Emerging mechanistic underpinnings and therapeutic targets for chemotherapy-related cognitive impairment

Nanotechnology Approaches for Prevention and Treatment of Chemotherapy-Induced Neurotoxicity, Neuropathy, and Cardiomyopathy in Breast and Ovarian Cancer Survivors

Nanotechnology has emerged as a promising approach for the targeted delivery of therapeutic agents while improving their efficacy and safety. As a result, nanomaterial development for the selective targeting of cancers, with the possibility of treating off-target, detrimental sequelae caused by chemotherapy, is an important area of research. Breast and ovarian cancer are among the most common cancer types in women, and chemotherapy is an essential treatment modality for these diseases. However, chemotherapy-induced neurotoxicity, neuropathy, and cardiomyopathy are common side effects that can affect breast and ovarian cancer survivors quality of life. Therefore, there is an urgent need to develop effective prevention and treatment strategies for these adverse effects. Nanoparticles (NPs) have extreme potential for enhancing therapeutic efficacy but require continued research to elucidate beneficial interventions for women cancer survivors. In short, nanotechnology-based approaches have emerged as promising strategies for preventing and treating chemotherapy-induced neurotoxicity, neuropathy, and cardiomyopathy. NP-based drug delivery systems and therapeutics have shown potential for reducing the side effects of chemotherapeutics while improving drug efficacy. In this article, the latest nanotechnology approaches and their potential for the prevention and treatment of chemotherapy-induced neurotoxicity, neuropathy, and cardiomyopathy in breast and ovarian cancer survivors are discussed.

Cognitive Symptoms Across Diverse Cancers

Importance

Psychosocial health services for adults with cancer should include support for cognitive symptoms and symptom clusters.

Objective

To characterize the frequency and severity of cognitive symptoms and to identify demographic and clinical risk factors associated with moderate to severe cognitive symptoms among outpatient adults with cancer seeking psychosocial support.

Design, Setting, and Participants

This cross-sectional study analyzed data from routine patient-reported symptom screening during clinic appointments at the Princess Margaret Cancer Centre in Toronto, Canada, between January 1, 2013, and December 31, 2019. Participants were outpatient adults (aged ≥18 years) with diverse cancer diagnoses who endorsed interest in receiving psychosocial support from a health care team member. Data analysis was performed from April 2020 to June 2024.

Main Outcomes and Measures

The presence and severity of cognitive symptoms as self-rated by participants were characterized across 12 cancer types: brain or central nervous system (CNS), breast, gastrointestinal, head and neck, gynecological, thyroid, lung and bronchus, sarcoma, genitourinary, melanoma, hematological, and all other cancers. Multivariable logistic regression was used to explore the associations between demographic, clinical, and symptom factors and moderate to severe cognitive symptoms.

Results

Across the sample of 5078 respondents (2820 females [55.5%]; mean [SD] age at time of survey, 56.0 [14.1] years) requesting psychosocial support, 3480 (68.5%) reported cognitive symptoms of any severity, ranging from 59.5% in sarcoma to 86.5% in brain or CNS cancer. Moderate to severe cognitive symptoms were reported by 1544 patients (30.4%), with the proportions being 51.3% for patients with brain or CNS, 37.0% for breast, 36.2% for thyroid, 30.9% for melanoma, 29.6% for head and neck, 28.3% for gastrointestinal, 28.2% for hematological, 28.1% for gynecological, 24.9% for lung and bronchus, 24.9% for sarcoma, 21.0% for genitourinary, and 26.8% for all other cancers. Across the entire sample, moderate to severe cognitive symptoms were associated with recurrence or progression involving the CNS (odds ratio [OR], 2.62; 95% CI, 1.80-3.81), depression (OR, 1.92; 95% CI, 1.59-2.31), tiredness (OR, 1.82; 95% CI, 1.52-2.19), drowsiness (OR, 1.64; 95% CI, 1.39-1.93), anxiety (OR, 1.57; 95% CI, 1.30-1.89), shortness of breath (OR, 1.38; 95% CI, 1.16-1.61), female sex (OR, 1.33; 95% CI, 1.14-1.56), first-line chemotherapy received (OR, 1.22; 95% CI, 1.05-1.41), and metastatic disease at diagnosis (OR, 0.74; 95% CI, 0.61-0.89). Within individual cancer types, tiredness and depression were consistently associated with moderate to severe cognitive symptoms.

Conclusions and Relevance

This cross-sectional study found that cognitive symptoms were frequently reported by patients across a wide range of cancer types; higher severity of cognitive symptoms was consistently associated with higher symptom burden. The findings could be used to inform decision-making regarding access to cognitive screening, assessment, and supportive care in outpatient oncology clinics.

Hormonal basis of brain fog in cancer treatment

The cognitive side effects of cancer treatment are common, but no targeted therapy exists yet to treat or prevent such neurological sequelae. We explore the role of hormones as mediators between cancer therapy and cognitive impairment, discussing potential future directions.

