Chemotherapy-induced neuropathy

Prevention of chemotherapy-induced peripheral neuropathy by the small-molecule inhibitor pifithrin-μ

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of cancer treatment. It is the most frequent cause of dose reduction or treatment discontinuation in patients treated for cancer with commonly used drugs including taxanes and platinum-based compounds. No FDA-approved treatments for CIPN are available. In rodents, CIPN is represented by peripheral mechanical allodynia in association with retraction of intraepidermal nerve fibers. The mechanism of chemotherapy-induced neurotoxicity is unclear, but it has been established that mitochondrial dysfunction is an important component of the dysregulation in peripheral sensory neurons. We have shown earlier that inhibition of mitochondrial p53 accumulation with the small compound pifithrin-μ (PFT-μ) prevents cerebral neuronal death in a rodent model of hypoxic-ischemic brain damage. We now explore whether PFT-μ is capable of preventing neuronal mitochondrial damage and CIPN in mice. We demonstrate for the first time that PFT-μ prevents both paclitaxel- and cisplatin-induced mechanical allodynia. Electron microscopic analysis of peripheral sensory nerves revealed that PFT-μ secured mitochondrial integrity in paclitaxel-treated mice. In addition, PFT-μ administration protects against chemotherapy-induced loss of intraepidermal nerve fibers in the paw. To determine whether neuroprotective treatment with PFT-μ would interfere with the antitumor effects of chemotherapy, ovarian tumor cells were cultured in vitro with PFT-μ and paclitaxel. Pifithrin-μ does not inhibit tumor cell death but even enhances paclitaxel-induced tumor cell death. These data are the first to identify PFT-μ as a potential therapeutic strategy for prevention of CIPN to combat one of the most devastating side effects of chemotherapy.

Prophylactic administration of an extract from Plantaginis Semen and its major component aucubin inhibits mechanical allodynia caused by paclitaxel in mice

The chemotherapeutic agent paclitaxel (PTX) causes peripheral neuropathy as a major dose-limiting side effect, and this peripheral neuropathy is difficult to control. Our previous report showed that prophylactic repetitive administration of goshajinkigan ( niú chē shèn qì wán), but not hachimijiogan ( bā wèi dì huáng wán), which lacks two of the constituents of goshajinkigan, inhibited PTX-induced mechanical allodynia in mice. Thus, the herbal medicines Plantaginis Semen ( chē qián zǐ) or Achyranthis Radix ( niú xī) may contribute to the inhibitory action of goshajinkigan on the exacerbation of PTX-induced mechanical allodynia [Andoh et al, J. Tradit. Complement. Med. 2014; 4: 293-297]. Therefore, in this study, we examined whether an extract of Plantaginis Semen (EPS) or Achyranthis Radix (EAR) would relieve PTX-induced mechanical allodynia in mice. A single intraperitoneal injection of PTX caused mechanical allodynia, which peaked on day 14 after injection. Repetitive oral administration of EPS, but not EAR, starting from the day after PTX injection significantly inhibited the exacerbation of PTX-induced mechanical allodynia. Repetitive intraperitoneal injection of aucubin, one of the main components of EPS, starting from the day after PTX injection also significantly reduced PTX-induced mechanical allodynia. However, repetitive intraperitoneal injection of geniposide acid (a precursor of aucubin) or catalpol (a metabolite of aucubin) did not prevent the exacerbation of mechanical allodynia. These results suggest that prophylactic administration of EPS is effective for preventing the exacerbation of PTX-induced allodynia. Aucubin may contribute to the inhibitory action of EPS on the exacerbation of PTX-induced allodynia.

Managing treatment-related peripheral neuropathy in patients with multiple myeloma

Peripheral neuropathy is one of the most important complications of multiple myeloma treatment. Neurological damage can be observed at the onset of the disease, due to the effect of monoclonal protein or radicular compression, but more often is treatment related. Vinca alkaloids in the past era, and more recently, thalidomide and bortezomib are mainly responsible. Degeneration of dorsal root ganglion is common, prevalently related to angiogenesis inhibition and cytokine modulation in the case of thalidomide and inhibition of the ubiquitin proteasome system in the case of bortezomib. Sensory neuropathy and neuropathic pain are more common; motor neuropathy and autonomic damage are less frequently observed. Neurotoxicity often affects patient's quality of life and requires dose modification or withdrawal of therapy, with a possible effect on the overall response. A prompt recognition of predisposing factors (such as diabetes mellitus, alcohol abuse, vitamin deficiencies, or viral infections) and appearance of signs and symptoms, through a periodic neurological assessment with appropriate scales, is extremely important. Effective management of treatment at the emergence of peripheral neuropathy can minimize the incidence and severity of this complication and preserve therapeutic efficacy. Dose adjustment could be necessary during treatment; moreover, gabapentin or pregabalin, tricyclic antidepressants, serotonin and norepinephrine reuptake inhibitors, carbamazepine, and opioid-type analgesics are suggested according to the pain severity. Some authors reported that patients who develop peripheral neuropathy during their multiple myeloma treatments presented a particular gene expression profile; therefore, future studies could be helpful for a better understanding of possible biological pathways underlying neurotoxicity.

Neuromuscular complications in cancer

Cancer is becoming a treatable and even often curable disease. The neuromuscular system can be affected by direct tumor invasion or metastasis, neuroendocrine, metabolic, dysimmune/inflammatory, infections and toxic as well as paraneoplastic conditions. Due to the nature of cancer treatment, which frequently is based on a DNA damaging mechanism, treatment related toxic side effects are frequent and the correct identification of the causative mechanism is necessary to initiate the proper treatment. The peripheral nervous system is conventionally divided into nerve roots, the proximal nerves and plexus, the peripheral nerves (mono- and polyneuropathies), the site of neuromuscular transmission and muscle. This review is based on the anatomic distribution of the peripheral nervous system, divided into cranial nerves (CN), motor neuron (MND), nerve roots, plexus, peripheral nerve, the neuromuscular junction and muscle. The various etiologies of neuromuscular complications - neoplastic, surgical and mechanic, toxic, metabolic, endocrine, and paraneoplastic/immune - are discussed separately for each part of the peripheral nervous system.

A safety evaluation of brentuximab vedotin for the treatment of Hodgkin lymphoma

INTRODUCTION

Brentuximab vedotin is an anti-CD30 monoclonal antibody-drug conjugate approved for treating relapsed or refractory Hodgkin lymphoma. The pivotal trial demonstrated brentuximab vedotin's efficacy and manageable toxicity profile with peripheral neuropathy and neutropenia being the most common side effects. The phase I study of brentuximab vedotin combined with ABVD or AVD revealed its contraindication with bleomycin due to pulmonary toxicity. As trials continue to investigate the drug in frontline and relapsed settings, emerging safety data will further define brentuximab vedotin's role in managing Hodgkin lymphoma.

AREAS COVERED

This article reviews the current literature on brentuximab vedotin in Hodgkin lymphoma treatment, both as a single agent and in combination regimens. The review focuses on safety findings from clinical trials, expected adverse events, and rare serious toxicities.

