Thalidomide-induced neuropathy: a ganglionopathy?

Considerations for a Reliable In Vitro Model of Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is widely recognized as a potentially severe toxicity that often leads to dose reduction or discontinuation of cancer treatment. Symptoms may persist despite discontinuation of chemotherapy and quality of life can be severely compromised. The clinical symptoms of CIPN, and the cellular and molecular targets involved in CIPN, are just as diverse as the wide variety of anticancer agents that cause peripheral neurotoxicity. There is an urgent need for extensive molecular and functional investigations aimed at understanding the mechanisms of CIPN. Furthermore, a reliable human cell culture system that recapitulates the diversity of neuronal modalities found in vivo and the pathophysiological changes that underlie CIPN would serve to advance the understanding of the pathogenesis of CIPN. The demonstration of experimental reproducibility in a human peripheral neuronal cell system will increase confidence that such an in vitro model is clinically useful, ultimately resulting in deeper exploration for the prevention and treatment of CIPN. Herein, we review current in vitro models with a focus on key characteristics and attributes desirable for an ideal human cell culture model relevant for CIPN investigations.

Thalidomide and Lenalidomide for Refractory Systemic/Cutaneous Lupus Erythematosus Treatment: A Narrative Review of Literature for Clinical Practice

BACKGROUND

Thalidomide has shown exceptional results in systemic/cutaneous lupus erythematosus(SLE/CLE). Recently, lenalidomide has been also prescribed for SLE/CLE treatment. Literature regarding efficacy/adverse events for these drugs is scarce with a single systematic review and meta-analysis focused solely on thalidomide for refractory cutaneous lupus subtypes.

OBJECTIVE

We, therefore, addressed in this narrative review the efficacy/adverse effects of thalidomide and lenalidomide for SLE and CLE. In addition, we provide a specialist approach for clinical practice based on the available evidence.

RESULTS

Efficacy of thalidomide for refractory cutaneous lupus treatment was demonstrated by several studies, mostly retrospective with small sample size(≤20). The frequency of peripheral polyneuropathy is controversial varying from 15-80% with no consistent data regarding cumulative dose and length of use. Drug withdrawn results in clinical partial/complete reversibility for most cases (70%). For lenalidomide, seven studies (small sample sizes) reported its efficacy for SLE/CLE with complete/partial response in all patients with a mean time to response of 3 months. Flare rate varied from 25-75% occurring 0.5-10 months after drug withdrawn. There were no reports of polyneuropathy/worsening of previous thalidomide-induced neuropathy, but most of them did not perform nerve conduction studies. Teratogenicity risk exist for both drugs and strict precautions are required.

CONCLUSIONS

Thalidomide is very efficacious as an induction therapy for patients with severe/refractory cutaneous lupus with high risk of scarring, but its longstanding use should be avoided due to neurotoxicity. Lenalidomide is a promising drug for skin lupus treatment, particularly regarding the apparent lower frequency of nerve side effects.

Clinical and biochemical markers in CIPN: A reappraisal

The increased survival of cancer patients has raised growing public health concern on associated long-term consequences of antineoplastic treatment. Chemotherapy-induced peripheral neuropathy (CIPN) is a primarily sensory polyneuropathy, which may be accompanied by pain, autonomic disturbances, and motor deficit. About 70% of treated cancer patients might develop CIPN during or after the completion of chemotherapy, and in most of them such complication persists after six months from the treatment. The definition of the potential risk of development and resolution of CIPN according to a clinical and biochemical profile would be certainly fundamental to tailor chemotherapy regimen and dosage on individual susceptibility. In recent years, patient-reported and clinician-related tools along with quality of life instruments have been featured as primary outcomes in clinical setting and randomized trials. New studies on metabolomics markers are further pursuing accurate and easily accessible indicators of peripheral nerve damage. The aim of this review is to outline the strengths and pitfalls of current knowledge on CIPN, and to provide a framework for future potential developments of standardized protocols involving clinical and biochemical markers for CIPN assessment and monitoring.

A Comparative Review of Chemotherapy-Induced Peripheral Neuropathy in In Vivo and In Vitro Models

Chemotherapy-induced peripheral neuropathy (CIPN) is an adverse effect caused by several classes of widely used anticancer therapeutics. Chemotherapy-induced peripheral neuropathy frequently leads to dose reduction or discontinuation of chemotherapy regimens, and CIPN symptoms can persist long after completion of chemotherapy and severely diminish the quality of life of patients. Differences in the clinical presentation of CIPN by widely diverse classifications of anticancer agents have spawned multiple mechanistic hypotheses that seek to explain the pathogenesis of CIPN. Despite its clinical relevance, common occurrence, and extensive investigation, the pathophysiology of CIPN remains unclear. Furthermore, there is no unequivocal gold standard for the prevention and treatment of CIPN. Herein, we review in vivo and in vitro models of CIPN with a focus on histopathological changes and morphological features aimed at understanding the pathophysiology of CIPN and identify gaps requiring deeper exploration. An elucidation of the underlying mechanisms of CIPN is imperative to identify potential targets and approaches for prevention and treatment.

Vinca alkaloids, thalidomide and eribulin-induced peripheral neurotoxicity: From pathogenesis to treatment

Vinca alkaloids, thalidomide, and eribulin are widely used to treat patients with childhood acute lymphoblastic leukemia (ALL), adults affected by multiple myeloma and locally invasive or metastatic breast cancer, respectively. However, soon after their introduction into clinical practice, chemotherapy-induced peripheral neurotoxicity (CIPN) emerged as their main non-hematological and among dose-limiting adverse events. It is generally perceived that vinca alkaloids and the antiangiogenic agent thalidomide are more neurotoxic, compared to eribulin. The exposure to these chemotherapeutic agents is associated with an axonal, length-dependent, sensory polyneuropathy of mild to moderate severity, whereas it is considered that the peripheral nerve damage, unless severe, usually resolves soon after treatment discontinuation. Advanced age, high initial and prolonged dosing, coadministration of other neurotoxic chemotherapeutic agents and pre-existing neuropathy are the common risk factors. Pharmacogenetic biomarkers might be used to define patients at increased susceptibility of CIPN. Currently, there is no established therapy for CIPN prevention or treatment; symptomatic treatment for neuropathic pain and dose reduction or withdrawal in severe cases is considered, at the cost of reduced cancer therapeutic efficacy. This review critically examines the pathogenesis, epidemiology, risk factors (both clinical and pharmacogenetic), clinical phenotype and management of CIPN as a result of exposure to vinca alkaloids, thalidomide and its analogue lenalidomide as also eribulin.