Precise timing of audiovisual stimulation conquers chemobrain

In a recent study, Kim et al. utilized gamma entrainment using sensory stimuli (GENUS) to rescue cognitive impairment and glial dysregulation associated with cisplatin and methotrexate chemotherapy, specifically when applied both throughout and after chemotherapy administration. GENUS provides a time-dependent, non-invasive method for treating chemobrain, with broader implications for resolving neurodegenerative neuroinflammation.

Construction and validation of a risk-prediction model for chemotherapy-related cognitive impairment in patients with breast cancer

PURPOSE

To identify risk factors of chemotherapy-related cognitive impairment (CRCI) and construct and validate a visual prediction model of such for patients with breast cancer.

METHODS

A multicenter, descriptive, and cross-sectional design was adopted. Data were collected from ten public tertiary hospitals in China. Cognitive function was assessed by using Functional Assessment of Cancer Therapy-cognitive function. Socio-demographic, clinical, psychological, and physical indicators were also assessed. The logistic prediction model was constructed by fivefold cross-validation. Then, a nomogram was utilized to visualize the prediction model, which was also evaluated via discrimination, calibration, and decision curve analysis.

RESULTS

A total of 71 breast cancer patients had CRCI with a prevalence of 9.58%. This visual prediction model was constructed based on education background, exercise frequency, chemotherapy times, and fatigue and demonstrated good discrimination, with an area under the receiver operating characteristic curve of 0.882. The calibration curve indicated good agreement between experimental and projected values, and the decision curve proved good clinical applicability.

CONCLUSION

Education background, exercise frequency, chemotherapy times, and fatigue were associated with high incidence of CRCI. The prediction model exhibits superior performance and has promise as a useful instrument for assessing the likelihood of CRCI in breast cancer patients.

IMPLICATIONS FOR CANCER SURVIVORS

Our findings could provide breast cancer survivors with risk screening based on CRCI predictors to implement prevention and early intervention, and help patients integrate into society and achieve comprehensive recovery.

Artificial and natural interventions for chemotherapy- and / or radiotherapy-induced cognitive impairment: A systematic review of animal studies

BACKGROUND

Cancer survivors frequently experience cognitive impairments. This systematic review assessed animal literature to identify artificial (pharmaceutical) or natural interventions (plant/endogenously-derived) to reduce treatment-related cognitive impairments.

METHODS

PubMed, EMBASE, PsycINFO, Web of Science, and Scopus were searched and SYRCLE's tool was used for risk of bias assessment of the 134 included articles.

RESULTS

High variability was observed and risk of bias analysis showed overall poor quality of reporting. Results generally showed positive effects in the intervention group versus cancer-therapy only group (67% of 156 cognitive measures), with only 15 (7%) measures reporting cognitive impairment despite intervention. Both artificial (61%) and natural (75%) interventions prevented cognitive impairment. Artificial interventions involving GSK3B inhibitors, PLX5622, and NMDA receptor antagonists, and natural interventions utilizing melatonin, curcumin, and N-acetylcysteine, showed most consistent outcomes.

CONCLUSIONS

Both artificial and natural interventions may prevent cognitive impairment in rodents, which merit consideration in future clinical trials. Greater consistency in design is needed to enhance the generalizability across studies, including timing of cognitive tests and description of treatments and interventions.

Neuroimaging based biotypes for precision diagnosis and prognosis in cancer-related cognitive impairment

Cancer related cognitive impairment (CRCI) is commonly associated with cancer and its treatments, yet the present binary diagnostic approach fails to capture the full spectrum of this syndrome. Cognitive function is highly complex and exists on a continuum that is poorly characterized by dichotomous categories. Advanced statistical methodologies applied to symptom assessments have demonstrated that there are multiple subclasses of CRCI. However, studies suggest that relying on symptom assessments alone may fail to account for significant differences in the neural mechanisms that underlie a specific cognitive phenotype. Treatment plans that address the specific physiologic mechanisms involved in an individual patient's condition is the heart of precision medicine. In this narrative review, we discuss how biotyping, a precision medicine framework being utilized in other mental disorders, could be applied to CRCI. Specifically, we discuss how neuroimaging can be used to determine biotypes of CRCI, which allow for increased precision in prediction and diagnosis of CRCI via biologic mechanistic data. Biotypes may also provide more precise clinical endpoints for intervention trials. Biotyping could be made more feasible with proxy imaging technologies or liquid biomarkers. Large cross-sectional phenotyping studies are needed in addition to evaluation of longitudinal trajectories, and data sharing/pooling is highly feasible with currently available digital infrastructures.

