Toxic neuropathy in patients with pre-existing neuropathy

Pain associated with breast cancer: etiologies and therapies

Pain associated with breast cancer is a prevalent problem that negatively affects quality of life. Breast cancer pain is not limited to the disease course itself but is also induced by current therapeutic strategies. This, combined with the increasing number of patients living with breast cancer, make pain management for breast cancer patients an increasingly important area of research. This narrative review presents a summary of pain associated with breast cancer, including pain related to the cancer disease process itself and pain associated with current therapeutic modalities including radiation, chemotherapy, immunotherapy, and surgery. Current pain management techniques, their limitations, and novel analgesic strategies are also discussed.

Peripheral neuropathy associated with monomethyl auristatin E-based antibody-drug conjugates

Since the successful approval of gemtuzumab ozogamicin, antibody-drug conjugates (ADCs) have emerged as a pivotal category of targeted therapies for cancer. Among these ADCs, the use of monomethyl auristatin E (MMAE) as a payload is prevalent in the development of ADC drugs, which has significantly improved overall therapeutic efficacy against various malignancies. However, increasing clinical observations have raised concerns regarding the potential nervous system toxicity associated with MMAE-based ADCs. Specifically, a higher incidence of peripheral neuropathy has been reported in ADCs incorporating MMAE as payloads. Considering the increasing global use of MMAE-based ADCs, it is imperative to provide an inclusive overview of diagnostic and management strategies for this adverse event. In this review, we examine current information and what future research directions are required to better understand and manage this type of clinical challenge.

Toxic Neuropathies

OBJECTIVE

The purpose of this article is to provide an overview and update on the most clinically relevant toxic neuropathies.

LATEST DEVELOPMENTS

Broadly, toxic neuropathies were previously quite rare with the notable exception of neuropathy from alcohol or older chemotherapeutics. The development of newer therapies, particularly immunotherapy to treat malignancy, has resulted in a substantial increase in the occurrence of toxic neuropathies that require timely recognition and treatment. The understanding of other toxic neuropathies continues to evolve, such as statin-induced neuropathy, which new evidence suggests is much less common than previously suspected.

ESSENTIAL POINTS

Toxic neuropathies can be caused by medications, supplements, and recreational substances that injure peripheral nerves. Medications have evolved in the past 2 decades, as have the types of neuropathies that can be seen as related toxicities. In some areas of medicine, new classes and generations of drugs are associated with a lower incidence of toxic neuropathy.

Effect of Exercise on Chemotherapy-Induced Peripheral Neuropathy Among Patients Treated for Ovarian Cancer: A Secondary Analysis of a Randomized Clinical Trial

Importance

Chemotherapy-induced peripheral neuropathy (CIPN), one of the most common and severe adverse effects of chemotherapy, is associated with worse quality of life among survivors of ovarian cancer. Currently, there is no effective treatment for CIPN.

Objective

To evaluate the effect of a 6-month aerobic exercise intervention vs attention-control on CIPN among women treated for ovarian cancer in the Women's Activity and Lifestyle Study in Connecticut (WALC) to provide evidence to inform the guidelines and recommendations for prevention or treatment of CIPN.

Design, Setting, and Participants

This prespecified secondary analysis evaluated the Women's Activity and Lifestyle Study in Connecticut (WALC), a multicentered, open-label, population-based, phase 3 randomized clinical trial of an aerobic exercise intervention vs attention control for CIPN in patients who were diagnosed with ovarian cancer. Only WALC participants who received chemotherapy were included in this analysis. Participants were randomized 1:1 to either a 6-month aerobic exercise intervention or to attention control. All analyses were conducted between September 2022 and January 2023.

Interventions

The exercise intervention consisted of home-based moderate-intensity aerobic exercise facilitated by weekly telephone counseling from an American College of Sports Medicine/American Cancer Society-certified cancer exercise trainer. Attention control involved weekly health education telephone calls from a WALC staff member.

Main Outcomes and Measure

Change in CIPN was the primary outcome in this secondary analysis. This outcome was represented by CIPN severity, which was self-measured by participants at baseline and 6 months using the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity scale, with a score range of 0 to 44. A mixed-effects model was used to assess the 6-month change in CIPN between the exercise intervention and attention control arms.

Results

Of the 134 participants (all females; mean [SD] age, 57.5 [8.3] years) included in the analysis, 69 were in the exercise intervention arm and 65 were in the attention control arm. The mean (SD) time since diagnosis was 1.7 (1.0) years. The mean (SD) baseline CIPN scores were 8.1 (5.6) in the exercise intervention arm and 8.8 (7.9) in the attention control arm (P = .56). At 6 months, the self-reported CIPN score was reduced by 1.3 (95% CI, -2.3 to -0.2) points in the exercise intervention arm compared with an increase of 0.4 (95% CI, -0.8 to 1.5) points in the attention control arm. The between-group difference was -1.6 (95% CI, -3.1 to -0.2) points. The point estimate was larger among the 127 patients with CIPN symptoms at enrollment (-2.0; 95% CI, -3.6 to -0.5 points).

Conclusions and Relevance

Findings of this secondary analysis of the WALC trial indicate that a 6-month aerobic exercise intervention vs attention control significantly improved self-reported CIPN among patients who were treated for ovarian cancer. While replication of the findings in other studies is warranted, incorporating referrals to exercise programs into standard oncology care could reduce CIPN symptoms and increase quality of life in patients with ovarian cancer.

Trial Registration

ClinicalTrials.gov Identifier: NCT02107066.

Persistent weekly paclitaxel-induced peripheral neuropathy in early breast cancer patients enrolled in a randomized trial of cryotherapy

Chemotherapy-induced peripheral neuropathy (CIPN) is a serious side effect of weekly paclitaxel-based chemotherapy for breast cancer, that can persist for years. Cryotherapy therapy is effective for preventing early CIPN, but its protective effect on persistent CIPN is uncertain. This is a cross-sectional study conducted as an ancillary analysis of a randomized trial investigating the preventive effect of cryotherapy on CIPN in breast cancer patients receiving weekly paclitaxel-based chemotherapy (UMIN000034966). Eligible patients were evaluated for CIPN at more than a year after completion of the chemotherapy (persistent CIPN). CIPN was defined as a 6 or more points reduction from baseline in the Functional Assessment of Cancer Therapy-Neurotoxicity (FACT-NTX) score. The incidence of early and persistent CIPN was compared between cryotherapy and control groups. Thirty-eight patients were examined for both early and persistent CIPN. The median time from completion of the weekly paclitaxel-based chemotherapy to the questionnaire for persistent CIPN was 2.3 (1.3-3.1) years. In all 38 patients, persistent CIPN was demonstrated in 10 (26.3%), respectively. There was a numerical, however not significant, reduction in the incidence of persistent CIPN (15.8% vs 36.8%, P = .1) in the cryotherapy group compared with the control group, respectively. In multivariate logistic regression analysis, age ≥ 65 was a substantial risk factor for persistent CIPN (HR: 14.7, 95%CI: 1.7-130.7, P = .01). In breast cancer patients receiving adjuvant weekly paclitaxel-based chemotherapy, cryotherapy resulted in a numerical, however not significant, reduction in the incidence of persistent CIPN and age>=65 was a risk factor for persistent CIPN.

