Thalidomide, a current teratogen in South America

Possible New Candidates Involved to Thalidomide-Related Limbs and Cardiac Defects: A Systems Biology Approach

Thalidomide is a known teratogen that causes malformations especially in heart and limbs. Its mechanism of teratogenicity is still not fully elucidated. Recently, a new target of thalidomide was described, TBX5, and was observed a new interaction between HAND2 and TBX5 that is disrupted in the presence of thalidomide. Therefore, our study aimed to raise potential candidates for thalidomide teratogenesis, through systems biology, evaluating HAND2 and TBX5 interaction and heart and limbs malformations of thalidomide. Genes and proteins related to TBX5 and HAND2 were selected through TF2DNA, REACTOME, Human Phenotype Ontology, and InterPro databases. Networks were assembled using STRING © database. Network analysis were performed in Cytoscape © and R v3.6.2. Differential gene expression (DGE) analysis was performed through gene expression omnibus. We constructed a network for HAND2 and TBX5 interaction; a network for heart and limbs malformations of TE; and the two joined networks. We observed that EP300 protein seemed to be important in all networks. We also looked for proteins containing C2H2 domain in the assembled networks. ZIC3, GLI1, GLI3, ZNF148, and PRDM16 were the ones present in both heart and limbs malformations of TE networks. Furthermore, in the DGE analysis after treatment with thalidomide, we observed that FANCB, ESCO2, and XRCC2 were downregulated and present both in heart and limbs networks. Through systems biology, we were able to point to different new proteins and genes, and selected specially EP300, which was important in all the analyzed networks, to be further evaluated in the TE teratogenicity.

Thalidomide control and use: are these appropriate to extend the use and mitigate the risk of teratogenicity in Brazil?

Drug utilization research to describe the control of thalidomide in Brazil and its use in Minas Gerais state. An online questionnaire was sent to the Brazilian federative units to collect data concerning distribution, dispensation, user registration, and thalidomide adverse events. Distribution (2011-2018) and dispensing (2015-2018) data in Minas Gerais were obtained through the pharmaceutical care management system. Analysis of variance and Tukey test were used for data comparisons. Of the 16 participating federative units, 100% and 50% used electronic distribution and dispensing systems, respectively, and about 43% registered users. Adverse event reporting systems were scarce. A 44% reduction was observed in the distribution in Minas Gerais for the period. Dispensing remained constant (mean 0.0004 DDD/1,000 inhabitants/day) and occurred mainly for erythema nodosum leprosum and multiple myeloma. Off-label use (2.2%) was increasing. Most users were male (mean age 56 years) and thirty percent of women were of childbearing age. Thalidomide surveillance is a public health challenge. Despite the increased use and mandatory control, there is no national standardization, and adverse event reporting is incipient.

Comparative analysis of the use and control of thalidomide in Brazil and different countries: is it possible to say there is safety?

INTRODUCTION

One of the biggest drug disasters in history has not prevented thalidomide from being used to treat various clinical conditions. Currently, Brazil has a worrying scenario: high consumption of the drug and, cases of pregnant women using thalidomide, even after adopting restrictive legislation.

AREAS COVERED

This review of the literature and legislation sought to comparatively analyze the monitoring of thalidomide use in Brazil and other countries that use this drug. Finally, we discuss the differences between the countries.

EXPERT OPINION

This analysis allows us to think beyond the safe use of thalidomide, but the safety provided by any type of monitoring system. It seems that out-patients that use unsafe drugs are exposed to some degree of risk. To improve safety, more extensive improvements are needed than monitoring systems related to the use of thalidomide. Its safe use depends on a drastic reduction in the incidence of leprosy and Erythema Nodosum Leprosum in the world; investment in research and development of safe and effective therapeutic alternatives to thalidomide; improvement of health systems and their health surveillance systems, particularly in primary health care; awareness of health professionals and patients for greater responsibility in the use of medicines, especially thalidomide.

The organization, weaknesses, and challenges of the control of thalidomide in Brazil: A review

The drug thalidomide has resurged in the world market under restrictive conditions for marketing and use. In Brazil, there are still cases of pregnant women using thalidomide even after the implementation of laws that regulate the control of use (Law No. 10.651/2003 and Collegiate Board Resolution No. 11/2011). The objective of this study was to discuss the control of thalidomide use in Brazil, based on a scoping review of the scientific literature, documents, and data from the Ministry of Health. A total of 51 studies and documents related to the following subthemes were selected: (1) organization of access and use of thalidomide in the health system; (2) epidemiological and population characteristics of people affected by leprosy; and (3) occurrence of pregnancy and cases of embryopathy with the use of thalidomide. The results showed that Brazil has no unified information database about thalidomide patients. Furthermore, there is inconsistency in the accreditation of public health centers that dispense this medicine, in a country that has a high consumption of thalidomide in the Unified Health System. A large part of this amount of dispensed medicine is intended for the treatment of erythema nodosum leprosum, mainly in the North, Northeast, and Central-West regions of the country, which are endemic for leprosy. This disease is the only one among the clinical indications of the medicine approved in Brazil that does not have a Clinical Protocol and Therapeutic Guidelines. The control of thalidomide use in Brazil presents historical regulatory failures. These are currently linked to the organization and structure of primary healthcare in the country, as well as to the lack of leadership of the Ministry of Health and National Health Surveillance Agency when it comes to managing the process of control of this use.

Molecular Mechanisms of the Teratogenic Effects of Thalidomide

Thalidomide was sold worldwide as a sedative over 60 years ago, but it was quickly withdrawn from the market due to its teratogenic effects. Thalidomide was later found to have therapeutic effects in several diseases, although the molecular mechanisms remained unclear. The discovery of cereblon (CRBN), the direct target of thalidomide, a decade ago greatly improved our understanding of its mechanism of action. Accumulating evidence has shown that CRBN functions as a substrate of Cullin RING E3 ligase (CRL4^CRBN), whose specificity is controlled by ligands such as thalidomide. For example, lenalidomide and pomalidomide, well-known thalidomide derivatives, degrade the neosubstrates Ikaros and Aiolos, resulting in anti-proliferative effects in multiple myeloma. Recently, novel CRBN-binding drugs have been developed. However, for the safe handling of thalidomide and its derivatives, a greater understanding of the mechanisms of its adverse effects is required. The teratogenic effects of thalidomide occur in multiple tissues in the developing fetus and vary in phenotype, making it difficult to clarify this issue. Recently, several CRBN neosubstrates (e.g., SALL4 (Spalt Like Transcription Factor 4) and p63 (Tumor Protein P63)) have been identified as candidate mediators of thalidomide teratogenicity. In this review, we describe the current understanding of molecular mechanisms of thalidomide, particularly in the context of its teratogenicity.