Chemobrain: An accelerated aging process linking adenosine A2A receptor signaling in cancer survivors

Chemotherapy has a significant positive impact in cancer treatment outcomes, reducing recurrence and mortality. However, many cancer surviving children and adults suffer from aberrant chemotherapy neurotoxic effects on learning, memory, attention, executive functioning, and processing speed. This chemotherapy-induced cognitive impairment (CICI) is referred to as "chemobrain" or "chemofog". While the underlying mechanisms mediating CICI are still unclear, there is strong evidence that chemotherapy accelerates the biological aging process, manifesting as effects which include telomere shortening, epigenetic dysregulation, oxidative stress, mitochondrial defects, impaired neurogenesis, and neuroinflammation, all of which are known to contribute to increased anxiety and neurocognitive decline. Despite the increased prevalence of CICI, there exists a lack of mechanistic understanding by which chemotherapy detrimentally affects cognition in cancer survivors. Moreover, there are no approved therapeutic interventions for this condition. To address this gap in knowledge, this review attempts to identify how adenosine signaling, particularly through the adenosine A2A receptor, can be an essential tool to attenuate accelerated aging phenotypes. Importantly, the adenosine A2A receptor uniquely stands at the crossroads of cancer treatment and improved cognition, given that it is widely known to control tumor induced immunosuppression in the tumor microenvironment, while also posited to be an essential regulator of cognition in neurodegenerative disease. Consequently, we propose that the adenosine A2A receptor may provide a multifaceted therapeutic strategy to enhance anticancer activity, while combating chemotherapy induced cognitive deficits, both which are essential to provide novel therapeutic interventions against accelerated aging in cancer survivors.

Advances in treatments of patients with classical and emergent neurological toxicities of anticancer agents

The neurotoxicity associated to the anticancer treatments has received a growing body of interest in the recent years. The development of innovating therapies over the last 20years has led to the emergence of new toxicities. Their diagnosis and management can be challenging in the clinical practice and further research is warranted to improve the understanding of their pathogenic mechanisms. Conventional treatments as radiation therapy and chemotherapy are associated to well-known and under exploration emerging central nervous system (CNS) and peripheral nervous system (PNS) toxicities. The identification of the risk factors and a better understanding of their pathogeny through a "bench to bedside and back again" approach, are the first steps towards the development of toxicity mitigation strategies. New imaging techniques and biological explorations are invaluable for their diagnosis. Immunotherapies have changed the cancer treatment paradigm from tumor cell centered to immune modulation towards an efficient anticancer immune response. The use of the immune checkpoints inhibitors (ICI) and chimeric antigen receptor (CAR-T cells) lead to an increase in the incidence of immune-mediated toxicities and new challenges in the neurological patient's management. The neurological ICI-related adverse events (n-irAE) are rare but potentially severe and may present with both CNS and PNS involvement. The most frequent and well characterized, from a clinical and biological standpoint, are the PNS phenotypes: myositis and polyradiculoneuropathy, but the knowledge on CNS phenotypes and their treatments is expanding. The n-irAE management requires a good balance between dampening the autoimmune toxicity without impairing the anticancer immunity. The adoptive cell therapies as CAR-T cells, a promising anticancer strategy, trigger cellular activation and massive production of proinflammatory cytokines inducing frequent and sometime severe toxicity known as cytokine release syndrome and immune effector cell-associated neurologic syndrome. Their management requires a close partnership between oncologist-hematologists, neurologists, and intensivists. The oncological patient's management requires a multidisciplinary clinical team (oncologist, neurologist and paramedical) as well as a research team leading towards a better understanding and a better management of the neurological toxicities.

The neural addiction of cancer

The recently uncovered key role of the peripheral and central nervous systems in controlling tumorigenesis and metastasis has opened a new area of research to identify innovative approaches against cancer. Although the 'neural addiction' of cancer is only partially understood, in this Perspective we discuss the current knowledge and perspectives on peripheral and central nerve circuitries and brain areas that can support tumorigenesis and metastasis and the possible reciprocal influence that the brain and peripheral tumours exert on one another. Tumours can build up local autonomic and sensory nerve networks and are able to develop a long-distance relationship with the brain through circulating adipokines, inflammatory cytokines, neurotrophic factors or afferent nerve inputs, to promote cancer initiation, growth and dissemination. In turn, the central nervous system can affect tumour development and metastasis through the activation or dysregulation of specific central neural areas or circuits, as well as neuroendocrine, neuroimmune or neurovascular systems. Studying neural circuitries in the brain and tumours, as well as understanding how the brain communicates with the tumour or how intratumour nerves interplay with the tumour microenvironment, can reveal unrecognized mechanisms that promote cancer development and progression and open up opportunities for the development of novel therapeutic strategies. Targeting the dysregulated peripheral and central nervous systems might represent a novel strategy for next-generation cancer treatment that could, in part, be achieved through the repurposing of neuropsychiatric drugs in oncology.

Long COVID Syndrome Presenting as Neuropsychiatric Exacerbations in Autism Spectrum Disorder: Insights for Treatment

COVID-19 causes not only severe respiratory symptoms, but also long-term sequelae, even if the acute-phase symptoms are minor. Neurological and neuropsychiatric symptoms are emerging as major long-term sequalae. In patients with pre-existing behavioral symptoms, such as individuals with autism spectrum disorders (ASD), the emergence of neuropsychiatric symptoms due to long COVID can be difficult to diagnose and manage. Herein, we present three ASD cases who presented with markedly worsening neuropsychiatric symptoms following COVID-19 exposure and subsequent difficulty in managing the post-COVID neuropsychiatric symptoms. Case 1 contracted SARS-CoV-2 during the early stages of the pandemic and treatment targeting COVID-19-induced immune activation was delayed. Case 2 was asymptomatic in the acute stage of a confirmed COVID-19 exposure, but still developed significant neuropsychiatric symptoms. Case 3 demonstrated a difficult course, partly due to pre-existing immune dysregulation and prior use of multiple immunomodulating agents. In cases 1 and 3 for whom serial blood samples were obtained, notable changes in the production of inflammatory and counter-regulatory cytokines by peripheral blood monocytes were observed. The presented cases illustrate the profound effects of COVID-19 on neuropsychiatric symptoms in ASD subjects and the difficulty of managing long-COVID symptoms.