Effective treatment of advanced Hodgkin lymphoma with a modified BEACOPP regimen for a patient with demyelinating hereditary motor and sensory neuropathy type 1 (HMSN1)

Treatment for Hodgkin lymphoma (HL) in adults comprises substantial risk of chemotherapy‐induced peripheral neurotoxicity. Here, we describe the case of patient with Charcot–Marie–Tooth disease or HSMN1 and advanced Hodgkin lymphoma undergoing treatment with modified BEACOPP achieving complete remission without major aggravation of neurological symptoms.

Physical impairments, sensory disturbance, and functional ability in a cancer patient with and without chemotherapy-induced peripheral neuropathy symptoms

OBJECTIVE

The present study examined the objective and patient-reported measures of physical impairments, sensory disturbance, and functional ability between cancer patients with and without chemotherapy-induced peripheral neuropathy (CIPN) symptoms.

METHODS

Forty-one cancer survivors exposed to neurotoxic chemotherapies were conveniently recruited and completed a single cross-sectional assessment of patient-reported outcomes (VAS for pain intensity and ABC scale) and objective assessments (SWM test, TUG test, 5xSTS test, Romberg test with eyes open and eyes closed, 6MWT, and FAB scale).

RESULTS

Cancer patients who had undergone chemotherapy with CIPN symptoms did significantly worse in the SWM test, TUG test, 5xSTS test, Romberg test with eyes closed, 6MWT, FAB scale, and ABC scale (p < 0.05) when compared with cancer survivors without CIPN symptoms.

CONCLUSION

Cancer survivors with CIPN symptoms have lower physical performance, sensory perception, and functional ability, which may increase the risk of falling and disability. These findings further emphasize the need for effective rehabilitation and interventions to treat CIPN symptoms and related physical impairment and functional deficits.

Effect of Menopausal Status on Chemotherapy-Induced Peripheral Neuropathy: Single-Institution Retrospective Audit

Introduction Paclitaxel can cause peripheral neuropathy in up to 60% of patients. Chemotherapy-induced peripheral neuropathy (CIPN) compromises quality of life and often leads to dose reduction or discontinuation of lifesaving chemotherapy. Preclinical models have suggested the possible neuroprotective effect of progesterone through remyelination and other mechanisms.

Objectives The aim of this study was to evaluate the incidence of CIPN for different menopausal status.

Materials and Methods We evaluated the effect of menopausal status, as a surrogate for circulating progesterone levels, on the risk of developing paclitaxel-induced peripheral neuropathy, in an audit of breast cancer patients. Data on CIPN (by clinical history and examination) and other variables were collected from the case charts of patients who had received paclitaxel-based chemotherapy for breast cancer at our institution.

Results Five hundred and fifty women were treated with either neoadjuvant or adjuvant paclitaxel in this period. Of these, 262 (47.6%) women were premenopausal, 49 (8.9%) were perimenopausal, and 239 (43.5%) were postmenopausal at the time of diagnosis. Forty-five (8.1%) women had pre-existing diabetes mellitus. Two hundred and fifty-six (82.31%) developed chemotherapy-induced amenorrhea (CIA).

CIPN was seen in 32.7% of women who continued to be premenopausal after receiving chemotherapy and 62.3% of postmenopausal women. Thirty-five (77.8%) out of forty-five diabetic women developed CIPN. On a multivariate logistic regression model, pre-existing diabetes mellitus (risk ratio [RR] = 2.64, 95% confidence interval [CI]: 1.26–5.52, p = 0.009), postmenopausal (RR = 2.84, 95% CI = 1.48–5.45, p = 0.002), and CIA status (RR = 2.17, 95% CI = 1.14–4.12, p = 0.018) were significantly associated with the development of CIPN. Number of cycles did not appear to have an impact (p= 0.819).

Conclusions Postmenopausal status was independently associated with higher incidence of CIPN. One of the possible mechanisms could be lower circulating progesterone levels in these patients. A randomized controlled trial (CTRI/2015/11/006381) is ongoing to test this hypothesis.

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.

Drug-Induced Peripheral Neuropathy: A Narrative Review

Background

Peripheral neuropathy is a painful condition deriving from many and varied etiologies. Certain medications have been implicated in the iatrogenic development of Drug Induced Peripheral Neuropathy (DIPN) and include chemotherapeutic agents, antimicrobials, cardiovascular drugs, psychotropic, anticonvulsants, among others. This review synthesizes current clinical concepts regarding the mechanism, common inciting medications, and treatment options for drug-induced peripheral neuropathy.

Methods

The authors undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question and inclusion/exclusion criteria. The most relevant and up to date research was included.

Results

Drug-induced peripheral neuropathy is a common and painful condition caused by many different and frequently prescribed medications. Most often, DIPN is seen in chemotherapeutic agents, antimicrobials, cardiovascular drugs, psychotropic, and anticonvulsant drugs. Certain drugs exhibit more consistent neuropathic side effects, such as the chemotherapeutic compounds, but others are more commonly prescribed by a larger proportion of providers, such as the statins. DIPN is more likely to occur in patients with concomitant risk factors such as preexisting neuropathy, diabetes, and associated genetically predisposing diseases. DIPN is often difficult to treat, however medications including duloxetine, and gabapentin are shown to reduce neuropathic pain. Advanced techniques of neuromodulation offer promise though further randomized and controlled studies are needed to confirm efficacy.

Conclusion

Awareness of the drugs covered in this review and their potential for adverse neuropathic effect is important for providers caring for patients who report new onset symptoms of pain, paresthesia, or weakness. Prevention of DIPN is especially important because treatment often proves challenging. While many pharmacologic therapies have demonstrated analgesic potential in the pain caused by DIPN, many patients remain refractive to treatment. More studies are needed to elucidate the effectiveness of interventional, neuromodulating therapies.

Charcot-Marie-Tooth Disease and Other Hereditary Neuropathies

PURPOSE OF REVIEW

This article provides an overview of Charcot-Marie-Tooth disease (CMT) and other inherited neuropathies. These disorders encompass a broad spectrum with variable motor, sensory, autonomic, and other organ system involvement. Considerable overlap exists, both phenotypically and genetically, among these separate categories, all eventually exhibiting axonal injury and neurologic impairment. Depending on the specific neural and non-neural localizations, patients experience varying morbidity and mortality. Neurologic evaluations, including neurophysiologic testing, can help diagnose and predict patient disabilities. Diagnosis is often complex, especially when genetic and acquired components overlap.

RECENT FINDINGS

Next-generation sequencing has greatly improved genetic diagnosis, with many third-party reimbursement parties now embracing phenotype-based panel evaluations. Through the advent of comprehensive gene panels, symptoms previously labeled as idiopathic or atypical now have a better chance to receive a specific diagnosis. A definitive molecular diagnosis affords patients improved care and counsel. The new classification scheme for inherited neuropathies emphasizes the causal gene names. A specific genetic diagnosis is important as considerable advances are being made in gene-specific therapeutics. Emerging therapeutic approaches include small molecule chaperones, antisense oligonucleotides, RNA interference, and viral gene delivery therapies. New therapies for hereditary transthyretin amyloidosis and Fabry disease are discussed.

