Role of a pre-existing neuropathy on the course of bortezomib-induced peripheral neurotoxicity

Axonal degeneration in chemotherapy-induced peripheral neurotoxicity: clinical and experimental evidence

Multiple pathological mechanisms are involved in the development of chemotherapy-induced peripheral neurotoxicity (CIPN). Recent work has provided insights into the molecular mechanisms underlying chemotherapy-induced axonal degeneration. This review integrates evidence from preclinical and clinical work on the onset, progression and outcome of axonal degeneration in CIPN. We review likely triggers of axonal degeneration in CIPN and highlight evidence of molecular pathways involved in axonal degeneration and their relevance to CIPN, including SARM1-mediated axon degeneration pathway. We identify potential clinical markers of axonal dysfunction to provide early identification of toxicity as well as present potential treatment strategies to intervene in axonal degeneration pathways. A greater understanding of axonal degeneration processes in CIPN will provide important information regarding the development and progression of axonal dysfunction more broadly and will hopefully assist in the development of successful interventions for CIPN and other neurodegenerative disorders.

Drug-Induced Peripheral Neuropathy: Diagnosis and Management

Peripheral neuropathy comes in all shapes and forms and is a disorder which is found in the peripheral nervous system. It can have an acute or chronic onset depending on the multitude of pathophysiologic mechanisms involving different parts of nerve fibers. A systematic approach is highly beneficial when it comes to cost-effective diagnosis. More than 30 causes of peripheral neuropathy exist ranging from systemic and auto-immune diseases, vitamin deficiencies, viral infections, diabetes, etc. One of the major causes of peripheral neuropathy is drug induced disease, which can be split into peripheral neuropathy caused by chemotherapy or by other medications. This review deals with the latest causes of drug induced peripheral neuropathy, the population involved, the findings on physical examination and various workups needed and how to manage each case.

Everyday living with pain - reported by patients with multiple myeloma

OBJECTIVES

The prevalence and impact of pain among patients with multiple myeloma (MM) in their everyday life require renewed attention. MM patients' survival has increased considerably over the last decades and active disease episodes are interrupted by longer periods with disease inactivity. The aim with this study is to explore pain intensity and pain interference with daily activities during periods of stable or inactive MM disease.

METHODS

In a cross-sectional study from September 2017 to May 2019, self-reliant MM patients in stable disease filled a comprehensive selection of validated questionnaires regarding pain, other symptoms and quality of life, which they experienced in their daily living. Patient reported pain intensity and interference with daily activities were analyzed for associations with several clinical and demographic factors and discussed from a total pain perspective. The two outcomes, pain intensity and pain interfering with daily activities, were analyzed in two age groups (<65 years or ≥65 years).

RESULTS

Among 92 participants, 80% experienced pain to interfere with their daily activities (equal in both age groups), and 63% reported moderate to severe pain intensity; (75% ≥65 years, and 49% <65 years). Pain intensity was significantly associated with signs of depression (OR 4.0 [95% CI: 1.2-13.9]) and age ≥65 years (OR 3.3 [95% CI: 1.2-9.2]). Pain interfering with daily activities was nearly significantly associated with bone involvement (OR 3.4 [95% CI: 1.0-11.6]) and signs of depression (OR 5.9 [95% CI: 1.0-36.3]). The patients were bothered with many problems in addition to pain; fatigue (91%), bone involvement (74%), signs of depression (41%), signs of anxiety (32%), comorbidity (29%) and uncertainty in relation to employment or pension (25%). Neuropathic pain was more prevalent in the feet (33% [95% CI: 23%, 43%]) compared with pain in the hands (13% [95% CI: 7%, 22%]).

CONCLUSIONS

In periods of stable disease, many MM patients continue to live with intense pain interfering with their daily activities. Additional or associated problems are the presence of bone involvement, neuropathic pain, older age, uncertainty in relation to employment or pension, comorbidity, signs of depression, anxiety and fatigue. This highlights the importance of health professionals being receptive to the patients' experience of pain throughout their trajectories, to assess pain systematically and to interpret this experience from a total pain perspective. While pain problems in relation to diagnosing and treating MM is well known, this study brings the message that even during periods of stable or inactive MM disease, the patients experience pain with a moderate to severe intensity, that interferes with their everyday living. The improved survival and the consequential long trajectories make coherence in the pain treatment even more important for the patients, who may see different professionals in different health care settings for different reasons. The patient group requires a coordinated, holistic patient-centered pain treatment throughout the disease trajectory.

