The Role of Immune Checkpoint Therapy in Propagating Neurologic Immune-Related Adverse Events: Inducing or "Unmasking" Autoimmunity?

Facial palsy induced by immune checkpoint blockade: A systematic analysis of clinical trials and a pharmacovigilance study of postmarketing data

BACKGROUND

To estimate the risk of facial nerve palsy (FP) associated with immune checkpoint inhibitors (ICIs), and to describe its clinical features.

METHODS

Data from randomized controlled trials (RCTs) and FDA Adverse Event Reporting System (FAERS) database were included. The primary outcome was the risk of FP events associated with ICIs. For data from RCTs, pooled analysis was performed by using risk ratios (RRs) with 95%CIs. In a separate retrospective pharmacovigilance study of FAERS, disproportionality was analyzed using the proportional reports reporting odds ratio (ROR) and information components (IC).

RESULTS

A total of 21 RCTs (193,05 patients) were included, ICIs were associated with increased risk of FP (OR = 3.07, 95%CI:1.43-6.58). Results of subgroup analysis indicated that OR of ICI-related FP did not vary significantly by tumor type, ICIs treatment schedule, case of events, study design, median PFS and publication status. FAERS pharmacovigilance data identified 274 cases of FP related to ICIs therapy. ICIs were significantly associated with over-reporting frequencies of FP (ROR = 3.03, 95%CI:2.69-3.42; IC = 1.56, 95%CI:1.38-1.76). The median onset time of FP was 5.5 weeks, drug interruption was recorded in 78.0% of cases, with a positive dechallenge in 82.8 % of cases, and 71.7% of cases were recovered or recovering.

CONCLUSIONS

These data suggest that ICIs were significantly associated with increased risk of FP in both trial settings and in clinical practice.

Evaluation and management of acute high-grade immunotherapy-related neurotoxicity

Immune checkpoint inhibitor monoclonal antibodies allow the host's immune system to attack tumors, which has revolutionized cancer care over the last decade. As the use of immune checkpoint inhibitors has expanded, so have autoimmune-like complications known as immune-related adverse events. These include the infrequent but increasingly more common, potentially deadly neurological immune related adverse events. When feeling acutely ill, patients will often seek care not from their oncologist but from their family physician, clinics, emergency, and urgent care sites, or other available providers. Thus, while assessing acutely ill cancer patients who are experiencing neurological symptoms, non-oncologists should be prepared to recognize, diagnose, and treat neurological immune related adverse events in addition to more familiar conditions. This narrative review is designed to update acute care clinicians on current knowledge and to present a symptom-based framework for evaluating and treating neurological immune related adverse events based on the leading immunotoxicity organizations' latest recommendations.

A review of neurotoxicities associated with immunotherapy and a framework for evaluation

Immuno-oncology agents, including immune checkpoint inhibitors (ICIs) and chimeric antigen receptor T (CAR-T) cell therapies, are increasing in use for a growing list of oncologic indications. While harnessing the immune system against cancer cells has a potent anti-tumor effect, it can also cause widespread autoimmune toxicities that limit therapeutic potential. Neurologic toxicities have unique presentations and can progress rapidly, necessitating prompt recognition. In this article, we review the spectrum of central and peripheral neurologic immune-related adverse events (irAEs) associated with ICI therapies, emphasizing a diagnostic framework that includes consideration of the therapy regimen, timing of symptom onset, presence of non-neurologic irAEs, pre-existing neurologic disease, and syndrome specific features. In addition, we review the immune effector cell-associated neurotoxicity syndrome (ICANS) associated with CAR-T cell therapy and address diagnostic challenges specific to patients with brain metastases. As immunotherapy use grows, so too will the number of patients affected by neurotoxicity. There is an urgent need to understand pathogenic mechanisms, predictors, and optimal treatments of these toxicities, so that we can manage them without sacrificing anti-tumor efficacy.