SUMMARY

Comprehensive genetic testing through a next-generation sequencing approach is simplifying diagnostic algorithms and affords significantly improved decision-making processes in neuropathy care. Genetic diagnosis is essential for pathogenic understanding and for gene therapy development. Gene-targeted therapies have begun entering the clinic. Currently, for most inherited neuropathy categories, specific symptomatic management and family counseling remain the mainstays of therapy.

Role of Kinematics Assessment and Multimodal Sensorimotor Training for Motion Deficits in Breast Cancer Chemotherapy-Induced Polyneuropathy: A Perspective on Virtual Reality Avatars

Chemotherapy-induced polyneuropathy (CIPN), one of the most severe and incapacitating side effects of chemotherapeutic drugs, is a serious concern in breast cancer therapy leading to dose diminution, delay, or cessation. The reversibility of CIPN is of increasing importance since active chemotherapies prolong survival. Clinical assessment tools show that patients experiencing sensorimotor CIPN symptoms not only do they have to cope with loss in autonomy and life quality, but CIPN has become a key restricting factor in treatment. CIPN incidence poses a clinical challenge and has lacked established and efficient therapeutic options up to now. Complementary, non-opioid therapies are sought for both prevention and management of CIPN. In this perspective, we explore the potential that digital interventions have for sensorimotor CIPN rehabilitation in breast cancer patients. Our primary goal is to emphasize the benefits and impact that Virtual Reality (VR) avatars and Machine Learning have in combination in a digital intervention aiming at (1) assessing the complete kinematics of deficits through learning underlying patient sensorimotor parameters, and (2) parameterize a multimodal VR simulation to drive personalized deficit compensation. We support our perspective by evaluating sensorimotor effects of chemotherapy, the metrics to assess sensorimotor deficits, and relevant clinical studies. We subsequently analyse the neurological substrate of VR sensorimotor rehabilitation, with multisensory integration acting as a key element. Finally, we propose a closed-loop patient-centered design recommendation for CIPN sensorimotor rehabilitation. Our aim is to provoke the scientific community toward the development and use of such digital interventions for more efficient and targeted rehabilitation.

Overview and critical revision of clinical assessment tools in chemotherapy-induced peripheral neurotoxicity

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a major toxicity of cancer treatment, leading to dose reduction and premature treatment cessation, potentially affecting patient function, and quality of life. The development of accurate and sensitive assessment tools for CIPN is essential to enable clinical monitoring during treatment, follow-up of long-term outcomes and measurement of toxicity in clinical trials. This review examines CIPN clinical assessment scales incorporating clinician-based, composite, and patient-reported outcomes (PROs), providing a systematic review of their properties and an updated critical analysis of recommendations on current evidence for their use. This systematic review of CIPN assessment tools identified 50 papers containing 41 assessment tools, across 4 categories (common toxicity criteria; composite neurological scale; PROs; pain scale). The majority of these tools were PROs, underscoring the importance of patient-based assessment of symptoms. While there has been considerable work in the field over the past 10 years, this review highlights significant gaps, including a lack of evaluation of responsiveness and problematic neuropathic pain evaluation. There remains a need for consensus on the best available tool and the need to modify existing instruments to improve utility.

6-Methoxyflavanone abates cisplatin-induced neuropathic pain apropos anti-inflammatory mechanisms: A behavioral and molecular simulation study

Cisplatin is used as a first line therapy in treating cancers. However, its use is often accompanied with the development of peripheral neuropathy. 6-Methoxyflavanone (6-MeOF) is a positive allosteric modulator at GABAA receptors and is known for attenuating diabetes-induced neuropathic pain. Neuropathy was induced in male Sprague-Dawley rats (150-250 g), via intraperitoneal injection of cisplatin (3 mg/kg) once a week for four consecutive weeks. 6-MeOF (25, 50 and 75 mg/kg, i.p) and gabapentin (75 mg/kg, i.p) were administered 30 min before each cisplatin injection. Static and dynamic allodynia were assessed using von Frey filaments and cotton buds. The anti-inflammatory activity was analyzed with plethysmometer. Body weights were also measured each week. The binding affinity of 6-MeOF with chloride channel, Cyclooxygenase-1 (COX-1) and Cyclooxygenase-2 (COX-2) was studied using docking approach. The in vitro COX-1 and COX-2 inhibitory effect of 6-MeOF was conducted with COX colorimetric assay. Administration of cisplatin for four consecutive weeks induced static (decreased paw withdrawal threshold; PWT) and dynamic allodynia (decreased paw withdrawal latency; PWL). Co-administration of 6-MeOF for four weeks significantly attenuated the cisplatin-induced expression of nocifensive behaviors observed as significant increase in PWT and PWL. Moreover, it also prevented the body weight loss induced by cisplatin administration. In silico studies depicted a good interaction of 6-MeOF with chloride ion channels and COX-1 and COX-2 enzymes. The in vitro study confirmed the inhibitory activity of 6-MeOF for COX-1 and COX-2. 6-MeOF may be effective in attenuating cisplatin-induced allodynia, probably through interaction with GABAergic receptors and reducing inflammation.

Incidence of peripheral neuropathy associated with eribulin mesylate versus vinorelbine in patients with metastatic breast cancer: sub-group analysis of a randomized phase III study

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most significant neurologic complications of chemotherapy, impacting patient's behavior and quality of life. CIPN is mostly sensory, with rare incidences of autonomic dysfunction and other neuropathy.

METHODS

We conducted a single-center sub-group analysis of patients with metastatic breast cancer enrolled in a phase III study (NCT02225470) set up to compare eribulin mesylate (1.4 mg/m² on days 1 and 8 every 21 days) with vinorelbine (25 mg/m² on days 1, 8, and 15 every 21 days). The analysis investigated incidence of peripheral neuropathy, time to onset of neuropathy, and safety.

RESULTS

Our analysis included 110 women with a mean age of 50.7 (SD = 10.9). The median accumulated dose of eribulin was 11.2 mg/m² and 125.0 mg/m² for vinorelbine. Among patients in the eribulin group, a performance status (ECOG PS) of 2 was correlated with peripheral sensory neuropathy (p = 0.015), and accumulated eribulin dose (≥ 10 mg/m²) was associated with all neuropathy and peripheral sensory neuropathy (p = 0.003 and p = 0.007, respectively). In the vinorelbine group, patient age (≥ 65 years) was positively associated with all neuropathy (p = 0.043). The time to onset of neuropathy appeared to be longer for eribulin versus vinorelbine (35.3 vs. 34.6 weeks; p = 0.046), with a significantly higher incidence of autonomic neuropathy at weeks 2 and 10 observed among patients receiving vinorelbine (p = 0.008 and p = 0.043, respectively).

CONCLUSION

Vinorelbine is associated with a higher incidence of autonomic neuropathy than eribulin in patients with metastatic breast cancer. Furthermore, the onset of neurotoxicity appears to occur earlier with vinorelbine than eribulin.