Recent advances in the molecular mechanism of thalidomide teratogenicity

Thalidomide was first marketed in 1957 but soon withdrawn because of its notorious teratogenicity. Studies on the mechanism of action of thalidomide revealed the pleiotropic properties of this class of drugs, including their anti-inflammatory, antiangiogenic and immunomodulatory activities. Based on their notable activities, thalidomide and its analogues, lenalidomide and pomalidomide, have been repurposed to treat erythema nodosum leprosum, multiple myeloma and other haematological malignancies. Thalidomide analogues were recently found to hijack CRL4^CRBN ubiquitin ligase to target a number of cellular proteins for ubiquitination and proteasomal degradation. Thalidomide-mediated degradation of SALL4 and p63, transcription factors essential for embryonic development, very likely plays a critical role in thalidomide embryopathy. In this review, we provide a brief retrospective summary of thalidomide-induced teratogenesis, the mechanism of thalidomide activity, and the latest advances in the molecular mechanism of thalidomide-induced birth malformations.

Underreporting of Fatal Congenital Zika Syndrome, Mexico, 2016-2017

To determine completeness of fatal congenital Zika syndrome reporting in Mexico, we examined data from the Mexican National Institute of Statistics and Geography. We found that an estimated 50% more infants died from microcephaly attributable to congenital Zika syndrome during 2016–2017 than were reported by the existing surveillance system.

Life situation of women impaired by Thalidomide embryopathy in North Rhine-Westphalia - a comparative analysis of a recent cross-sectional study with earlier data

Background

Between 1957 and 1961 the substance Thalidomide was sold in West Germany and taken by many women as a sedative during pregnancy. This lead to miscarriages and infants been born with several severe malformations. The aim of this study was to describe the current situation of women impaired by Thalidomide induced embryopahty in North Rhine-Westphalia (Nordrhein-Westfalen), Germany, in comparison with the results found in a study done in 2002 by Nippert et al.

Methods

Questionnaires as well as examinations were performed. Data were compared using descriptive and inductive statistical methods.

Results

Both studies show that women impaired by Thalidomide embryopathy face a poorer health status than women their age in the general population and live in fear of further deteriorating health. The majority can only work reduced hours or are already retired due to poor health. Most of those who need assistance are being assisted by their social environment, while professional care is still utilized in only few cases.

Conclusions

An obvious need for a shift in the provision of assistance and/or care provided was found as the social environment supporting the impaired women is also aging and therefore in high danger of breaking apart.

Trial registration

The study has been registered at German Clinical Trials Register, DRKS00010593, on 07.06.2016 retrospectively.

A clinical review and introduction of the diagnostic algorithm for thalidomide embryopathy (DATE)

Thalidomide embryopathy results from the ingestion of thalidomide in the first trimester during pregnancy, causing multiple forms of congenital abnormalities of variable severity that involve all systems. The skeletal findings most frequently affect the limbs, particularly the upper limbs and hands. Increasingly, several genetic disorders with similar birth defects have been identified. New cases of malformations owing to possible exposure to thalidomide continue to present through both historical and current usage. However, inadequate proof of ingestion, marked phenotypic variation and the possibility of an alternative genetic condition, hinder the diagnosis of thalidomide embryopathy. We introduce a 'diagnostic algorithm for thalidomide embryopathy' (DATE) diagnostic software that can potentially provide a numerical score for the likelihood of birth defects in an individual as being caused by exposure to thalidomide and to provide a differential diagnosis based on the pattern of malformation.

The teratogenic effects of thalidomide on limbs

Thalidomide remains notorious as a result of the damage it caused to children born to mothers who used it to treat morning sickness between 1957 and 1961. The re-emergence of the drug to treat a range of conditions including erythema nodosum leprosum (a complication of leprosy) has led to a new generation of thalidomide damaged children being born in Brazil. Although thalidomide affects most of the developing tissues and organs of the body, the damage to the limbs is striking. Indeed phocomelia, the severe reduction or loss of the proximal long bones with retention of the distal hand/foot plate remains the stereotypical image of thalidomide. This review focuses on the type and range of damage thalidomide caused to the limbs, reviews current understanding of the mechanisms underlying thalidomide-induced limb malformations and outlines some of the challenges remaining in elucidating its teratogenicity.

In vivo screening and discovery of novel candidate thalidomide analogs in the zebrafish embryo and chicken embryo model systems

Thalidomide, a drug known for its teratogenic side-effects, is used successfully to treat a variety of clinical conditions including leprosy and multiple myeloma. Intense efforts are underway to synthesize and identify safer, clinically relevant analogs. Here, we conduct a preliminary in vivo screen of a library of new thalidomide analogs to determine which agents demonstrate activity, and describe a cohort of compounds with anti-angiogenic properties, anti-inflammatory properties and some compounds which exhibited both. The combination of the in vivo zebrafish and chicken embryo model systems allows for the accelerated discovery of new, potential therapies for cancerous and inflammatory conditions.