EXPERT OPINION

Brentuximab vedotin is a breakthrough antibody-drug conjugate that may provide new options in earlier lines of therapy for Hodgkin lymphoma. Results from the ongoing phase III trial comparing ABVD to AVD + brentuximab vedotin will inform whether brentuximab vedotin adds benefit to frontline therapy over the current standard of care. The optimal duration of treatment and brentuximab vedotin's potential as an alternative to radiation in early stage disease still warrant investigation.

Research design considerations for chronic pain prevention clinical trials: IMMPACT recommendations

Although certain risk factors can identify individuals who are most likely to develop chronic pain, few interventions to prevent chronic pain have been identified. To facilitate the identification of preventive interventions, an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain. We present general design considerations for prevention trials in populations that are at relatively high risk for developing chronic pain. Specific design considerations included subject identification, timing and duration of treatment, outcomes, timing of assessment, and adjusting for risk factors in the analyses. We provide a detailed examination of 4 models of chronic pain prevention (ie, chronic postsurgical pain, postherpetic neuralgia, chronic low back pain, and painful chemotherapy-induced peripheral neuropathy). The issues discussed can, in many instances, be extrapolated to other chronic pain conditions. These examples were selected because they are representative models of primary and secondary prevention, reflect persistent pain resulting from multiple insults (ie, surgery, viral infection, injury, and toxic or noxious element exposure), and are chronically painful conditions that are treated with a range of interventions. Improvements in the design of chronic pain prevention trials could improve assay sensitivity and thus accelerate the identification of efficacious interventions. Such interventions would have the potential to reduce the prevalence of chronic pain in the population. Additionally, standardization of outcomes in prevention clinical trials will facilitate meta-analyses and systematic reviews and improve detection of preventive strategies emerging from clinical trials.

Evaluation of Cisplatin Neurotoxicity in Cultured Rat Dorsal Root Ganglia via Cytosolic Calcium Accumulation

BACKGROUND

Calcium homeostasis is considered to be important in antineoplastic as well as in neurotoxic adverse effects of cisplatin.

AIMS

This study aimed to investigate the role of Ca(2+) in cisplatin neurotoxicity in cultured rat dorsal root ganglia (DRG) cells.

STUDY DESIGN

Cell culture study.

METHODS

DRG cells prepared from 1-day old Sprague-Dawley rats were used to determine the role of Ca(2+) in the cisplatin (10-600 μM) neurotoxicity. The cells were incubated with cisplatin plus nimodipine (1-3 μM), dizocilpine (MK-801) (1-3 μM) or thapsigargin (100-300 nM). Toxicity of cisplatinon DRG cells was determined by the MTT assay.

RESULTS

The neurotoxicity of cisplatin was significant when used in high concentrations (100-600 μM). Nimodipine (1 μM) but not MK-801 or thapsigargin prevented the neurotoxic effects of 200 μM of cisplatin.

CONCLUSION

Voltage-dependent calcium channels may play a role in cisplatin neurotoxicity.

Capecitabine and bevacizumab with or without vinorelbine in first-line treatment of HER2/neu-negative metastatic or locally advanced breast cancer: final efficacy and safety data of the randomised, open-label superiority phase 3 CARIN trial

The study was designed to evaluate efficacy and superiority of capecitabine/bevacizumab + vinorelbine (CAP/BEV/VIN) compared to CAP/BEV alone. Main purpose was to introduce a taxane-/anthracycline-free first-line treatment in advanced breast cancer (ABC), in order to avoid long-term toxicities. In this open-label, superiority, phase 3 trial, patients with HER2-negative ABC were randomized 1:1 to receive either oral CAP at 1000 mg/m² [twice daily, days 1–14, q3w] plus intravenous BEV at 15 mg/kg [day 1, q3w] (arm A) or in addition to this protocol intravenous VIN at 25 mg/m² [days 1 + 8, q3w] (arm B) until disease progression, unacceptable toxicity or withdrawal of consent. Between 26 February 2009 and 26 October 2012, we randomised 600 patients (arm A N = 300; arm B N = 300) from 57 German outpatient-centres and 2 university hospitals. Median progression-free survival (PFS) (primary endpoint) was not improved with VIN (CAP/BEV, 8.8 months; CAP/BEV/VIN, 9.6 months; HR 0.84 [95 % CI 0.70–1.01], P = 0.058). Median overall survival (OS) (secondary endpoint) was 25.1 and 27.2 months for CAP/BEV and CAP/BEV/VIN, respectively, average HR 0.85 [95 % CI 0.70–1.03], P = 0.104). The 1- and 2-year OS rates appeared to be similar (78.0 and 77.0 %; 53.0 and 54.0 %). Toxicity profiles were generally mild and manageable. Adverse events occurred more frequently in arm B. Regarding the balance between clinical efficacy (PFS, OS) and toxicity, the CAP/BEV combination provides a favourable treatment option in first-line ABC avoiding taxane- and/or anthracycline-induced long-term toxicity. Superiority of CAP/BEV/VIN was not met, and side effects were even enhanced. Nevertheless, no safety issues occurred.

Nerve growth factor alters microtubule targeting agent-induced neurotransmitter release but not MTA-induced neurite retraction in sensory neurons

Peripheral neuropathy is a dose-limiting side effect of anticancer treatment with the microtubule-targeted agents (MTAs), paclitaxel and epothilone B (EpoB); however, the mechanisms by which the MTAs alter neuronal function and morphology are unknown. We previously demonstrated that paclitaxel alters neuronal sensitivity, in vitro, in the presence of nerve growth factor (NGF). Evidence in the literature suggests that NGF may modulate the neurotoxic effects of paclitaxel. Here, we examine whether NGF modulates changes in neuronal sensitivity and morphology induced by paclitaxel and EpoB. Neuronal sensitivity was assessed using the stimulated release of calcitonin gene-related peptide (CGRP), whereas morphology of established neurites was evaluated using a high content screening system. Dorsal root ganglion cultures, maintained in the absence or presence of NGF, were treated from day 7 to day 12 in culture with paclitaxel (300nM) or EpoB (30nM). Following treatment, the release of CGRP was stimulated using capsaicin or high extracellular potassium. In the presence of NGF, EpoB mimicked the effects of paclitaxel: capsaicin-stimulated release was attenuated, potassium-stimulated release was slightly enhanced and the total peptide content was unchanged. In the absence of NGF, both paclitaxel and EpoB decreased capsaicin- and potassium-stimulated release and the total peptide content, suggesting that NGF may reverse MTA-induced hyposensitivity. Paclitaxel and EpoB both decreased neurite length and branching, and this attenuation was unaffected by NGF in the growth media. These differential effects of NGF on neuronal sensitivity and morphology suggest that neurite retraction is not a causative factor to alter neuronal sensitivity.

Translation and transcultural adaptation of Pain Quality Assessment Scale (PQAS) to Brazilian version

INTRODUCTION

Most cancer patients are treated with chemotherapy, and peripheral neuropathy is a serious and common clinical problem affecting patients undergoing cancer treatment. However, the symptoms are subjective and underdiagnosed by health professionals. Thus, it becomes necessary to develop self-report instruments to overcome this limitation and improve the patient's perception about his medical condition or treatment.