Distinct sleep disturbance and cognitive dysfunction profiles in oncology outpatients receiving chemotherapy

PURPOSE

Sleep disturbance and cancer-related cognitive impairment (CRCI) are two of the most common symptoms reported by patients undergoing chemotherapy. Less is known about how these symptoms co-occur and their associated risk factors. Study purposes were to identify subgroups of patients with distinct sleep disturbance and CRCI profiles and evaluate for differences among the subgroups in demographic and clinical characteristics, symptom severity scores, and QOL outcomes.

METHODS

A total of 1,333 oncology outpatients receiving chemotherapy completed self-report questionnaires on sleep disturbance and cognitive dysfunction six times over two cycles of chemotherapy. Latent profile analysis was used to identify distinct sleep disturbance AND cognitive dysfunction profiles. Parametric and non-parametric tests were used to evaluate for differences among the classes.

RESULTS

Two distinct profiles were identified (i.e., Low = low levels of both sleep disturbance and cognitive dysfunction (53.5%); High = high levels of both sleep disturbance and cognitive dysfunction (45.5%)). Patients in the High class were younger, more likely to be female, had a lower functional status and a higher level of comorbidity. In addition, these patients had a higher symptom burden and a lower quality of life.

CONCLUSION

Almost half of the patients undergoing chemotherapy experienced clinically meaningful levels of both symptoms. Of note, sleep disturbance is frequently overlooked by both clinicians and patients. Clinicians need to recommend cognitive rehabilitation and physical activity programs to decrease patients' symptom burden.

Cerebral glucose changes after chemotherapy and their relation to long-term cognitive complaints and fatigue

Purpose

To investigate the short-term cerebral metabolic effects of intravenous chemotherapy and their association with long-term fatigue/cognitive complaints.

Experimental design

Using [¹⁸F]-FDG-PET/CT whole-body scans, we retrospectively quantified relative cerebral glucose metabolism before and after neoadjuvant chemotherapy in a cohort of patients treated for non-metastatic breast cancer (2009-2019). Self-report of cognitive complaints and fatigue were prospectively assessed 7 ± 3 years after therapy. Metabolic changes were estimated with i) robust mixed-effects modelling in regions-of-interest (frontal, parietal, temporal, occipital, and insular cortex) and ii) general-linear modelling of whole-brain voxel-wise outcomes. iii) The association between metabolic changes and self-reported outcomes was evaluated using linear regression-analysis.

Results

Of the 667 screened patients, 263 underwent PET/CT before and after chemotherapy and 183 (48 ± 9 years) met the inclusion criteria. After chemotherapy, decreased frontal and increased parietal and insular metabolism were observed (|ß|>0.273, p_FDR<0.008). Separately, additional increased occipital metabolism after epiribucin+ cyclophosphamide (EC) and temporal metabolism after EC+ fluorouracil chemotherapy were observed (ß>0.244, p_FDR≤0.048). Voxel-based analysis (p_cluster-FWE<0.001) showed decreased metabolism in the paracingulate gyrus (-3.2 ± 3.9%) and putamen (3.1 ± 4.1%) and increased metabolism in the lateral cortex (L=2.9 ± 3.1%) and pericentral gyri (3.0 ± 4.4%). Except for the central sulcus, the same regions showed changes in EC, but not in FEC patients. Of the 97 self-reported responders, 23% and 27% experienced extreme fatigue and long-term cognitive complaints, respectively, which were not associated with metabolic changes.

Conclusion

Both hyper- and hypometabolism were observed after chemotherapy for breast cancer. Combined with earlier findings, this study could support inflammatory mechanisms resulting in relative hypermetabolism, mainly in the parietal/occipital cortices. As early metabolic changes did not precede long-term complaints, further research is necessary to identify vulnerable patients.

Mini-Review: Aplastic Myelin Following Chemotherapy

The contribution of chemotherapy to improved outcomes for cancer patients is unquestionable. Yet as its applications broaden, so do the concerns for the long-term implications of chemotherapy on the health of cancer survivors, with chemotherapy-related cognitive impairment as a cause for particular urgency. In this mini review, we explore myelin aplasticity following chemotherapy, discussing the role of myelin plasticity in healthy cognition and failure of myelin plasticity chiefly due microenvironmental aberrations in chemotherapy-related cognitive impairment. Possible therapeutic strategies to mitigate chemotherapy-induced myelin dysfunction are also discussed.