Chemotherapy-Induced Peripheral Neuropathy and Changes in Cytoskeleton

Despite the different antineoplastic mechanisms of action, peripheral neurotoxicity induced by all chemotherapy drugs (anti-tubulin agents, platinum compounds, proteasome inhibitors, thalidomide) is associated with neuron morphological changes ascribable to cytoskeleton modifications. The "dying back" degeneration of distal terminals (sensory nerves) of dorsal root ganglia sensory neurons, observed in animal models, in in vitro cultures and biopsies of patients is the most evident hallmark of the perturbation of the cytoskeleton. On the other hand, in highly polarized cells like neurons, the cytoskeleton carries out its role not only in axons but also has a fundamental role in dendrite plasticity and in the organization of soma. In the literature, there are many studies focused on the antineoplastic-induced alteration of microtubule organization (and consequently, fast axonal transport defects) while very few studies have investigated the effect of the different classes of drugs on microfilaments, intermediate filaments and associated proteins. Therefore, in this review, we will focus on: (1) Highlighting the fundamental role of the crosstalk among the three filamentous subsystems and (2) investigating pivotal cytoskeleton-associated proteins.

[Chemotherapy-induced peripheral neuropathy: Symptomatology and epidemiology]

Chemotherapy-induced peripheral neuropathy (CIPN) is common with specific semiological characteristics. When CIPN appears, there are many difficulties in guaranteeing sustained treatment, especially with optimal protocol. Moreover, CIPN have bad repercussions on quality of life after cancer disease. In this article, we have achieved a current state of CIPN and try to report details about semiological characteristics and topography. We have also produced some epidemiological data. Nonetheless, we have not voluntarily introduced treatment because it will be the topic of further work.

[Clinical and electromyography characteristics of chemotherapy-induced polyneuropathy]

AIM

The study aimed at determining clinical and electromyography characteristics and developing the methods of CIPN treatment.

MATERIAL AND METHODS

A clinical and electromyographic examinations and treatment of 30 with CIPN symptoms developed after polychemotherapy were performed. The authors developed treatment schemes included allopathic, homeopathic drugs, hydrotherapy and pharmacopuncture.

RESULTS AND CONCLUSION

Most of the patients were diagnosed with axonal polyneuropathy with affection of long nerves of the limbs, some patients had a combination of axonopathy with myelopathy. After treatment, regression of neuropathy symptoms and improvement of quality of life was noted in all patients.

Risk-reduction and treatment of chemotherapy-induced peripheral neuropathy

INTRODUCTION

Chemotherapy-induced peripheral neuropathy (CIPN), a common adverse effect of several chemotherapeutic agents, has a significant impact on quality of life and may even compromise treatment efficacy, requiring chemotherapy dose reduction or discontinuation. CIPN is predominantly related with sensory rather than motor symptoms and the most common related cytotoxic agents are platinum compounds, taxanes and vinca alkaloids. CIPN symptoms may resolve after treatment cessation, but they can also be permanent and continue for years. Areas covered: We present an overview of CIPN pathophysiology, clinical assessment, prevention and treatment identified through a Pubmed search. Expert commentary: No substantial progress has been made in the last few years within the field of prevention and/or treatment of CIPN, in spite of remarkable efforts. Continuous research could expand our knowledge about chemotherapeutic-specific neuropathic pathways and eventually lead to the conception of innovative and targeted agents for the prevention and/or treatment of this debilitating chemotherapy adverse effect.

Long-Term Effects, Pathophysiological Mechanisms, and Risk Factors of Chemotherapy-Induced Peripheral Neuropathies: A Comprehensive Literature Review

Neurotoxic anticancer drugs, such as platinum-based anticancer drugs, taxanes, vinca alkaloids, and proteasome/angiogenesis inhibitors are responsible for chemotherapy-induced peripheral neuropathy (CIPN). The health consequences of CIPN remain worrying as it is associated with several comorbidities and affects a specific population of patients already impacted by cancer, a strong driver for declines in older adults. The purpose of this review is to present a comprehensive overview of the long-term effects of CIPN in cancer patients and survivors. Pathophysiological mechanisms and risk factors are also presented. Neurotoxic mechanisms leading to CIPNs are not yet fully understood but involve neuronopathy and/or axonopathy, mainly associated with DNA damage, oxidative stress, mitochondria toxicity, and ion channel remodeling in the neurons of the peripheral nervous system. Classical symptoms of CIPNs are peripheral neuropathy with a “stocking and glove” distribution characterized by sensory loss, paresthesia, dysesthesia and numbness, sometimes associated with neuropathic pain in the most serious cases. Several risk factors can promote CIPN as a function of the anticancer drug considered, such as cumulative dose, treatment duration, history of neuropathy, combination of therapies and genetic polymorphisms. CIPNs are frequent in cancer patients with an overall incidence of approximately 38% (possibly up to 90% of patients treated with oxaliplatin). Finally, the long-term reversibility of these CIPNs remain questionable, notably in the case of platinum-based anticancer drugs and taxanes, for which CIPN may last several years after the end of anticancer chemotherapies. These long-term effects are associated with comorbidities such as depression, insomnia, falls and decreases of health-related quality of life in cancer patients and survivors. However, it is noteworthy that these long-term effects remain poorly studied, and only limited data are available such as in the case of bortezomib and thalidomide-induced peripheral neuropathy.