OBJECTIVE

Translate and culturally adapt the Brazilian version of the Pain Quality Assessment Scale, constituting a useful tool for assessing the quality of neuropathic pain in cancer patients.

METHOD

The procedure followed the steps of translation, back translation, analysis of Portuguese and English versions by a committee of judges, and pretest. Pretest was conducted with 30 cancer patients undergoing chemotherapy following internationally recommended standards, and the final versions were compared and evaluated by a committee of researchers from Brazil and MAPI Research Trust, the scale's creators.

RESULTS

Versions one and two showed 100% semantic equivalence with the original version. Back-translation showed difference between the linguistic translation and the original version. After evaluation by the committee of judges, a flaw was found in the empirical equivalence and idiomatic equivalence. In pretest, two people did not understand the item 12 of the scale, without interfering in the final elaboration.

CONCLUSION

The translated and culturally adapted instrument is now presented in this publication, and currently it is in the process of clinical validation in Brazil.

Riboflavin Arrests Cisplatin-Induced Neurotoxicity by Ameliorating Cellular Damage in Dorsal Root Ganglion Cells

Cis-Diamminedichloroplatinum II- (CP-) induced neurotoxicity is one of the least explored aspects of this drug. Dorsal root ganglia (DRG) cells are considered as the primary target, and their damage plays a vital role in pathogenesis and etiology of CP-induced neurotoxicity. The present study is aimed at confirming if riboflavin (RF) has any protective role in shielding the DRG from CP-induced toxicity. After conducting the established treatment strategy on mice under photoillumination, it was observed that, despite the fact that RF alone is partially toxic, its combination with CP significantly ameliorated the drug-induced damage in DRG cells as evidenced by histological analysis. In addition, it was interesting to observe that the combination group (RF + CP) was able to induce apoptosis in the target cells up to a significant extent which is considered as the most preferred way of countering cancer cells. Therefore, RF can act as an effective adjuvant compound in CP-based chemoradiotherapy to improve clinical outcomes in the contemporary anticancer treatment regimes.

Predictors of duloxetine response in patients with oxaliplatin-induced painful chemotherapy-induced peripheral neuropathy (CIPN): a secondary analysis of randomised controlled trial - CALGB/alliance 170601

Duloxetine is an effective treatment for oxaliplatin-induced painful chemotherapy-induced peripheral neuropathy (CIPN). However, predictors of duloxetine response have not been adequately explored. The objective of this secondary and exploratory analysis was to identify predictors of duloxetine response in patients with painful oxaliplatin-induced CIPN. Patients (N = 106) with oxaliplatin-induced painful CIPN were randomised to receive duloxetine or placebo. Eligible patients had chronic CIPN pain and an average neuropathic pain score ≥4/10. Duloxetine/placebo dose was 30 mg/day for 7 days, then 60 mg/day for 4 weeks. The Brief Pain Inventory-Short Form and the EORTC QLQ-C30 were used to assess pain and quality of life, respectively. Univariate and multiple logistic regression analyses were performed to identify demographic, physiologic and psychological predictors of duloxetine response. Higher baseline emotional functioning predicted duloxetine response (≥30% reduction in pain; OR 4.036; 95% CI 0.999-16.308; p = 0.050). Based on the results from a multiple logistic regression using patient data from both the duloxetine and placebo treatment arms, duloxetine-treated patients with high emotional functioning are more likely to experience pain reduction (p = 0.026). In patients with painful, oxaliplatin-induced CIPN, emotional functioning may also predict duloxetine response. ClinicalTrials.gov, Identifier NCT00489411.

Natural products and complementary therapies for chemotherapy-induced peripheral neuropathy: A systematic review

Chemotherapy-induced peripheral neuropathy (CIPN) is a serious dose-limiting side-effect without any FDA-approved treatment option. Prior reviews focus mostly on pharmacological interventions, but nonpharmaceutical interventions have also been evaluated. A Web of Science and PubMed database search to identify relevant RCTs from January 2005 to May 2015 included the terms: CIPN, cancer; and supplements, vitamin E, goshajinkigan, kampo, acetyl-L-carnitine, carnitine, alpha-lipoic acid, omega-3, glutamine, or glutamate; or massage, acupuncture, mind-body practice, yoga, meditation, Tai-Chi, physical activity, or exercise. Of 1465 publications screened, 12 RCTs evaluated natural products and one evaluated electroacupuncture. Vitamin E may help prevent CIPN. L-Glutamine, goshajinkigan, and omega-3 are also promising. Acetyl-L-carnitine may worsen CIPN and alpha-lipoic acid activity is unknown. Electroacupuncture was not superior to placebo. No RCTs were published regarding other complementary therapies, although some studies mention positive incidental findings. Natural products and complementary therapies deserve further investigation, given the lack of effective CIPN interventions.

The Analgesic Effect of Rolipram, a Phosphodiesterase 4 Inhibitor, on Chemotherapy-Induced Neuropathic Pain in Rats

BACKGROUND

Chemotherapy-induced neuropathic pain is a significant side effect of chemotherapeutic agents. Currently, there are no effective analgesics for chemotherapy-induced neuropathic pain. Rolipram is a selective phosphodiesterase 4 inhibitor, which increases intracellular cyclic AMP in nerve and immune cells. The aim of our study was to determine the analgesic effects of rolipram on paclitaxel (PAC)-induced neuropathic pain in rats.

METHODS

Chemotherapy-induced neuropathic pain was produced by intraperitoneal injection of PAC on 4 alternate days in male Sprague-Dawley rats. Mechanical allodynia was measured by using von Frey filaments.

RESULTS

After the rats developed PAC-induced pain behavior (such as mechanical allodynia), a single intraperitoneal injection and continuous infusion of rolipram ameliorated PAC-induced pain behavior. In addition, systemic infusion of the drug during the early phase of developing pain behavior did not prevent the development of mechanical allodynia induced by PAC.

CONCLUSIONS

These results suggest that rolipram alleviated mechanical allodynia induced by PAC in rats. Thus, phosphodiesterase 4 inhibitors may prove useful in the treatment of chemotherapy-induced neuropathic pain. However, further studies are needed to clarify their effects in clinical settings.

Incidence and risk of peripheral neuropathy with nab-paclitaxel in patients with cancer: a meta-analysis

Nab-paclitaxel, a Cremophor EL-free formulation of paclitaxel, is used to treat various malignancies. Peripheral neuropathy is one of its major toxicities, although the overall incidence remains unclear. We performed a meta-analysis to calculate the incidence of peripheral neuropathy in cancer patients treated with nab-paclitaxel and to compare the relative risk (RR) with conventional taxanes. The electronic databases were searched for relevant clinical trials. Eligible studies included phase II and III prospective clinical trials of cancer patients treated with nab-paclitaxel with toxicity profile on peripheral neuropathy. Statistical analyses were done to calculate summary incidences, RRs and 95% confidence intervals (CI), using fixed-effects or random-effects models based on the heterogeneity of the included studies. Nineteen trials were selected for the meta-analysis, yielding a total of 2878 cancer patients. The overall incidences of peripheral neuropathy (all-grade) was 51.0% (95% CI: 45.1-57.6%), and that of high-grade peripheral neuropathy was 12.4% (9.8-15.7%). The RRs of peripheral neuropathy of nab-paclitaxel compared to taxanes were not increased for all-grade and high-grade peripheral neuropathy. Nab-paclitaxel is associated with an increased risk of developing peripheral neuropathy. Future clinical studies are still needed to investigate the risk reduction and possible use of nab-paclitaxel.