Experiences of language and communication after brain-tumour treatment: A long-term follow-up after glioma surgery

The purpose of this study was to explore how persons having received various treatments for glioma, a type of brain tumour, experience their language, speech, and communication in everyday life. Twelve persons with low-grade glioma and one with high-grade glioma who had undergone tumour resection in 2014-2016 in different tumour locations were interviewed using a semi-structured protocol. The video-recorded interviews were transcribed and analysed using qualitative content analysis, which revealed three manifest categories, nine sub-categories and one latent theme. Participants experienced changed communication that affected word finding, motor speech and comprehension. They also expressed how communication required a greater effort; time and context were important factors and participants felt frustrated with their communication. Further, they were dealing with changes and used multiple strategies to manage communication. For most participants it did not affect their everyday life, but it was not like before. In addition, participants adapted their way of living to manage illness-related problems. Uncertainty was a latent theme which emanated from the participants' illness experience, reflecting how living with a slow-growing brain tumour affects life-decisions and views of perceived symptoms. Discussion of how results can be interpreted in relation to previous research and health care are included.

Chemobrain in Breast Cancer: Mechanisms, Clinical Manifestations, and Potential Interventions

Among the potential adverse effects of breast cancer treatment, chemotherapy-related cognitive impairment (CRCI) has gained increased attention in the past years. In this review, we provide an overview of the literature regarding CRCI in breast cancer, focusing on three main aspects. The first aspect relates to the molecular mechanisms linking individual drugs commonly used to treat breast cancer and CRCI, which include oxidative stress and inflammation, reduced neurogenesis, reduced levels of specific neurotransmitters, alterations in neuronal dendrites and spines, and impairment in myelin production. The second aspect is related to the clinical characteristics of CRCI in patients with breast cancer treated with different drug combinations. Data suggest the incidence rates of CRCI in breast cancer vary considerably, and may affect more than 50% of treated patients. Both chemotherapy regimens with or without anthracyclines have been associated with CRCI manifestations. While cross-sectional studies suggest the presence of symptoms up to 20 years after treatment, longitudinal studies confirm cognitive impairments lasting for at most 4 years after the end of chemotherapy. The third and final aspect is related to possible therapeutic interventions. Although there is still no standard of care to treat CRCI, several pharmacological and non-pharmacological approaches have shown interesting results. In summary, even if cognitive impairments derived from chemotherapy resolve with time, awareness of CRCI is crucial to provide patients with a better understanding of the syndrome and to offer them the best care directed at improving quality of life.

Neuroinflammation as potential precursor of leukoencephalopathy in early-stage breast cancer patients: A cross-sectional PET-MRI study

Background

Although chemotherapy-induced leukoencephalopathy has been described in case and cohort studies, literature remains inconclusive about its prevalence and mechanisms. Therefore, we investigated the presence of leukoencephalopathy after multiagent chemotherapy in women treated for breast cancer and potential underlying neuroinflammatory processes.

Methods

In this exploratory study, 15 chemotherapy-treated and 15 age-matched chemotherapy-naïve patients with early-stage breast cancer, as well as 15 healthy controls underwent simultaneous PET-MR neuroimaging, including T1-weighted MPRAGE, T2-weighted FLAIR and dynamic PET with the 18-kDA translocator protein (TSPO) radioligand [¹⁸F]DPA-714. Total and regional (juxtacortical, periventricular, deep white matter and infratentorial) lesion burden were compared between the groups with one-way ANOVA. With paired t-tests, [¹⁸F]DPA-714 volume of distribution [V_T, including partial volume correction (PVC)] in lesioned and normal appearing white matter (NAWM) were compared within subjects, to investigate inflammation. Finally, two general linear models were used to examine the predictive values of neurofilament light-chain (NfL) serum levels on (1) total lesion burden or (2) PVC [¹⁸F]DPA-714 V_T of lesions showing elevated inflammation.

Results

No significant differences were found in total or localized lesion burden. However, significantly higher (20–45%) TSPO uptake was observed in juxtacortical lesions (p ≤ 0.008, t ≥ 3.90) compared to NAWM in both cancer groups, but only persisted for chemotherapy-treated patients after PVC (p = 0.005, t = 4.30). NfL serum levels were not associated with total lesion volume or tracer uptake in juxtacortical lesions.

Conclusion

This multimodal neuroimaging study suggests that neuroinflammatory processes could be involved in the development of juxtacortical, but not periventricular or deep white matter, leukoencephalopathy shortly after chemotherapy for early-stage breast cancer.

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No increased white matter lesion load in breast cancer patients.

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No differences in TSPO uptake in periventricular or deep white matter lesions.

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Higher TSPO uptake in juxtacortical lesions in chemotherapy-treated breast cancer patients.

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TSPO uptake in inflammatory lesions and NfL levels not significantly associated, despite a trend.

