revisited

The use of thalidomide in relation to dermatology is well- known and enough data is available in the literature about various aspects of thalidomide. Despite being an interesting and useful drug for many dermatoses, it is associated with many health hazards including the birth defects, phocomelia. We hereby present a comprehensive review about thalidomide and its application in dermatology.

Thalidomide and dexamethasone: therapy for multiple myeloma

Multiple myeloma is a plasma cell malignancy that remains incurable with current treatment approaches including high-dose therapy and autologous stem cell transplantation. Thalidomide represents a major advance in the treatment of this disorder, having demonstrated significant activity in all phases of the disease. Thalidomide exerts its antimyeloma effect through multiple mechanisms including antiangiogenesis, immunomodulation and induction of apoptosis in tumor cells, as well as its effect on the tumor microenvironment. Corticosteroids have formed the mainstay of myeloma therapy for decades along with the alkylating agents and have demonstrated synergy when used in combination with thalidomide. The combination of thalidomide and dexamethasone has demonstrated remarkable activity in the treatment of both newly diagnosed as well as relapsed myeloma, and has become an important addition to the armamentarium of myeloma therapies. Overall responses of approximately 70% have been seen with this combination in patients with newly diagnosed myeloma. The combination is associated with an increased risk of deep vein thrombosis necessitating routine prophylactic anticoagulation. Other drugs have been added to this combination that also result in improved response rates. Currently, this combination is used in newly diagnosed patients as an induction therapy prior to stem cell transplant, for those who fail to achieve adequate response to dexamethasone alone or in whom a relatively rapid response is desired based on clinical presentation. Thalidomide analogs with a better safety profile are currently undergoing evaluation in the clinic.

Thalidomide: an old drug with new action

Thalidomide is a drug that, since its development, has made history in the world of medicine--having been withdrawn and now has returned with a boom as an anticancer and immunomodulatory drug. However, its mode of action in various diseases (i.e. different types of hematologic malignancies, solid tumors) as well as in various infections (i.e. pneumonia, tuberculosis, HIV infection etc.) and related inflammatory conditions is not well understood. As the immune system plays an important role in the pathogenesis of both infection-related as well as noninfectious (i.e. cancer) inflammatory diseases, much research has been done in the past few years to discover and design better immunomodulatory agents. Such immunomodulatory agents should be able to target the immune system in such a way that host suffers minimum damage and normal function of the immune system remains intact. In the present review an attempt is made to highlight the immunomodulatory action of thalidomide in various pathologic conditions.

The rise, fall and subsequent triumph of thalidomide: lessons learned in drug development

Perhaps no other drug in modern medicine rivals the dramatic revitalization of thalidomide. Originally marketed as a sedative, thalidomide gained immense popularity worldwide among pregnant women because of its effective anti-emetic properties in morning sickness. Mounting evidence of human teratogenicity marked a dramatic fall from grace and led to widespread social, legal and economic ramifications. Despite its tragic past thalidomide emerged several decades later as a novel and highly effective agent in the treatment of various inflammatory and malignant diseases. In 2006 thalidomide completed its remarkable renaissance becoming the first new agent in over a decade to gain approval for the treatment of plasma cell myeloma. The catastrophic collapse yet subsequent revival of thalidomide provides important lessons in drug development. Never entirely abandoned by the medical community, thalidomide resurfaced as an important drug once the mechanisms of action were further studied and better understood. Ongoing research and development of related drugs such as lenalidomide now represent a class of irreplaceable drugs in hematological malignancies. Further, the tragedies associated with this agent stimulated the legislation which revamped the FDA regulatory process, expanded patient informed consent procedures and mandated more transparency from drug manufacturers. Finally, we review recent clinical trials summarizing selected medical indications for thalidomide with an emphasis on hematologic malignancies. Herein, we provide a historic perspective regarding the up-and-down development of thalidomide. Using PubMed databases we conducted searches using thalidomide and associated keywords highlighting pharmacology, mechanisms of action, and clinical uses.