Long-term course of oxaliplatin-induced polyneuropathy: a prospective 2-year follow-up study

This prospective study sought to identify the potential reversibility of oxaliplatin-induced peripheral neuropathy (OXAIPN) by following-up its long-term course 2 years after discontinuation of oxaliplatin (OXA)-based chemotherapy. Participants were 91 colorectal cancer patients treated with OXA-based chemotherapy. Neurological assessment, clinical Total Neuropathy Score© (TNSc©) and nerve conduction studies were performed at baseline (T0), the end of chemotherapy (T1) and 2 years (T2) after discontinuation of chemotherapy. A total of 73 of 91 (80%) patients experienced OXAIPN at T1. At a median follow-up of 25 months, persistence of chronic OXAIPN was present in 61 of 73 patients (84%) and complete resolution was present in 12 patients (17%). Longitudinal comparison of TNSc© values between T1 and T2 revealed that the overall severity of OXAIPN in those 61 patients significantly decreased over time. Median TNSc© values were nine (range: 2-15) at T1 vs. four (range: 2-12) at T2 (P < 0.001). Likewise, sensory nerve conduction measures at T2 significantly improved in all sensory nerves tested, compared with T1. Severity of OXAIPN at T2 was significantly associated (P < 0.001) with high severity of OXAIPN at T1. In conclusion, persistence of OXAIPN beyond 2 years after finishing chemotherapy is common. Clinical and neurophysiological improvement is observed, although recovery is often incomplete.

Corneal Confocal Microscopy Detects Small Fibre Neuropathy in Patients with Upper Gastrointestinal Cancer and Nerve Regeneration in Chemotherapy Induced Peripheral Neuropathy

There are multiple neurological complications of cancer and its treatment. This study assessed the utility of the novel non-invasive ophthalmic technique of corneal confocal microscopy in identifying neuropathy in patients with upper gastrointestinal cancer before and after platinum based chemotherapy. In this study, 21 subjects with upper gastrointestinal (oesophageal or gastric) cancer and 21 healthy control subjects underwent assessment of neuropathy using the neuropathy disability score, quantitative sensory testing for vibration perception threshold, warm and cold sensation thresholds, cold and heat induced pain thresholds, nerve conduction studies and corneal confocal microscopy. Patients with gastro-oesophageal cancer had higher heat induced pain (P = 0.04) and warm sensation (P = 0.03) thresholds with a significantly reduced sural sensory (P<0.01) and peroneal motor (P<0.01) nerve conduction velocity, corneal nerve fibre density (CNFD), nerve branch density (CNBD) and nerve fibre length (CNFL) (P<0.0001). Furthermore, CNFD correlated significantly with the time from presentation with symptoms to commencing chemotherapy (r = -0.54, P = 0.02), and CNFL (r = -0.8, P<0.0001) and CNBD (r = 0.63, P = 0.003) were related to the severity of lymph node involvement. After the 3^rd cycle of chemotherapy, there was no change in any measure of neuropathy, except for a significant increase in CNFL (P = 0.003). Corneal confocal microscopy detects a small fibre neuropathy in this cohort of patients with upper gastrointestinal cancer, which was related to disease severity. Furthermore, the increase in CNFL after the chemotherapy may indicate nerve regeneration.

A New Rat Model of Cisplatin-induced Neuropathic Pain

Background

Chemotherapy-induced peripheral neuropathy is a major side effect of anti-cancer drugs, and our knowledge of its mechanisms is lacking. Several models for chemotherapy-induced neuropathy have been introduced. However, the outcomes of these models differ significantly among laboratories. Our object was to create a model of chemotherapy-induced neuropathy in rats with cancer.

Methods

Female Sprague-Dawley rats were used. Mammary rat metastasis tumor (MRMT-1) cells were implanted subcutaneously in rats. Chemotherapy-induced peripheral neuropathy was induced by injection of cisplatin once a day for four days. The responses to mechanical and thermal stimuli were examined using von Frey filaments, acetone, and radiant heat.

Results

Cisplatin (2 mg/kg/day) produced mechanical allodynia, while it did not induce cold allodynia or thermal hyperalgesia. This dose of cisplatin could work successfully against cancer. Body weight loss was not observed in cisplatin-treated rats, nor were other abnormal behaviors noted in the same rats.

Conclusions

Repeated injection of intraperitoneal cisplatin induced peripheral neuropathic pain in rats. Thus, this type of rat model has broad applicability in studies related to searching for the mechanism of cisplatin-induced mechanical allodynia and agents for the treatment of neuropathic pain.

Chemotherapy-induced peripheral neuropathy after neoadjuvant or adjuvant treatment of breast cancer: a prospective cohort study

PURPOSE

The purposes of this study were to estimate the incidence of chemotherapy-induced peripheral neuropathy (CIPN) and to identify its main determinants and impact in patient-reported outcomes.

METHODS

We performed a prospective cohort study including 296 patients with incident breast cancer submitted to chemotherapy, followed for 1 year. Patients with incident CIPN were reevaluated 6 months after this diagnosis. Relative risks (RR) with 95 % confidence intervals (95 % CI) were computed to quantify the relation between different clinical characteristics and the occurrence of CIPN, using Poisson regression. The variation of patient-reported outcomes between baseline and 1-year follow-up assessments was compared between patients with and without CIPN.

RESULTS

The cumulative incidence of CIPN in the first year after diagnosis was 28.7 % (95 % CI 23.8-34.1), and more than 80 % of the patients were still symptomatic after 6 months. Among the latter, there was a significant decrease in the median total neuropathy score, clinical version (7 versus 4) between the two periods. In multivariable analysis, the risk of CIPN was higher for treatment with docetaxel (cumulative doses ≤300 mg/m(2), RR = 6.96, 95 % CI 2.53-19.10; >300 mg/m(2), RR = 13.32; 95 % CI 4.11-43.14). Alcohol consumption and diabetes were not significantly associated with CIPN. There were no significant differences in the variation of patient-reported outcomes between the baseline and 1-year follow-up evaluations.

CONCLUSIONS

CIPN was frequent in this contemporary cohort of early-stage breast cancer patients and was strongly associated with docetaxel-based regimens. Symptoms persisted for at least 6 months in most patients, but severity was low and CIPN had no impact on patient-reported outcomes.