Cyclophosphamide and epirubicin induce high apoptosis in microglia cells while epirubicin provokes DNA damage and microglial activation at sub-lethal concentrations

Chemotherapy Related Cognitive Impairment (CRCI), also called chemobrain, diminishes cancer patient's life quality. Breast cancer (BC) patients have been described to be importantly affected, however, the mechanism leading to CRCI has not been fully elucidated. Recent research proposes microglia as the main architect of CRCI, thus dysregulations in these cells could trigger CRCI. The aim of this research was to evaluate the effects of two drugs commonly used against breast cancer, cyclophosphamide (CTX) and epirubicin (EPI), on the microglia cell line SIM-A9, using the BC cell line, 4T1, as a control. Our results show that CTX and EPI decrease microglia-cell viability and increase cell death on a concentration-dependent manner, being 5 and 2 times more cytotoxic to microglia cell line than to breast cancer 4T1cells, respectively. Both chemotherapies induce cell cycle arrest and a significant increase in p53, p16 and γ-H2AX in breast cancer and microglia cells. Furthermore, mitochondrial membrane potential (ΔΨm) diminishes as cell death increases, and both chemotherapies induce reactive oxygen species (ROS) production on SIM-A9 and 4T1. Moreover, caspase activation increases with treatments and its pharmacological blockade inhibits CTX and EPI induced-cell death. Finally, low concentrations of CTX and EPI induce γ-H2AX, and EPI induces cytokine release, NO production and Iba-1 overexpression. These findings indicate that microglia cells are more sensitive to CTX and EPI than BC cells and undergo DNA damage and cell cycle arrest at very low concentrations, moreover EPI induces microglia activation and a pro-inflammatory profile.

Cognitive adverse effects of chemotherapy and immunotherapy: are interventions within reach?

One in three people will be diagnosed with cancer during their lifetime. The community of cancer patients is growing, and several common cancers are becoming increasingly chronic; thus, cancer survivorship is an important part of health care. A large body of research indicates that cancer and cancer therapies are associated with cognitive impairment. This research has mainly concentrated on chemotherapy-associated cognitive impairment but, with the arrival of immunotherapies, the focus is expected to widen and the number of studies investigating the potential cognitive effects of these new therapies is rising. Meanwhile, patients with cognitive impairment and their healthcare providers are eagerly awaiting effective approaches to intervene against the cognitive effects of cancer treatment. In this Review, we take stock of the progress that has been made and discuss the steps that need to be taken to accelerate research into the biology underlying cognitive decline following chemotherapy and immunotherapy and to develop restorative and preventive interventions. We also provide recommendations to clinicians on how to best help patients who are currently experiencing cognitive impairment.

Cancer-related cognitive impairment is associated with perturbations in inflammatory pathways

Cancer-related cognitive impairment (CRCI) is a significant problem for patients receiving chemotherapy. While a growing amount of pre-clinical and clinical evidence suggests that inflammatory mechanisms underlie CRCI, no clinical studies have evaluated for associations between CRCI and changes in gene expression. Therefore, the purpose of this study was to evaluate for differentially expressed genes and perturbed inflammatory pathways across two independent samples of patients with cancer who did and did not report CRCI. The Attentional Function Index (AFI) was the self-report measure used to assess CRCI. AFI scores of <5 and of >7.5 indicate low versus high levels of cognitive function, respectively. Of the 185 patients in Sample 1, 49.2% had an AFI score of <5 and 50.8% had an AFI score of >7.5. Of the 158 patients in Sample 2, 50.6% had an AFI score of <5 and 49.4% had an AFI score of >7.5. Data from 182 patients in Sample 1 were analyzed using RNA-seq. Data from 158 patients in Sample 2 were analyzed using microarray. Twelve KEGG signaling pathways were significantly perturbed between the AFI groups, five of which were signaling pathways related to inflammatory mechanisms (e.g., cytokine-cytokine receptor interaction, tumor necrosis factor signaling). This study is the first to describe perturbations in inflammatory pathways associated with CRCI. Findings highlight the role of cytokines both in terms of cytokine-specific pathways, as well as pathways involved in cytokine production and cytokine activation. These findings have the potential to identify new targets for therapeutics and lead to the development of interventions to improve cognition in patients with cancer.

Changes in cytokine levels in breast cancer patients with CRCI before or after CALM intervention