Non-Hematologic Toxicity of Bortezomib in Multiple Myeloma: The Neuromuscular and Cardiovascular Adverse Effects

Simple Summary

Multiple myeloma (MM) is a still uncurable tumor of mainly elderly patients originating from the terminally differentiated B cells. Introduction to the treatment of MM patients of a new class of drugs called proteasome inhibitors (bortezomib followed by carfilzomib and ixazomib) significantly improved disease control. Proteasome inhibitors interfere with the major mechanism of protein degradation in a cell leading to the severe imbalance in the protein turnover that is deadly to MM cells. Currently, these drugs are the mainstream of MM therapy but are also associated with an increased rate of the injuries to multiple organs and tissues. In this review, we summarize the current knowledge on the molecular mechanisms of the first-in-class proteasome inhibitor bortezomib-induced disturbances in the function of peripheral nerves and cardiac and skeletal muscle.

Abstract

The overall approach to the treatment of multiple myeloma (MM) has undergone several changes during the past decade. and proteasome inhibitors (PIs) including bortezomib, carfilzomib, and ixazomib have considerably improved the outcomes in affected patients. The first-in-class selective PI bortezomib has been initially approved for the refractory forms of the disease but has now become, in combination with other drugs, the backbone of the frontline therapy for newly diagnosed MM patients, as well as in the maintenance therapy and relapsed/refractory setting. Despite being among the most widely used and highly effective agents for MM, bortezomib can induce adverse events that potentially lead to early discontinuation of the therapy with negative effects on the quality of life and outcome of the patients. Although peripheral neuropathy and myelosuppression have been recognized as the most relevant bortezomib-related adverse effects, cardiac and skeletal muscle toxicities are relatively common in MM treated patients, but they have received much less attention. Here we review the neuromuscular and cardiovascular side effects of bortezomib. focusing on the molecular mechanisms underlying its toxicity. We also discuss our preliminary data on the effects of bortezomib on skeletal muscle tissue in mice receiving the drug.

Bortezomib and other proteosome inhibitors-induced peripheral neurotoxicity: From pathogenesis to treatment

Proteasome inhibitors (PIs), especially bortezomib (BTZ), have come to the forefront over the last years because of their unprecedented efficacy mainly against multiple myeloma (MM). Unfortunately, peripheral neuropathy (PN) secondary to treatment of MM with PIs has emerged as a clinically relevant complication, which negatively impacts the quality of life of MM survivors. Bortezomib-induced peripheral neuropathy (BIPN) is a dose-limiting toxicity, which develops in 30% to 60% of patients during treatment. Typically, BIPN is a length-dependent sensory axonopathy characterized by numbness, tingling, and severe neuropathic pain in stocking and glove distribution. BIPN mechanisms have not yet been fully elucidated. Experimental studies suggest that aggresome formation, endoplasmic reticulum stress, myotoxicity, microtubule stabilization, inflammatory response, and DNA damage could contribute to this neurotoxicity. A new generation of structurally distinct PIs has been developed, being increasingly used in clinical settings. Carfilzomib exhibits a much lower neurotoxicity profile, with a significantly lower incidence of PN compared to BTZ. Pre-existing PN increases the risk of developing BIPN. Besides, BIPN is related to dose, schedule and mode of administration and modifications of these factors have lowered the incidence of PN. However, to date there is no cure for PIs-induced PN (PIIPN), and a careful neurological monitoring and dose adjustment is a key strategy for preserving quality of life. This review critically looks at the pathogenesis, incidence, risk factors, both clinical and pharmacogenetics, clinical phenotype and management of PIIPN. We also make recommendations for further elucidating the whole clinical spectrum of PIIPN.

Role of Pregabalin in Treatment of Polyneuropathy in Multiple Myeloma Patients: A Retrospective Study

OBJECTIVES

Polyneuropathy (PN) is a frequent and significant clinical manifestation of multiple myeloma that may be observed at onset of disease or induced during treatment as a therapy-related complication. Polyneuropathy may be a relevant issue in myeloma patients owing to its significant impact on the quality of life, considering that it may lead to dose reduction or treatment discontinuation. The present retrospective study intended to evaluate efficacy of pregabalin (PGB) in treatment of PN in multiple myeloma patients.

MATERIALS AND METHODS

Medical charts of 108 consecutive PN myeloma patients were reviewed. Data regarding the tumor history and therapy as well as the clinical and neurophysiological examinations 6 months before and after initiation of PGB therapy were collected.

RESULTS

Thirty-eight medical charts had all the requested information. All patients (n = 38) underwent bortezomib-based treatment; 19 were previously treated and 19 were treatment naive. At first neurologic visit, all patients had PN symptoms (grade 2 of National Cancer Institute-Common Toxicity Criteria) without relevant pain. Neurophysiological evaluation showed a significant decrease in sensory nerve action potential amplitude (P = 0.006), conduction velocity (P = 0.006), and distal latency (P = 0.03) of sensory nerves between the first and the last neurological examination, in all patient population. Similar results were observed in treatment-naive patients, when the study cohort was stratified according to previous treatment. On the contrary, no significant differences were found between the first and the last neurophysiological follow-up evaluation in previously treated patients. Six months after PGB treatment, all patients reported disappearance of neurological symptoms (grade 0 National Cancer Institute-Common Toxicity Criteria).

