Neurological adverse effects due to programmed death 1 (PD-1) inhibitors

Neurological adverse events related to immune-checkpoint inhibitors in Spain: a retrospective cohort study

BACKGROUND

Neurological immune-related adverse events associated with immune checkpoint inhibitors can have several clinical manifestations, but the syndromes and prognostic factors are still not well known. We aimed to characterise and group the clinical features, with a special focus in patients presenting with encephalopathy, and to identify predictors of response to therapy and survival.

METHODS

This retrospective observational study included patients with neurological immune-related adverse events from 20 hospitals in Spain whose clinical information, serum samples, and CSF samples were studied at Hospital Clinic de Barcelona, Barcelona, Spain. Patients with pre-existing paraneoplastic syndromes or evidence of alternative causes for their neurological symptoms were excluded. We reviewed the clinical information, classified their clinical features, and determined the presence of neural antibodies. Neurological status was assessed by the treating physician one month after adverse event onset (as improvement vs no improvement) and at the last evaluation (complete recovery or modified Rankin Scale score decrease of at least 2 points, indicating good outcome, vs all other modified Rankin Scale scores, indicating poor outcome); if the participant had died, the date and cause of death were recorded. We used Fisher's exact tests and Mann-Whitney U tests to analyse clinical features, and multivariable logistic regression to analyse prognostic factors.

FINDINGS

From Jan 1, 2018, until Feb 1, 2023, 83 patients with suspected neurological immune-related adverse events after use of immune checkpoint inhibitors were identified, of whom 64 patients were included. These patients had a median age of 67 years (IQR 59-74); 42 (66%) were male and 22 (34%) were female. The predominant tumours were lung cancer (30 [47%] patients), melanoma (13 [21%] patients), and renal cell carcinoma (seven [11%] patients). Neural antibodies were detected in 14 (22%) patients; 52 (81%) patients had CNS involvement and 12 (19%) had peripheral nervous system involvement. Encephalopathy occurred in 45 (70%) patients, 12 (27%) of whom had antibodies or well defined syndromes consistent with definite paraneoplastic or autoimmune encephalitis, 24 (53%) of whom had encephalitis without antibodies or clinical features characteristic of a defined syndrome, and nine (20%) of whom had encephalopathy without antibodies or inflammatory changes in CSF or brain MRI. Nine (14%) of 64 patients had combined myasthenia and myositis, five of them with myocarditis. Even though 58 (91%) of 64 patients received steroids and 31 (48%) of 64 received additional therapies, 18 (28%) did not improve during the first month after adverse event onset, and 11 of these 18 people died. At the last follow-up for the 53 remaining patients (median 6 months, IQR 3-13), 20 (38%) had a poor outcome (16 deaths, one related to a neurological immune-related adverse event). Mortality risk was increased in patients with lung cancer (vs those with other cancers: HR 2·5, 95% CI 1·1-6·0) and in patients with encephalopathy without evidence of CNS inflammation or combined myocarditis, myasthenia, and myositis (vs those with the remaining syndromes: HR 5·0, 1·4-17·8 and HR 6·6, 1·4-31·0, respectively).

INTERPRETATION

Most neurological immune-related adverse events involved the CNS and were antibody negative. The presence of myocarditis, myasthenia, and myositis, of encephalopathy without inflammatory changes, or of lung cancer were independent predictors of death. Most deaths occurred during the first month of symptom onset. If our findings are replicated in additional cohorts, they could confirm that these patients need early and intensive treatment.

FUNDING

The Instituto de Salud Carlos III and the European Union.

Case Report: ICIs-induced Guillain-Barré syndrome recovered from mycophenolate mofetil

The emergence of immune checkpoint inhibitors (ICIs) has significantly prolonged the survival time of cancer patients. However, it may also lead to various immune-related adverse events (irAEs), including Guillain-Barré syndrome (GBS), a rare type of irAE. Most GBS patients can recover spontaneously due to the self-limited nature of the disease, but severe cases can result in respiratory failure or even death. Here we report a rare case of GBS occurring in a 58-year-old male patient with non-small cell lung cancer (NSCLC) who developed muscle weakness and numbness of the extremities during chemotherapy combined with KN046, a PD-L1/CTLA-4 bispecific antibody. Despite receiving methylprednisolone and γ-globulin, the patient's symptoms did not improve. However, there was significant improvement after treatment with mycophenolate mofetil (MM) capsules, which is not a routine regimen for GBS. To the best of our knowledge, this is the first reported case of ICIs-induced GBS that responded well to mycophenolate mofetil instead of methylprednisolone or γ-globulin. Thus, it provides a new treatment option for patients with ICIs-induced GBS.