Hypothermia for preventing chemotherapy-induced neuropathy - a pilot study on safety and tolerability in healthy controls

INTRODUCTION

Chemotherapy-induced peripheral neuropathy (CIPN) is a major dose-limiting side effect of several chemotherapeutic agents, often leading to treatment discontinuation. Up to 20% of patients treated with weekly paclitaxel experience severe CIPN and no effective treatment has been established so far. The mechanisms of CIPN damage are unclear, but are directly dose-related. We had earlier demonstrated, in rats, the influence of hypothermia in reducing nerve blood flow. Here, we hypothesize that continuous flow limb hypothermia during chemotherapy reduces the incidence and severity of CIPN, by limiting deliverance of the neurotoxic drug to the peripheral nerves. In this study, prior to assessing the effect of hypothermia in preventing CIPN in cancer subjects undergoing paclitaxel chemotherapy, we assess the safety and tolerable temperatures for limb hypothermia in healthy human subjects.

MATERIAL AND METHODS

In 15 healthy human subjects, hypothermia was administered as continuous flow cooling, unilaterally, via a thermoregulator setup covering the digits up to the elbow/knee, along with continuous skin temperature monitoring. Thermoregulator coolant temperatures between 25 °C and 20 °C were tested for tolerability, based on a carefully designed temperature regulation protocol, and maintained for three hours mimicking the duration of chemotherapy. Tolerability was evaluated using various safety and tolerability scores to monitor the subjects.

RESULTS

At the end of the cooling session the healthy subjects presented without significant adverse effects, the main being brief mild skin erythema and transient numbness. Coolant temperatures as low as 22 °C were well tolerated continuously over three hours.

CONCLUSION

Our results confirm the safety and tolerability of continuous flow limb hypothermia in healthy subjects. Further studies will use 22 °C thermoregulator temperature to investigate hypothermia in preventing CIPN in breast cancer patients receiving adjuvant weekly paclitaxel. This pilot study may contribute to alleviating chemotherapy dose limitation due to CIPN and increase the likelihood of success of chemotherapy.

Balance impairments and neuromuscular changes in breast cancer patients with chemotherapy-induced peripheral neuropathy

OBJECTIVE

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of cancer treatment. Resulting sensory and motor dysfunctions often lead to functional impairments like gait or balance disorders. As the underlying neuromuscular mechanisms are not fully understood, we compared balance performance of CIPN patients with healthy controls (CON) to specify differences responsible for postural instability.

METHODS

20 breast cancer patients with CIPN (PAT) and 16 matched CONs were monitored regarding centre of pressure displacement (COP) and electromyographic activity of M. soleus, gastrocnemius, tibialis anterior, rectus femoris and biceps femoris. We calculated antagonistic co-contraction indices (CCI) and elicited soleus H-reflexes to evaluate changes in the elicitability and sensitivity of spinal reflex circuitry.

RESULTS

PAT's COP displacement was greater than CON's (p=.013) and correlated significantly with the level of CCIs and self-reported CIPN symptoms. PAT revealed prolonged H-wave latency (p=.021), decreased H-reflex elicitability (p=.001), and increased H-reflex sensitivity from bi- to monopedal stance (p=.004).

CONCLUSIONS

We summarise that CIPN causes balance impairments and leads to changes in elicitability and sensitivity of spinal reflex circuitry associated with postural instability. We assume that increased simultaneous antagonistic muscle activation may be used as a safety strategy for joint stiffness to compensate for neuromuscular degradation.

SIGNIFICANCE

Sensorimotor training has the potential to influence neuromuscular mechanisms in order to improve balance performance. Therefore, this training modality should be evaluated as a possible treatment strategy for CIPN.

Axonal Transport Impairment in Chemotherapy-Induced Peripheral Neuropathy

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

Current View in Platinum Drug Mechanisms of Peripheral Neurotoxicity

Peripheral neurotoxicity is the dose-limiting factor for clinical use of platinum derivatives, a class of anticancer drugs which includes cisplatin, carboplatin, and oxaliplatin. In particular cisplatin and oxaliplatin induce a severe peripheral neurotoxicity while carboplatin is less neurotoxic. The mechanisms proposed to explain these drugs' neurotoxicity are dorsal root ganglia alteration, oxidative stress involvement, and mitochondrial dysfunction. Oxaliplatin also causes an acute and reversible neuropathy, supposed to be due by transient dysfunction of the voltage-gated sodium channels of sensory neurons. Recent studies suggest that individual genetic variation may play a role in the pathogenesis of platinum drug neurotoxicity. Even though all these mechanisms have been investigated, the pathogenesis is far from clearly defined. In this review we will summarize the current knowledge and the most up-to-date hypotheses on the mechanisms of platinum drug-induced peripheral neurotoxicity.

Neuropathies associated with lymphoma†

Neuropathy occurs with various manifestations as a consequence of lymphoma, and an understanding of the etiology is necessary for proper treatment. Advances in medical imaging have improved the detection of peripheral nerve involvement in lymphoma, yet tissue diagnosis is often equally important. The neoplastic involvement of the peripheral nervous system (PNS) in lymphoma can occur within the cerebrospinal fluid (CSF), inside the dura, or outside of the CSF space, affecting nerve root plexuses and peripheral nerves. The infiltration of either cranial or peripheral nerves in lymphoma is termed neurolymphomatosis (NL). These infiltrations can occur as mononeuropathy, multifocal neuropathy, symmetric neuropathies, or plexopathies. In rare cases, intravascular lymphoma (IL) can affect the PNS and an even rarer condition is the combination of NL and IL. Immune-mediated and paraneoplastic neuropathies are important considerations when treating patients with lymphoma. Demyelinating neuropathies, such as Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy, occur more frequently in non-Hodgkin's lymphoma than in Hodgkin's disease. Paraproteinemic neuropathies can be associated with lymphoma and paraneoplastic neuropathies are rare. While the treatment of lymphomas has improved, a knowledge of neurotoxic, radiotherapy, neoplastic, immune-mediated and paraneoplastic effects are important for patient care.

Assessment of chemotherapy-induced peripheral neuropathy using the LDIFLARE technique: a novel technique to detect neural small fiber dysfunction

INTRODUCTION

The diagnosis and quantification of chemotherapy-induced peripheral neuropathy (CIPN) remains a challenge. Conventional methods including quantitative sensory testing (QST), nerve conduction tests, and biopsy are unable to detect subclinical changes, and do not consistently correlate with severity of patients' symptoms and functional impairment. This study aims to determine the utility of the LDI (laser Doppler imager) FLARE technique in the diagnosis of CIPN and whether it correlates with symptom severity.

MATERIALS AND METHODS

We assessed 24 patients with established CIPN [12 due to platinum analogs (PA) and 12 to Taxanes (TX)] and 24 matched healthy controls (HC). All underwent neurophysiological examination including vibration perception threshold (VPT), sural nerve amplitude (SNAP) and conduction velocity (SNCV), LDIFLARE, and fasting biochemistry. The QLQ-CIPN20 questionnaire was used to assess symptom severity.

RESULTS

HC, combined chemotherapy (CG), PA , and TX groups were matched for age, sex, BMI, and blood pressure. The LDIFLARE was significantly reduced in CG compared to HC (P =< 0.0001), whereas SNAP (P = 0.058) and SNCV (P = 0.054) were not. The LDIFLARE correlated with the QLQ-CIPN20 symptom scores in all three categories namely, CG (P =< 0.0001), PA (P = 0.001) and TX (P = 0.027) whilst, VPT, SNAP, and SNCV did not.

