Nerve excitability assessment in chemotherapy-induced neurotoxicity

What is the Reason That the Pharmacological Future of Chemotherapeutics in the Treatment of Lung Cancer Could Be Most Closely Related to Nanostructures? Platinum Drugs in Therapy of Non-Small and Small Cell Lung Cancer and Their Unexpected, Possible Interactions. The Review

Over the course of several decades, anticancer treatment with chemotherapy drugs for lung cancer has not changed significantly. Unfortunately, this treatment prolongs the patient's life only by a few months, causing many side effects in the human body. It has also been proven that drugs such as Cisplatin, Carboplatin, Oxaliplatin and others can react with other substances containing an aromatic ring in which the nitrogen atom has a free electron group in its structure. Thus, such structures may have a competitive effect on the nucleobases of DNA. Therefore, scientists are looking not only for new drugs, but also for new alternative ways of delivering the drug to the cancer site. Nanotechnology seems to be a great hope in this matter. Creating a new nanomedicine would reduce the dose of the drug to an absolute minimum, and thus limit the toxic effect of the drug; it would allow for the exclusion of interactions with competitive compounds with a structure similar to nucleobases; it would also permit using the so-called targeted treatment and bypassing healthy cells; it would allow for the introduction of other treatment options, such as radiotherapy directly to the cancer site; and it would provide diagnostic possibilities. This article is a review that aims to systematize the knowledge regarding the anticancer treatment of lung cancer, but not only. It shows the clear possibility of interactions of chemotherapeutics with compounds competitive to the nitrogenous bases of DNA. It also shows the possibilities of using nanostructures as potential Platinum drug carriers, and proves that nanomedicine can easily become a new medicinal product in personalized medicine.

Axonal excitability as an early biomarker of nerve involvement in hereditary transthyretin amyloidosis

OBJECTIVES

The treatment of hereditary transthyretin amyloidosis polyneuropathy (ATTRv-PN) has been revolutionised by genetic therapies, with dramatic improvements in patient outcomes. Whilst the optimal timing of treatment initiation remains unknown, early treatment is desirable. Consequently, the aim of the study was to develop biomarkers of early nerve dysfunction in ATTRv-PN.

METHODS

Ulnar motor and sensory axonal excitability studies were prospectively undertaken on 22 patients with pathogenic hereditary transthyretin amyloid (ATTRv) gene variants, 12 with large fibre neuropathy (LF+) and 10 without (LF-), with results compared to age- and sex-matched healthy controls.

RESULTS

In motor axons we identified a continuum of change from healthy controls, to LF- and LF+ ATTRv with progressive reduction in hyperpolarising threshold electrotonus (TEh40(10-20 ms): p = 0.04, TEh40(20-40 ms): p = 0.01 and TEh40(90-10 ms): p = 0.01), suggestive of membrane depolarisation. In sensory axons lower levels of subexcitability were observed on single (SubEx) and double pulse (SubEx2) recovery cycle testing in LF+ (SubEx: p = 0.015, SubEx2: p = 0.015, RC(2-1): p = 0.04) suggesting reduced nodal slow potassium conductance, which promotes sensory hyperexcitability, paraesthesia and pain. There were no differences in sensory or motor excitability parameters when comparing different ATTRv variants.

CONCLUSIONS

These progressive changes seen across the disease spectrum in ATTRv-PN suggest that axonal excitability has utility to identify early and progressive nerve dysfunction in ATTRv, regardless of genotype.

SIGNIFICANCE

Axonal excitability is a promising early biomarker of nerve dysfunction in ATTRv-PN.

Predictive Biomarkers of Oxaliplatin-Induced Peripheral Neurotoxicity

Oxaliplatin (OXA) is a platinum compound primarily used in the treatment of gastrointestinal cancer. OXA-induced peripheral neurotoxicity (OXAIPN) is the major non-hematological dose-limiting toxicity of OXA-based chemotherapy and includes acute transient neurotoxic effects that appear soon after OXA infusion, and chronic non-length dependent sensory neuronopathy symmetrically affecting both upper and lower limbs in a stocking-and-glove distribution. No effective strategy has been established to reverse or treat OXAIPN. Thus, it is necessary to early predict the occurrence of OXAIPN during treatment and possibly modify the OXA-based regimen in patients at high risk as an early diagnosis and intervention may slow down neuropathy progression. However, identifying which patients are more likely to develop OXAIPN is clinically challenging. Several objective and measurable early biomarkers for OXAIPN prediction have been described in recent years, becoming useful for informing clinical decisions about treatment. The purpose of this review is to critically review data on currently available or promising predictors of OXAIPN. Neurological monitoring, according to predictive factors for increased risk of OXAIPN, would allow clinicians to personalize treatment, by monitoring at-risk patients more closely and guide clinicians towards better counseling of patients about neurotoxicity effects of OXA.