CONCLUSIONS

In this retrospective study, improvement in neurological symptoms during PGB therapy was observed in the total population, despite the presence of a distal, sensory axonal neuropathy, as evidenced by neurophysiological examination.

The Effect of Docosahexaenoic Acid and α-Lipoic Acid as Prevention of Bortezomib-Related Neurotoxicity in Patients With Multiple Myeloma

Background and Aims: In cancer patients, a common complication during chemotherapy is chemotherapy-induced peripheral neuropathy (CIPN). For this reason, we decided to conduct a phase II prospective study on 33 patients with multiple myeloma at first diagnosis, to evaluate whether a nutraceutical compound given for 6 months during bortezomib (BTZ) treatment succeeded in preventing the onset of neurotoxicity. Methods: Neurological evaluation, electroneurography, and functional and quality of life (QoL) scales were performed at baseline and after 6 months. We administered a tablet containing docosahexaenoic acid 400 mg, α-lipoic acid 600 mg, vitamin C 60 mg, and vitamin E 10 mg bid for 6 months. Results: Concerning the 25 patients who completed the study, at 6-month follow-up, 10 patients had no neurotoxicity (NCI-CTCAE [National Cancer Institute-Common Terminology Criteria for Adverse Events] = 0), while 13 progressed to NCI-CTCAE grade 1, 1 had NCI-CTCAE grade 1 with pain, and 1 experienced a NCI-CTCAE grade 2. Painful symptoms were reported only in 2 patients, and we observed stability on functional and QoL scales in all patients. None of the 25 patients stopped chemotherapy due to neurotoxicity. Conclusions: Our data seem to indicate that the co-administration of a neuroprotective agent during BTZ treatment can prevent the appearance/worsening of symptoms related to CIPN, avoiding the interruption of BTZ and maintaining valuable functional autonomy to allow normal daily activities. We believe that prevention remains the mainstay to preserve QoL in this particular patient population, and that future studies with a larger patient population are needed.

Model-based clustering for identifying disease-associated SNPs in case-control genome-wide association studies

Genome-wide association studies (GWASs) aim to detect genetic risk factors for complex human diseases by identifying disease-associated single-nucleotide polymorphisms (SNPs). The traditional SNP-wise approach along with multiple testing adjustment is over-conservative and lack of power in many GWASs. In this article, we proposed a model-based clustering method that transforms the challenging high-dimension-small-sample-size problem to low-dimension-large-sample-size problem and borrows information across SNPs by grouping SNPs into three clusters. We pre-specify the patterns of clusters by minor allele frequencies of SNPs between cases and controls, and enforce the patterns with prior distributions. In the simulation studies our proposed novel model outperforms traditional SNP-wise approach by showing better controls of false discovery rate (FDR) and higher sensitivity. We re-analyzed two real studies to identifying SNPs associated with severe bortezomib-induced peripheral neuropathy (BiPN) in patients with multiple myeloma (MM). The original analysis in the literature failed to identify SNPs after FDR adjustment. Our proposed method not only detected the reported SNPs after FDR adjustment but also discovered a novel BiPN-associated SNP rs4351714 that has been reported to be related to MM in another study.

Neurologic complications of kidney transplantation

Renal transplant is the most common organ transplant in the United States, and the frequency of kidney transplants continues to rise as transplant offers improved survival and quality of life compared to dialysis. However, complications are not uncommon and patients frequently encounter issues requiring hospitalization, especially in the first year postoperatively. Complications that arise are typically related to surgical complications, immunosuppressive medications, or infection due to immunosuppression. Neurological complications are fairly common post-operatively, and are associated with increased morbidity and mortality in this population. This review discusses the most common etiologies of neurological complications after kidney transplant, including infection, malignancy, medication related, acute neuropathy, and other neurological pathology.

Prevention of Bortezomib-Related Peripheral Neuropathy With Docosahexaenoic Acid and α-Lipoic Acid in Patients With Multiple Myeloma: Preliminary Data

Background and Aims: Peripheral neuropathy is a common complication of chemotherapy that can induce marked disability that negatively affects the quality of life in patients with multiple myeloma (MM). The aim of this study was to prevent the onset or the worsening of peripheral neuropathy in MM patients treated with bortezomib (BTZ), using a new nutritional neuroprotective compound. We report preliminary results of 18 out of 33 patients who completed the study. Methods: We administered a tablet of Neuronorm to patients, containing docosahexaenoic acid 400 mg, α-lipoic acid 600 mg, vitamin C 60 mg, and vitamin E 10 mg bid for the whole follow-up period. Neurological visit assessment, electroneurography, and evaluation scales were performed at baseline and after 6 months. Results: At 6 months, 8 patients had no chemotherapy-induced peripheral neuropathy, while 10 patients experienced chemotherapy-induced peripheral neuropathy of grade 1 according to the Common Terminology Criteria for Adverse Events, one of them with pain. Seventeen patients did not report painful symptoms; no limitation of functional autonomy and stability in quality of life domains explored was observed. Conclusions: Our results seem to indicate that early introduction of a neuroprotective agent in our patients with MM treated with BTZ could prevent the onset or the worsening of neuropathic pain, avoiding the interruption of the therapy with BTZ, and maintaining a good functional autonomy to allow normal daily activities. Despite the limitations due to the fact that this is a preliminary study, in a small population, with short follow-up, our data seem to indicate that the nutraceutical may have some potential to be considered for a future trial.

