Neurological Complications of Conventional and Novel Anticancer Treatments

Immune-Related Peripheral Neuropathy Associated with Immune Checkpoint Inhibitors: Case Report and Review of Literature

Immune checkpoint inhibitors (ICIs) are a group of drugs that have improved outcomes for patients with various cancers. Generally considered safe and well tolerated, these drugs are occasionally linked to immune-mediated or immune-related adverse events. Among these, autoimmune neurological events are rare, displaying varying incidence rates across different studies. Peripheral neuropathy, although one of the more common neurological immune-related events, is at times underestimated. This case report highlights an adult patient diagnosed with metastatic intrahepatic cholangiocarcinoma. Initially, the patient underwent chemoimmunotherapy with gemcitabine, cisplatin, and durvalumab for eight cycles, achieving partial response without significant toxicity. Following this, the patient continued with maintenance monotherapy with durvalumab every 28 days. After completing six cycles of maintenance therapy, the patient suddenly experienced paresthesia and hypoesthesia in four limbs, accompanied by apraxia in the hands that was more pronounced on the right side. Additionally, the patient reported neuropathic pain in the right arm and encountered limitations in certain instrumental activities of daily living. Diagnostic studies, including laboratory and electrophysiological studies, combined with the clinical presentation, identified immune-related peripheral polyneuropathy. Durvalumab was suspended and prednisolone therapy was initiated, resulting in a rapid resolution of all neuropathic symptoms. In addition to the clinical case, this article reviews the literature on immunotherapy-associated peripheral neuropathy.

Protective Effects of Glatiramer Acetate Against Paclitaxel-Induced Peripheral Neuropathy in Rats: A Role for Inflammatory Cytokines and Oxidative Stress

Chemotherapy-induced peripheral neuropathy (CIPN) is a major challenge for cancer patients who undergo chemotherapy with paclitaxel. Therefore, finding effective therapies for CIPN is crucial. Glatiramer acetate is used to treat multiple sclerosis that exerts neuroprotective properties in various studies. We hypothesized that glatiramer acetate could also improve the paclitaxel-induced peripheral neuropathy. We used a rat model of paclitaxel (2 mg/kg/every other day for 7 doses)-induced peripheral neuropathy. Rats were treated with either different doses of glatiramer acetate (1, 2, 4 mg/kg/day) or its vehicle for 14 days in separate groups. The mechanical and thermal sensitivity of the rats by using the Von Frey test and the Hot Plate test, respectively, were assessed during the study. The levels of oxidative stress (malondialdehyde and superoxide dismutase), inflammatory markers (TNF-α, IL-10, NF-kB), and nerve damage (H&E and S100B staining) in the sciatic nerves of the rats were also measured at the end of study. Glatiramer acetate (2 and 4 mg/kg) exerted beneficial effects on thermal and mechanical allodynia tests. It also modulated the inflammatory response by reducing TNF-α and NF-κB levels, enhancing IL-10 production, and improving the oxidative stress status by lowering malondialdehyde and increasing superoxide dismutase activity in the sciatic nerve of the rats. Furthermore, glatiramer acetate enhanced nerve conduction velocity in all treatment groups. Histological analysis revealed that glatiramer acetate (2 and 4 mg/kg) prevented paclitaxel-induced damage to the nerve structure. These results suggest that glatiramer acetate can alleviate the peripheral neuropathy induced by paclitaxel.

Morphofunctional characterisation of axonal damage in different rat models of chemotherapy-induced peripheral neurotoxicity: The role of nerve excitability testing

BACKGROUND AND AIMS

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a common and long-lasting adverse event of several anticancer compounds, for which treatment has not yet been developed. To fill this gap, preclinical studies are warranted, exploiting highly translational outcome measure(s) to transfer data from bench to bedside. Nerve excitability testing (NET) enables to test in vivo axonal properties and can be used to monitor early changes leading to axonal damage.

METHODS

We tested NET use in two different CIPN rat models: oxaliplatin (OHP) and paclitaxel (PTX). Animals (female) were chronically treated with either PTX or OHP and compared to respective control animals. NET was performed as soon as the first injection was administered. At the end of the treatment, CIPN onset was verified via a multimodal and robust approach: nerve conduction studies, nerve morphometry, behavioural tests and intraepidermal nerve fibre density.