Teratogens: a public health issue - a Brazilian overview

Congenital anomalies are already the second cause of infant mortality in Brazil, as in many other middle-income countries in Latin America. Birth defects are a result of both genetic and environmental factors, but a multifactorial etiology has been more frequently observed. Here, we address the environmental causes of birth defects - or teratogens - as a public health issue and present their mechanisms of action, categories and their respective maternal-fetal deleterious effects. We also present a survey from 2008 to 2013 of Brazilian cases involving congenital anomalies (annual average of 20,205), fetal deaths (annual average of 1,530), infant hospitalizations (annual average of 82,452), number of deaths of hospitalized infants (annual average of 2,175), and the average cost of hospitalizations (annual cost of $7,758). Moreover, we report on Brazilian cases of teratogenesis due to the recent Zika virus infection, and to the use of misoprostol, thalidomide, alcohol and illicit drugs. Special attention has been given to the Zika virus infection, now proven to be responsible for the microcephaly outbreak in Brazil, with 8,039 cases under investigation (from October 2015 to June 2016). From those cases, 1,616 were confirmed and 324 deaths occurred due to microcephaly complications or alterations on the central nervous system. Congenital anomalies impact life quality and raise costs in specialized care, justifying the classification of teratogens as a public health issue.

A new mammalian model system for thalidomide teratogenesis: Monodelphis domestica

From 1957 to 1962, thalidomide caused birth defects in >10,000 children. While the drug was pulled from the market, thalidomide is currently prescribed to treat conditions including leprosy. As a result, a new generation of babies with thalidomide defects is being born in the developing world. This represents a serious problem, as the mechanisms by which thalidomide disrupts development remain unresolved. This lack of resolution is due, in part, to the absence of an appropriate mammalian model for thalidomide teratogenesis. We test the hypothesis that opossum (Monodelphis domestica) is well suited to model human thalidomide defects. Results suggest that opossum embryos exposed to thalidomide display a range of phenotypes (e.g., heart, craniofacial, limb defects) and penetrance similar to humans. Furthermore, all opossums with thalidomide defects exhibit vascular disruptions. Results therefore support the hypotheses that opossums make a good mammalian model for thalidomide teratogenesis, and that thalidomide can severely disrupt angiogenesis in mammals.

Human teratogens and genetic phenocopies. Understanding pathogenesis through human genes mutation

Exposure to teratogenic drugs during pregnancy is associated with a wide range of embryo-fetal anomalies and sometimes results in recurrent and recognizable patterns of malformations; however, the comprehension of the mechanisms underlying the pathogenesis of drug-induced birth defects is difficult, since teratogenesis is a multifactorial process which is always the result of a complex interaction between several environmental factors and the genetic background of both the mother and the fetus. Animal models have been extensively used to assess the teratogenic potential of pharmacological agents and to study their teratogenic mechanisms; however, a still open issue concerns how the information gained through animal models can be translated to humans. Instead, significant information can be obtained by the identification and analysis of human genetic syndromes characterized by clinical features overlapping with those observed in drug-induced embryopathies. Until now, genetic phenocopies have been reported for the embryopathies/fetopathies associated with prenatal exposure to warfarin, leflunomide, mycophenolate mofetil, fluconazole, thalidomide and ACE inhibitors. In most cases, genetic phenocopies are caused by mutations in genes encoding for the main targets of teratogens or for proteins belonging to the same molecular pathways. The aim of this paper is to review the proposed teratogenic mechanisms of these drugs, by the analysis of human monogenic disorders and their molecular pathogenesis.

The impact of thalidomide use in birth defects in Brazil

Although the thalidomide tragedy occurred more than 50 years ago, the medication is still being used worldwide for different reasons, and several aspects regarding its teratogenicity remain unsolved. Despite the strict regulation implemented, new cases of thalidomide embryopathy (TE) are still being registered in Brazil. Furthermore, the molecular processes that lead to malformations when the embryo is exposed to thalidomide have not yet been fully identified. In this article, we perform a critical analysis of thalidomide's history in Brazil, highlighting aspects of the occurrence of TE over the decades. Finally, we present the main perspectives and challenges for ongoing surveillance and prevention of TE in Brazil. The effective control of dispensing thalidomide, especially in areas where leprosy is endemic, is one of the most important and challenging points. Furthermore, the emergence of thalidomide analogues is fast approaching, and their availability would pose additional concerns. The understanding of the molecular mechanisms and targets of thalidomide in both experimental and human models is essential for generating new insights into teratogenic mechanisms, so that safer thalidomide analogues can be developed.

Shared mechanism of teratogenicity of anti-angiogenic drugs identified in the chicken embryo model

Angiogenesis, the formation of new blood vessels, is essential for tumor growth, stabilization and progression. Angiogenesis inhibitors are now widely used in the clinic; however, there are relatively few published studies on the mechanism of their presumed teratogenic effects. To address this issue, we screened a variety of angiogenesis inhibitors in developing zebrafish and chicken embryo models to assess for developmental defects and potential teratogenic effects. We confirmed previous reports that sunitinib, sorafenib and TNP-470 are teratogenic and demonstrate that axitinib, pazopanib, vandetanib, and everolimus are also teratogens in these models. A dose response study identified the drugs inhibit HUVEC cell proliferation in vitro, and also target the developing blood vessels of embryos in vivo. This provides further evidence for the potential risk of fetal toxicity when using these drugs in a clinical setting, and emphasizes the importance of the development and maintenance of the vasculature in the embryo. We conclude that angiogenesis inhibitors, regardless of the molecular target, are teratogenic when exposed to chicken embryos.

Degenerative Changes in the Cervical Spine Are More Common in Middle-Aged Individuals with Thalidomide Embryopathy than in Healthy Controls

Background

Thalidomide was used as a sedative drug for pregnant women in the 1950–60:s and resulted in children born with thalidomide embryopathy (TE), including upper limb malformations. These may alter the motion pattern of the cervical spine by the use of head/shoulder and mouth grip.

Aims

To compare degenerative changes in the cervical spine in TE individuals with healthy controls (CTR).

Methods and Procedures

Twenty-seven middle-aged TE individuals and 27 age- and gender-matched CTR were examined by cervical spine MRI. The presence of malformations, disc herniation(s), osteophytes, nerve and medullary compression and the degree of disc degeneration (DD) were evaluated.

Outcomes and Results

Significantly higher degree of DD was seen in the TE group compared with the controls (p<0.001). Similar frequencies of disc herniation and disc space narrowing were observed in the two groups, but more foraminal narrowing was seen in the TE group (p = 0.002). DD was observed relatively frequently at all cervical levels in the TE group, however, mainly at the two lower levels in the CTR.