Time-to-Event Modeling of Peripheral Neuropathy: Platform Analysis of Eight Valine-Citrulline-Monomethylauristatin E Antibody-Drug Conjugates

Peripheral neuropathy (PN) is a common long-term debilitating toxicity of antimicrotubule agents. PN was the most frequent adverse event resulting in dose modifications and/or discontinuation of treatment for valine-citrulline-monomethylauristatin E antibody-drug conjugates (ADCs) developed at Genentech. A pooled time-to-event analysis across eight ADCs (~700 patients) was performed to evaluate the relationship between the ADC exposure and the risk for developing a clinically significant (grade ≥ 2) PN. In addition, the impact of demographic and pathophysiological risk factors on the risk for PN was explored. The time-to-event analysis suggested that the development of PN risk increased with ADC exposure, treatment duration, body weight, and previously reported PN. This model can be used to inform clinical strategies such as adaptations to dosing regimen and/or treatment duration as well as inform clinical eligibility to reduce the incidence of grade ≥ 2 PN.

Rational treatment of chemotherapy-induced peripheral neuropathy with capsaicin 8% patch: from pain relief towards disease modification

Purpose

Chemotherapy-induced peripheral neuropathy (CIPN) with associated chronic pain is a common and disabling condition. Current treatments for neuropathic pain in CIPN are largely ineffective, with unfavorable side-effects. The capsaicin 8% patch (capsaicin 179 mg patch) is approved for the treatment of neuropathic pain: a single topical cutaneous application can produce effective pain relief for up to 12 weeks. We assessed the therapeutic potential of capsaicin 8% patch in patients with painful CIPN, and its mechanism of action.

Patients and methods

16 patients with chronic painful CIPN (mean duration 2.5 years), in remission for cancer and not receiving chemotherapy, were treated with 30 min application of capsaicin 8% patch to the feet. Symptoms were monitored using the 11-point numerical pain rating scale (NPRS), and questionnaires. Investigations were performed at baseline and three months after patch application, including skin biopsies with a range of markers, and quantitative sensory testing (QST).

Results

Patients reported significant reduction in spontaneous pain (mean NPRS: −1.27; 95% CI 0.2409 to 2.301; p=0.02), touch-evoked pain (−1.823; p=0.03) and cold-evoked pain (−1.456; p=0.03). Short-Form McGill questionnaire showed a reduction in neuropathic (p=0.0007), continuous (p=0.01) and overall pain (p=0.004); Patient Global Impression of Change showed improvement (p=0.001). Baseline skin biopsies showed loss of intra-epidermal nerve fibers (IENF), and also of sub-epidermal nerve fibers quantified by image analysis. Post-patch application skin biopsies showed a significant increase towards normalization of intra-epidermal and sub-epidermal nerve fibers (for IENF: structural marker PGP9.5, p=0.009; heat receptor TRPV1, p=0.027; regenerating nerve marker GAP43, p=0.04). Epidermal levels of Nerve Growth Factor (NGF), Neurotrophin-3 (NT-3), and Langerhans cells were also normalized. QST remained unchanged and there were no systemic side-effects, as in previous studies.

Conclusion

Capsaicin 8% patch provides significant pain relief in CIPN, and may lead to regeneration and restoration of sensory nerve fibers ie, disease modification.

Individually tailored whole-body vibration training to reduce symptoms of chemotherapy-induced peripheral neuropathy: study protocol of a randomised controlled trial-VANISH

INTRODUCTION

Chemotherapy-induced peripheral neuropathy (CIPN) is a prevalent and clinically meaningful side effect of cancer treatment. CIPN is induced by neurotoxic agents, causing severe sensory and/or motor deficits, resulting in disability and poor recovery, reducing patients' quality of life and limiting medical therapy. To date, effective treatment options are lacking. Whole-body vibration (WBV) training can attenuate motor and sensory deficits. We are conducting a two-armed, multicentre, assessor-blinded, randomised controlled trial, to investigate the effects of WBV on relevant symptoms of CIPN and determine the training characteristics.

METHODS AND ANALYSIS

In this ongoing study, 44 patients who have completed therapy in the past 3 months, with a neurologically confirmed CIPN are assessed before and after a 12-week intervention and follow-up. The intervention group receives WBV twice a week. Exercises are individually tailored according to the initially determined optimal neuromuscular response. The control group receives care as usual.Primary endpoint is the patient reported reduction of CIPN-related symptoms (Functional Assessment of Cancer Therapy/Gynaecology Oncology Group-Neurotoxicity). Secondary endpoints are compound muscle action potentials, distal motor latency, conduction velocity, F-waves from the tibial and peroneal nerve, antidromic sensory nerve conduction studies of the sural nerve, normalised electromyographic activity, peripheral deep sensitivity, proprioception, balance, pain, the feasibility of training settings, quality of life and the level of physical activity.

AIM, ETHICS AND DISSEMINATION

The study was approved by both responsible ethics committees. (1) Our results may contribute to a better understanding of the effects of WBV on motor and sensory functions and (2) may provide information whether WBV at the most effective setting, is feasible for neuropathic patients. (3) Our results may also contribute to improve supportive care in oncology, thereby enhancing quality of life and enabling the optimal medical therapy. All results will be published in international peer-reviewed journals as well as a manual for clinical practice.

TRIAL REGISTRATION NUMBER

NCT03032718.

Chemotherapy-Induced Peripheral Neuropathy in Egyptian Patients: Single Institution Retrospective Analysis

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a major toxicity that requires treatment modification or cessation and worsens patients’ quality of life. Its incidence is 30–40%. Occurrence and severity depend on treatment- and patient-related factors. The symptoms are self-limiting with recovery rate about 50%. Methods: This retrospective analysis took place in our chemotherapy unit. We included patients treated between January 2014 and December 2015. Results: 250 patients were eligible. 53 received paclitaxel, 78 received docetaxel, 64 received cisplatin and 55 received oxaliplatin. Mean age was 50.11 years. Frequency of CIPN was 46.8% (Grade I 70.9%, GII 24.7%, GIII 4.4%). It was 74% with oxaliplatin, 73.5% with paclitaxel, 35.9% with cisplatin and 17.9% with docetaxel. After median of 6 months 24% of patients recovered completely. No significant correlation between occurrence of CIPN and age (p = 0.781), while was significant with cisplatin (p = 0.043). Diabetic patients had higher incidence (p = 0.007). With cisplatin, median cumulative dose of 450 mg/m2 and ≥ 6 cycles had higher incidence of CIPN (p 0.006 and 0.010; respectively). With oxaliplatin, none was correlated with CIPN frequence. With paclitaxel, CIPN was more frequent if ≥ 4 cycles were received (p = 0.005). With docetaxel, > 4 cycles or cumulative dose ≥ 360 mg/m2 had higher occurrence of GII CIPN (p < 0.001 for both). Conclusion: CIPN is common problem that affects patients’ quality of life and leads to treatment interruption. There are many factors affecting its incidence and severity.

Pre-treatment anxiety is associated with persistent chemotherapy-induced peripheral neuropathy in women treated with neoadjuvant chemotherapy for breast cancer

OBJECTIVE

Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent adverse reaction caused by chemotherapeutic agents, especially the taxanes. CIPN can persist from months to years after completion of chemotherapy, decreasing quality of life for cancer survivors. The aim of this study was to explore the incidence and risk factors of persistent CIPN among women with breast cancer receiving neoadjuvant chemotherapy.