Longitudinal Patterns of Thalidomide Neuropathy in Children and Adolescents

OBJECTIVE

To characterize the longitudinal clinical and electrophysiological patterns of thalidomide neuropathy in children and adolescents.

STUDY DESIGN

Retrospective analysis of clinical records at a tertiary care children's hospital, including serial electrophysiological studies.

RESULTS

Sixteen patients aged 6-24 years received thalidomide to treat Crohn's disease from 2002 to 2012. Nine subjects had electrophysiological evidence of sensorimotor axonal polyneuropathy, 8 of whom had sensory and/or motor symptoms. The patients with polyneuropathy received thalidomide for 5 weeks to 52 months, with cumulative doses ranging from 1.4 to 207.7 g. All subjects with cumulative doses greater than 60 g developed polyneuropathy, and 4 of the 5 subjects who received thalidomide for more than 20 months developed polyneuropathy. The 7 subjects who had normal neurophysiological studies received therapy for 1 week to 25 months, with cumulative doses ranging from 0.7 to 47 g. In contrast to some previous reports, several patients had sensorimotor polyneuropathies, rather than pure sensory neuropathies. In patients with neuropathy who received therapy for more than 24 months and had 3 or more electromyography studies, the severity of the neuropathy plateaued.

CONCLUSIONS

Factors in addition to the total dose may contribute to the risk profile for thalidomide neuropathy, including pharmacogenetic susceptibilities. The severity of the neuropathy does not worsen relentlessly. Children, adolescents, and young adults receiving thalidomide should undergo regular neurophysiological studies to monitor for neuropathy.

Prediction of peripheral neuropathy in multiple myeloma patients receiving bortezomib and thalidomide: a genetic study based on a single nucleotide polymorphism array

Bortezomib- and thalidomide-based therapies have significantly contributed to improved survival of multiple myeloma (MM) patients. However, treatment-induced peripheral neuropathy (TiPN) is a common adverse event associated with them. Risk factors for TiPN in MM patients include advanced age, prior neuropathy, and other drugs, but there are conflicting results about the role of genetics in predicting the risk of TiPN. Thus, we carried out a genome-wide association study based on more than 300 000 exome single nucleotide polymorphisms in 172 MM patients receiving therapy involving bortezomib and thalidomide. We compared patients developing and not developing TiPN under similar treatment conditions (GEM05MAS65, NCT00443235). The highest-ranking single nucleotide polymorphism was rs45443101, located in the PLCG2 gene, but no significant differences were found after multiple comparison correction (adjusted P = .1708). Prediction analyses, cytoband enrichment, and pathway analyses were also performed, but none yielded any significant findings. A copy number approach was also explored, but this gave no significant results either. In summary, our study did not find a consistent genetic component associated with TiPN under bortezomib and thalidomide therapies that could be used for prediction, which makes clinical judgment essential in the practical management of MM treatment.

Long-term Outcomes of Thalidomide Therapy for Adults With Refractory Crohn's Disease

BACKGROUND & AIMS

Little is known about the efficacy and safety of thalidomide therapy for patients with refractory Crohn's disease (CD), particularly in respect to long-term outcomes of patients.

METHODS

We conducted a retrospective multicenter observational study to evaluate thalidomide efficacy and the probability of its withdrawal because of either toxicity or lack/loss of efficacy. We analyzed data from 77 patients with active intestinal and/or perineal CD, refractory to conventional immunosuppressive therapies, treated with thalidomide at 5 tertiary referral inflammatory bowel disease centers in France. We also analyzed the long-term efficacy of thalidomide.

RESULTS

Fifty-four percent of the patients were in clinical remission after thalidomide treatment within the first year. The proportions of patients from whom thalidomide was withdrawn because of lack/loss of efficacy and/or toxicity were 35% at 3 months of treatment, 69% at 12 months, and 88% at 24 months. The proportions of patients from whom thalidomide was withdrawn because of toxicity alone were 22% at 3 months, 34% at 12 months, and 46% at 24 months. Overall, neuropathy occurred in 30 patients and was the main reason for thalidomide withdrawal.

CONCLUSIONS

On the basis of a retrospective multicenter observational study, thalidomide therapy is effective in most patients with refractory active intestinal and/or perineal CD. However, its toxicity limits its use as a maintenance therapy.

Chemotherapy-induced peripheral neuropathy: an update on the current understanding

Chemotherapy-induced peripheral neuropathy is a common side effect of selected chemotherapeutic agents. Previous work has suggested that patients often under report the symptoms of chemotherapy-induced peripheral neuropathy and physicians fail to recognize the presence of such symptoms in a timely fashion. The precise pathophysiology that underlies chemotherapy-induced peripheral neuropathy, in both the acute and the chronic phase, remains complex and appears to be medication specific. Recent work has begun to demonstrate and further clarify potential pathophysiological processes that predispose and, ultimately, lead to the development of chemotherapy-induced peripheral neuropathy. There is increasing evidence that the pathway to neuropathy varies with each agent. With a clearer understanding of how these agents affect the peripheral nervous system, more targeted treatments can be developed in order to optimize treatment and prevent long-term side effects.

Axonal Transport Impairment in Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-Induced Peripheral Neuropathy (CIPN) is a dose-limiting side effect of several antineoplastic drugs which significantly reduces patients’ quality of life. Although different molecular mechanisms have been investigated, CIPN pathobiology has not been clarified yet. It has largely been recognized that Dorsal Root Ganglia are the main targets of chemotherapy and that the longest nerves are the most damaged, together with fast axonal transport. Indeed, this bidirectional cargo-specific transport has a pivotal role in neuronal function and its impairment is involved in several neurodegenerative and neurodevelopmental diseases. Literature data demonstrate that, despite different mechanisms of action, all antineoplastic agents impair the axonal trafficking to some extent and the severity of the neuropathy correlates with the degree of damage on this bidirectional transport. In this paper, we will examine the effect of the main old and new chemotherapeutic drug categories on axonal transport, with the aim of clarifying their potential mechanisms of action, and, if possible, of identifying neuroprotective strategies, based on the knowledge of the alterations induced by each drugs.