HiSStology: high spectral and spatial resolution magnetic resonance imaging detection of vasculature validated by histology and micro-computed tomography

High spectral and spatial resolution (HiSS) data, acquired with echo-planar spectroscopic imaging (EPSI), can be used to acquire water spectra from each small image voxel. These images are sensitive to changes in local susceptibility caused by superparamagnetic iron oxide particles (SPIO); therefore, we hypothesized that images derived from HiSS data are very sensitive to tumor neovasculature following injection of SPIO. Accurate image registration was used to validate HiSS detection of neovasculature with histology and micro-computed tomographic (microCT) angiography. Athymic nude mice and Copenhagen rats were inoculated with Dunning AT6.1 prostate tumor cells in the right hind limb. The tumor region was imaged pre- and post-intravenous injection of SPIO. Three-dimensional assemblies of the CD31-stained histologic slices of the mouse legs and the microCT images of the rat vascular casts were registered with EPSI. The average distance between HiSS-predicted regions of high vascular density on magnetic resonance imaging and CD31-stained regions on histology was 200 μm. Similarly, vessels identified by HiSS in the rat images coincided with vasculature in the registered microCT image. The data demonstrate a strong correlation between tumor vasculature identified using HiSS and two gold standards: histology and microCT angiography.

History of multiple myeloma

Multiple Myeloma has been recognized since Ancient Times. The first well-documented case was reported in 1844 by Samuel Solly. The most commonly recognized case is that of Thomas Alexander McBean, a highly respectable tradesman from London in 1850. Mr. McBean excreted a large amount of protein that was described by Henry Bence Jones in the middle of the 19th century. Jones was a well-known physician and made many contributions to medicine. One of the best known cases of multiple myeloma was that of Dr. Loos that was reported by Otto Kahler. The recognition of plasma cells and subsequently their product, a monoclonal protein has been described in detail. The authors have reviewed the treatment of multiple myeloma including the novel agents, thalidomide, bortezomib and lenalidomide.

Characterization of response to radiation mediated gene therapy by means of multimodality imaging

Imaging techniques are under development to facilitate early analysis of spatial patterns of tumor response to combined radiation and antivascular gene therapy. A genetically modified, replication defective adenoviral vector (Ad.EGR-TNFalpha), injected intratumorally, mediates infected cells to express tumor necrosis factor alpha (TNFalpha), which is increased after exposure to radiation. The goal of this study was to characterize an image based "signature" for response to this combined radiation and gene therapy in mice with human prostate xenografts. This study is part of an imaged guided therapy project where such a signature would be useful in guiding subsequent treatments. Changes in the tumor micro-environment were assessed using MRI registered with electron paramagnetic resonance imaging which provides images of tissue oxygenation. Dynamic contrast-enhanced MRI was used to assess tissue perfusion. When compared with null vector (control) treatment, the ratio of contrast agent (Gd-DTPA-BMA) washout rate to uptake rate was lower (P = 0.001) after treatment, suggesting a more balanced perfusion. Concomitantly, oxygenation significantly increased in the treated animals and decreased or did not change in the control animals (P < 0.025). This is the first report of minimally invasive, quantitative, absolute oxygen measurements correlated with tissue perfusion in vivo.

Supplements for immune enhancement in hematologic malignancies

This brief review aims to discuss the various cellular immunological aspects and related mechanisms of the use of specific components from traditional herbal medicines. We begin with lessons learned from thalidomide as an effective single drug with multiple mechanisms of action to treat multiple myeloma. Examples of “supplements” or integrative therapy will be drawn from arsenic trioxide, medicinal mushrooms including Coriolus vesicular and Ganoderma lucidum, followed by the discussion of beta-glucans affecting various immunological important cellular subsets. Different classes of compounds may enhance distinct immune cell populations that might contribute to a multi-targeted holistic effects on anti-cancer treatment. Finally, we conclude by highlighting an herbal formulation PHY906 as a potential adjunct to chemotherapy that might become one of the first US Food and Drug Administration (FDA) approved oral herbal medicines for anti-cancer adjunct treatment.