Conclusions and Implications

Middle-aged individuals with TE have a higher frequency of degenerative changes in the cervical spine than controls, possibly caused by an altered load on the cervical spine.

Thalidomide embryopathy: Follow-up of cases born between 1959 and 2010

BACKGROUND

Thalidomide is a known teratogen and it is estimated that more than ten thousand babies were affected by thalidomide embryopathy (TE), which is characterized mainly by limb defects, but can involve many organs and systems. Most people with TE were only evaluated at birth and it is not well established if thalidomide exposure during embryonic development leads to later effects. We analyzed the clinical history of adults with TE to better understand this gap in the clinical findings of TE.

METHODS

Brazilian individuals with TE were invited to answer a clinical questionnaire which considered family history, social information, medical history, and current clinical and psychological health status. A clinical examination was also performed, including on the infant subjects to evaluate congenital anomalies. The characterization of the features was analyzed using descriptive statistics and Chi-square or Fisher's exact test.

RESULTS

The congenital anomalies caused by thalidomide were reviewed in 28 Brazilian individuals, and the questionnaire was applied to the 23 adult subjects with TE (aged 19 to 55). Progressive deafness and dental loss were reported. From the comparison of TE individuals with the general Brazilian population, the early onset of cardiovascular diseases (p = 0.009) and a higher frequency of psychological disorders (p = 0.011) were observed.

CONCLUSION

Although there is no sufficient evidence that thalidomide exposure caused or worsened the described events, this approach helps to better understand the TE phenotype, improves the clinical diagnosis, and can lead to adequate health support for these individuals.

Thalidomide-induced teratogenesis: history and mechanisms

Nearly 60 years ago thalidomide was prescribed to treat morning sickness in pregnant women. What followed was the biggest man‐made medical disaster ever, where over 10,000 children were born with a range of severe and debilitating malformations. Despite this, the drug is now used successfully to treat a range of adult conditions, including multiple myeloma and complications of leprosy. Tragically, a new generation of thalidomide damaged children has been identified in Brazil. Yet, how thalidomide caused its devastating effects in the forming embryo remains unclear. However, studies in the past few years have greatly enhanced our understanding of the molecular mechanisms the drug. This review will look at the history of the drug, and the range and type of damage the drug caused, and outline the mechanisms of action the drug uses including recent molecular advances and new findings. Some of the remaining challenges facing thalidomide biologists are also discussed. Birth Defects Research (Part C) 105:140–156, 2015. © 2015 The Authors Birth Defects Research Part C: Embryo Today: Reviews Published by Wiley Periodicals, Inc.

Multicenter investigation of lifestyle-related diseases and visceral disorders in thalidomide embryopathy at around 50 years of age

Background

In utero exposure to thalidomide causes a wide range of birth defects, including phocomelia, hearing loss and visceral disorders, known as thalidomide embryopathy (TE). Fifty years after the first report of TE, we conducted the first cross‐sectional multicenter study to investigate the development of lifestyle‐related diseases and identify risk factors for visceral disorders in subjects with TE.

Methods

Seventy‐six cases with TE (31 men, 45 women) underwent medical examinations between 2011 and 2014 to determine the types of TE‐related anomalies (limbs, auditory organs, or visceral organs) and lifestyle‐related diseases present. Logistic multiple regression analyses, adjusted for gender and age, were conducted between TE and lifestyle‐related diseases and to evaluate association between block vertebra and gallbladder aplasia.

Results

Fatty liver (FL), nonalcoholic FL disease and dyslipidemia were detected in 52.6%, 35.0%, and 23.7% of subjects, respectively, with higher incidences among men. Dyslipidemia was detected in 40.0% of subjects with FL and was significantly associated with FL (odds ratio = 8.86; p = 0.008). Block vertebrae were detected in 44.4% of subjects with gallbladder aplasia, and this association was significant (odds ratio = 9.96; p = 0.006).

Conclusion

Subjects with TE have also a risk for lifestyle‐related disease as well as the general Japanese population. In addition, cervical spine radiography and magnetic resonance imaging are recommended to assess block vertebrae in subjects with TE with gallbladder aplasia who develop shoulder pain. Birth Defects Research (Part A) 103:787–793, 2015. © 2015 The Authors Birth Defects Research Part A: Clinical and Molecular Teratology Published by Wiley Periodicals, Inc.

Clinical use and control of the dispensing of thalidomide in Brasilia-Federal District, Brazil, from 2001 to 2012

The use of thalidomide was never discontinued in Brazil where it is prescribed for leprosy type 2 reaction. Babies with birth defects compatible with the thalidomide embryopathy phenotype were born after 1965, an indication that control on drug dispensing and use failed in the country. The article reports data on thalidomide dispensing and clinical uses in the Federal District in 2011/12, when new rules were put into effect, and data on drug dispensing and use obtained ten years earlier. It was found that the number of patients making use of thalidomide declined from 819 in 2001 to 369 in 2011/12. Leprosy accounted for over 70% of prescriptions in both time periods analyzed in this study. In the same time interval, however, use for lupus erythematosus decreased from 13.7 to 4.9%, while that for multiple myeloma increased from 2.9 to 20.3% of all prescriptions. Thalidomide prescription for the remaining approved indications was far less frequent, and so was the use for off label indications that accounted for <1% of prescriptions in 2001 and 2011/12. Registration of prescribing doctors, patients and dispensing units at the state department of health, apparently rendered this control more effective and reliable.

Long-term follow-up of thalidomide embryopathy: malformations and development of osteoarthritis in the lower extremities and evaluation of upper extremity function

BACKGROUND

Between 1959 and 1962, several children with multiple malformations were born after maternal intake of thalidomide during pregnancy, known as thalidomide embryopathy (TE).

OBJECTIVES

The aim of this study was to evaluate the malformations, their long-term effect on the function of the extremities and the development of degenerative osteoarthritis (OA) in the lower extremities.