METHODS

In this prospective study, we recruited women with breast cancer receiving neoadjuvant chemotherapy, including four cycles of docetaxel. Participants reported neuropathic symptoms of tingling/numbness at baseline, at the end of chemotherapy treatment, and at 8 months after completion of chemotherapy. Candidate factors associated with CIPN were assessed before chemotherapy.

RESULTS

Among 111 participants, 50 (45.0%) experienced CIPN during chemotherapy, and 21 (18.9%) reported persistent CIPN after chemotherapy. Univariate logistic regression analysis revealed that development of CIPN was significantly associated with pre-treatment numbness (odds ratio [OR], 4.02; 95% confidence interval [CI], 1.09-7.40; p = .033), and persistent CIPN was significantly associated with pre-treatment numbness (OR, 3.60; 95% CI, 1.12-11.61; p = .032) and pre-treatment anxiety (OR, 5.02; 95% CI, 1.84-13.70; p = .002). Multivariate analysis indicated that pre-treatment anxiety remained significantly associated with persistent CIPN (OR, 4.01; 95% CI, 1.25-12.87; p = .020).

CONCLUSION

Our results suggested that pre-treatment anxiety might be related to a patient's risk for persistent CIPN in women with breast cancer undergoing neoadjuvant chemotherapy. Further research is required to investigate if interventions targeting pre-treatment anxiety could provide prevention and management for persistent CIPN.

Antineoplastic agents exacerbating Charcot Marie Tooth disease: red flags to avoid permanent disability

BACKGROUND

Charcot Marie Tooth (CMT) disease is the most common form of hereditary neuropathy. Due to the high prevalence of mild and undiagnosed forms, patients with CMT disease may be exposed to severe neurotoxicity following the administration of neurotoxic chemotherapies. The aim of this report is to alert oncologists to the potential to precipitate severe irreversible peripheral neuropathies when administering neurotoxic compounds to undiagnosed CMT patients.

MATERIAL AND METHODS

A retrospective research in the OncoNeuroTox database was performed (2010-2016), searching for patients with the diagnosis of chemotherapy-induced peripheral neuropathy (CIPN) and CMT disease. A comprehensive literature review for previously published cases was performed using the Pubmed and Cochrane databases (1972-2017).

RESULTS

Among 428 patients with CIPN, we identified eight patients with concomitant CMT disease. Seven patients out of the eight had no previous diagnosis of CMT disease, although accurate familial history disclosed mild signs of peripheral neuropathy in five cases. Patients themselves had minor stigmata of long-standing peripheral damage. Patients received chemotherapy regimens based on vinca alkaloids, taxanes or a combination of vinca alkaloids and platinum compounds. In two cases, cumulative doses were below or equal to the expected neurotoxic threshold. Following chemotherapy administration, patients developed severe length-dependent sensory-motor deficits. Despite early drug discontinuation, most patients remained severely disabled.

CONCLUSION

A brief checklist to disclose long-standing signs of peripheral neuropathy could be helpful to detect patients with undiagnosed hereditary neuropathies who could be at risk of developing severe irreversible neurotoxicity following the administration of neurotoxic agents.

Chemotherapy-Associated Peripheral Neuropathy in Patients With Early-Stage Breast Cancer: A Systematic Review

Breast cancer is the most common cancer among women worldwide, and survival rates are increasing. Chemotherapy-associated peripheral neuropathy (PN) is clinically important because of effects on quality of life (QOL) and potential effects on dose limitations. This adverse drug reaction is associated with certain classes of chemotherapy and commonly presents as peripheral sensory neuropathy whose natural course is largely unknown. The literature was reviewed to determine the frequency and characteristics of PN associated with adjuvant chemotherapy in early-stage breast cancer (ESBC) to explore the potential impact on long-term (one or more years after diagnosis) health outcomes and QOL. MEDLINE, PubMed, Embase, and the Cochrane Library were searched for relevant English-language randomized controlled trials, systematic reviews, meta-analyses, and case-control and cohort studies published between January 1990 and July 1996. Included studies were limited to current adjuvant regimens (eg, anthracyclines, taxanes, cyclophosphamide, platinum compounds). Two investigators independently reviewed abstracts, full-text articles, and extracted data from fair- and good-quality studies. Discrepancies in quality assessment and data extraction were resolved by consensus. We identified 364 articles; 60 were eligible for full-text review. Only five reports of four studies provided data beyond one year post-treatment initiation. Studies used different measures to assess PN. Neuropathic symptoms persisted in 11.0% to more than 80% of participants at one to three years following treatment. There is a paucity of data describing persistent PN in ESBC patients. Consistent use of validated measures and well-conducted randomized clinical trials or observational studies are needed to evaluate the incidence, persistence, and QOL associated with the long-term effects of PN.

Chemotherapy-induced peripheral neuropathy: A current review

Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting side effect experienced by patients receiving treatment for cancer. Approximately 30 to 40% of patients treated with neurotoxic chemotherapy will develop CIPN, and there is considerable variability in its severity between patients. It is often sensory-predominant with pain and can lead to long-term morbidity in survivors. The prevalence and burden of CIPN late effects will likely increase as cancer survival rates continue to improve. In this review, we discuss the approach to peripheral neuropathy in patients with cancer and address the clinical phenotypes and pathomechanisms of specific neurotoxic chemotherapeutic agents. Ann Neurol 2017;81:772-781.

Pathophysiology of Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced neuropathy is a common, dose-dependent adverse effect of several antineoplastics. It can lead to detrimental dose reductions and discontinuation of treatment, and severely affects the quality of life of cancer survivors. Clinically, chemotherapy-induced peripheral neuropathy presents as deficits in sensory, motor, and autonomic function which develop in a glove and stocking distribution due to preferential effects on longer axons. The pathophysiological processes are multi-factorial and involve oxidative stress, apoptotic mechanisms, altered calcium homeostasis, axon degeneration and membrane remodeling as well as immune processes and neuroinflammation. This review focusses on the commonly used antineoplastic substances oxaliplatin, cisplatin, vincristine, docetaxel, and paclitaxel which interfere with the cancer cell cycle-leading to cell death and tumor degradation-and cause severe acute and chronic peripheral neuropathies. We discuss drug mechanism of action and pharmacokinetic disposition relevant to the development of peripheral neuropathy, the epidemiology and clinical presentation of chemotherapy-induced neuropathy, emerging insight into genetic susceptibilities as well as current understanding of the pathophysiology and treatment approaches.