Multiple myeloma

Multiple myeloma is a clonal plasma cell malignancy that accounts for slightly more than 10% of all hematologic cancers. In this paper, we present a historically focused review of the disease, from the description of the first case in 1844 to the present. The evolution of drug therapy and stem-cell transplantation for the treatment of myeloma, as well as the development of new agents, is discussed. We also provide an update on current concepts of diagnosis and therapy, with an emphasis on how treatments have emerged from a historical perspective after certain important discoveries and the results of experimental studies.

Thalidomide for treatment of intestinal involvement of juvenile-onset Behçet disease

BACKGROUND

Thalidomide has been identified and its anti-inflammatory and immunomodulatory properties clarified. This report expands our report of 2 entero-Behçet disease children who developed significant steroid toxicity and improved dramatically with thalidomide.

METHODS

We studied the effects of thalidomide in 7 juvenile-onset patients with severe, recurrent intestinal involvement of Behçet disease. Thalidomide was given at an initial dose of 2 mg/kg per day, and the dose was increased to 3 mg/kg per day if necessary (3 of 7 patients) or decreased to 1-0.5 mg/kg per day according to the responses to the drug.

RESULTS

All 7 patients showed dramatic improvement in clinical symptoms with thalidomide therapy, and they successfully discontinued steroid therapy. Patients receiving thalidomide were monitored for prolonged neurotoxicity, and the treatment and a few side effects were well tolerated by all patients.

CONCLUSIONS

Our results indicate that thalidomide can be an efficacious medication in appropriately selected patients with some inflammatory bowel diseases with many chances of success.

Evaluation of interferon alpha-2B and thalidomide in patients with disseminated malignant melanoma, phase 2, SWOG 0026

BACKGROUND

Southwest Oncology Group protocol 0026 evaluated interferon alpha-2b plus thalidomide in patients with disseminated melanoma. Endpoints were 6-month progression-free survival rate, response rate, and toxicity.

METHODS

Twenty-six patients with Stage IV melanoma, measurable or nonmeasurable disease, performance status of 0-2, and adequate renal and hepatic functions were registered. One prior systemic therapy for Stage IV disease was required. Interferon was administered subcutaneously (1 million U) twice daily; thalidomide was orally administered (200-400 mg) each evening in a dose-escalating manner. Response evaluations using Response Evaluation Criteria in Solid Tumors were performed every 8 weeks.

RESULTS

After 2 sudden deaths and 1 grade 4 treatment-related pulmonary embolism, this study was temporarily closed. One patient with deep-vein thrombosis and 2 with grade 3 cardiac arrhythmias were reported. The relationship of these events to the treatment was worrisome but not definitive. Grade 3 treatment-related adverse events occurred in 14 of 26 patients. Because of concern for patient safety the study was permanently closed. No treatment responses were seen in the 22 evaluable patients. Estimated 6-month progression-free survival rate was 15% (95% confidence interval [CI], 2%-29%), estimated 6-month overall survival was 58% (95% CI, 39%-77%), and estimated response probability was 0 of 22 (95% CI, 0%-15%).

CONCLUSIONS

This regimen demonstrated a lack of response and was associated with multiple severe toxicities. Further investigation of interferon alpha-2b and thalidomide in this dose and schedule is not warranted.

A phase II trial of thalidomide in patients with refractory endometrial cancer and correlation with angiogenesis biomarkers: a Gynecologic Oncology Group study

OBJECTIVES

A phase II trial was conducted to evaluate the anti-tumor activity and adverse effects of thalidomide in persistent or recurrent endometrial cancer refractory to cytotoxic chemotherapy and to correlate angiogenesis biomarker expression with clinical outcome.

METHODS

Consenting patients were treated until progression or intolerable toxicity with an oral starting dose of 200 mg thalidomide/day that was to increase by 200 mg every 2 weeks to a target dose of 1000 mg/day. Vascular endothelial growth factor (VEGF), basic fibroblastic growth factor (bFGF), and soluble endothelial protein C receptor (sEPCR) were analyzed by ELISA in pre and post-treatment specimens.