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.

Impact of concomitant dexamethasone dosing schedule on bortezomib-induced peripheral neuropathy in multiple myeloma

Peripheral neuropathy (PN) is the most troublesome adverse event associated with the proteasome inhibitor bortezomib. Studies suggest an inflammatory aetiology for bortezomib-induced PN (BiPN) and it has been hypothesized that reducing inflammation with concomitant dexamethasone may reduce BiPN incidence and/or severity. We retrospectively analysed PN rates from 32 studies (2697 patients with previously untreated multiple myeloma) incorporating bortezomib and differing dexamethasone schedules: partnered dosing (days of and after bortezomib), weekly dosing, and other dosing schedules (e.g. days 1-4, 8-11). Pooled overall PN rates were 45·5%, 63·9%, and 47·5%, respectively, with 5·3%, 11·0%, and 9·6% grade ≥3. Adjusting for potential confounders (age, gender, presence of thalidomide, bortezomib treatment duration), PN rates in patients on partnered dosing schedules appeared lower than in patients on weekly or other dosing schedules. Analyses conducted using patient-level data suggest that cumulative dexamethasone dose, a potential confounding factor, is unlikely to have influenced the analyses. Findings were similar in a separate pooled analysis excluding data from regimens incorporating thalidomide, when pooled overall PN rates were 50·1%, 63·9%, and 48·3%, respectively, with 4·2%, 11·0%, and 8·6% grade ≥3. These findings suggest that partnered dexamethasone dosing may result in less severe BiPN compared with alternative dexamethasone dosing schedules.

Neurophysiological and clinical outcomes in chemotherapy-induced neuropathy in cancer

Chemotherapy induced peripheral neuropathy (CIPN) is a significant toxicity of cancer treatment, with the potential to affect long-term function and quality of life in cancer survivors. There remains a lack of consensus around optimal assessment techniques. While current approaches to CIPN assessment are focused on clinical grading scales, it is becoming increasingly evident that a more comprehensive multimodal assessment package is necessary to accurately characterise the impact of CIPN as well as gauge the utility of neuroprotective mechanisms. Neurophysiological techniques provide objective biomarkers and may enable early detection of toxicity while patient reported outcomes are necessary to determine the significance of symptoms to individual patients. In addition to providing an objective assessment, clinical neurophysiological techniques provide important insights into the contributory pathophysiological mechanisms of CIPN with different chemotherapy agents. There is a paucity of implementation of these techniques in the clinical trial setting. The present Review aims to facilitate the use of neurophysiological studies as part of comprehensive assessment packages for the monitoring of CIPN by summarising current understanding of neurophysiological changes that underlie the development of neuropathy, clinical presentations and patient reported outcomes as well as advantages and limitations of current techniques for the neurophysiological assessment of CIPN.

An Overview of Bortezomib-Induced Neurotoxicity

The boronic acid dipeptide bortezomib, able to induce tumor cell death by degradation of key proteins, is the first proteasome inhibitor drug to enter clinical practice. It is employed as first-line treatment in relapsed or resistant multiple myeloma (MM) patients. However, bortezomib often induces a dose-limiting toxicity in the form of painful sensory neuropathy, which can mainly be reduced by subcutaneous administration or dose modification. In this review we focus on the current understanding of the pathophysiological mechanisms of bortezomib-induced neuropathy to allow further studies in animal models and humans, including analysis of clinical and pharmacogenetic aspects, to optimize the treatment regimens.

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.

Bortezomib treatment produces nocifensive behavior and changes in the expression of TRPV1, CGRP, and substance P in the rat DRG, spinal cord, and sciatic nerve