CONCLUSION

Our findings suggest that the LDIFLARE technique is more helpful in confirming the diagnosis of CIPN in patients with distal sensory symptoms than current commonly used methods. Moreover, this novel test fulfils the unmet need for a diagnostic test that relates to the severity of symptoms. This may be useful in quantifying early changes in small fibre function indicating early CIPN.

Peripheral Neuropathy: A Practical Approach to Diagnosis and Symptom Management

Peripheral neuropathy is one of the most prevalent neurologic conditions encountered by physicians of all specialties. Physicians are faced with 3 distinct challenges in caring for patients with peripheral neuropathy: (1) how to efficiently and effectively screen (in less than 2 minutes) an asymptomatic patient for peripheral neuropathy when they have a disorder in which peripheral neuropathy is highly prevalent (eg, diabetes mellitus), (2) how to clinically stratify patients presenting with symptoms of neuropathy to determine who would benefit from specialty consultation and what testing is appropriate for those who do not need consultation, and (3) how to treat the symptoms of painful peripheral neuropathy. In this concise review, we address these 3 common clinical scenarios. Easily defined clinical patterns of involvement are used to identify patients in need of neurologic consultation, the yield of laboratory and other diagnostic testing is reviewed for the evaluation of length-dependent, sensorimotor peripheral neuropathies (the most common form of neuropathy), and an algorithmic approach with dosing recommendations is provided for the treatment of neuropathic pain associated with peripheral neuropathy.

CB1 Knockout Mice Unveil Sustained CB2-Mediated Antiallodynic Effects of the Mixed CB1/CB2 Agonist CP55,940 in a Mouse Model of Paclitaxel-Induced Neuropathic Pain

Cannabinoids suppress neuropathic pain through activation of cannabinoid CB1 and/or CB2 receptors; however, unwanted CB1-mediated cannabimimetic effects limit clinical use. We asked whether CP55,940 [(-)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4-(3-hydroxypropyl)cyclohexanol], a potent cannabinoid that binds with similar affinity to CB1 and CB2 in vitro, produces functionally separable CB1- and CB2-mediated pharmacological effects in vivo. We evaluated antiallodynic effects, possible tolerance, and cannabimimetic effects (e.g., hypothermia, catalepsy, CB1-dependent withdrawal signs) after systemic CP55,940 treatment in a mouse model of toxic neuropathy produced by a chemotherapeutic agent, paclitaxel. The contribution of CB1 and CB2 receptors to in vivo actions of CP55,940 was evaluated using CB1 knockout (KO), CB2KO, and wild-type (WT) mice. Low-dose CP55,940 (0.3 mg/kg daily, i.p. ) suppressed paclitaxel-induced allodynia in WT and CB2KO mice, but not CB1KO mice. Low-dose CP55,940 also produced hypothermia and rimonabant-precipitated withdrawal in WT, but not CB1KO, mice. In WT mice, tolerance developed to CB1-mediated hypothermic effects of CP55,940 earlier than to antiallodynic effects. High-dose CP55,940 (10 mg/kg daily, i.p.) produced catalepsy in WT mice, which precluded determination of antiallodynic efficacy but produced sustained CB2-mediated suppression of paclitaxel-induced allodynia in CB1KO mice; these antiallodynic effects were blocked by the CB2 antagonist 6-iodopravadoline (AM630). High-dose CP55,940 did not produce hypothermia or rimonabant-precipitated withdrawal in CB1KO mice. Our results using the mixed CB1/CB2 agonist CP55,940 document that CB1 and CB2 receptor activations produce mechanistically distinct suppression of neuropathic pain. Our study highlights the therapeutic potential of targeting cannabinoid CB2 receptors to bypass unwanted central effects associated with CB1 receptor activation.

APE1, the DNA base excision repair protein, regulates the removal of platinum adducts in sensory neuronal cultures by NER

Peripheral neuropathy is one of the major side effects of treatment with the anticancer drug, cisplatin. One proposed mechanism for this neurotoxicity is the formation of platinum adducts in sensory neurons that could contribute to DNA damage. Although this damage is largely repaired by nuclear excision repair (NER), our previous findings suggest that augmenting the base excision repair pathway (BER) by overexpressing the repair protein APE1 protects sensory neurons from cisplatin-induced neurotoxicity. The question remains whether APE1 contributes to the ability of the NER pathway to repair platinum-damage in neuronal cells. To examine this, we manipulated APE1 expression in sensory neuronal cultures and measured Pt-removal after exposure to cisplatin. When neuronal cultures were treated with increasing concentrations of cisplatin for two or three hours, there was a concentration-dependent increase in Pt-damage that peaked at four hours and returned to near baseline levels after 24h. In cultures where APE1 expression was reduced by ∼ 80% using siRNA directed at APE1, there was a significant inhibition of Pt-removal over eight hours which was reversed by overexpressing APE1 using a lentiviral construct for human wtAPE1. Overexpressing a mutant APE1 (C65 APE1), which only has DNA repair activity, but not its other significant redox-signaling function, mimicked the effects of wtAPE1. Overexpressing DNA repair activity mutant APE1 (226 + 177APE1), with only redox activity was ineffective suggesting it is the DNA repair function of APE1 and not its redox-signaling, that restores the Pt-damage removal. Together, these data provide the first evidence that a critical BER enzyme, APE1, helps regulate the NER pathway in the repair of cisplatin damage in sensory neurons.

Therapeutic strategies for cancer treatment related peripheral neuropathies

OPINION STATEMENT

Chemotherapy-induced peripheral neuropathy (CIPN) is a common toxicity associated with multiple chemotherapeutic agents. CIPN may have a detrimental impact on patients' quality of life and functional ability, as well as result in chemotherapy dose reductions. Although symptoms of CIPN can improve with treatment completion, symptoms may persist. Currently, the treatment options for CIPN are quite limited. Duloxetine, a serotonin-norepinephrine reuptake inhibitor, has the most evidence supporting its use in the treatment of CIPN. Other agents with potential benefit for the treatment of established CIPN include gabapentinoids, venlafaxine, tricyclic antidepressants, and a topical gel consisting of the combination of amitriptyline, ketamine, and baclofen; none of these, however, has been proven to be helpful and ongoing/future studies may well show that they are not beneficial. The use of these agents is often based on their efficacy in the treatment of non-CIPN neuropathic pain, but this does not necessarily mean that they will be helpful for CIPN-related symptoms. Other nonpharmacologic interventions including acupuncture and Scrambler therapy are supported by positive preliminary data; however, further larger, placebo-controlled trial data are needed to confirm or refute their effectiveness.