RESULTS

Twenty-four of twenty-seven patients enrolled in the study were eligible, of whom 2 reached the target dose, 8 progressed before achieving the target dose, and 14 refused or had toxicity that prohibited escalation. Two patients (8.3%) remained progression-free>or=6 months. There were 3 (12.5%) with partial responses, 2 (8.3%) with stable disease, 15 (62.5%) with increasing disease, and 4 (16.7%) who were inevaluable for response. Median progression-free survival and overall survival were 1.7 months and 6.3 months, respectively. No grade 4 toxicities were observed. Common grade 3 toxicities included hematologic (n=3), cardiovascular (n=3), constitutional (n=3), and neurologic (n=4). Thalidomide did not decrease VEGF or bFGF levels but reduced sEPCR levels in serum. Elevated plasma vascular endothelial growth factor levels were associated with increased risk of progression and death.

CONCLUSIONS

Thalidomide demonstrated limited ability to delay progression (as measured by PFS at 6 months), produce objective responses, or reduce angiogenic marker levels in chemotherapy refractory endometrial cancer. VEGF level appears to be prognostically significant in such patients, independent of thalidomide treatment.

Thalidomide and lenalidomide in the treatment of multiple myeloma

Although multiple myeloma (MM) is incurable with currently available treatments, the introduction of thalidomide and the development of safer and more active thalidomide analogues represent a major advance in the therapy of this disease. Thalidomide, initially introduced for treatment of MM because of its anti-angiogenic properties, has shown remarkable activity alone and in combination with other drugs in patients across all stages of the disease. Given the potential for teratogenicity with thalidomide and the non-haematologic toxicities of the drug, several analogues referred to as "immunomodulatory drugs" (IMiDs) were developed with the intent of enhancing the immunomodulatory effect while minimizing the teratogenic risk. Lenalidomide (CC-5013) and Actimid (CC-4047) are the first such analogues to undergo clinical testing. Lenalidomide has shown impressive activity in relapsed refractory myeloma as well as newly diagnosed disease. The precise mechanism of anti-MM activity of thalidomide and the IMiDs is not clear, but studies suggest that several other mechanisms besides anti-angiogenic effects may play a role. In this paper we review the development, pharmacology, mechanism of action, pre-clinical and clinical efficacy, and the current status of thalidomide and the IMiDs in the treatment of MM.

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.

The current status of thalidomide in the management of multiple myeloma

Early anticancer research involving thalidomide was abandoned in the 1960s as the catastrophe surrounding the drug emerged, but research efforts were picked up in the 1990s when thalidomide's antiangiogenic and anti-tumour necrosis factor properties were explored. More than 50,000 patients with multiple myeloma are estimated to have been treated with thalidomide to date. Research with thalidomide provides clear and convincing evidence that thalidomide monotherapy is efficacious in relapsed and refractory patients with multiple myeloma. Results typically show a consistent 30% (95% confidence interval 27-32%) response rate (partial response + complete response, defined as a reduction of at least 50% in the monoclonal protein). Thalidomide treatment compares favourably with other typical treatments for multiple myeloma. In seven trials that included 332 patients, vincristine, adriamycin and dexamethasone (VAD) had a response rate of 39% (32-45%), while a trial in 193 patients showed a response rate with bortezomib of 27% (21-34%). The use of thalidomide in combination therapy could boost its efficacy further. More studies to look at the toxicity of the drug need to be carried out. Despite thalidomide's dark past, this drug is of major interest and could be brought back to clinical use in a controlled manner.