METHODS

All living persons with TE in Sweden were invited to participate in the study. Thirty-one patients were examined clinically as a part of a multi-disciplinary follow-up programme. Evaluation of upper and lower limb function was performed by validated questionnaires [Disabilities of the Arm, Shoulder and Hand (DASH) and Rheumatoid and Arthritis Outcome Score (RAOS), respectively] and radiographic appearance of lower limbs by the use of spiral computed tomography.

RESULTS

Five individuals had severe malformations of the lower limbs and proximal femoral focal deficiency (PFFD), with significantly reduced function as found on the RAOS values. Twenty-seven patients had two fully functional arms and hands, despite the fact that 8% of shoulders, 26% of elbows/forearms and 70% of hands were malformed. Loss of gripping function did not significantly affect the upper extremity function, as measured by the DASH score. Ten patients without major deformities had OA in the hips and 15 in the knees, mostly mild and with no effect on the RAOS value.

CONCLUSION

A wide variety of malformations in the upper and lower limbs was found in the study group. Degenerative changes were found in the hips and the knees but were mostly mild and without major clinical significance. Despite upper limb anomalies that affected the fine motor skills, upper extremity function was not significantly reduced for most individuals. Individuals with PFFD along with major deformities of upper limbs had a reduced function of upper as well as lower limbs.

Thalidomide Embryopathy: An Enigmatic Challenge

Thalidomide remains one of the world’s most notorious drugs due to the severe birth defects it induced in children between 1957 and 1962. Yet, to some this drug is a lifesaver, as it now enjoys renaissance in the treatment for a wide range of conditions including leprosy, multiple myeloma, Behcet’s disease, and some cancers. However, thalidomide has also been linked to causing a new generation of thalidomide survivors in Brazil, where the drug is used to treat leprosy. Surprisingly how thalidomide causes birth defects and how it acts in the treatment of clinical conditions are still far from clear. In the past decade great strides in our understanding of the actions of the drug, as well as molecular targets, have been made. The purpose of this review is to look at the recent work carried out into understanding how thalidomide causes birth defects, it’s molecular targets and the challenges that remain to be elucidated. These challenges include identifying clinically relevant but nonteratogenic forms of the drug, and the mechanisms underlying phocomelia and species specificity.

Late-onset neurological symptoms in thalidomide-exposed subjects: a study of an Australasian cohort

BACKGROUND AND PURPOSE

Thalidomide was marketed for the treatment of morning sickness and resulted in foetal death and physical deformities. The exact mechanism of action of thalidomide in its teratogenicity is still actively debated in the literature.

METHODS

This study reviewed 16 of the confirmed Australasian victims of in utero exposure to thalidomide who now presented with new-onset neurological symptoms in the fourth and fifth decades.

RESULTS

Clinical neurological examination and neurophysiological investigations revealed that new symptoms were due in part to compressive neuropathies, often exacerbated by the adaptations made to accommodate the disability and poor mobility arising from the limb deformities. Other subjects were found to have musculoskeletal symptoms due to compensatory postures employed to perform tasks of daily living.

CONCLUSIONS

The study provides no evidence of ongoing loss of neurons or late reactivated neural degeneration and no evidence of a generalized peripheral neuropathy. Rather, the development of new symptoms in subjects can be explained by compressive neuropathies and compensatory postures employed to perform tasks of daily living.

Deciphering the mystery of thalidomide teratogenicity

Thalidomide was originally developed in 1954 as a sedative that was commonly used to ameliorate morning sickness. However, thalidomide exposure during the first trimester of pregnancy caused multiple birth defects (e.g. phocomelia and amelia), affecting ≈ 10,000 children worldwide in the late 1950s and early 1960s. Thalidomide is now recognized as a clinically effective, albeit strictly restricted, drug for the treatment of leprosy and multiple myeloma. Investigators have studied thalidomide teratogenicity for half a century, proposing over 30 hypotheses to account for its actions. Among these, the anti-angiogenesis and oxidative stress models have gained widespread support. Nonetheless, the precise molecular mechanisms and direct targets of thalidomide have not heretofore been elucidated. We developed ferrite-glycidyl methacrylate beads that enable magnetic separation and efficient purification of ligand-binding molecules; the beads were recently employed to identify cereblon as a primary target of thalidomide. Cereblon forms an E3 ubiquitin ligase complex with DDB1, Cul4A, and Roc1, which is important for the expression of fibroblast growth factor 8, an essential regulator of limb development. Expression of a drug binding-deficient mutant of cereblon suppressed thalidomide-induced effects in zebrafish and chicks. This suggests that thalidomide downregulates fibroblast growth factor 8 expression and induces limb malformation by binding to wild-type cereblon, inhibiting the function of the associated E3 ubiquitin ligase. The present review summarizes the teratogenicity of thalidomide, including existing models for its mode of action, and discusses the identification of cereblon as a key molecule for deciphering the longstanding mystery of thalidomide teratogenicity.

Phocomelia: a worldwide descriptive epidemiologic study in a large series of cases from the International Clearinghouse for Birth Defects Surveillance and Research, and overview of the literature

Epidemiologic data on phocomelia are scarce. This study presents an epidemiologic analysis of the largest series of phocomelia cases known to date. Data were provided by 19 birth defect surveillance programs, all members of the International Clearinghouse for Birth Defects Surveillance and Research. Depending on the program, data corresponded to a period from 1968 through 2006. A total of 22,740,933 live births, stillbirths and, for some programs, elective terminations of pregnancy for fetal anomaly (ETOPFA) were monitored. After a detailed review of clinical data, only true phocomelia cases were included. Descriptive data are presented and additional analyses compared isolated cases with those with multiple congenital anomalies (MCA), excluding syndromes. We also briefly compared congenital anomalies associated with nonsyndromic phocomelia with those presented with amelia, another rare severe congenital limb defect. A total of 141 phocomelia cases registered gave an overall total prevalence of 0.62 per 100,000 births (95% confidence interval: 0.52-0.73). Three programs (Australia Victoria, South America ECLAMC, Italy North East) had significantly different prevalence estimates. Most cases (53.2%) had isolated phocomelia, while 9.9% had syndromes. Most nonsyndromic cases were monomelic (55.9%), with an excess of left (64.9%) and upper limb (64.9%) involvement. Most nonsyndromic cases (66.9%) were live births; most isolated cases (57.9%) weighed more than 2,499 g; most MCA (60.7%) weighed less than 2,500 g, and were more likely stillbirths (30.8%) or ETOPFA (15.4%) than isolated cases. The most common associated defects were musculoskeletal, cardiac, and intestinal. Epidemiological differences between phocomelia and amelia highlighted possible differences in their causes.