To investigate neurochemical changes associated with bortezomib-induced painful peripheral neuropathy (PN), we examined the effects of a single-dose intravenous administration of bortezomib and a well-established "chronic" schedule in a rat model of bortezomib-induced PN. The TRPV1 channel and sensory neuropeptides CGRP and substance P (SP) were studied in L4-L5 dorsal root ganglia (DRGs), spinal cord, and sciatic nerve. Behavioral measures, performed at the end of the chronic bortezomib treatment, confirmed a reduction of mechanical nociceptive threshold, whereas no difference occurred in thermal withdrawal latency. Western blot analysis showed a relative increase of TRPV1 in DRG and spinal cord after both acute and chronic bortezomib administration. Reverse transcriptase-polymerase chain reaction revealed a decrease of TRPV1 and CGRP mRNA relative levels after chronic treatment. Immunohistochemistry showed that in the DRGs, TRPV1-, CGRP-, and SP-immunoreactive neurons were mostly small- and medium-sized and the proportion of TRPV1- and CGRP-labeled neurons increased after treatment. A bortezomib-induced increase in density of TRPV1- and CGRP-immunoreactive innervation in the dorsal horn was also observed. Our findings show that bortezomib-treatment selectively affects subsets of DRG neurons likely involved in the processing of nociceptive stimuli and that neurochemical changes may contribute to development and persistence of pain in bortezomib-induced PN.

Impact of dose modification on intravenous bortezomib-induced peripheral neuropathy in multiple myeloma patients

PURPOSE

Patients discontinue bortezomib treatment despite good response to the therapy because of bortezomib-induced neuropathy. Early and active dose reduction is recommended for efficacy of treatment. This study evaluates patterns of bortezomib-associated neuropathy and examines the effectiveness of dose modification on symptom management and treatment compliance.

METHODS

This is a retrospective cohort study of multiple myeloma patients who received bortezomib intravenously from 2009 to 2012 at Samsung Medical Center, Seoul, Korea. Peripheral neuropathy was assessed using neurotoxicity subscale of the FACT/GOG-Ntx at daily clinical practice; physicians modified the dosage and schedule of bortezomib treatment. Mixed-effect models were used for evaluating changes of neuropathy symptoms over time. Linear spline models and multivariate logistic regression were used for testing the effectiveness of interventions.

RESULTS

There were 1,060 visits of 55 multiple myeloma patients during the study period. Patients were most likely to have numbness of feet, painful burning in feet, muscle weakness, and the symptoms worsened over time (P < 0.05). For patients who received intervention (n = 32, 58.1 %), neuropathy symptoms were significantly decreased after the intervention (coefficient, -0.1 (95 % confidence interval (CI), -0.8, 0.6)). The intervention group had on average 5.19 (95 % CI, 3.79, 6.59) more bortezomib administrations and was 1.4 times more likely to complete the treatment (odds ratio, 1.40 (95 % CI, 0.31, 6.32)) than the nonintervention group.

CONCLUSION

Close monitoring of peripheral neuropathy in patients receiving bortezomib is a feasible and useful way to manage neuropathy in the real world.

Chemotherapy-induced peripheral neuropathy in adults: a comprehensive update of the literature

Commonly used chemotherapeutic agents in oncology/hematology practice, causing toxic peripheral neuropathy, include taxanes, platinum compounds, vinca alkaloids, proteasome inhibitors, and antiangiogenic/immunomodulatory agents. This review paper intends to put together and discuss the spectrum of chemotherapy-induced peripheral neuropathy (CIPN) characteristics so as to highlight areas of future research to pursue on the topic. Current knowledge shows that the pathogenesis of CIPN still remains elusive, mostly because there are several sites of involvement in the peripheral nervous system. In any case, it is acknowledged that the dorsal root ganglia of the primary sensory neurons are the most common neural targets of CIPN. Both the incidence and severity of CIPN are clinically under- and misreported, and it has been demonstrated that scoring CIPN with common toxicity scales is associated with significant inter-observer variability. Only a proportion of chemotherapy-treated patients develop treatment-emergent and persistent CIPN, and to date it has been impossible to predict high-and low-risk subjects even within groups who receive the same drug regimen. This issue has recently been investigated in the context of pharmacogenetic analyses, but these studies have not implemented a proper methodological approach and their results are inconsistent and not really clinically relevant. As such, a stringent approach has to be implemented to validate that information. Another open issue is that, at present, there is insufficient evidence to support the use of any of the already tested chemoprotective agents to prevent or limit CIPN. The results of comprehensive interventions, including clinical, neurophysiological, and pharmacogenetic approaches, are expected to produce a consistent advantage for both doctors and patients and thus allow the registration and analysis of reliable data on the true characteristics of CIPN, eventually leading to potential preventive and therapeutic interventions.