Converging Mechanisms of Epileptogenesis and Their Insight in Glioblastoma

Glioblastoma (GBM) is the most common and advanced form of primary malignant tumor occurring in the adult central nervous system, and it is frequently associated with epilepsy, a debilitating comorbidity. Seizures are observed both pre- and post-surgical resection, indicating that several pathophysiological mechanisms are shared but also prompting questions about how the process of epileptogenesis evolves throughout GBM progression. Molecular mutations commonly seen in primary GBM, i.e., in PTEN and p53, and their associated downstream effects are known to influence seizure likelihood. Similarly, various intratumoral mechanisms, such as GBM-induced blood-brain barrier breakdown and glioma-immune cell interactions within the tumor microenvironment are also cited as contributing to network hyperexcitability. Substantial alterations to peri-tumoral glutamate and chloride transporter expressions, as well as widespread dysregulation of GABAergic signaling are known to confer increased epileptogenicity and excitotoxicity. The abnormal characteristics of GBM alter neuronal network function to result in metabolically vulnerable and hyperexcitable peri-tumoral tissue, properties the tumor then exploits to favor its own growth even post-resection. It is evident that there is a complex, dynamic interplay between GBM and epilepsy that promotes the progression of both pathologies. This interaction is only more complicated by the concomitant presence of spreading depolarization (SD). The spontaneous, high-frequency nature of GBM-associated epileptiform activity and SD-associated direct current (DC) shifts require technologies capable of recording brain signals over a wide bandwidth, presenting major challenges for comprehensive electrophysiological investigations. This review will initially provide a detailed examination of the underlying mechanisms that promote network hyperexcitability in GBM. We will then discuss how an investigation of these pathologies from a network level, and utilization of novel electrophysiological tools, will yield a more-effective, clinically-relevant understanding of GBM-related epileptogenesis. Further to this, we will evaluate the clinical relevance of current preclinical research and consider how future therapeutic advancements may impact the bidirectional relationship between GBM, SDs, and seizures.

Neurologic adverse events of cancer immunotherapy

Cancer immunotherapy encompasses a wide range of treatment modalities that harness the anti-tumor effects of the immune system and have revolutionized oncological treatment in recent years, with approval for its use in more and more cancers. However, it is not without side effects. Several neurological adverse events have been recognized associated with immune checkpoint inhibitors (ICI) and chimeric antigen receptor (CAR) T-cell therapy, the two main classes of cancer immunotherapy. With the increase in the prevalence of oncological diseases and this type of therapy, it is improbable that neurologists, oncologists, hematologists, and other healthcare professionals who deal with cancer patients will not encounter this type of neurologic complication in their practice in the following years. This article aims to review the epidemiology, clinical manifestations, diagnosis, and management of neurological complications associated with ICI and CAR T-cell therapy.

Neurological Manifestations Related to Immune Checkpoint Inhibitors: Reverse Translational Research by Using the European Real-World Safety Data

Immune checkpoint inhibitors (ICIs) are widely used improving clinical outcomes in many cancer patients. However, they can induce serious consequences, like neurological immune-related adverse drug reactions (NirADRs). Although these are rare complications, they can be serious with important impact on patients' quality of life. Our purpose is to describe these adverse events observed in the European clinical practice context. We carried out a descriptive analysis of individual case safety reports (ICSRs) related to ICIs collected until February 7, 2020, in the European spontaneous reporting database, EudraVigilance, and reported nervous disorders as suspect adverse drug reactions (ADRs). NirADRs were classified according to the Medical Dictionary for Regulatory Activities (MedDRA). In order to identify a hypothetical different reporting probability of the NirADR types between the ICI classes, we carried out a disproportionality analysis. The reporting odds ratio (ROR) with 95% CI was computed comparing the different ICI classes to each other based on their pharmacological target [the cytotoxic T-lymphocyte antigen-4 (CTLA-4), the programmed death-1 (PD-1) or its ligand (PD-L1)]. Finally, we researched in the literature the hypothesized mechanisms, which could explain the onset of these ICI-related neurological complications. Overall, we found 4,875 cases describing 6,429 ICI-related suspected NirADRs. ICI-related neurotoxicities include a wide range of central and peripheral events. These were mainly related to anti-PD-1 agents and occurred in male patients (59%). Our analysis confirmed a gender difference of NirADRs. Twenty-three percent of the events (comprising myasthenia gravis, neuropathy peripheral, and cerebral infarction) had unfavorable fallouts, including fatal outcome (7%). Majority of the NirADRs were categorized as "Neurological disorders NEC" HLGTs MedDRA (2,076; 32%). In 1,094 cases (22%), more NirADRs overlapped with other neurologic complications. An interesting overlapping of myasthenia gravis with myositis or myocarditis emerged. From our disproportionality analysis, an increased reporting probability of peripheral neuropathies and headaches emerged with ipilimumab when compared to anti-PD-1 and anti-PD-L1 agents. However, neuromuscular disorders were more probably reported with anti-PD-1. Several pathogenic mechanisms, including neuronal damage by T cells and autoantibodies and/or cytokine-mediated inflammation processes, have been hypothesized. However, the pathogenesis of these ICI-related complications is not completely understood. Considering the recent marketing authorizations of ICIs, further studies are strongly needed to monitor their neurologic safety profile.