Thalidomide revisited: pharmacology and clinical applications

Thalidomide is attracting new interest. Since the discovery of its remarkable efficacy in erythema nodosum leprosum, the drug has been used successfully in a variety of dermatologic and other diseases whose apparent common thread is immune dysregulation. Meanwhile, immunomodulatory and anti-inflammatory activities of thalidomide, particularly its inhibition of tumour necrosis factor alpha (TNF-alpha), have been identified and elucidated. The drug has also been found to inhibit angiogenesis. Recent clinical trials have shown thalidomide effective in graft-versus-host disease, Behçet's syndrome and aphthous ulcers and wasting associated with HIV infection. Provocative findings in other diseases, including primary HIV infection, HIV-associated diarrhoea, inflammatory bowel disease, cancer and sepsis, have suggested additional clinical applications. Use of thalidomide in women capable of childbearing is controversial. However, guidelines have emerged for prevention of teratogenicity and peripheral neuropathy, the drug's other major adverse effect. With appropriate safeguards, thalidomide may hold benefit for patients with a broad variety of disorders in which existing treatments are inadequate. Its current use may represent only a small part of its therapeutic potential.

Thalidomide: Current Role in the Treatment of Non-Plasma Cell Malignancies

Thalidomide, initially introduced as a sedative, was withdrawn from the market in the early 1960s after it was found to be a teratogen. However, it later found use as an investigational agent in the treatment of erythema nodosum leprosum, oral ulcers, graft versus host disease, and wasting associated with the human immunodeficiency syndrome. Its antiangiogenic properties were recognized in the early 1990s during a period where the importance of angiogenesis became increasingly apparent as a critical step in the in the proliferation and spread of malignant neoplasms. This led to the evaluation of thalidomide as an antiangiogenic agent in the treatment of several cancers. Thalidomide has already become part of standard therapy for the treatment of patients with relapsed and refractory multiple myeloma. It has also been found to have varying degree of benefit in various other malignancies. Although more clinical trials are needed, Kaposi's sarcoma and myelofibrosis represent other malignancies in which thalidomide has already demonstrated promising activity. The mechanism of action of thalidomide in cancer is still unclear, but do appear to be mediated by several other mechanisms in addition to its anti-angiogenic properties. This article reviews the current status of thalidomide for the treatment of non-plasma-cell malignancies.

Thalidomide

Despite its history as a human teratogen, thalidomide is emerging as a treatment for cancer and inflammatory diseases. Although the evolution of its clinical application could not have been predicted from the tragedy associated with its misuse in the past, its history serves as a lesson in drug development that underscores the need to understand the molecular pharmacology of a compound's activity, including associated toxicities. Here, we summarise the applications for thalidomide with an emphasis on clinical trials published over the past 10 years, and consider our knowledge of the molecular pharmacology of the drug in the context of clinical trial data, attempting to provide a mechanism-guided understanding of its activity.

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.

Antiproliferative effect of thalidomide alone and combined with carmustine against C6 rat glioma

Thalidomide could have therapeutic applications in neoplasms and in other diseases, particularly those of autoimmune origin. The objective of this study was to investigate the effect of various doses of thalidomide on the growth of C6 glioma in rats, and to determine its effects on parameters of cell proliferation and angiogenesis. Additionally, we investigated a potential enhancement of the antitumoral action of thalidomide when combined with a low dose of the antineoplastic carmustine. C6 glioma cells were implanted subcutaneously in Wistar rats. A highly malignant glioma developed in 80% of animals. When the tumour reached 2.0 cm diameter thalidomide was administered at doses of 100, 200 or 400 mg/kg/day. When given at a dose of 400 mg/kg/day thalidomide significantly reduced the tumour volume, the mitotic index and cell proliferation but not the vascular density. The combination of thalidomide plus carmustine increased the inhibitory effect on tumoral growth. Our results indicate that thalidomide is effective against malignant glioma; apparently by an antiproliferative effect, rather than by inhibition of angiogenesis; when combined with carmustine it could increase the response of glioma to antineoplastic treatment.

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.

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.