Evaluation of tubulin polymerization and chronic inhibition of proteasome as citotoxicity mechanisms in bortezomib-induced peripheral neuropathy

Bortezomib (BTZ) is the first proteasome inhibitor entered in clinical practice. Peripheral neuropathy is likely to be a class side effect of these drugs, although its severity is largely variable, and it deserves to be further investigated, since the mechanisms of BTZ-induced peripheral neurotoxicity (BiPN) are still unknown.   In our study, we investigated in vivo and in vitro possible pathogenic events relevant to BiPN using a well-established rat model, with particular reference to the extent of proteasome inhibition and the effects on α-tubulin polymerization in sciatic nerves and dorsal root ganglia specimens obtained from animals treated with chronic regimens at a dose of 0.2 mg/kg intravenously. The same assessments were also performed after a single injection. Moreover, these studies were replicated in vitro using embryonic DRG neurons exposed to 100 nM BTZ and adult DRG neurons exposed to 10-50 nM BTZ for 24 h and 48 h. A significant increase in the polymerized fraction of α-tubulin and prolonged proteasome inhibition were observed after the chronic BTZ treatment in vivo. Recovery to physiological levels was observed after a 4-week follow-up post-treatment period. Proteasome inhibition and increased α-tubulin polymerization were also observed following BTZ treatment of both embryonic and adult DRG neurons in vitro. Our in vivo results suggest that proteasome inhibition and alteration of tubulin dynamics contribute to BiPN. The in vitro systems here described reliably replicate the in vivo results, and might therefore be used for further mechanistic studies on the effects of proteasome inhibitors on neurons.

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.

Bortezomib-induced painful neuropathy in patients with multiple myeloma

Neurotoxicity towards the peripheral nervous system which appears clinically in the form of painful neuropathy is an essential dose-limiting factor during the treatment of multiple myeloma. In this review article different forms of this painful neuropathy are presented together with currently available diagnostic tools which are usually applied to confirm the diagnosis. Also, the most often used neurological scales estimating neurological deficit are presented. Special attention is paid to the management of the reversibility of bortezomib-induced neuropathic pain.

Phytohemagglutinin-induced IL2 mRNA in whole blood can predict bortezomib-induced peripheral neuropathy for multiple myeloma patients

The proteasome inhibitor bortezomib has revolutionized the treatment of multiple myeloma. However, bortezomib-induced peripheral neuropathy (BiPN) is a serious complication that compromises clinical outcome. If patients with a risk of developing BiPN could be predicted, physicians might prefer weekly, reduced-dose, or subcutaneous approaches. To seek biomarkers for BiPN, we conducted a multicenter prospective study using a simple and unique system. Multiple myeloma patients received twice-weekly or weekly 1.3 mg/m(2) bortezomib intravenously, and a 2-ml sample of whole blood was obtained before treatment and 2-3 days and 1-3 weeks after the first dose. Induction of gene expression was then quantified by real-time PCR. Of a total of 64 enrolled patients, 53 patient samples qualified for mRNA analysis. The BiPN grade was associated with phytohemagglutinin-induced IL2, IFNG and TNFSF2, as well as with lipopolysaccharide-induced IL6 levels. More importantly, of the 19 patients showing a 3-fold increase in phytohemagglutinin-induced IL2, 14 did not suffer from BiPN (73.7% prediction), whereas of the 34 patients with a <3-fold increase, 23 experienced BiPN (67.6% prediction). Therefore, we concluded that pretreatment of phytohemagglutinin-induced IL2 mRNA levels in whole blood serve as a promising biomarker for predicting BiPN, and this finding warrants validation in a larger study.

Bortezomib-induced painful peripheral neuropathy: an electrophysiological, behavioral, morphological and mechanistic study in the mouse

Bortezomib is the first proteasome inhibitor with significant antineoplastic activity for the treatment of relapsed/refractory multiple myeloma as well as other hematological and solid neoplasms. Peripheral neurological complications manifesting with paresthesias, burning sensations, dysesthesias, numbness, sensory loss, reduced proprioception and vibratory sensitivity are among the major limiting side effects associated with bortezomib therapy. Although bortezomib-induced painful peripheral neuropathy is clinically easy to diagnose and reliable models are available, its pathophysiology remains partly unclear.

In this study we used well-characterized immune-competent and immune-compromised mouse models of bortezomib-induced painful peripheral neuropathy. To characterize the drug-induced pathological changes in the peripheral nervous system, we examined the involvement of spinal cord neuronal function in the development of neuropathic pain and investigated the relevance of the immune response in painful peripheral neuropathy induced by bortezomib.

We found that bortezomib treatment induced morphological changes in the spinal cord, dorsal roots, dorsal root ganglia (DRG) and peripheral nerves. Neurophysiological abnormalities and specific functional alterations in Aδ and C fibers were also observed in peripheral nerve fibers. Mice developed mechanical allodynia and functional abnormalities of wide dynamic range neurons in the dorsal horn of spinal cord. Bortezomib induced increased expression of the neuronal stress marker activating transcription factor-3 in most DRG. Moreover, the immunodeficient animals treated with bortezomib developed a painful peripheral neuropathy with the same features observed in the immunocompetent mice.

In conclusion, this study extends the knowledge of the sites of damage induced in the nervous system by bortezomib administration. Moreover, a selective functional vulnerability of peripheral nerve fiber subpopulations was found as well as a change in the electrical activity of wide dynamic range neurons of dorsal horn of spinal cord. Finally, the immune response is not a key factor in the development of morphological and functional damage induced by bortezomib in the peripheral nervous system.