Management of Oxaliplatin-Induced Peripheral Sensory Neuropathy

Oxaliplatin-induced peripheral neurotoxicity (OIPN) is a severe and potentially permanent side effect of cancer treatment affecting the majority of oxaliplatin-treated patients, mostly with the onset of acute symptoms, but also with the establishment of a chronic sensory loss that is supposed to be due to dorsal root ganglia neuron damage. The pathogenesis of acute as well as chronic OIPN is still not completely known, and this is a limitation in the identification of effective strategies to prevent or limit their occurrence. Despite intense investigation at the preclinical and clinical levels, no treatment can be suggested for the prevention of OIPN, and only limited evidence for the efficacy of duloxetine in the treatment setting has been provided. In this review, ongoing neuroprotection clinical trials in oxaliplatin-treated patients will be analyzed with particular attention paid to the hypothesis leading to the study, to the trial strengths and weaknesses, and to the outcome measures proposed to test the efficacy of the therapeutic approach. It can be concluded that (1) prevention and treatment of OIPN still remains an important and unmet clinical need, (2) further, high-quality research is mandatory in order to achieve reliable and effective results, and (3) dose and schedule modification of OHP-based chemotherapy is currently the most effective approach to limit the severity of OIPN.

Cold aggravates abnormal excitability of motor axons in oxaliplatin-treated patients

INTRODUCTION

Cold allodynia is often seen in the acute phase of oxaliplatin treatment, but the underlying pathophysiology remains unclear.

METHODS

Patients scheduled for adjuvant oxaliplatin for colorectal cancer were examined with quantitative sensory testing and nerve excitability tests at baseline and after the second or third oxaliplatin cycle at different skin temperatures.

RESULTS

Seven patients were eligible for examination. All patients felt evoked pain and tingling when touching something cold after oxaliplatin infusion. Oxaliplatin decreased motor nerve superexcitability (P < .001), increased relative refractory period (P = .011), and caused neuromyotonia-like after-activity. Cooling exacerbated these changes and prolonged the accommodation half-time.

DISCUSSION

The findings suggest that a combined effect of oxaliplatin and cooling facilitates nerve excitability changes and neuromyotonia-like after-activity in peripheral nerve axons. A possible mechanism is the slowing in gating of voltage-dependent fast sodium and slow potassium channels, which results in symptoms of cold allodynia.

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

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

Possible association of CAG repeat polymorphism in KCNN3 encoding the potassium channel SK3 with oxaliplatin-induced neurotoxicity

INTRODUCTION

Data suggest a role of the potassium channel SK3 (KCNN3 gene) in oxaliplatin-induced neurotoxicity (OIN). Length variations in the polymorphic CAG repeat of the KCNN3 gene may be associated with the risk of OIN.

MATERIALS AND METHODS

We performed patch-clamp experiments on HEK293 cell lines, expressing SK3 channel isoforms with short (11) or long (24) CAG repetitions, to measure intracellular calcium concentrations to test the effects of oxaliplatin on current density. A retrospective study was carried out on patients with colorectal cancer who had received oxaliplatin-based chemotherapy. DNA for KCNN3 genotyping was extracted from leukocytes. The region containing the CAG repeats was amplified by PCR and the products separated by capillary electrophoresis for length analysis. The patients were divided into three groups depending on whether they carried two short alleles, one short allele and one long allele, or two long alleles. The primary endpoint was the onset of grade 2 or 3 neuropathy to oxaliplatin.

RESULTS

There was no difference in current density, but oxaliplatin induced a differential effect on apamin-sensitive current density between the two isoforms expressed in the HEK cell lines. There was a significant reduction of store-operated calcium entry into cells expressing the short and more active isoform only after high concentration of oxaliplatin exposition. Eighty-six patients were included in the clinical study. There was no significant association between OIN and KCNN3 polymorphism for the three groups.