RESULTS

NET showed the typical pattern of axonal hyperexcitability in the 72 h following the first OHP administration, whereas it showed precocious signs of axonal damage in PTX animals. At the end of the month of treatment, OHP animals showed a pattern compatible with a mild axonal sensory polyneuropathy. Instead, PTX cohort was characterised by a rather severe sensory axonal polyneuropathy with minor signs of motor involvement.

INTERPRETATION

NET after the first administration demonstrated the ongoing OHP-related channelopathy, whereas in PTX cohort it showed precocious signs of axonal damage. Therefore, NET could be suggested as an early surrogate marker in clinical trials, to detect precocious changes leading to axonal damage.

Incidence and risk factors for developing chemotherapy-induced neuropathic pain in 500 cancer patients: A file-based observational study

OBJECTIVE

To define the incidence and risk factors for developing chemotherapy-induced neuropathic pain (CINP).

METHODS

Retrospective, file-based analysis on cancer patients who received any type of conventional chemotherapy and for whom neurological evaluation was asked to reveal the extent of chemotherapy-induced peripheral neurotoxicity (CIPN) with or without CINP. CINP was assessed by means of the PI-NRS and Douleur Neuropathique-4 questionnaire. The total neuropathy score-clinical version graded the severity of CIPN.

RESULTS

The medical files of 500 chemotherapy-treated cancer patients were reviewed. Any grade chronic CIPN was disclosed in 343 (68.6%) patients and CINP in 127 (37%) of them, corresponding to an overall percentage of 25.4% among all 500 included patients. The logistic regression analysis identified as independent predictors for CINP development the presence of uncomplicated diabetes (OR: 2.17; p = .039) and grade 2-3 chronic CIPN (OR: 1.61; p < .001) as also the administration of combined paclitaxel plus cisplatin (reference variable), compared to oxaliplatin (OR: 0.18; p = .001) and taxanes (OR: 0.16; p < .001). The increased severity of acute OXAIPN was associated with CINP (OR: 4.51; p < .001). OXA-treated patients with persistent CINP presented a worst likelihood to improve after chemotherapy discontinuation, than patients receiving combined paclitaxel plus cisplatin (OR: 50; p < .001).

CONCLUSION

The incidence of CINP in our cohort was comparable to previous reports, with severities fluctuating upwards during chemotherapy and declined post-chemotherapy. Uncomplicated diabetes, the combined paclitaxel plus cisplatin treatment and the increased severity of acute oxaliplatin neurotoxicity mostly increase the risk for developing CINP. OXA-treated patients present less possibilities to recover from CINP after chemotherapy discontinuation, than other chemotherapies.

Brachial plexopathy after breast cancer: A persistent late effect of radiotherapy

Radiation-induced brachial plexopathy (RIBP) is an iatrogenic, progressively disabling, and often very late effect of adjuvant radiotherapy most commonly seen in breast cancer survivors but also in those treated for lymphoma, lung, and head and neck cancers. In late-onset RIBP following breast cancer, the nerve injury is chronic and irreversible, occurring more commonly when axillary and/or supraclavicular nodes have been irradiated, as well as the breast/chest wall. RIBP is manifested initially by paresthesia, hypoesthesia, dysesthesia, and later by weakness in the ipsilateral hand with those symptoms progressing distally to proximally up through the shoulder. Depressed/absent deep tendon reflexes in the upper extremity and muscle fasciculations occur also. Neither patients nor their health care providers tend to associate these unusual neurological symptoms with cancer treatments received ≥20 years prior, often failing to link these sensory-motor symptoms with radiotherapy decades before. Because long-term follow-up of these patients now typically falls to general practitioners, many cases may be missed or misdiagnosed because of the rarity of this disorder. Physiatrists and allied rehabilitation professionals must be aware of this progressively disabling, incurable condition to provide appropriate diagnoses and compensatory rehabilitation therapies. Additionally, professional oncology organizations should include RIBP in their long-term, survivorship guidelines for breast cancer. Researchers examining the iatrogenic late effects of radiotherapy should extend their follow-up periods well beyond the current 5-6 years to ascertain the true incidence of RIBP today. Rehabilitation providers must continue to advocate for awareness, diagnosis, and management of iatrogenic outcomes experienced by long-term cancer survivors.