Lenalidomide in patients with chemotherapy-induced polyneuropathy and relapsed or refractory multiple myeloma: results from a single-centre prospective study

Lenalidomide, an immunomodulatory drug used in myeloma therapy, has been claimed to be less neurotoxic than thalidomide, but evidence is still weak. We prospectively assessed lenalidomide safety in myeloma patients to evaluate whether it would induce or modify a previously ensued chemotherapy-induced peripheral neuropathy (CIPN). Thirty consecutive patients (17 men, mean age 63.7 ± 9.4) previously treated with bortezomib and/or thalidomide and starting on lenalidomide (25 mg/day for 21-day cycles) for relapsed or refractory myeloma were assessed at baseline, 6, and 12 months from the beginning of lenalidomide with Total Neuropathy Score clinical version (TNSc), Eastern Cooperative Oncology Group (ECOG) performance status, and numeric rating scale (NRS) for pain. TNSc >2 was considered significant for CIPN. TNSc changes of at least 4 points from baseline value were considered clinically relevant. At baseline 16 of the 30 patients (53.3%) had CIPN (mean TNSc 5.8, range 3-15). After 6 months, 13 patients were unchanged, 1 improved, and 2 worsened. After 12 months the patient who had improved persisted stable, and the two who had worsened returned to TNSc baseline value. The 14 patients without CIPN at baseline did not develop neuropathy. NRS and ECOG performance status persisted unchanged. Our results demonstrate lenalidomide safety and very low neurotoxicity also in patients with pre-existing CIPN treated for 1 year.

Bioenergetic deficits in peripheral nerve sensory axons during chemotherapy-induced neuropathic pain resulting from peroxynitrite-mediated post-translational nitration of mitochondrial superoxide dismutase

Many of the widely used anticancer drugs induce dose-limiting peripheral neuropathies that undermine their therapeutic efficacy. Animal models of chemotherapy-induced painful peripheral neuropathy (CIPN) evoked by a variety of drug classes, including taxanes, vinca alkaloids, platinum-complexes, and proteasome-inhibitors, suggest that the common underlying mechanism in the development of these neuropathies is mitotoxicity in primary nerve sensory axons (PNSAs) arising from reduced mitochondrial bioenergetics [eg adenosine triphosphate (ATP) production deficits due to compromised respiratory complex I and II activity]. The causative mechanisms of this mitotoxicity remain poorly defined. However, peroxynitrite, an important pro-nociceptive agent, has been linked to mitotoxicity in several disease states and may also drive the mitotoxicity associated with CIPN. Our findings reveal that the development of mechano-hypersensitivity induced by paclitaxel, oxaliplatin, and bortezomib was prevented by administration of the peroxynitrite decomposition catalyst Mn(III) 5,10,15,20-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTE-2-PyP(5+)) without interfering with their anti-tumor effects. Peak CIPN was associated with the nitration and inactivation of superoxide dismutase in the mitochondria, but not in the cytosol, as well as a significant decrease in ATP production within the PNSAs; all of these events were attenuated by MnTE-2-PyP(5+). Our results provide continued support for the role of mitotoxicity in the development of CIPN across chemotherapeutic drug classes, and identify peroxynitrite as a key mediator in these processes, thereby providing the rationale towards development of "peroxynitrite-targeted" therapeutics for CIPN.

Subclinical pretreatment sensory deficits appear to predict the development of pain and numbness in patients with multiple myeloma undergoing chemotherapy

PURPOSE

Chemotherapy-induced peripheral neuropathy is a major complication in the treatment for cancer, including multiple myeloma (MM). Patients may develop painful and non-painful (e.g., numbness) neuropathy symptoms that impair function and often persist after therapy is terminated. This study tested the hypothesis that baseline subclinical neuropathy, as assessed by sensory thresholds, is related to the development of neuropathy symptoms (e.g., pain and numbness) in patients with MM undergoing treatment with chemotherapy.

METHODS

Patients (n = 56) who had undergone two or fewer cycles of induction therapy and who had no evident neuropathy were assessed using quantitative sensory tests to determine multiple-modality sensory thresholds. Patient-reported pain and numbness were assessed through induction therapy (16 weeks) via the MD Anderson Symptom Inventory. A subset of participants (n = 15) continued reporting on their symptoms for an additional 16 weeks ("maintenance phase").

RESULTS

Patients with sharpness detection deficits at baseline (n = 11, 20 % of sample) reported less severe pain and numbness during induction therapy and less numbness during maintenance therapy (P < 0.05). During the maintenance phase, patients with warmth detection deficits (n = 5, 38 % of sample) reported more severe pain and numbness, and those with skin temperature deficits (n = 7, 47 % of maintenance sample) reported more severe pain (P < 0.05). These deficits were related to patient reported difficulty walking, a common symptom of peripheral neuropathy.