The clinical implications of thalidomide in inflammatory bowel diseases

Thalidomide has anti-inflammatory and anti-angiogenetic activity that makes it suitable for treating inflammatory bowel diseases (IBD). The recent guidelines from the European Crohn's and Colitis Organization/European Society for Pediatric Gastroenterology Hepatology and Nutrition conclude that thalidomide cannot be recommended in refractory pediatric Crohn's disease but that it may be considered in selected cohorts of patients who are not anti-TNFα agent responders. The main adverse effect is the potential teratogenicity that renders the long-term use of thalidomide problematic in young adults due to the strict need for contraceptive use. In short-term use it is relatively safe; the most likely adverse effect is the neuropathy, which is highly reversible in children. So far the use of thalidomide is reported in 223 adult and pediatric IBD patients (206 with Crohn's disease). In the following sections, the authors will discuss efficacy and safety of thalidomide, in the short-term treatment of IBD.

Bortezomib- and thalidomide-induced peripheral neuropathy in multiple myeloma: clinical and molecular analyses of a phase 3 study

A subanalysis of the GIMEMA-MMY-3006 trial was performed to characterize treatment-emergent peripheral neuropathy (PN) in patients randomized to thalidomide-dexamethasone (TD) or bortezomib-TD (VTD) before and after double autologous transplantation (ASCT) for multiple myeloma (MM). A total of 236 patients randomized to VTD and 238 to TD were stratified according to the emergence of grade ≥2 PN. Gene expression profiles (GEP) of CD138+ plasma cells were analyzed in 120 VTD-treated patients. The incidence of grade ≥2 PN was 35% in the VTD arm and 10% in the TD arm (P < 0.001). PN resolved in 88 and 95% of patients in VTD and TD groups, respectively. Rates of complete/near complete response, progression-free and overall survival were not adversely affected by emergence of grade ≥2 PN. Baseline characteristics were not risk factors for PN, while GEP analysis revealed the deregulated expression of genes implicated in cytoskeleton rearrangement, neurogenesis, and axonal guidance. In conclusion, in comparison with TD, incorporation of VTD into ASCT was associated with a higher incidence of PN which, however, was reversible in most of the patients and did not adversely affect their outcomes nor their ability to subsequently receive ASCT. GEP analysis suggests an interaction between myeloma genetic profiles and development of VTD-induced PN.

Therapy-related peripheral neuropathy in multiple myeloma patients

This review discusses the most common issues concerning multiple myeloma (MM)-related peripheral neuropathy (PN). This is an important MM complication, observed in up to 54% of newly diagnosed patients, caused by the disease itself or its treatment. Although its aetiology is largely unknown, a number of mechanisms are suspected. It is important to know the neurological status of a patient, as many new antimyeloma medicines can trigger or exacerbate any pre-existing neuropathy. Examples include thalidomide-induced and bortezomib-induced PN (TiPN and BiTN, respectively), which are key MM treatment options. TiPN is usually sensory and sensorimotor, whereas BiPN is typically sensory. The mechanisms of chemotherapy-induced neurotoxicity in MM are well known; thalidomide seems to induce PN through its antiangiogenic properties, whereas bortezomib neurotoxicity is connected with disrupted calcium homeostasis. TiPN incidence ranges from 25% to 75%, and its prevalence and severity appears to be dose-dependent. BiPN incidence is almost 40% and is dose-related as well. Poor (25%) reversibility of TiPN prompted the recommendations for dose and exposure reduction, whereas BiPN cases are mostly reversible (64%). Peripheral sensory neuropathy is very rare in patients receiving bendamustine monotherapy. Because of this favourable toxicity profile, bendamustine may be considered a promising option for combination therapies in pre-existing PN in myeloma patients. Considering the lack of curative therapy for treatment-emergent PN, prevention is a key management strategy in MM patients. All patients should be evaluated for PN before the administration of a neurotoxic drug, and those under treatment should be closely monitored by a neurologist.

Chemotherapy-induced peripheral neuropathies in hematological malignancies

Recent developments in the treatment of hematological malignancies, especially with the advent of proteasome inhibitors and immunomodulatory drugs in plasma cell dyscrasias, call for an increased collaboration between hematologists and neurologists. This collaboration involves differentiating chemotherapy-induced peripheral neuropathies (CiPN) from disease-related neurologic complications, early recognition of CiPN and treatment of neuropathic pain. Multiple myeloma, Waldenstrom's macroglobulinemia and light-chain amyloidosis frequently present with peripheral neuropathy. In addition, multiple myeloma, non-Hodgkin lymphomas and leukemia's may mimic peripheral neuropathy by compression or invasion of the extra/intradural space. Platinum compounds, vinca alkaloids, proteasome inhibitors and immunomodulatory drugs may all cause CiPN, each with different and often specific clinical characteristics. Early recognition, by identifying the distinct clinical phenotype of CiPN, is of crucial importance to prevent irreversible neurological damage. No recommendations can be given on the use of neuroprotective strategies because of a lack of convincing clinical evidence. Finally, CiPN caused by vinca-alkaloids, proteasome inhibitors and immunomodulatory drugs is often painful and neurologists are best equipped to treat this kind of painful neuropathy.