Small molecule inhibitors of PSD95-nNOS protein-protein interactions as novel analgesics

Aberrant increases in NMDA receptor (NMDAR) signaling contributes to central nervous system sensitization and chronic pain by activating neuronal nitric oxide synthase (nNOS) and generating nitric oxide (NO). Because the scaffolding protein postsynaptic density 95kDA (PSD95) tethers nNOS to NMDARs, the PSD95-nNOS complex represents a therapeutic target. Small molecule inhibitors IC87201 (EC5O: 23.94 μM) and ZL006 (EC50: 12.88 μM) directly inhibited binding of purified PSD95 and nNOS proteins in AlphaScreen without altering binding of PSD95 to ErbB4. Both PSD95-nNOS inhibitors suppressed glutamate-induced cell death with efficacy comparable to MK-801. IC87201 and ZL006 preferentially suppressed phase 2A pain behavior in the formalin test and suppressed allodynia induced by intraplantar complete Freund's adjuvant administration. IC87201 and ZL006 suppressed mechanical and cold allodynia induced by the chemotherapeutic agent paclitaxel (ED50s: 2.47 and 0.93 mg/kg i.p. for IC87201 and ZL006, respectively). Efficacy of PSD95-nNOS disruptors was similar to MK-801. Motor ataxic effects were induced by MK-801 but not by ZL006 or IC87201. Finally, MK-801 produced hyperalgesia in the tail-flick test whereas IC87201 and ZL006 did not alter basal nociceptive thresholds. Our studies establish the utility of using AlphaScreen and purified protein pairs to establish and quantify disruption of protein-protein interactions. Our results demonstrate previously unrecognized antinociceptive efficacy of ZL006 and establish, using two small molecules, a broad application for PSD95-nNOS inhibitors in treating neuropathic and inflammatory pain. Collectively, our results demonstrate that disrupting PSD95-nNOS protein-protein interactions is effective in attenuating pathological pain without producing unwanted side effects (i.e. motor ataxia) associated with NMDAR antagonists.

Correspondence between neurophysiological and clinical measurements of chemotherapy-induced peripheral neuropathy: secondary analysis of data from the CI-PeriNomS study

Chemotherapy-induced peripheral neuropathy (CIPN) lacks standardized clinical measurement. The objective of the current secondary analysis was to examine data from the CIPN Outcomes Standardization (CI-PeriNomS) study for associations between clinical examinations and neurophysiological abnormalities. Logistic regression estimated the strength of associations of vibration, pin, and monofilament examinations with lower limb sensory and motor amplitudes. Examinations were classified as normal (0), moderately abnormal (1), or severely abnormal (2). Among 218 participants, those with class 1 upper extremity (UE) and classes 1 or 2 lower extremity (LE) monofilament abnormality were 2.79 (95% confidence interval [CI]: 1.28-6.07), 3.49 (95%CI: 1.61-7.55), and 4.42 (95%CI: 1.35-14.46) times more likely to have abnormal sural nerve amplitudes, respectively, compared to individuals with normal examinations. Likewise, those with class 2 UE and classes 1 or 2 LE vibration abnormality were 8.65 (95%CI: 1.81-41.42), 2.54 (95%CI: 1.19-5.41), and 7.47 (95%CI: 2.49-22.40) times more likely to have abnormal sural nerve amplitudes, respectively, compared to participants with normal examinations. Abnormalities in vibration and monofilament examinations are associated with abnormal sural nerve amplitudes and are useful in identifying CIPN.

Oxaliplatin enhances gap junction-mediated coupling in cell cultures of mouse trigeminal ganglia

Communications between satellite glial cells and neighboring neurons within sensory ganglia may contribute to neuropathic and inflammatory pain. To elucidate the role of satellite glial cells in chemotherapy-induced pain, we examined the effects of oxaliplatin on the gap junction-mediated coupling between these cells. We also examined whether the gap junction blocker, carbenoxolone, can reverse the coupling. Primary cultures of mice trigeminal ganglia, 24-48h after cell isolation, were used. Satellite glial cells were injected with Lucifer yellow in the presence or absence of oxaliplatin (60 μM). In addition, the effect of carbenoxolone (100 μM) on coupling, and the expression of connexin 43 proteins were evaluated. Dye coupling between adjacent satellite glial cells was significantly increased (2.3-fold, P<0.05) following a 2h incubation with oxaliplatin. Adding carbenoxolone to the oxaliplatin-treated cultures reversed oxaliplatin-evoked coupling to baseline (P<0.05). Immunostaining showed no difference between expression of connexin 43 in control and oxaliplatin-treated cultures. Our findings indicated that oxaliplatin-increased gap junction-mediated coupling between satellite glial cells in primary cultures of mouse trigeminal ganglia, and carbenoxolone reversed this effect. Hence, it is proposed that increased gap junction-mediated coupling was seen between satellite glial cells in TG. This observation together with our previous data obtained from a behavioral study suggests that this phenomenon might contribute to chemotherapy-induced nociception following oxaliplatin treatment.

Cancer treatment-related neuropathic pain syndromes--epidemiology and treatment: an update

Cancer treatment-related chronic neuropathic pain (NP) is a pervasive and distressing problem that negatively influences function and quality of life for countless cancer survivors. It occurs because of cancer treatment-induced damage to peripheral and central nervous system structures. NP becomes chronic when pain signal transmission persists, eventually sensitizing neurons in the dorsal horn and other pain-processing regions in the central nervous system. Frequently overlooked, NP due to cancer treatment has been understudied. Consequently, only a few pharmacologic interventions have been shown to be effective based on the results of randomized controlled trials. Future research designed to explore pathophysiologic mechanisms and effective mechanism-targeted interventions is sorely needed.

Mechanisms of chemotherapy-induced behavioral toxicities

While chemotherapeutic agents have yielded relative success in the treatment of cancer, patients are often plagued with unwanted and even debilitating side-effects from the treatment which can lead to dose reduction or even cessation of treatment. Common side effects (symptoms) of chemotherapy include (i) cognitive deficiencies such as problems with attention, memory and executive functioning; (ii) fatigue and motivational deficit; and (iii) neuropathy. These symptoms often develop during treatment but can remain even after cessation of chemotherapy, severely impacting long-term quality of life. Little is known about the underlying mechanisms responsible for the development of these behavioral toxicities, however, neuroinflammation is widely considered to be one of the major mechanisms responsible for chemotherapy-induced symptoms. Here, we critically assess what is known in regards to the role of neuroinflammation in chemotherapy-induced symptoms. We also argue that, based on the available evidence, neuroinflammation is unlikely the only mechanism involved in the pathogenesis of chemotherapy-induced behavioral toxicities. We evaluate two other putative candidate mechanisms. To this end we discuss the mediating role of damage-associated molecular patterns (DAMPs) activated in response to chemotherapy-induced cellular damage. We also review the literature with respect to possible alternative mechanisms such as a chemotherapy-induced change in the bioenergetic status of the tissue involving changes in mitochondrial function in relation to chemotherapy-induced behavioral toxicities. Understanding the mechanisms that underlie the emergence of fatigue, neuropathy, and cognitive difficulties is vital to better treatment and long-term survival of cancer patients.

Clinical presentation and electrophysiological findings of porphyric neuropathies: a follow-up study

INTRODUCTION

A case series of acute intermittent porphyria (AIP) is described that focuses on the clinical course of the disease with regard to neurological manifestations of the peripheral nervous system.