CONCLUSION

We observed a slight association between OIN and CAG repeat polymorphisms of the KCNN3 gene in a preclinical model, but not a clinical study.

The incidence of acute oxaliplatin-induced neuropathy and its impact on treatment in the first cycle: a systematic review

BACKGROUND

Although acute oxaliplatin-induced neuropathy (OXIPN) is frequently regarded to be transient, recent studies have reported prolongation of infusion times, dose reduction and treatment cessation following the first dose of oxaliplatin in quarter of patients. Acute OXIPN is also a well-established risk factor for chronic neuropathy. However, there is underreporting of these parameters during the acute phase (≤ 14 days). This paper systematically reviews the incidence of acute OXIPN and its impact on treatment in the first cycle.

METHODS

A systematic literature search was performed using PubMed and Medline. Published original articles were included if they described details about prevalence of oxaliplatin-induced acute neuropathy.

RESULTS

Fourteen studies, comprised of 6211 patients were evaluated. The majority of patients were treated with oxaliplatin in combination with leucovorin and fluorouracil (FOLFOX). Most studies used the National Cancer Institute Common Toxicity Criteria to assess acute neuropathy. Acute neuropathy (Grades 1-4) was the most common event with prevalence ranging from 4-98%, followed by haematological (1.4-81%) and gastrointestinal (1.2-67%) toxicities, respectively. Drug regimens, starting dose of oxaliplatin and neuropathy assessment tools varied across studies. In addition, moderate to severe toxicities were common in patients that received a large dose of oxaliplatin (> 85 mg/m2) and/ or combined drugs. The majority of studies did not report the factors affecting acute neuropathy namely the range (minimal) doses required to evoke acute neuropathy, patient and clinical risk factors. In addition, there was no systematic reporting of the number of patients subjected to prolonged infusion, dose reduction, treatment delay and treatment cessation during the acute phase.

CONCLUSION

Despite the heterogeneity of studies regarding oxaliplatin starting dose, drug regimen, neuropathy assessment tools and study design, a large number of patients developed acute neuropathy. To develop a better preventive and therapeutic guideline for acute/chronic neuropathy, a prospective study should be conducted in a large cohort of patients in relation to drug regimen, starting/ranges (minimal) of doses producing acute neuropathy, treatment compliance, patient and clinical risk factors using a standardised neuropathy assessment tool.

Axonal excitability changes and acute symptoms of oxaliplatin treatment: In vivo evidence for slowed sodium channel inactivation

OBJECTIVE

Neurotoxicity is the most frequent dose-limiting side effect of the anti-cancer agent oxaliplatin, but the mechanisms are not well understood. This study used nerve excitability testing to investigate the pathophysiology of the acute neurotoxicity.

METHODS

Questionnaires, quantitative sensory tests, nerve conduction studies and nerve excitability testing were undertaken in 12 patients with high-risk colorectal cancer treated with adjuvant oxaliplatin and in 16 sex- and age-matched healthy controls. Examinations were performed twice for patients: once within 3 days after oxaliplatin treatment (post-infusion examination) and once shortly before the following treatment (recovery examination).

RESULTS

The most frequent post-infusion symptoms were tingling paresthesias and cold allodynia. The most prominent nerve excitability change was decreased superexcitability of motor axons which correlated with the average intensity of abnormal sensations (Spearman Rho = 0.80, p < .01). The motor nerve excitability changes were well modeled by a slowing of sodium channel inactivation, and were proportional to dose/m² with a half-life of about 10d.

CONCLUSIONS

Oxaliplatin induces reversible slowing of sodium channel inactivation in motor axons, and these changes are closely related to the reversible cold allodynia. However, further studies are required due to small sample size in this study.

SIGNIFICANCE

Nerve excitability data provide an index of sodium channel dysfunction: an objective biomarker of acute oxaliplatin neurotoxicity.