Chemotherapy-induced peripheral neurotoxicity: a critical analysis

With a 3-fold increase in the number of cancer survivors noted since the 1970s, there are now over 28 million cancer survivors worldwide. Accordingly, there is a heightened awareness of long-term toxicities and the impact on quality of life following treatment in cancer survivors. This review will address the increasing importance and challenge of chemotherapy-induced neurotoxicity, with a focus on neuropathy associated with the treatment of breast cancer, colorectal cancer, testicular cancer, and hematological cancers. An overview of the diagnosis, symptomatology, and pathophysiology of chemotherapy-induced peripheral neuropathy will be provided, with a critical analysis of assessment strategies, neuroprotective approaches, and potential treatments. The review will concentrate on neuropathy associated with taxanes, platinum compounds, vinca alkaloids, thalidomide, and bortezomib, providing clinical information specific to these chemotherapies.

Therapeutic effects of thalidomide in hematologic disorders: a review

The extensive autoimmune, anti-inflammatory, and anticancer applications of thalidomide have inspired a growing number of studies and clinical trials. As an inexpensive agent with relatively low toxicity, thalidomide is regarded as a promising therapeutic candidate, especially for malignant diseases. We review its therapeutic effects in hematology, including those on multiple myeloma, Waldenstroem macroglobulinemia, lymphoma, mantle-cell lymphoma, myelodysplastic syndrome, hereditary hemorrhagic telangiectasia, and graftversus-host disease. Most studies have shown satisfactory results, although several have reported the opposite. Aside from optimal outcomes, the toxicities and adverse effects of thalidomide should also be examined. The current work includes a discussion of the mechanisms through which the novel biological effects of thalidomide occur, although more studies should be devoted to this aspect. With appropriate safeguards, thalidomide may benefit patients suffering from a broad variety of disorders, particularly refractory and resistant diseases.

Management of treatment-emergent peripheral neuropathy in multiple myeloma

Peripheral neuropathy (PN) is one of the most important complications of multiple myeloma (MM) treatment. PN can be caused by MM itself, either by the effects of the monoclonal protein or in the form of radiculopathy from direct compression, and particularly by certain therapies, including bortezomib, thalidomide, vinca alkaloids and cisplatin. Clinical evaluation has shown that up to 20% of MM patients have PN at diagnosis and as many as 75% may experience treatment-emergent PN during therapy. The incidence, symptoms, reversibility, predisposing factors and etiology of treatment-emergent PN vary among MM therapies, with PN incidence also affected by the dose, schedule and combinations of potentially neurotoxic agents. Effective management of treatment-emergent PN is critical to minimize the incidence and severity of this complication, while maintaining therapeutic efficacy. Herein, the state of knowledge regarding treatment-emergent PN in MM patients and current management practices are outlined, and recommendations regarding optimal strategies for PN management during MM treatment are provided. These strategies include early and regular monitoring with neurological evaluation, with dose modification and treatment discontinuation as indicated. Areas requiring further research include the development of MM-specific, patient-focused assessment tools, pharmacogenomic analysis of patient DNA, and trials to assess the efficacy of pharmacological interventions.

Genetic factors underlying the risk of thalidomide-related neuropathy in patients with multiple myeloma

PURPOSE

To indentify genetic variation that can modulate and predict the risk of developing thalidomide-related peripheral neuropathy (TrPN).

PATIENTS AND METHODS

We analyzed DNA from 1,495 patients with multiple myeloma. Using a custom-built single nucleotide polymorphism (SNP) array, we tested the association of TrPN with 3,404 SNPs. The SNPs were selected in predicted functional regions within 964 genes spanning 67 molecular pathways thought to be involved in the pathogenesis, treatment response, and adverse effects associated with myeloma and its therapy. Patient cases and controls were derived from two large clinical trials that compared thalidomide with conventional-based treatment in myeloma patients (Medical Research Council Myeloma-IX and HOVON-50/GMMG-HD3).

RESULTS

We report TrPN associations with SNPs-ABCA1 (rs363717), ICAM1 (rs1799969), PPARD (rs2076169), SERPINB2 (rs6103), and SLC12A6 (rs7164902)-where we show cross validation of the associations in both trials. To investigate whether TrPN SNP associations were related to exposure to thalidomide only or general drug-related peripheral neuropathy, we performed a second analysis on patients treated with vincristine. We report SNPs associated with vincristine neuropathy, with a seemingly distinct underlying genetic mechanism.

CONCLUSION

Our results are consistent with the hypothesis that an individual's risk of developing a peripheral neuropathy after thalidomide treatment can be mediated by polymorphisms in genes governing repair mechanisms and inflammation in the peripheral nervous system. These findings will contribute to the development of future neuroprotective strategies with thalidomide therapy and the better use of this important compound.

Peripheral neuropathy and new treatments for multiple myeloma: background and practical recommendations

In multiple myeloma, peripheral neuropathy has for a long time been considered as mainly secondary to the plasma cell dyscrasia itself. With the advent of new targeted drugs such as thalidomide and bortezomib, the iatrogenic neurotoxicity has become the leading cause of peripheral neuropathy. This review discusses the pathogenesis, incidence, risk factors, diagnosis, characteristics, and management of peripheral neuropathy related to new multiple myeloma drugs, mainly bortezomib and thalidomide. The current knowledge of the pathophysiology of the new forms of peripheral neuropathy is still limited. The mechanisms involved depend on the agents used, patient's medical history, and duration of exposure and/or treatment doses or sequence. Diagnosis of such peripheral neuropathy is often easier than treatment. A full anamnesis and regular clinical evaluation are necessary. Electrophysiological assessments may support the diagnosis, although their contribution remains insufficient. Complex clinical features may require a specialized neurological assessment within the context of a multi-disciplinary approach. Finally, early detection of peripheral neuropathy and the use of dose adjustment algorithms as in the case of bortezomib, should help reduce the side effects while maintaining anti-tumor efficacy.