Epidemiological surveillance of birth defects compatible with thalidomide embryopathy in Brazil

The thalidomide tragedy of the 1960s resulted in thousands of children being born with severe limb reduction defects (LRD), among other malformations. In Brazil, there are still babies born with thalidomide embryopathy (TE) because of leprosy prevalence, availability of thalidomide, and deficiencies in the control of drug dispensation. Our objective was to implement a system of proactive surveillance to identify birth defects compatible with TE. Along one year, newborns with LRD were assessed in the Brazilian hospitals participating in the Latin-American Collaborative Study of Congenital Malformations (ECLAMC). A phenotype of LRD called thalidomide embryopathy phenotype (TEP) was established for surveillance. Children with TEP born between the years 2000–2008 were monitored, and during the 2007–2008 period we clinically investigated in greater detail all cases with TEP (proactive period). The period from 1982 to 1999 was defined as the baseline period for the cumulative sum statistics. The frequency of TEP during the surveillance period, at 3.10/10,000 births (CI 95%: 2.50–3.70), was significantly higher than that observed in the baseline period (1.92/10,000 births; CI 95%: 1.60–2.20), and not uniformly distributed across different Brazilian regions. During the proactive surveillance (2007–2008), two cases of suspected TE were identified, although the two mothers had denied the use of the drug during pregnancy. Our results suggest that TEP has probably increased in recent years, which coincides with the period of greater thalidomide availability. Our proactive surveillance identified two newborns with suspected TE, proving to be a sensitive tool to detect TE. The high frequency of leprosy and the large use of thalidomide reinforce the need for a continuous monitoring of TEP across Brazil.

Teratogenic effects of thalidomide: molecular mechanisms

Fifty years ago, prescription of the sedative thalidomide caused a worldwide epidemic of multiple birth defects. The drug is now used in the treatment of leprosy and multiple myeloma. However, its use is limited due to its potent teratogenic activity. The mechanism by which thalidomide causes limb malformations and other developmental defects is a long-standing question. Multiple hypotheses exist to explain the molecular mechanism of thalidomide action. Among them, theories involving oxidative stress and anti-angiogenesis have been widely supported. Nevertheless, until recently, the direct target of thalidomide remained elusive. We identified a thalidomide-binding protein, cereblon (CRBN), as a primary target for thalidomide teratogenicity. Our data suggest that thalidomide initiates its teratogenic effects by binding to CRBN and inhibiting its ubiquitin ligase activity. In this review, we summarize the biology of thalidomide, focusing on the molecular mechanisms of its teratogenic effects. In addition, we discuss the questions still to be addressed.

Thalidomide: the tragedy of birth defects and the effective treatment of disease

Thalidomide was a widely used drug in the late 1950s and early 1960s for the treatment of nausea in pregnant women. It became apparent in the 1960s that thalidomide treatment resulted in severe birth defects in thousands of children. Though the use of thalidomide was banned in most countries at that time, thalidomide proved to be a useful treatment for leprosy and later, multiple myeloma. In rural areas of the world that lack extensive medical surveillance initiatives, thalidomide treatment of pregnant women with leprosy has continued to cause malformations. Research on thalidomide mechanisms of action is leading to a better understanding of molecular targets. With an improved understanding of these molecular targets, safer drugs may be designed. The thalidomide tragedy marked a turning point in toxicity testing, as it prompted United States and international regulatory agencies to develop systematic toxicity testing protocols; the use of thalidomide as a tool in developmental biology led to important discoveries in the biochemical pathways of limb development. In celebration of the Society of Toxicology's 50th Anniversary, which coincides with the 50th anniversary of the withdrawal of thalidomide from the market, it is appropriate to revisit the lessons learned from the thalidomide tragedy of the 1960s.

Fluorothalidomide: a characterization of maternal and developmental toxicity in rabbits and mice

The expanding therapeutic uses of thalidomide (TD) are limited by its teratogenic side effects. Although the therapeutic and teratogenic effects may be stereoselectively separable, rapid in vivo racemization of the TD isomers confounds the corroboration of this distinction. Herein we evaluated the potential of fluorothalidomide (FTD), the closest structural analog of TD with stable, nonracemizing isomers, as a model compound for studying stereoselectivity in TD teratogenesis. In contrast to TD, FTD was a potent maternal and fetal toxicant in both rabbits and mice in vivo. Furthermore, FTD rapidly degraded in vivo, presumably via hydrolysis, which in vitro was up to 22-fold faster for FTD than TD. Most critically, in an established rabbit embryo culture model for TD teratogenesis, FTD did not initiate the limb bud embryopathies observed with TD. The chemical instability and strikingly different maternal and developmental toxicological profiles of FTD and TD make FTD an unsuitable compound for studying stereoselective mechanisms of TD teratogenesis.

Embryopathic effects of thalidomide and its hydrolysis products in rabbit embryo culture: evidence for a prostaglandin H synthase (PHS)-dependent, reactive oxygen species (ROS)-mediated mechanism

Thalidomide (TD) causes birth defects in humans and rabbits via several potential mechanisms, including bioactivation by embryonic prostaglandin H synthase (PHS) enzymes to a reactive intermediate that enhances reactive oxygen species (ROS) formation. We show herein that TD in rabbit embryo culture produces relevant embryopathies, including decreases in head/brain development by 28% and limb bud growth by 71% (P<0.05). Two TD hydrolysis products, 2-phthalimidoglutaramic acid (PGMA) and 2-phthalimidoglutaric acid (PGA), were similarly embryopathic, attenuating otic vesicle (ear) and limb bud formation by up to 36 and 77%, respectively (P<0.05). TD, PGMA, and PGA all increased embryonic DNA oxidation measured as 8-oxoguanine (8-oxoG) by up to 2-fold (P<0.05). Co- or pretreatment with the PHS inhibitors eicosatetraynoic acid (ETYA) or acetylsalicylic acid (ASA), or the free-radical spin trap phenylbutylnitrone (PBN), completely blocked embryonic 8-oxoG formation and/or embryopathies initiated by TD, PGMA, and PGA. This is the first demonstration of limb bud embryopathies initiated by TD, as well as its hydrolysis products, in a mammalian embryo culture model of a species susceptible to TD in vivo, indicating that all likely contribute to TD teratogenicity in vivo, in part through PHS-dependent, ROS-mediated mechanisms.