Thalidomide in the treatment of multiple myeloma

Thalidomide--banned from clinical use in the 1960s because of severe teratogenicity--is now back in clinical practice as an effective agent in the treatment of relapsed and refractory multiple myeloma. Several clinical trials have determined that thalidomide is active in 25-35% of patients with relapsed myeloma. The role of thalidomide in early-stage myeloma is being actively investigated. Thalidomide has antiangiogenic and immunomodulatory properties and is an effective inhibitor of TNF-alpha. However, the mechanism of its action in myeloma remains unclear. Major toxicities of thalidomide include constipation, sedation, skin rash, fatigue and peripheral neuropathy. This paper summarizes the current status of thalidomide in multiple myeloma.

Thalidomide in the treatment of cancer

Thalidomide caused severe malformations in babies born to mothers taking the drug for morning sickness in the late 1950s and early 1960s. It is now known that these teratogenic effects are due to potent anti-angiogenic and immunomodulatory actions. These properties have lead to the testing of thalidomide in a number of infective, inflammatory and malignant conditions. Promising activity has been reported in myeloma, AIDS-related Kaposi's sarcoma, renal cell carcinoma and glioblastoma multiforme. A review is presented of the history of thalidomide and its recent development with an emphasis on applications in malignant disease.

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.

Phase II evaluation of thalidomide in patients with metastatic breast cancer

PURPOSE

To determine the efficacy, safety, pharmacokinetics, and effect on serum angiogenic growth factors of two dose levels of thalidomide in patients with metastatic breast cancer.

PATIENTS AND METHODS

Twenty-eight patients with progressive metastatic breast cancer were randomized to receive either daily 200 mg of thalidomide or 800 mg to be escalated to 1,200 mg. Fourteen heavily pretreated patients were assigned to each dose level. Each cycle consisted of 8 weeks of treatment. Pharmacokinetics and growth factor serum levels were evaluated.

RESULTS

No patient had a true partial or complete response. On the 800-mg arm, 13 patients had progressive disease at or before 8 weeks of treatment and one refused to continue treatment. The dose was reduced because of somnolence to 600 mg for five patients and to 400 mg for two and was increased for one to 1,000 mg and for four to 1,200 mg. On the 200-mg arm, 12 patients had progressive disease at or before 8 weeks and two had stable disease at 8 weeks, of whom one was removed from study at week 11 because of grade 3 neuropathy and the other had progressive disease at week 16. Dose-limiting toxicities included somnolence and neuropathy. Adverse events that did not require dose or schedule modifications included constipation, fatigue, dry mouth, dizziness, nausea, anorexia, arrhythmia, headaches, skin rash, hypotension, and neutropenia. Evaluation of circulating angiogenic factors and pharmacokinetic studies failed to provide insight into the reason for the lack of efficacy.

CONCLUSION

Single-agent thalidomide has little or no activity in patients with heavily pretreated breast cancer. Further studies that include different patient populations and/or combinations with other agents might be performed at the lower dose levels.

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.

The clinical experience with antiangiogenic agents

Antiangiogenic agents have been recently recognized to be potentially useful in the treatment of malignant processes. There has been a resulting flood of these agents into the clinical research field, forcing researchers to consider the unique problems which these agents pose. As these are agents with a novel, angiostatic mechanism of action, new clinical trial designs may become necessary to move these agents from the phase 1 level on to clinical use. Currently, several of these agents are being or have been tested in clinical trials. In this article, we review the available clinical data with antiangiogenic agents from other investigators, and our own experience with pentosan polysulfate.

Thalidomide for autoimmune disease

The therapeutic efficacy of thalidomide in erythema nodosum leprosum suggests that thalidomide might play a useful therapeutic role in other human immune-complex diseases. Thalidomide has shown anti-inflammatory or immunosuppressive actions in several animal models. Current evidence suggests that its rapid activity in ENL may result from suppression of neutrophil chemotaxis and phagocytosis. Scattered anecdotal clinical reports of apparent response to thalidomide in various autoimmune diseases are hardly conclusive, but underline the desirability of appropriate pilot trials of thalidomide in autoimmune diseases, particularly those in which immune complex deposition plays a prominent role. Provided that a contraindication in fertile women is strictly observed, thalidomide therapy appears to be quite safe.