Dealing with neuropathy in plasma-cell dyscrasias

Peripheral neuropathy (PN) is a frequent complication of plasma-cell dyscrasias such as monoclonal gammopathy of undetermined significance, multiple myeloma, Waldenström's disease, POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome, Castleman's disease, and light-chain amyloidosis. PN can be associated with the underlying disease or it can related to the treatment. The novel immunomodulatory drugs thalidomide and lenalidomide and the proteasome inhibitor bortezomib have changed the standard treatment of multiple myeloma. Treatment-related PN induced by thalidomide (TiPN) or bortezomib (BiPN) has become the most frequent cause of symptomatic polyneuropathy in multiple myeloma and related diseases. Dealing with PN has become a major challenge in current clinical practice for multiple myeloma patients. This review deals with practical issues such as etiology, incidence, symptoms, and clinical management of treatment-emergent PN. The major focus of the hematologist should be on the prevention of PN, primarily by frequent monitoring of the patient and by timely and adequate dose reduction of thalidomide and bortezomib. Thalidomide should not be given for periods longer than 18 months, and if it is, then patients should be carefully monitored with a low threshold for discontinuation in the face of any emergent neuropathy. In the case of BiPN, the dose of bortezomib should be reduced and/or the administration interval should be prolonged from biweekly to weekly. Adequate pain management and supportive care require a multidisciplinary approach involving the treating physician, expert nursing staff, and a neurologist as clinically indicated.

Multiple myeloma, painful neuropathy, acupuncture?

Thalidomide and bortezomib are remarkably efficacious in the treatment of multiple myeloma. Unfortunately, their use can cause sensory neuropathy, a common and serious adverse event that frequently limits dose and duration of treatment. Although the relationship between peripheral neuropathy and therapeutic dose is controversial, many authors have demonstrated a positive correlation between neuropathy and cumulative dose, dose intensity, and length of therapy. Peripheral neuropathic pain is the most troublesome symptom of neuropathy. Spontaneous pain, allodynia, hyperalgesia, and hyperpathia are often associated with decreased physical activity, increased fatigue, mood, and sleep problems. Symptoms are often difficult to manage, and available treatment options rarely provide total relief. Moreover, the adverse effects of these treatments often limit their use. Several studies have demonstrated the efficacy of acupuncture, with fewer adverse effects than analgesic drugs, in the treatment of painful diabetic and human immunodeficiency virus-related neuropathy. However, the effectiveness of acupuncture in treating toxic neuropathy has not been assessed. Although its putative mechanisms remain elusive, acupuncture has strong potential as an adjunctive therapy in thalidomide- or bortezomib-induced painful neuropathy, and a better understanding might guide its use in the management of chemotherapy-induced neuropathic pain. Well-designed clinical trials with adequate sample size and power are warranted.

Positive and negative effects of thalidomide on refractory cutaneous lupus erythematosus

BACKGROUND

Thalidomide is used in cutaneous lupus erythematosus (CLE) refractory to conventional therapies. Peripheral neuropathy (PN) is the most severe side effect, but the incidence of PN and its relation to thalidomide dose are still unclear.

OBJECTIVE

To prospectively evaluate the efficacy as well as the occurrence of PN in CLE patients treated with thalidomide, and to assess whether PN, when occurs, correlates with thalidomide dose and/or length of treatment.

METHODS

Fourteen female patients with CLE in low-dose thalidomide therapy were followed for up to 24 months. Prior to, and regularly during treatment patients underwent rheumatological, dermatological, neurological and electrophysiological evaluations. A decline in sural SNAP of 50% or more from baseline value was considered as criterion of sensory axonal PN.

RESULTS

All patients showed a dramatic improvement of skin manifestations. Ten patients (71.4%) developed a sensory axonal PN. The median time free from this complication was 14 months. No correlations were found between age of the patients nor thalidomide cumulative dose and occurrence of PN (Mann-Whitney U Test; p>0.16). Other adverse effects were: tremor, paresthesias, somnolence, amenhorrea, constipation and thoracic pain.

CONCLUSIONS

Low does thalidomide is efficacious in treating CLE, but PN is a common complication whose occurrence does not seem to correlate with total thalidomide dose, whereas with the duration of therapy. A closer electrophysiological follow-up is therefore recommended in the long-term treatment.

Chemotherapy-induced neuropathy

Neurotoxic side effects of cancer therapy are second in frequency to hematological toxicity. Unlike hematological side effects that can be treated with hematopoietic growth factors, neuropathies cannot be treated and protective treatment strategies have not been effective. For the neurologist, the diagnosis of a toxic neuropathy is primarily based on the case history, the clinical and electrophysiological findings, and knowledge of the pattern of neuropathy associated with specific agents. In most cases, toxic neuropathies are length-dependent, sensory, or sensorimotor neuropathies often associated with pain. The platinum compounds are unique in producing a sensory ganglionopathy. Neurotoxicity is usually dependent on cumulative dose. Severity of neuropathy increases with duration of treatment and progression stops once drug treatment is completed. The platinum compounds are an exception where sensory loss may progress for several months after cessation of treatment ("coasting"). As more effective multiple drug combinations are used, patients will be treated with several neurotoxic drugs. Synergistic neurotoxicity has not been extensively investigated. Pre-existent neuropathy may influence the development of a toxic neuropathy. Underlying inherited or inflammatory neuropathies may predispose patients to developing very severe toxic neuropathies. Other factors such as focal radiotherapy or intrathecal administration may enhance neurotoxicity. The neurologist managing the cancer patient who develops neuropathy must answer a series of important questions as follows: (1) Are the symptoms due to peripheral neuropathy? (2) Is the neuropathy due to the underlying disease or the treatment? (3) Should treatment be modified or stopped because of the neuropathy? (4) What is the best supportive care in terms of pain management or physical therapy for each patient? Prevention of toxic neuropathies is most important. In patients with neuropathy, restorative approaches have not been well established. Symptomatic and other management are necessary to maintain and improve quality of life.