METHODS

Eight patients were diagnosed with AIP on the basis of characteristic clinical findings, erythrocyte porphobilinogendeaminase activity, neuropathic patterns, serial changes in nerve conduction studies (NCS), and temporal relationship of central nervous system involvement.

RESULTS

Six patients diagnosed with AIP<2 months after symptom onset had neuropathy that was predominantly upper extremity, motor, and proximal. NCS recovery rates were slower in the lower than the upper limbs. Two patients diagnosed >2 months after symptom onset had distal sensorimotor polyneuropathy.

CONCLUSIONS

The findings from this case series suggest that the peripheral nerves may be differentially and selectively involved in different diagnostic stages of porphyric neuropathy.

Quality of life and resilience related to chemotherapy-induced peripheral neuropathy in patients post treatment with platinums and taxanes

The aim of this study was to ascertain patients' quality of life and resilience related to chemotherapy-induced peripheral neuropathy (CIPN) after treatment with platinum- and taxane-based chemotherapy drugs. A self-administered questionnaire combining the EORTC QLQ-C30 (version 3), the EORTC QLQ-CIPN20 and the resilience scale RS-14TM was posted to a non-probability sample of 100 patients who had recently completed treatment with a platinum- or taxane-based drug. In total, 86 completed questionnaires were returned (86% response rate). Participants rated their overall quality of life and overall health over the previous week. The combined global health status score was 70, indicating that participants had a relatively high health status. Similar to the scores on the EORTC QLQ-30, scores for the EORTC QLQ-CIPN20 showed that the majority of participants indicated experiencing very little impact (not at all, a little) on sensory, motor and autonomic scales. However, motor scale items were generally rated lower than items concerning sensory functioning. The study results are an encouraging indication of minimal impact on quality of life when treatment with taxanes and platinums ended. The results also indicate that resilience scores among the participants were moderately high.

Methotrexate chemotherapy triggers touch-evoked pain and increased CGRP-positive sensory fibres in the tibial periosteum of young rats

Although bone pain caused by cancer chemotherapy is a well-recognized and significant problem, with approximately 1 in 10 childhood cancer patients being reported to experience isolated bone pain along with other skeletal complications, the underlying mechanisms are poorly understood and there is no specific treatment. In this study, effects of methotrexate (MTX) treatment on pain in the hind legs and the extent of sensory innervation of the tibial bone were examined through a 20-day time course in young rats after 5 daily 0.75 mg/kg MTX injections. MTX treatment increased von-Frey filament stimulation-induced mechanical allodynia and palpation nocifensive score in the tibia. MTX-treated rats showed trends in reduced loading (numbers of stands) on hind limbs after palpation, commencing early during treatment and 2 weeks after the end of treatment despite no signs of ongoing pain during normal locomotion. Immunohistochemical analyses showed an increase in innervation of calcitonin gene-related peptide (CGRP)-positive sensory nerve fibres in tibial periosteum on days preceding and overlapping with those rats with touch-evoked pain responses and the bone repair phase. These data suggest that methotrexate chemotherapy triggers touch-evoked pain involving enhanced sensory nerve innervation of the bone.

Chronic cannabinoid receptor 2 activation reverses paclitaxel neuropathy without tolerance or cannabinoid receptor 1-dependent withdrawal

BACKGROUND

Mixed cannabinoid receptor 1 and 2 (CB1 and CB2) agonists such as Δ(9)-tetrahydrocannabinol (Δ(9)-THC) can produce tolerance, physical withdrawal, and unwanted CB1-mediated central nervous system side effects. Whether repeated systemic administration of a CB2-preferring agonist engages CB1 receptors or produces CB1-mediated side effects is unknown.

METHODS

We evaluated antiallodynic efficacy, possible tolerance, and cannabimimetic side effects of repeated dosing with a CB2-preferring agonist AM1710 in a model of chemotherapy-induced neuropathy produced by paclitaxel using CB1 knockout (CB1KO), CB2 knockout (CB2KO), and wild-type (WT) mice. Comparisons were made with the prototypic classic cannabinoid Δ(9)-THC. We also explored the site and possible mechanism of action of AM1710.

RESULTS

Paclitaxel-induced mechanical and cold allodynia developed to an equivalent degree in CB1KO, CB2KO, and WT mice. Both AM1710 and Δ(9)-THC suppressed established paclitaxel-induced allodynia in WT mice. In contrast to Δ(9)-THC, chronic administration of AM1710 did not engage CB1 activity or produce antinociceptive tolerance, CB1-mediated cannabinoid withdrawal, hypothermia, or motor dysfunction. Antiallodynic efficacy of systemic administration of AM1710 was absent in CB2KO mice and WT mice receiving the CB2 antagonist AM630, administered either systemically or intrathecally. Intrathecal administration of AM1710 also attenuated paclitaxel-induced allodynia in WT mice, but not CB2KO mice, implicating a possible role for spinal CB2 receptors in AM1710 antiallodynic efficacy. Finally, both acute and chronic administration of AM1710 decreased messenger RNA levels of tumor necrosis factor-α and monocyte chemoattractant protein 1 in lumbar spinal cord of paclitaxel-treated WT mice.

CONCLUSIONS

Our results highlight the potential of prolonged use of CB2 agonists for managing chemotherapy-induced allodynia with a favorable therapeutic ratio marked by sustained efficacy and absence of tolerance, physical withdrawal, or CB1-mediated side effects.

Candidate pathway-based genetic association study of platinum and platinum-taxane related toxicity in a cohort of primary lung cancer patients

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is a common toxicity secondary to chemotherapy. Genetic factors may be important in predisposing patients to this adverse effect.

PATIENTS AND METHODS

We studied 950 primary lung cancer patients, who received platinum or platinum-combination drug chemotherapy and who had DNA available for study. We analyzed epidemiological risk factors in 279 CIPN patients and 456 non-CIPN patients and genetic risk factors in 141 CIPN patients and 259 non-CIPN patients. The risk factors studied included demographic, diagnostic, and treatment data, as well as 174 tag SNPs (single nucleotide polymorphisms) across 43 candidate genes in the glutathione, cell cycle, DNA repair, cell signaling, and apoptosis pathways.

RESULTS

Patients who had diabetes mellitus were more likely to have CIPN (p=0.0002). Other epidemiologic risk factors associated with CIPN included number of cycles (p=0.0004) and type of concurrent chemotherapy (p<0.001). SNPs most associated with CIPN were in glutathione peroxidase 7 (GPX7) gene (p values 0.0015 and 0.0028, unadjusted and adjusted) and in ATP-binding cassette sub-family C member 4 (ABCC4) gene (p values 0.037 and 0.006, unadjusted and adjusted). We also found other suggestive associations in methyl-o-guanine-methyl-transferase (MGMT) and glutathione-S-transferase (GST) isoforms.

CONCLUSIONS

Epidemiological and genetic risk factors associated with CIPN in this cohort, included the type of chemotherapy drug, intensity of chemotherapy treatment, and genes known to be associated with chemotherapy resistance. These findings suggest that differentiating between cytotoxic and neurotoxic mechanisms of chemotherapy drugs is challenging but represents an important step toward individualized therapy and improving quality of life for patients.