To investigate the changes in cytokine (interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α) and interleukin 4 (IL-4)) levels and cognitive function before and after managing cancer and living meaningfully (CALM) intervention, in early-stage breast cancer patients with chemotherapy-related cognitive impairment (CRCI). One hundred and twenty-eight breast cancer patients with CRCI enrolled in this study, there are fifty patients underwent with 6 CALM interventions and seventy-eight patient care as usual (CAU). Cytokine (IL-1β, TNF-α and IL-4) levels in the patients were assessed, and the patients were evaluated with the Mini-Mental State Examination (MMSE), Prospective Memory (PM) and Retrospective Memory (RM), and Quality-of-life (QOL) and Psychological Distress Thermometer (DT) assessments before CALM intervention (BCM), after CALM intervention (ACM) and care of usual (CAU). Measures at these two time points and two groups were compared. There were significant differences in the performance on the RM, PM, MMSE, QOL and DT measures after, compared to before (t=8.126, t=8.007, t=-10.789, t=9.236, t=17.649, respectively; P<0.05), the CALM intervention, compared to CAU (t=-7.408, t=-7.300, t=8.128, t=-8.851, t=-10.572, respectively; P<0.05). In addition, cytokine levels, including IL-1β, TNF-α and IL-4, were significantly different before and after the CALM intervention (t=5.073, t=4.228, t=5.815, respectively; P<0.05) and the two groups (ACM vs CAU) were distinctly different (t=-3.353, t=-2.694, t=-3.268, respectively; P<0.05). furthermore, the cytokine levels (IL-1β, TNF-α and IL-4) have linear correlation with cognitive function before and after CALM intervention (r=-0.343/r=0.538, r=-0.375/r=-0.330, r=-0.310/r=-0.541, respectively; P<0.05). The present results indicated that CALM intervention could alleviate CRCI and that this process is accompanied by changes in IL-1β, TNF-α and IL-4 levels. These results further confirm that cytokines may be involved in CRCI and that CALM may become an efficient method to relieve CRCI-related symptoms in breast cancer patients.

Endocrine Therapy With or Without CDK4/6 Inhibitors in Women With Hormone-receptor Positive Breast Cancer: What do we Know About the Effects on Cognition?

Adjuvant endocrine therapy (ET) is the cornerstone of treatment for hormone-receptor positive breast cancer. Recently, ET is increasingly combined with "cyclin-dependent kinases 4 and 6'' (CDK4/6) inhibitors. Given the importance of estrogens in neural processes and the role of cyclin D in hippocampal cell proliferation, it is plausible that these therapies affect cognition, but studies on these potential cognitive effects are sparse. In this review, we summarize existing knowledge on the cognitive effects of ET and CDK4/6 inhibitors in pre-, peri- and postmenopausal patients with breast cancer. We show that several clinical studies support adverse cognitive effects, especially on verbal memory, after ET-induced decrease of estrogen-levels or inactivation of estrogen-receptors. Clinical studies on the cognitive effects of CDK4/6 inhibitors are virtually non-existent and no conclusions can yet be drawn. Longitudinal studies on the cognitive effects of the combined ET-CDK4/6 inhibitors are highly needed to properly inform patients about potential short-term and long-term cognitive side effects. These studies should preferably include cognitive assessments (including a measurement prior to ET), and be designed in such a way that they can account for variables such as type and duration of ET, CDK4/6 inhibition, menopausal status, and other disease- and treatment-related symptoms that can impact cognition, such as fatigue and distress.

Elevated Oxidative Stress and DNA Damage in Cortical Neurons of Chemotherapy Patients

The unintended neurologic sequelae of chemotherapy contribute to significant patient morbidity. Chemotherapy-related cognitive impairment (CRCI) is observed in up to 80% of cancer patients treated with chemotherapy and involves multiple cognitive domains including executive functioning. The pathophysiology underlying CRCI and the neurotoxicity of chemotherapy is incompletely understood, but oxidative stress and DNA damage are highly plausible mechanisms based on preclinical data. Unfortunately, validating pathways relevant to CRCI in humans is limited by an absence of relevant neuropathologic studies of patient brain tissue. In the present study, we stained sections of frontal lobe autopsy tissue from cancer patients treated with chemotherapy (n = 15), cancer patients not treated with chemotherapy (n = 10), and patients without history of cancer (n = 10) for markers of oxidative stress (nitrotyrosine, 4-hydroxynonenal) and DNA damage (pH2AX, pATM). Cancer patients treated with chemotherapy had increased staining for markers of oxidative stress and DNA damage in frontal lobe cortical neurons compared to controls. We detected no statistically significant difference in oxidative stress and DNA damage by the duration between last administration of chemotherapy and death. The study highlights the potential relevance of oxidative stress and DNA damage in the pathophysiology of CRCI and the neurotoxicity of chemotherapy.

Anticancer Drugs and the Nervous System

PURPOSE OF REVIEW

This article reviews the clinical features, prognosis, and treatment of neurotoxicity from anticancer drugs, including conventional cytotoxic chemotherapy, biologics, and targeted therapies, with a focus on the newer immunotherapies (immune checkpoint inhibitors and chimeric antigen receptor T cells).

RECENT FINDINGS

Whereas neurologic complications from traditional chemotherapy are widely recognized, newer cancer therapies, in particular immunotherapies, have unique and distinct patterns of neurologic adverse effects. Anticancer drugs may cause central or peripheral nervous system complications. Neurologic complications of therapy are being seen with increasing frequency as patients with cancer are living longer and receiving multiple courses of anticancer regimens, with novel agents, combinations, and longer duration. Neurologists must know how to recognize treatment-related neurologic toxicity since discontinuation of the offending agent or dose adjustment may prevent further or permanent neurologic injury. It is also imperative to differentiate neurologic complications of therapy from cancer progression into the nervous system and from comorbid neurologic disorders that do not require treatment dose reduction or discontinuation.