Thalidomide-induced limb defects: resolving a 50-year-old puzzle

Despite the recent discovery that thalidomide causes limb defects by targeting highly angiogenic, immature blood vessels, several challenges still remain and new ones have arisen. These include understanding the drug's species specificity, determining molecular target(s) in the endothelial cell, shedding light on the molecular basis of phocomelia and producing a form of the drug that is clinically effective without having side effects. Now that the trigger of thalidomide-induced teratogenesis has been uncovered, a framework is proposed, incorporating and uniting previous models of thalidomide action, explaining how thalidomide causes not just limb defects, but also all the other defects it induces.

Sea urchin embryos exposed to thalidomide during early cleavage exhibit abnormal morphogenesis later in development

BACKGROUND

Clinical use of thalidomide has increased drastically, pushing the questions concerning the teratogenic mechanisms of this drug back to the forefront. Progress in understanding the teratogenic mechanisms has been slow, with the lack of non-primate vertebrate animal models susceptible to the classic reduction deformities remaining a concern. Sea urchin embryos have been used as model organisms for developmental studies for the last century. Like vertebrates, they are deuterostomes and share similar developmental and signaling pathways suggesting they may be an effective system for thalidomide studies. Therefore, we tested sea urchin embryos to see if they were sensitive to the effects of thalidomide.

METHODS

Sea urchin embryos were obtained using standard spawning and fertilization techniques. Thalidomide dissolved in DMSO was added to embryo cultures either at fertilization or during early cleavage. Samples of the embryos were evaluated during specific development stages.

RESULTS

Lytechinus pictus embryos exposed to 400 microM thalidomide at fertilization or within a window during early cleavage (2-6 hours post-fertilization) exhibit significant levels of abnormal embryos (60-82%) at the pluteus stage, compared to controls levels (< or =10%). Strongylocentrotus purpuratus embryos exposed at initial fertilization or during early cleavage (2-6 hours post-fertilization) exhibit similar responses with significant abnormal levels ranging from (55-70%) at pluteus stage.

CONCLUSIONS

Both species of sea urchin tested were susceptible to thalidomide-induced teratogenesis during cleavage (4-16 cell stages). This response during cleavage stages warrants further study and indicates that sea urchin embryos may prove to be a useful tool for studying thalidomide effects early in development.

Oral and maxillofacial surgery for the pregnant patient

This article describes clinical approaches for the perioperative management of the pregnant oral and maxillofacial surgical patient. The following topics are discussed: ethical principles of treatment during pregnancy, physiologic changes and their treatment considerations, fetal and maternal risks of various medications, medical problems occurring during pregnancy, and common minimally invasive approaches that the surgeon can apply to minimize the risk to the mother and unborn child. The strategies discussed provide successful treatment outcomes during this important time in the female surgical patient's life.

New cases of thalidomide embryopathy in Brazil

Thalidomide is the best known human teratogen. Although withdrawn from the market in 1961, thalidomide was remarketed after 1965 in several countries, for the treatment of erythema nodosum leprosum. Thalidomide has a potent immunomodulatory property and has now a number of approved and off-label uses in dermatologic, oncologic, infectious and gastrointestinal conditions. In the U.S., FDA approved the use of thalidomide in 1998, but no cases of thalidomide embriophaty were registered after that. Since 1996 no new cases were reported in Latin America. However, the Teratogen Information Service (TIS) Porto Alegre, recorded three new cases of thalidomide embriophaty born in Brazil since 2005. Considering that these three cases were not registered through a systematic surveillance system, but that came to our attention through a series of coincidental random events, it can be assumed that the actual occurrence of affected babies by thalidomide continues being as frequent as denounced ten years ago.

Inherited Thrombocytopenia: Congenital Amegakaryocytic Thrombocytopenia and Thrombocytopenia With Absent Radii

Thrombocytopenia in the newborn period can signify an inherited platelet disorder. Congenital amegakaryocytic thrombocytopenia (CAMT) and thrombocytopenia with absent radii (TAR) share features of isolated thrombocytopenia, reduced or absent marrow megakaryocytes, impaired responsiveness to thrombopoietin (TPO), and high plasma TPO levels. These disorders are most readily distinguished from each other by the finding of radial aplasia in TAR and the presence of c-MPL mutations in CAMT. In addition, their long-term outcomes are strikingly different: the development of trilineage marrow failure in CAMT in contrast to the general improvement of thrombocytopenia in TAR. The differential diagnosis for CAMT and TAR also includes other congenital disorders in which thrombocytopenia and radial abnormalities can be seen. In this article we will review our molecular and clinical understanding of these two inherited disorders of amegakaryocytosis.

The myelodysplastic syndromes: diagnosis and treatment

The myelodysplastic syndromes (MDSs) are common, acquired, clinically challenging hematologic conditions that are characterized by bone marrow failure and a risk of progression to acute leukemia. These disorders can arise de novo, especially in elderly patients or, less often, as a consequence of prior chemotherapy or radiotherapy for an unrelated disease. The MDS classification systems were revised recently and updated. These refined classification and prognostic schemes help stratify patients by their risk of leukemia progression and death; this knowledge can help clinicians select appropriate therapy. Although many treatments for MDS have been proposed and evaluated, at present, only hematopoietic stem cell transplantation offers any real hope for cure, and no available therapy beyond general supportive care offers benefit to more than a minority of patients. However, recent clinical trials enrolling patients with MDS have reported encouraging results with use of newer drugs, including lenalidomide, decitabine, and darbepoetin alfa. Other exciting treatment regimens are being tested. Here, we present a contemporary, practical clinical approach to the diagnosis and risk-stratified treatment of MDS. We review when to suspect MDS, detail how to evaluate patients who may have a form of the condition, explain key features of treatments that are currently available in the United States, and summarize a general, common-sense therapeutic approach to patients with MDS.