CONCLUSION

Our results suggest that baseline subclinical sensory deficits may be related to a patient's risk for developing chemotherapy-induced peripheral neuropathy.

Chemotherapy-induced peripheral neurotoxicity can be misdiagnosed by the National Cancer Institute Common Toxicity scale

The assessment of chemotherapy-induced peripheral neurotoxicity (CIPN) is still uncertain as several of the most frequently used scales do not rely on a formal neurological evaluation and depend on patients' reports and examiners' interpretations. The aim of this study was to compare the assessment of CIPN using the National Cancer Institute Common Toxicity Criteria (NCI-CTC) scale and a formal neurological assessment scored with the Total Neuropathy Score (TNS, i.e., a composite scale designed to grade the impairment in neuropathy patients) to identify possible discrepancies in the diagnosis. In this prospective study, 155 patients treated with cisplatin/carboplatin or with paclitaxel/docetaxel and CIPN were examined in a collaborative oncological/neurological multi-center trial using the NCI-CTC scale and the TNS; the results were then extensively compared. We evidenced that the TNS allows possible misdiagnosed neuropathies to be revealed. In fact, the NCI-CTC evaluation performed by experienced examiners overestimated the occurrence of motor neuropathy, possibly because of the presence of confounding factors (e.g., fatigue, depression, cachexia), which might be difficult to be ruled out without a formal neurological examination. This study strongly indicates that a more formal neurological assessment of patients with CIPN than that achievable with the common toxicity scales (e.g., NCI-CTC) is advisable.

Chemotherapy-induced peripheral neuropathy in pediatric cancer patients

Chemotherapy forms the backbone of treatment for many types of pediatric cancers, but a main side effect of treatment is chemotherapy-induced peripheral neuropathy (CIPN). Damage to the peripheral nervous system by chemotherapeutic agents can occur at the axon, cell body, or myelin level, and the mechanism of damage differs based on the specific chemotherapeutic agent used. This review provides background on the current knowledge of pathophysiology, assessment, and intervention for CIPN, focusing specifically on issues relevant in pediatric cancers patients. Although specific, standardized measures of CIPN are available for adults, such measures are limited for use in the pediatric populations. Likewise, clinical trials for prevention and treatment of this neuropathy and related symptoms are rare in pediatrics, but some information can be gained from the basic and adult literature.

Peripheral neuropathy during bortezomib treatment of multiple myeloma: a review of recent studies

Treatment-emergent peripheral neuropathy (PN) is an important dose-limiting toxicity during treatment of multiple myeloma (MM). Bortezomib-induced PN (BIPN) occurred in 37-44% of clinical trial patients with MM, with the cumulative treatment dose as its single most significant predictor. This review discusses the clinical profile of BIPN in the treatment of MM and guidelines for its management. Lower rates of BIPN observed during treatment of solid tumors compared with rates of hematologic cancers are also discussed. Several areas of research are reviewed that may improve the management of BIPN, including co-therapies with the novel heat shock protein inhibitor tanespimycin, which appears to reduce the incidence of BIPN, and recent studies with second-generation proteasome inhibitors such as carfilzomib and NPI-0052. Adherence to the National Cancer Institute dose-modification algorithm is the most effective method for mitigating BIPN. Reversal of BIPN after treatment cessation occurs in most cases, but recovery in some patients takes as long as 1.7 years, and some individuals fail to return to baseline neurologic function. BIPN can cause a significant reduction in quality of life, primarily due to severe treatment-emergent pain. Ongoing research may provide additional information about the mechanism of BIPN and strategies to reduce PN.

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.

Prophylactic antivirals may be helpful in prevention of varicella-zoster virus reactivation in myeloma, but are they safe?

PURPOSE

Retrospective analysis of two recent multiple myeloma (MM) clinical trials suggested that the use of bortezomib may be associated with an increased incidence of herpes zoster infections. Therefore, prophylactic use of antivirals has been advocated by some authors. This article explores the potential risks and pitfalls linked to routine acyclovir prophylaxis in bortezomib-treated MM.

SUMMARY

use of antivirals can be associated with important nephro- and neurotoxicity. The nephrotoxicity induced by MM itself and its supportive therapies, superimposed to aging and inherent immunosuppression in myeloma, makes the development of renal impairment even more likely. On the other hand, sensory neuropathy is known to occur both during myeloma progression and in the setting of bortezomib therapy. Furthermore, preexisting nephropathy in MM patients can contribute to the occurrence of serious neurologic toxicity with acyclovir.

CONCLUSIONS

long-term acyclovir prophylaxis in MM patients treated with bortezomib may cause severe renal and neurological toxicity. Prevention of these complications can be achieved through either withholding of the antivirals or a very close monitoring of both neurologic status and renal function in this patient population. This highlights the importance of both clinician's and pharmacist's involvement in optimization of myeloma patient care.