Selected Risk Nutritional Factors for Chemotherapy-Induced Polyneuropathy

The present study seeks to identify the nutritional risk factors involved in the development of neuropathies induced by chemotherapeutic treatments. Unlike the gastrointestinal or hematological adverse effects of chemotherapy there is no protective treatment strategy for polyneuropathy. The aim of this study was to find possible deficiencies in nutritional factors, which can be used for supplementation in the future for prevention of chemotherapy-induced neuropathy development. We analyzed 70 patients undergoing paclitaxel chemotherapy and evaluated the risk factors involved in chemotherapy-induced peripheral neuropathy (CIPN). Several risk factors were considered in the development of CIPN, including deficiency of vitamin B1, B6, and D and fatty acids. The occurrence of CIPN complication in 60% cases was observed. We found significant differences in vitamin D and saturated fatty acid concentration. Vitamin D levels in the group without CIPN were estimated to be 38.2 (24.95, 47.63) nmol/L, whereas in the group with CIPN it was determined to be 25.6 (19.7, 32.55) nmol/L, p = 0.008. The level of total saturated fatty acids in the group without CIPN was of 32.613 Area % (31.322; 36.262), whereas in the group with CIPN it was of 34.209 Area % (32.86; 39.386), p = 0.01. The obtained results suggest a diet lower in saturated fatty acid content during chemotherapy. The most significant finding was that supplementation of vitamin D before chemotherapy could be an efficient neuroprotective in CIPN prophylaxis, as significantly lower levels 25OH derivative of vitamin D were observed in the CIPN group throughout the study period.

Towards a functional pathology of hereditary neuropathies

A growing number of hereditary neuropathies have been assigned to causative gene defects in recent years. The study of human nerve biopsy samples has contributed substantially to the discovery of many of these neuropathy genes. Genotype-phenotype correlations based on peripheral nerve pathology have provided a comprehensive picture of the consequences of these mutations. Intriguingly, several gene defects lead to distinguishable lesion patterns that can be studied in nerve biopsies. These characteristic features include the loss of certain nerve fiber populations and a large spectrum of distinct structural changes of axons, Schwann cells and other components of peripheral nerves. In several instances the lesion patterns are directly or indirectly linked to the known functions of the mutated gene. The present review is designed to provide an overview on these characteristic patterns. It also considers other aspects important for the manifestation and pathology of hereditary neuropathies including the role of inflammation, effects of chemotherapeutic agents and alterations detectable in skin biopsies.

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.

Acupuncture and Reflexology for Chemotherapy-Induced Peripheral Neuropathy in Breast Cancer

BACKGROUND

Treatment of chemotherapy-induced peripheral neuropathy (CIPN), which affects approximately 30% to 40% of patients treated with neuropathy-causing agents, is mainly symptomatic. Currently available interventions are of little benefit.

STUDY DESIGN

This study was conducted as a retrospective analysis of the efficacy of acupuncture and reflexology in alleviating CIPN in breast cancer patients.

METHODS

Medical records of 30 consecutive breast cancer patients who received both chemotherapy and treatment for CIPN according to our Acupuncture and Reflexology Treatment for Neuropathy (ART-N) protocol between 2011 and 2012 were reviewed. Symptom severity was rated at baseline, during, and after treatment.

RESULTS

The records of 30 breast cancer patients who had been concomitantly treated with chemotherapy and ART-N for CIPN were retrieved. Two records were incomplete, leaving a total of 28 patients who were enrolled into the study. Twenty patients (71%) had sensory neuropathy, 7 (25%) had motor neuropathy, and 1 (4%) had both sensory and motor neuropathy. Only 2 (10%) of the 20 patients with grades 1 to 2 neuropathy still reported symptoms at 12 months since starting the ART-N protocol. All 8 patients who presented with grades 3 to 4 neuropathy were symptom-free at the 12-month evaluation. Overall, 26 patients (93%) had complete resolution of CIPN symptoms.

CONCLUSION

The results of this study demonstrated that a joint protocol of acupuncture and reflexology has a potential to improve symptoms of CIPN in breast cancer patients. The protocol should be validated on a larger cohort with a control group. It also warrants testing as a preventive intervention.

Electrodiagnosis in Cancer Rehabilitation

With numerous advancements in early detection and multimodal therapy, cancer has become a chronic disease. As the number of cancer survivors continues to increase, physiatrists and other neuromuscular disease specialists are more likely to encounter individuals with residual impairments, disabilities, and/or handicaps resulting from cancer or related treatments. The patient with cancer is especially prone to injury directed at the peripheral nervous system at multiple anatomic levels. Electrodiagnosis is an invaluable tool in the evaluation of neuromuscular disorders in this patient population.

Prevention of vincristine-induced peripheral neuropathy by genetic deletion of SARM1 in mice

Peripheral polyneuropathy is a common and dose-limiting side effect of many important chemotherapeutic agents. Most such neuropathies are characterized by early axonal degeneration, yet therapies that inhibit this axonal destruction process do not currently exist. Recently, we and others discovered that genetic deletion of SARM1 (sterile alpha and TIR motif containing protein 1) dramatically protects axons from degeneration after axotomy in mice. This finding fuels hope that inhibition of SARM1 or its downstream components can be used therapeutically in patients threatened by axonal loss. However, axon loss in most neuropathies, including chemotherapy-induced peripheral neuropathy, is the result of subacute/chronic processes that may be regulated differently than the acute, one time insult of axotomy. Here we evaluate if genetic deletion of SARM1 decreases axonal degeneration in a mouse model of neuropathy induced by the chemotherapeutic agent vincristine. In wild-type mice, 4 weeks of twice-weekly intraperitoneal injections of 1.5 mg/kg vincristine cause pronounced mechanical and heat hyperalgesia, a significant decrease in tail compound nerve action potential amplitude, loss of intraepidermal nerve fibres and significant degeneration of myelinated axons in both the distal sural nerve and nerves of the toe. Neither the proximal sural nerve nor the motor tibial nerve exhibit axon loss. These findings are consistent with the development of a distal, sensory predominant axonal polyneuropathy that mimics vincristine-induced peripheral polyneuropathy in humans. Using the same regimen of vincristine treatment in SARM1 knockout mice, the development of mechanical and heat hyperalgesia is blocked and the loss in tail compound nerve action potential amplitude is prevented. Moreover, SARM1 knockout mice do not lose unmyelinated fibres in the skin or myelinated axons in the sural nerve and toe after vincristine. Hence, genetic deletion of SARM1 blocks the development of vincristine-induced peripheral polyneuropathy in mice. Our results reveal that subacute/chronic axon loss induced by vincristine occurs via a SARM1 mediated axonal destruction pathway, and that blocking this pathway prevents the development of vincristine-induced peripheral polyneuropathy. These findings, in conjunction with previous studies with axotomy and traumatic brain injury, establish SARM1 as the central determinant of a fundamental axonal degeneration pathway that is activated by diverse insults. We suggest that targeting SARM1 or its downstream effectors may be a viable therapeutic option to prevent vincristine-induced peripheral polyneuropathy and possibly other peripheral polyneuropathies.

Polymorphism of CYP3A4 and ABCB1 genes increase the risk of neuropathy in breast cancer patients treated with paclitaxel and docetaxel

BACKGROUND

Interindividual variability of pharmacogenetics may account for unpredictable neurotoxicities of taxanes.

METHODS

From March 2011 to June 2015, female patients with operable breast cancer who had received docetaxel- or paclitaxel-containing adjuvant chemotherapy were included in this study. All patients were treated with single-agent paclitaxel intravenously (IV) 175 mg/m(2) every 3 weeks for four cycles, or IV 80 mg/m(2) weekly for 12 cycles, and IV 100 mg/m(2) docetaxel for four cycles as adjuvant treatment. We evaluated the relationship between neurotoxicity of taxanes and single-nucleotide polymorphisms of ABCB1, CYP3A4, ERCC1, ERCC2, FGFR4, TP53, ERBB2, and CYP2C8 genes. Taxane-induced neurotoxicity during the treatment was evaluated according to the National Cancer Institute Common Toxicity Criteria version 4.03 prior to each cycle. Chi-squared tests were used to compare the two groups, and multivariate binary logistic regression models were used for determining possible risk factors of neuropathy.