Patient perceptions of altering chemotherapy treatment due to peripheral neuropathy

PURPOSE

Clinical practice guidelines recommend altering neurotoxic chemotherapy treatment in patients experiencing intolerable chemotherapy-induced peripheral neuropathy (CIPN). The primary objective of this survey was to understand patient's perspectives on altering neurotoxic chemotherapy treatment, including their perceptions of the benefits of preventing irreversible CIPN and the risks of reducing treatment efficacy.

METHODS

A cross-sectional online survey was distributed via social networks to patients who were currently receiving or had previously received neurotoxic chemotherapy for cancer. Survey results were analyzed using descriptive statistics and qualitative analysis.

RESULTS

Following data cleaning, 447 participants were included in the analysis. The median age was 57 years, 93% were white, and most were from the UK (53%) or USA (38%). Most participants who were currently or recently treated expected some CIPN symptom resolution (86%), but 45% of those who had completed treatment more than a year ago reported experiencing no symptom resolution. Participants reported that they would discontinue chemotherapy treatment for less severe CIPN if they knew their symptoms would be permanent than if symptoms would disappear after treatment. Most patients stated that the decision to alter chemotherapy or not was usually made collaboratively between the patient and their treating clinician (61%). The most common reason participants were reluctant to talk with their clinician about CIPN was fear that treatment would be altered. Participants noted a need for improved understanding of CIPN symptoms and their permanence, better patient education relating to CIPN prior to and after treatment, and greater clinician understanding and empathy around CIPN.

CONCLUSIONS

This survey highlights the importance of shared decision-making, including a consideration of both the long-term benefits and risks of altering neurotoxic chemotherapy treatment due to CIPN. Additional work is needed to develop decision aids and other communication tools that can be used to improve shared decision making and help patients with cancer achieve their treatment goals.

Gait analysis in chemotherapy-induced peripheral neurotoxicity rodent models

Gait analysis could be used in animal models as an indicator of sensory ataxia due to chemotherapy-induced peripheral neurotoxicity (CIPN). Over the years, gait analysis in in vivo studies has evolved from simple observations carried out by a trained operator to computerised systems with machine learning that allow the quantification of any variable of interest and the establishment of algorithms for behavioural classification. However, there is not a consensus on gait analysis use in CIPN animal models; therefore, we carried out a systematic review. Of 987 potentially relevant studies, 14 were included, in which different methods were analysed (observation, footprint and CatWalk™). We presented the state-of-the-art of possible approaches to analyse sensory ataxia in rodent models, addressing advantages and disadvantages of different methods available. Semi-automated methods may be of interest when preventive or therapeutic strategies are evaluated, also considering their methodological simplicity and automaticity; up to now, only CatWalk™ analysis has been tested. Future studies should expect that CIPN-affected animals tend to reduce hind paw support due to pain, allodynia or loss of sensation, and an increase in swing phase could or should be observed. Few available studies documented these impairments at the last time point, and only appeared later on respect to other earlier signs of CIPN (such as altered neurophysiological findings). For that reason, gait impairment could be interpreted as late repercussions of loss of sensory.

Toxic medications in Charcot-Marie-Tooth patients: A systematic review

BACKGROUND AND AIMS

Several widely used medications, with a relevant efficacy profile, are toxic to the peripheral nervous system and an even larger number of agents are suspected to be neurotoxic. There are concerns about the use of these drugs in patients with Charcot-Marie-Tooth disease (CMT), a hereditary motor and sensory neuropathy. This review provides evidence-based updated recommendations on this clinically relevant topic.

METHODS

A systematic review of the available studies/reports written in English was performed from July to September 2022 including in the search string all reported putative neurotoxic drugs.

RESULTS

The results of our systematic review provide evidence-based support for the statement that use of vincristine, and possibly paclitaxel, can occasionally induce an atypical, and more severe, course of drug-related peripheral neurotoxicity in CMT patients. It is therefore reasonable to recommend caution in the use of these compounds in CMT patients. However, no convincing evidence for a similar recommendation could be found for all other drugs.

INTERPRETATION

It is important that patients with CMT are not denied effective treatments that may prolong life expectancy for cancer or improve their health status if affected by non-oncological diseases. Accurate monitoring of peripheral nerve function in CMT patients treated with any neurotoxic agent remains mandatory to detect the earliest signs of neuropathy worsening and atypical clinical courses. Neurologists monitoring CMT patients as part of their normal care package or for natural history studies should keep detailed records of exposures to neurotoxic medications and support reporting of accelerated neuropathy progression if observed.