Childhood thalidomide neuropathy: a clinical and neurophysiologic study

Thalidomide was recently reintroduced to treat several immune-mediated pathologies. Peripheral neuropathy is a significant side effect limiting its clinical use. Our aims include: (1) describing and identifying the incidence of clinical or electrophysiologic peripheral neuropathy in children, (2) determining whether peripheral neuropathy correlates with cumulative dose of thalidomide and with age, and (3) defining its reversibility rate. We studied 13 children manifesting immune-mediated pathologies treated with thalidomide at doses ranging from 25-100 mg/day. Clinical and neurophysiologic evaluation was performed before and after starting treatment. Seven children (53.8%) showed neurophysiologic signs of sensory peripheral axonal polyneuropathy. Five presented associated clinical symptoms, while the other two only presented subclinical, neurophysiologic signs of peripheral neuropathy. We found a significant correlation between the incidence of peripheral neuropathy and thalidomide cumulative dose (P = 0.02). We observed a lower incidence of peripheral neuropathy at a cumulative dose <20 gm, and a correlation with age (P < 0.01). The clinical and electrophysiologic recovery rate was 40%, and clinical improvement alone was observed in another 40%. Thalidomide induces dose-dependent and age-dependent peripheral neuropathy at a significant frequency in childhood (53.8%). In our experience a cumulative dosage at >20 gm and long-term administration for >10 months seem to increase the risk of peripheral neuropathy. We propose clinical and neurophysiologic follow-up every 3 months to identify and monitor possible side effects.

Peripheral nervous system involvement in patients with cancer

Involvement of the peripheral nervous system (PNS) is common in patients with cancer and any part, including motor neurons, sensory ganglia, nerve roots, plexuses, cranial and peripheral nerves, and neuromuscular junctions, can be affected. Different mechanisms can initiate damage associated with cancer-related PNS disorders. These include tumour infiltration, toxicity of treatments, metabolic and nutritional perturbations, cachexia, virus infections, and paraneoplastic neurological syndromes. The type of cancer, lymphoma, or solid tumour is a further determinant of a PNS disorder. In this Review we discuss the different causes and mechanisms of disorders of the PNS in patients with cancer and we will focus on their assessment and diagnosis.

Neurologic toxicities of cancer therapies

Neurologic dysfunction is a well-recognized adverse effect of cancer therapeutics. The most common manifestations include peripheral neuropathy and encephalopathy. Often, symptoms resolve or improve upon removal of the offending agent; therefore, it is essential that clinicians recognize the symptoms and signs of injury. Occasionally, symptoms persist or develop after discontinuation of medication and may culminate in disability and diminished quality of life. As our understanding of neurotoxicity improves, medications with less potential for injury may be developed. In addition, potential antidotes to prevent or reverse injury may emerge. This review focuses on the clinical features, mechanisms, and possible therapeutics of the neurotoxicity of chemotherapy. In particular, oxaliplatin, thalidomide, methotrexate, ifosfamide, cytarabine, amifostine, acetyl-L-carnitine, methylene blue, cytokines, and neurotrophins are discussed.

Development of neuropathy in patients with myeloma treated with thalidomide: patterns of occurrence and the role of electrophysiologic monitoring

PURPOSE

Peripheral neuropathy frequently limits the duration of treatment with thalidomide for patients with multiple myeloma. We assessed the time course of occurrence, possible predictive factors, and the utility of serial nerve electrophysiological studies (NES) for detecting onset of neuropathy.

PATIENTS AND METHODS

Seventy-five patients with relapsed/refractory myeloma were enrolled onto a multicenter trial of dose-escalating thalidomide with or without interferon. Patients underwent clinical assessment plus NES at baseline and every 3 months. Time to development of neuropathy according to clinical or NES criteria was compared. Patient and treatment-related factors were compared as predictors of neuropathy.

RESULTS

Thirty-nine percent had some NES abnormalities at baseline. Patients received thalidomide at a median dose-intensity of 373 mg/d. Thirty-one of 75 patients (41%) developed neuropathy during thalidomide treatment; 11 patients (15%) discontinued treatment with thalidomide due to neuropathy. The actuarial incidence of neuropathy increased from 38% at 6 months to 73% at 12 months, with 81% of responding patients developing this complication. Serial NES did not reliably predict the imminent development of clinical neuropathy requiring thalidomide cessation, nor were patient age, sex, or prior therapy predictive. Patients who developed neuropathy had a longer duration of thalidomide exposure (median, 268 v 89 days; P = .0001). Cumulative dose or dose-intensity received was not predictive.

CONCLUSION

The majority of patients will develop peripheral neuropathy given sufficient length of treatment with thalidomide. To minimize the risk of neurotoxicity, therapy should be limited to less than 6 months. Electrophysiologic monitoring provides no clear benefit versus careful clinical evaluation for the development of clinically significant neuropathy.

The role of neuroinflammation in neuropathic pain: mechanisms and therapeutic targets

Neuroinflammation is a proinflammatory cytokine-mediated process that can be provoked by systemic tissue injury but it is most often associated with direct injury to the nervous system. It involves neural-immune interactions that activate immune cells, glial cells and neurons and can lead to the debilitating pain state known as neuropathic pain. It occurs most commonly with injury to peripheral nerves and involves axonal injury with Wallerian degeneration mediated by hematogenous macrophages. Therapy is problematic but new trials with anti-cytokine agents, cytokine receptor antibodies, cytokine-signaling inhibitors, and glial and neuron stabilizers provide hope for future success in treating neuropathic pain.

Advances in Understanding Drug-Induced Neuropathies

Many commonly used medications have neurotoxic adverse effects; the most common of these is peripheral neuropathy. Neuropathy can be a dose-limiting adverse effect for many medications used in life-threatening conditions, such as malignancy and HIV-related disease. Epidemiological evidence supports previous case reports of HMG-CoA reductase inhibitors (or 'statins') causing an axonal sensorimotor neuropathy or a purely small-fibre neuropathy in some patients. The neuropathy improves when the medication is withdrawn. Despite the association between HMG-CoA reductase inhibitors and neuropathy, the risk is low compared with the significant vascular protective benefits. Oxaliplatin, a new platinum chemotherapy agent designed to have fewer adverse effects than other such agents, has been shown to cause a transient initial dysaesthesia in addition to an axonal polyneuropathy. Thalidomide, an old therapy currently being utilised for new therapeutic indications (e.g. treatment of haematological malignancies), is associated with a painful, axonal sensorimotor neuropathy that does not improve on withdrawal of the drug. Nucleoside reverse transcriptase inhibitors are important components of highly active antiretroviral therapy, but are associated with a sensory neuropathy that is likely to be due to a direct effect of these drugs on mitochondrial DNA replication. New research demonstrates that lactate levels may help discriminate between neuropathy caused by nucleoside analogues and HIV-induced neuropathy. Understanding the mechanism of drug-induced neuropathy has led to advances in preventing this disabling condition.