RESULTS

Pharmacogenetic analysis was performed in 219 females. ABCB1 3435 TT genotype had significantly higher risk for grade ≥2 neurotoxicity (odds ratio [OR]: 2.759, 95% confidence interval [CI]: 1.172-6.493, P: 0.017) compared to TC and CC genotype, and also CYP3A4 392 AA and AG genotype had significantly higher risk for grade ≥2 neurotoxicity (OR: 2.259, 95% CI: 1.033-4.941, P: 0.038) compared to GG genotype. For FDGF4 gene with AG and GG genotype, OR was 1.879 (95% CI: 1.001-3.525, P: 0.048) compared to AA genotype with regard to any grade of neuropathy risk. We could not find any other association of other genotypes with neurotoxicity grades.

CONCLUSION

ABCB1 3435 TT genotype and CYP3A4 392 AA/AG genotypes may be used as predictors of neurotoxicity during taxane chemotherapy.

Target-enrichment sequencing and copy number evaluation in inherited polyneuropathy

OBJECTIVE

To assess the efficiency of target-enrichment next-generation sequencing (NGS) with copy number assessment in inherited neuropathy diagnosis.

METHODS

A 197 polyneuropathy gene panel was designed to assess for mutations in 93 patients with inherited or idiopathic neuropathy without known genetic cause. We applied our novel copy number variation algorithm on NGS data, and validated the identified copy number mutations using CytoScan (Affymetrix). Cost and efficacy of this targeted NGS approach was compared to earlier evaluations.

RESULTS

Average coverage depth was ∼760× (median = 600, 99.4% > 100×). Among 93 patients, 18 mutations were identified in 17 cases (18%), including 3 copy number mutations: 2 PMP22 duplications and 1 MPZ duplication. The 2 patients with PMP22 duplication presented with bulbar and respiratory involvement and had absent extremity nerve conductions, leading to axonal diagnosis. Average onset age of these 17 patients was 25 years (2-61 years), vs 45 years for those without genetic discovery. Among those with onset age less than 40 years, the diagnostic yield of targeted NGS approach is high (27%) and cost savings is significant (∼20%). However, the cost savings for patients with late onset age and without family history is not demonstrated.

CONCLUSIONS

Incorporating copy number analysis in target-enrichment NGS approach improved the efficiency of mutation discovery for chronic, inherited, progressive length-dependent polyneuropathy diagnosis. The new technology is facilitating a simplified genetic diagnostic algorithm utilizing targeted NGS, clinical phenotypes, age at onset, and family history to improve diagnosis efficiency. Our findings prompt a need for updating the current practice parameters and payer guidelines.

Management of Charcot-Marie-Tooth disease: improving long-term care with a multidisciplinary approach

Charcot–Marie–Tooth (CMT) disease is the most common inherited neuropathy and one of the most common inherited diseases in humans. The diagnosis of CMT is traditionally made by the neurologic specialist, yet the optimal management of CMT patients includes genetic counselors, physical and occupational therapists, physiatrists, orthotists, mental health providers, and community resources. Rapidly developing genetic discoveries and novel gene discovery techniques continue to add a growing number of genetic subtypes of CMT. The first large clinical natural history and therapeutic trials have added to our knowledge of each CMT subtype and revealed how CMT impacts patient quality of life. In this review, we discuss several important trends in CMT research factors that will require a collaborative multidisciplinary approach. These include the development of large multicenter patient registries, standardized clinical instruments to assess disease progression and disability, and increasing recognition and use of patient-reported outcome measures. These developments will continue to guide strategies in long-term multidisciplinary efforts to maintain quality of life and preserve functionality in CMT patients.

A Hyperresponsive HPA Axis May Confer Resilience Against Persistent Paclitaxel-Induced Mechanical Hypersensitivity

Paclitaxel (PAC) treatment is associated with persistent, debilitating neuropathic pain that affects the hands and feet. Female sex and biological stress responsivity are risk factors for persistent pain, but it is unclear whether these important biologically based factors confer risk for PAC-induced neuropathic pain. To determine the relative contributions of sex and hypothalamic-pituitary-adrenal (HPA)-axis stress responsivity to PAC-induced mechanical hypersensitivity, we employed a PAC protocol consisting of three, 2-week cycles of every-other-day doses of PAC 1 mg/kg versus saline (Week 1) and recovery (Week 2), totaling 42 days, in mature male and female Fischer 344, Lewis, and Sprague Dawley (SD) rats, known to differ in HPA axis stress responsivity. Mechanical sensitivity was operationalized using von Frey filaments, per the up-down method. Among PAC-injected rats, SD rats exhibited significantly greater mechanical hypersensitivity relative to accumulative PAC doses compared to Fischer 344 rats. Lewis rats were not significantly different in mechanical hypersensitivity from SD or Fischer 344 rats. At the end of the protocol, PAC-injected SD rats exhibited profound mechanical hypersensitivity, whereas the PAC-injected Fischer 344 rats appeared relatively resilient to the long-term effects of PAC and exhibited mechanical sensitivity that was not statistically different from their saline-injected counterparts. Sex differences were mixed and noted only early in the PAC protocol. Moderate HPA axis stress responsivity may confer additional risk for the painful effects of PAC. If these findings hold in humans, clinicians may be better able to identify persons who may be at increased risks for developing neuropathic pain during PAC therapy.

Long-term Toxicity of Cancer Treatment in Older Patients

With earlier cancer diagnosis among older patients with cancer, the possibility of curing cancer increases. However, cancer treatment may have a long-lasting impact on older cancer survivors. It is vital to screen, diagnose, and properly manage the long-term toxicities of cancer treatment in order to maintain the quality of life of older cancer survivors.

Exacerbation of Charcot-Marie-Tooth type 2E neuropathy following traumatic nerve injury

Charcot-Marie-Tooth disease (CMT) is the most commonly inherited peripheral neuropathy. CMT disease signs include distal limb neuropathy, abnormal gait, sensory defects, and deafness. We generated a novel line of CMT2E mice expressing hNF-L(E397K), which displayed muscle atrophy of the lower limbs without denervation, proximal reduction in large caliber axons, and decreased nerve conduction velocity. In this study, we challenged wild type, hNF-L and hNF-L(E397K) mice with crush injury to the sciatic nerve. We analyzed functional recovery by measuring toe spread and analyzed gait using the Catwalk system. hNF-L(E397K) mice demonstrated reduced recovery from nerve injury consistent with increased susceptibility to neuropathy observed in CMT patients. In addition, hNF-L(E397K) developed a permanent reduction in their ability to weight bear, increased mechanical allodynia, and premature gait shift in the injured limb, which led to increasingly disrupted interlimb coordination in hNF-L(E397K). Exacerbation of neuropathy after injury and identification of gait alterations in combination with previously described pathology suggests that hNF-L(E397K) mice recapitulate many of clinical signs associated with CMT2. Therefore, hNF-L(E397K) mice provide a model for determining the efficacy of novel therapies.