ECLAMC: the Latin-American collaborative study of congenital malformations

DEFINITION

ECLAMC ('Estudio Colaborativo Latino Americano de Malformaciones Congenitas') is a program for the clinical and epidemiological investigation of risk factors in the etiology of congenital anomalies in Latin-American hospitals, using a case-control methodological approach. It is a voluntary agreement among professionals lacking institutional base as well as designated budgets. ECLAMC has been usually funded by research-funding agencies rather than public health ministries. The National Research Councils of Argentina and Brazil have been the main sources of support during its 36 years of existence. Since vital and health statistics are unreliable in South America, ECLAMC collects all the information required for the denominators in a hospital-based sample of births. ECLAMC can be defined as a continental network of persons interested in research and prevention of birth defects.

HISTORY AND EVOLUTION

From the institutional point of view, ECLAMC has had headquarters in diverse centers of Argentina and Brazil, but always as an independent research project, without a defined administrative link. ECLAMC began operating in 1967, as an investigation limited to the city of Buenos Aires, Argentina, and it gradually expanded until covering all the 10 countries of South America as well as Costa Rica and the Dominican Republic. Even though ECLAMC has maintained essentially the same original experimental design since 1967, due to the data accumulated by the program, the increasing experience as well as the development in science, technical modifications occurred including a DNA bank and a fully informatized data handling system. Since 1974 ECLAMC has been a founder member of the International Clearinghouse for Birth Defects Monitoring Systems; since 1994 a WHO Collaborating Center for the Prevention of Congenital Malformations, and since 2000 a collaborating member of the NIH Global Netwok for Women's and Children's Health Research.

METHODOLOGY

The maternity hospital network of ECLAMC examines around 200,000 births per year. All major and minor anomalies diagnosed at birth in infants weighing 500 g or more are registered according to a manual of procedures. The next non-malformed baby of the same sex born in the same hospital is selected as a control subject for each case. Thus, a one-to-one healthy control group matched by sex, time and place of birth is obtained. As a system of epidemic surveillance, ECLAMC systematically observes the fluctuations in the frequencies of different malformations and, in the case of an alarm for a probable epidemic of a given malformation, at a given moment, and given area, it acts to identify its cause. As termination of pregnancy has severe legal restrictions in South America, prevention of birth defects should concentrate on primary, preconceptional and tertiary measures. Tertiary measures aim to avoid complications of the affected patients from the medical, psychological, and social standpoints.

Thalidomide: an old drug with new clinical applications

Thalidomide has several targets and mechanisms of action: a hypnosedative effect, several immunomodulatory properties with an effect on the production of TNF-alpha and the balance between the different lymphocyte subsets and an antiangiogenic action. Thalidomide has been used in several cutaneous inflammatory disorders (e.g., erythema nodosum leprosum in lepromatous leprosy, cutaneous lupus erythematosus and severe aphtosis), cancers (e.g., relapsed/refractory multiple myeloma, malignant melanoma and systemic signs in cancer) and inflammatory conditions (e.g., Crohn's disease and rheumatoid arthritis). Several side effects are associated with thalidomide. Some are major, such as teratogenicity, peripheral neuropathy and deep vein thrombosis. Somnolence and rash are frequently reported when thalidomide is used at higher doses as an anticarcinogenic agent and can lead to dose reduction or treatment discontinuation depending on severity. Minor side effects include abdominal pain and endocrine disturbances. To prevent the teratogenicity, use of thalidomide is strictly controlled in western countries with close adherence to a birth control programme. Close monitoring for early development of peripheral neuropathy is also recommended.

Risk of drug-induced congenital defects

Defects attributable to drug therapy represent about 1% of congenital defects of known aetiology. This means that a precautionary attitude and correct use of drugs in fertile, and especially pregnant, women is a feasible form of prevention. Drugs currently in use with proven teratogenic effect number approximately 25, but new pharmaceutical drugs are constantly in preparation. Recognition of a drug-induced teratogenic effect is a complex procedure taking into account not only experimental animal data but also experience in humans. Considering that 40% of pregnancies are not planned, it follows that any drug with known or suspected teratogenic potential must be used only under strict medical control. Also, adequate knowledge on potential teratogenicity of a drug permits modification of therapy before conception. It goes without saying that any drug should be used during pregnancy only if it is essential, and it would be prudent to use only those where adequate information is provided and prior clinical experience is available. Teratology Information Services can assist both physicians and patients when any doubt exists.

Thalidomide : mécanismes d'action et indications en hématologie

Purpose. - Thalidomide, a major teratogen drug, was rehabilitated mainly in malignant hemopathy. Current knowledge and key points. - Thalidomide-mechanisms of action are well known, multiple, they combine immunomodulatory, antiangiogenic properties, and the modulation of cytokines, particularly tumour necrosis factor-alpha. Multiple trials are ongoing, however, the main indication remain multiple myeloma with a response rate of 30% in relapsed patients. Future prospects and projects. - New structural analogues of the thalidomide which priviligiate some of the thalidomide-specific mechanisms of action, the selected cytokine inhibitory drugs (SelCIDS) and the immunomodulatory drugs (IMiDs) family are under evaluation. The IMiDs, which mechanism is based on stimulation of T lymphopoiesis rather than inhibition of tumour necrosis factor-alpha, are under clinical trials in multiple myeloma with interesting results.

Medical genetics in developing countries

Since Watson & Crick's 1953 description of the structure of DNA, significant progress has been achieved in the control of congenital disorders, most of which has benefited industrialized countries. Little advantage accrued to developing nations, most of which in the same time frame achieved a significant epidemiological transition, resulting in congenital disorders attaining public health significance. The burden of congenital disorders in these lower-resource countries is high and they need to develop medical genetic services. We present a new pragmatic approach for the care and prevention of congenital disorders in these countries, pioneered initially by the World Health Organization.