Toxic neuropathy

PURPOSE OF REVIEW

This paper examines recent research on toxic neuropathy and potential therapeutic developments. It also summarizes reports of new agents reported to cause peripheral neuropathy.

RECENT FINDINGS

Gene therapy with vasoactive endothelial growth factor, neurotrophic substances such as nerve growth factor and neurotrophin-3 are reported to reverse or protect against neurotoxicity in animal models. The neuroprotective effects of more established therapeutic agents like vitamin E, tacrolimus (FK 506) and erythropoietin hold promise for the immediate future. Cisplatin and high-dose pyridoxine are used more frequently to produce robust models of peripheral neuropathy in animals. Statins do appear to cause peripheral neuropathy. The incidence is low, however, and compared to its benefits in terms of cardiovascular protection, relatively innocuous. The profile of thalidomide neuropathy is becoming clearer as the indications for this drug increases. The incidence of thalidomide neuropathy is high, up to three quarters in some series, and although the information on dose dependency is variable, lower cumulative doses appear to be less toxic. Like thalidomide bortezomib, a novel proteosome inhibitor, is reportedly effective in the treatment of multiple myeloma and is associated with peripheral neuropathy. Oxaliplatin and epothilone are emerging anticancer drugs with neurotoxic potential. Similarly, leflunomide, a new disease modifying-agent approved for the treatment of rheumatoid arthritis, is reported to cause neuropathy.

SUMMARY

The study of toxic neuropathy is not only enhancing our knowledge of the mechanisms of neurotoxicity but also the neurobiology of peripheral neuropathy in general; and is likely to reveal avenues for therapeutics.

Neurological toxicity of long-term (>1 yr) thalidomide therapy in patients with multiple myeloma

OBJECTIVE

Thalidomide is remarkably active in advanced relapsed and refractory multiple myeloma (MM), so that its use has been recently proposed either in newly diagnosed patients or as maintenance treatment after conventional or high-dose therapy. This latter therapeutic approach has risen the concern of side-effects of long-term therapy with this drug.

METHODS

We analysed long-term toxicity of 40 patients (27 M, 13 F, median age = 61.5 yr) who received salvage therapy with thalidomide +/- dexamethasone for longer than 12 months (median 15, range 12-44) at our centre. All the patients had achieved at least a stable disease upon treatment with thalidomide alone (200-400 mg/d, n = 20) or thalidomide (200 mg/d) and dexamethasone (40 mg/d for 4 d every 4 wk) (n = 20).

RESULTS AND CONCLUSIONS

Neurotoxicity was the most troublesome and frequent toxic effect that was observed after long-term treatment, the incidence averaging 75%. Among these 30 patients symptoms included paraesthesias, tremor and dizziness. Neurotoxicity was grade 1 in six patients (15%); grade 2 in 13 patients (32.5%), thus determining thalidomide dose reduction to 100 mg/d; and grade 3 in 11 patients (27.5%) who had subsequently to interrupt therapy despite their response. Electromyographic study, performed in patients with grade >/=2 neurotoxicity, revealed a symmetrical, mainly sensory peripheral neuropathy, with minor motor involvement. The severity of neurotoxicity was not related to cumulative or daily thalidomide dose, but only to the duration of the disease prior to thalidomide treatment, although no patients presented neurological symptoms at study entry. These results suggest that long-term thalidomide therapy in MM may be hampered by the remarkable neurotoxicity of the drug, and that a neurological evaluation should be mandatory prior to thalidomide treatment, in order to identify patients at risk of developing a peripheral neuropathy.

Chemotherapy-induced peripheral neurotoxicity

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a major clinical problem because it represents the dose-limiting side effects of a significant number of antineoplastic drugs. The incidence of CIPN varies depending on the drugs and schedules used, and this can be quite high, particularly when neurophysiological methods are used to make a diagnosis. However, even when CIPN is not a dose-limiting side effect, its onset may severely affect the quality of life of cancer patients and cause chronic discomfort. In this review the features of CIPN due to the administration of the most widely used drugs, such as platinum drugs, taxanes and vinca alkaloids, and of two old drugs with new clinical applications, suramin and thalidomide, will be discussed. Moreover, the earliest data regarding the neurotoxicity of some new classes of very promising antineoplastic agents, such as epothilones and proteasome inhibitors, will be discussed. Finally, the data available on neuroprotectants, evaluated in the attempt to prevent CIPN, will be summarised.

Thalidomide neuropathy in childhood

Thalidomide was withdrawn from world markets in 1961 following recognition of its teratogenic effects. More recently, however, thalidomide treatment has been reintroduced to adult and paediatric practice for a variety of dermatologic, immunologic, rheumatologic and neoplastic disorders. Neuropathy is a significant side effect of thalidomide therapy, which may limit its clinical use. We report four cases of sensorimotor axonal neuropathy in children aged 10-15 years, treated with thalidomide for myxopapillary ependymoma, Crohn's disease and recurrent giant aphthous ulceration. Thalidomide neuropathy is often associated with proximal weakness and may progress even after discontinuation of treatment, in the phenomenon of 'coasting'. Children treated with thalidomide should undergo regular neurophysiologic studies in order to detect presymptomatic or progressive peripheral neuropathy.