Neurological complications of cancer immunotherapy

Immunotherapy has emerged as a powerful therapeutic approach in many areas of clinical oncology and hematology. The approval of ipilimumab, a monoclonal antibody targeting the immune cell receptor CTLA-4, has marked the beginning of the era of immune checkpoint inhibitors. In the meantime, numerous antibodies targeting the PD-1 pathway have expanded the class of clinically approved immune checkpoint inhibitors. Furthermore, novel antibodies directed against other immune checkpoints are currently in clinical evaluation. More recently, bispecific antibodies, which link T cells directly to tumor cells as well as adoptive T cell transfer with immune cells engineered to express a chimeric antigen receptor, have been approved in certain indications. Neurological complications associated with the use of these novel immunotherapeutic concepts have been recognized more and more frequently. Immune checkpoint inhibitors may cause various neurological deficits mainly by alterations of the peripheral nervous system's integrity. These include radiculopathies, neuropathies, myopathies as well as myasthenic syndromes. Side effects involving the central nervous system are less frequent but may result in severe clinical symptoms and syndromes. The administration of chimeric antigen receptor (CAR) T cell is subject to rigorous patient selection and their use is frequently associated with neurological complications including encephalopathy and seizures, which require immediate action and appropriate therapeutic measures. Close clinical monitoring for neurological symptoms is key for early recognition of immunotherapy-related side effects. Comprehensive diagnostic work-up and adequate therapeutic measures are essential to avoid further clinical deterioration and residual neurological deficits.

Immune Checkpoint Inhibitor-Induced Polymyositis and Myasthenia Gravis with Fatal Outcome

We here report on a 74-year-old man diagnosed with a pT3cN0 BRAF-mutated and mismatch repair-deficient adenocarcinoma in the colon ascendens and 3 liver metastases. After hemicolectomy, the patient received treatment with the PD-1 inhibitor pembrolizumab. Three weeks later (on day 22), laboratory tests showed leukocytosis and an increase in transaminases; immune checkpoint inhibitor (ICI)-induced hepatitis was suspected and prednisolone therapy was initiated. On day 29, the patient was acutely hospitalized due to dyspnea, somnolence and walking difficulties. Dysarthria, hoarseness, muscle pain and weakness had developed and the dose of prednisolone was increased. Serum levels of lactate dehydrogenase, creatine kinase and myoglobin were increased and ICI-induced myositis was suspected. Antibodies against acetylcholine receptor and titin were present, indicating myasthenia gravis. Eventually, bulbar myopathy developed, including dysarthria and dysphagia, and the patient could no longer attain saturation without oxygen. The patient was transferred to the intensive care unit, intubated and given methylprednisolone, intravenous immunoglobulins and infliximab. The patient developed carbon dioxide retention and died on day 39. Microscopical examination of the intercostal musculature, diaphragm, cervical musculature and tongue showed inflammatory infiltration and fibrosis consistent with a pronounced myositis. In the liver, microscopical examination did not show metastases from colorectal cancer but instead a hepatocellular cancer. The cause of death was determined as respiratory insufficiency due to polymyositis. In conclusion, ICIs may induce myositis combined with neurological immune-related adverse events. In patients developing muscle weakness and pain under ICI therapy, myositis should be suspected.