Pharmacological Modulation of the Mitochondrial Electron Transport Chain in Paclitaxel-Induced Painful Peripheral Neuropathy

Paclitaxel is an effective first-line chemotherapeutic with the major dose-limiting side effect of painful neuropathy. Mitochondrial dysfunction and oxidative stress have been implicated in paclitaxel-induced painful neuropathy. Here we show the effects of pharmacological modulation of mitochondrial sites that produce reactive oxygen species using systemic rotenone (complex I inhibitor) or antimycin A (complex III inhibitor) on the maintenance and development of paclitaxel-induced mechanical hypersensitivity in adult male Sprague Dawley rats. The maximally tolerated dose (5 mg/kg) of rotenone inhibited established paclitaxel-induced mechanical hypersensitivity. However, some of these inhibitory effects coincided with decreased motor coordination; 3 mg/kg rotenone also significantly attenuated established paclitaxel-induced mechanical hypersensitivity without any motor impairment. The maximally tolerated dose (.6 mg/kg) of antimycin A reversed established paclitaxel-induced mechanical hypersensitivity without any motor impairment. Seven daily doses of systemic rotenone or antimycin A were given either after paclitaxel administration or before and during paclitaxel administration. Rotenone had no significant effect on the development of paclitaxel-induced mechanical hypersensitivity. However, antimycin A significantly inhibited the development of paclitaxel-induced mechanical hypersensitivity when given before and during paclitaxel administration but had no effect when given after paclitaxel administration. These studies provide further evidence of paclitaxel-evoked mitochondrial dysfunction in vivo, suggesting that complex III activity is instrumental in paclitaxel-induced pain.

PERSPECTIVE

This study provides further in vivo evidence that mitochondrial dysfunction is a key contributor to the development and maintenance of chemotherapy-induced painful neuropathy. This work also indicates that selective modulation of the electron transport chain can induce antinociceptive effects in a preclinical model of paclitaxel-induced pain.

Taxane induced neuropathy in patients affected by breast cancer: Literature review

Taxane induced neuropathy (TIN) is the most limiting side effect of taxane based chemotherapy, relative to the majority of breast cancer patients undergoing therapy with both docetaxel and paclitaxel. The symptoms begin symmetrically from the toes, because the tips of the longest nerves are affected for first. The patients report sensory symptoms such as paresthesia, dysesthesia, numbness, electric shock-like sensation, motor impairment and neuropathic pain. There is a great inter-individual variability among breast cancer women treated with taxanes, in fact 20-30% of them don't develop neurotoxicity. Actually, there is no standard therapy for TIN, although many medications, antioxidants and natural substances have been tested in vitro and in vivo. We will summarize all most recent literature data on TIN prevention and treatment, in order to reach an improvement in TIN management. Further studies are needed to evaluate new therapies that restore neuronal function and improve life quality of patients.

Overview of neuropathy associated with taxanes for the treatment of metastatic breast cancer

Taxanes are an established option in the standard treatment paradigm for patients with metastatic breast cancer (MBC). Neuropathy is a common, dose-limiting side effect of taxane therapy that is often managed by dose reductions and delays. The severity, time to onset, and improvement in neuropathy are important considerations for patient management and vary among currently approved taxanes. The rate of grade ≥3 neuropathy with taxanes has been shown to be dose and schedule dependent; however, time to improvement to grade ≤1 is typically shorter for nab-paclitaxel than for other taxanes in patients with MBC. Many tools for assessing patient-reported neuropathy exist. Because MBC is incurable and patient quality of life must be critically considered when making treatment decisions, there is a need for more prospective trials to assess patient-reported neuropathy. Validated predictors of taxane-related neuropathy may play an important role in treatment decisions in the future. This review will focus on the toxicity profile (i.e., neuropathy) of each of the taxanes used in the treatment of MBC, will provide updates on tools used for the assessment of neuropathy, and will highlight newly discovered predictors of taxane-related neuropathy.

Bilateral cystoid macular edema following docetaxel chemotherapy in a patient with retinitis pigmentosa: a case report

Background

Docetaxel is a chemotherapeutic agent of the taxane class of drugs for the treatment of breast cancer. We present a female patient who noted decreased vision after docetaxel treatment.

Case presentation

A 45-year-old female patient received docetaxel treatment after resection of a breast carcinoma. Funduscopy and optical coherence tomography (OCT) showed cystoid macular edema on both eyes. Dilated funduscopy also showed bone spicule-like pigmented deposits, typical for retinitis pigmentosa. Besides the fundus appearance restricted peripheral vision and scotopic electroretinogram confirmed the diagnosis of retinitis pigmentosa. Chemotherapy was discontinued following a consulation with the oncologist of the patient. After five weeks, visual acuity improved significantly along with decrease of retinal thickness measured by OCT.

Conclusion

Docetaxel may cause ocular adverse effects such as cystoid macular edema. Ophthalmological examination is warranted for patients with visual complaints during docetaxel chemotherapy.

Clinical description of toxic neuropathies

Toxic neuropathy, although rare, is an important consideration in the setting of a known or suspected toxic exposure in the workplace or other environment. This chapter discusses the clinical and electrodiagnostic evaluation of peripheral neuropathies, highlighting findings that direct further workup and may point to specific toxins as etiology. The difficulty of establishing causality of a toxin in relation to peripheral neuropathy is discussed; guidelines for establishing causality are presented. Examples of common industrial toxins are listed, including their typical industrial uses and their mechanisms of action in producing neuropathy. Characteristic clinical presentations of specific toxic neuropathies are highlighted with selected case studies.

Identification of toxic neuropathies: cardinal tenets

ABSTRACT: 

Human toxic peripheral neuropathies (TxPN) due to occupational chemical exposure are relatively rare compared with medically related peripheral neuropathies. They are however difficult to diagnose due to their clinical and electrophysiologic similarity to nontoxic peripheral neuropathy. Understanding the cardinal tenets of neurotoxicology, as it applies to TxPN, helps differentiate between the toxic and nontoxic peripheral neuropathy. These tenets include: strong dose–response relationship, consistency of clinical response, proximity of symptoms to exposure, correlation between severity of neuropathy and degree of exposure, and improvement of PNS signs and symptoms follows cessation of exposure. A thorough clinical and occupational history is essential in identifying the possibility of a TxPN.

Vincristine-induced polyneuropathy in a child with stage I Wilms' tumour presenting with unilateral abducens nerve palsy

A 4-year-old boy presented with right esotropia while receiving vincristine and dactinomycin for stage I Wilms' tumour according to the National Wilms Tumour Study-5 protocol. On examination, he had isolated limitation of his right lateral gaze. CT of the brain and cerebrospinal fluid examination were normal. A nerve conduction velocity study which was performed on the peripheral nerves revealed predominant motor polyneuropathy compatible with axonal loss involving the upper limbs. The patient had received a cumulative vincristine dose of 17 mg/m(2) before developing esotropia. Vincristine-induced abducens nerve mononeuropathy and subclinical motor polyneuropathy was suspected. Unilateral esotropia markedly improved after the discontinuation of vincristine and a short course of oral pyridoxine treatment.