Platinum-induced neurotoxicity: A review of possible mechanisms

Patients treated with platinum-based chemotherapy frequently experience neurotoxic symptoms, which may lead to premature discontinuation of therapy. Despite discontinuation of platinum drugs, these symptoms can persist over a long period of time. Cisplatin and oxaliplatin, among all platinum drugs, have significant neurotoxic potential. A distal dose-dependent symmetrical sensory neuropathy is the most common presentation of platinum neurotoxicity. DNA damage-induced apoptosis of dorsal root ganglion (DRG) neurons seems to be the principal cause of neurological symptoms. However, DRG injury alone cannot explain some unique symptoms such as cold-aggravated burning pain affecting distal extremities that is observed with oxaliplatin administration. In this article, we briefly reviewed potential mechanisms for the development of platinum drugs-associated neurological manifestations.

Chemotherapy-Induced Peripheral Neuropathy Assessment Tools: A Systematic Review

PROBLEM IDENTIFICATION

Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting chemotherapy toxicity, which has a long-lasting effect and decreases quality of life. Although several tools have been developed to detect CIPN, the study quality, psychometric properties, and practicality of CIPN assessment tools have not been systematically reviewed.
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LITERATURE SEARCH

Electronic searches using keywords were conducted in Medline, PubMed, CINAHL®, and Cochrane Library for articles published from 1980-2015. Eligible studies were included if they involved patients with cancer receiving chemotherapy, provided CIPN assessment tools with psychometric properties, and were published in English.
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DATA EVALUATION

Data were extracted, and study quality was assessed. CIPN tools were evaluated in terms of psychometric properties and practicality.
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SYNTHESIS

A total of 19 studies describing 20 tools were reviewed. The quality of studies varied from strong to weak. The validity ranged from low to high, and the reliability with internal consistency ranged from 0.56-0.96. Poor inter-rater agreement was found. Not all of the tools were deemed practical.
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CONCLUSIONS

Considering the psychometric properties and practicality, two tools (Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity [FACT/GOG-Ntx] and Total Neuropathy Score [TNS]) are recommended for assessing CIPN.
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IMPLICATIONS FOR NURSING

Routine assessment of CIPN and choosing appropriate assessment tools are imperative. The FACT/GOG-Ntx and TNS are recommended for clinical use.

Peripheral nerve axonal excitability studies: expanding the neurophysiologist's armamentarium

Nerve excitability studies have emerged as a recent novel non-invasive technique that offers complementary information to that provided by more conventional nerve conduction studies, the latter which provide only limited indices of peripheral nerve function. Such novel tools allow for the assessment of peripheral axonal biophysical properties that include ion channels, energy-dependent pumps and membrane potential in health and disease. With improvements in technique and development of protocols, a typical study can be completed in a short period of time and rapid measurement of multiple excitability indices can be achieved that provide insight into different aspects of peripheral nerve function. The advent of automated protocols for the assessment of nerve excitability has promoted their use in previous studies investigating disease pathophysiology such as in metabolic, toxic and demyelinating neuropathies, amyotrophic lateral sclerosis, stroke, spinal cord injury and inherited channelopathies. In more recent years, the use of nerve excitability studies have additionally provided insights into the pathophysiological mechanisms underlying cerebellar disorders that include stroke and familial cerebellar ataxias such as episodic ataxia types 1 and 2. Moreover, this technique may have diagnostic and therapeutic implications that may encompass a broader range of neurodegenerative cerebellar ataxias in years to come. In the foreseeable future, this technique may eventually be incorporated into clinical practice expanding the currently available armamentarium to the neurophysiologist.

Potassium and the excitability properties of normal human motor axons in vivo

Hyperkalemia is an important cause of membrane depolarization in renal failure. A recent theoretical model of axonal excitability explains the effects of potassium on threshold electrotonus, but predicts changes in superexcitability in the opposite direction to those observed. To resolve this contradiction we assessed the relationship between serum potassium and motor axon excitability properties in 38 volunteers with normal potassium levels. Most threshold electrotonus measures were strongly correlated with potassium, and superexcitability decreased at higher potassium levels (P = 0.016), contrary to the existing model. Improved modelling of potassium effects was achieved by making the potassium currents obey the constant-field theory, and by making the potassium permeabilities proportional to external potassium, as has been observed in vitro. This new model also accounted well for the changes in superexcitability and other excitability measures previously reported in renal failure. These results demonstrate the importance of taking potassium levels into account when assessing axonal membrane dysfunction by excitability testing, and provide evidence that potassium currents are activated by external potassium in vivo.