SUMMARY

Neurotoxicity from cancer therapy is common, with effects seen on both the central and peripheral nervous systems. Immune checkpoint inhibitor therapy and chimeric antigen receptor T-cell therapy are new cancer treatments with distinct patterns of neurologic complications. Early recognition and appropriate management are essential to help prevent further neurologic injury and optimize oncologic management.

Long-COVID syndrome-associated brain fog and chemofog: Luteolin to the rescue

COVID-19 leads to severe respiratory problems, but also to long-COVID syndrome associated primarily with cognitive dysfunction and fatigue. Long-COVID syndrome symptoms, especially brain fog, are similar to those experienced by patients undertaking or following chemotherapy for cancer (chemofog or chemobrain), as well in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) or mast cell activation syndrome (MCAS). The pathogenesis of brain fog in these illnesses is presently unknown but may involve neuroinflammation via mast cells stimulated by pathogenic and stress stimuli to release mediators that activate microglia and lead to inflammation in the hypothalamus. These processes could be mitigated by phytosomal formulation (in olive pomace oil) of the natural flavonoid luteolin.

Higher Levels of Stress Are Associated With a Significant Symptom Burden in Oncology Outpatients Receiving Chemotherapy

CONTEXT

A cancer diagnosis and associated treatments, as well as the uncertainty of the disease course, are stressful experiences for most patients. However, little information is available on the relationship between stress and symptom burden.

OBJECTIVES

The study purpose was to evaluate for differences in the severity of fatigue, lack of energy, sleep disturbance, and cognitive function, among three groups of patients with distinct stress profiles.

METHODS

Patients receiving chemotherapy (n = 957) completed measures of general, cancer-specific, and cumulative life stress and symptom inventories. Latent profile analysis was used to identify subgroups of patients with distinct stress profiles.

RESULTS

Three distinct subgroups of patients were identified (i.e., stressed [39.3%], normative [54.3%], resilient [5.7%]). For cognitive function, significant differences were found among the latent classes (stressed < normative < resilient). For both sleep disturbance and morning and evening fatigue, compared to the normative and resilient classes, the stressed class reported higher severity scores. Compared to the normative and resilient classes, the stressed class reported low levels of morning energy. Compared to the normative class, the stressed class reported lower levels of evening energy.

CONCLUSIONS

Consistent with our a priori hypothesis, patients in the stressed class had the highest symptom severity scores for all four symptoms and all these scores were above the clinically meaningful cutoffs for the various instruments.

Chronic Oral Administration of Magnesium-L-Threonate Prevents Oxaliplatin-Induced Memory and Emotional Deficits by Normalization of TNF-α/NF-κB Signaling in Rats

Antineoplastic drugs such as oxaliplatin (OXA) often induce memory and emotional deficits. At present, the mechanisms underlying these side-effects are not fully understood, and no effective treatment is available. Here, we show that the short-term memory deficits and anxiety-like and depression-like behaviors induced by intraperitoneal injections of OXA (4 mg/kg per day for 5 consecutive days) were accompanied by synaptic dysfunction and downregulation of the NR2B subunit of N-methyl-D-aspartate receptors in the hippocampus, which is critically involved in memory and emotion. The OXA-induced behavioral and synaptic changes were prevented by chronic oral administration of magnesium-L-threonate (L-TAMS, 604 mg/kg per day, from 2 days before until the end of experiments). We found that OXA injections significantly reduced the free Mg²⁺ in serum and cerebrospinal fluid (from ~ 0.8 mmol/L to ~ 0.6 mmol/L). The Mg²⁺ deficiency (0.6 mmol/L) upregulated tumor necrosis factor (TNF-α) and phospho-p65 (p-p65), an active form of nuclear factor-kappaB (NF-κB), and downregulated the NR2B subunit in cultured hippocampal slices. Oral L-TAMS prevented the OXA-induced upregulation of TNF-α and p-p65, as well as microglial activation in the hippocampus and the medial prefrontal cortex. Finally, similar to oral L-TAMS, intracerebroventricular injection of PDTC, an NF-κB inhibitor, also prevented the OXA-induced memory/emotional deficits and the changes in TNF-α, p-p65, and microglia. Taken together, the activation of TNF-α/NF-κB signaling resulting from reduced brain Mg²⁺ is responsible for the memory/emotional deficits induced by OXA. Chronic oral L-TAMS may be a novel approach to treating chemotherapy-induced memory/emotional deficits.

Myelin Plasticity and Repair: Neuro-Glial Choir Sets the Tuning

The plasticity of the central nervous system (CNS) in response to neuronal activity has been suggested as early as 1894 by Cajal (1894). CNS plasticity has first been studied with a focus on neuronal structures. However, in the last decade, myelin plasticity has been unraveled as an adaptive mechanism of importance, in addition to the previously described processes of myelin repair. Indeed, it is now clear that myelin remodeling occurs along with life and adapts to the activity of neuronal networks. Until now, it has been considered as a two-part dialog between the neuron and the oligodendroglial lineage. However, other glial cell types might be at play in myelin plasticity. In the present review, we first summarize the key structural parameters for myelination, we then describe how neuronal activity modulates myelination and finally discuss how other glial cells could participate in myelinic adaptivity.