Moderate-to-severe eosinophilia induced by treatment with immune checkpoint inhibitors: 37 cases from a national reference center for hypereosinophilic syndromes and the French pharmacovigilance database

Exploring the Dynamics of Immune Checkpoint Inhibitor-Induced Eosinophilia in Advanced/Metastatic Melanoma: A Comprehensive Retrospective Analysis

BACKGROUND

Immune-related eosinophilia has emerged as an adverse event associated with immune checkpoint inhibitors (ICIs). Its prevalence, severity, duration, clinical significance, diagnostic approach, and management remain unexplored.

METHODS

We conducted a retrospective review of melanoma patient records at a university referral center. Our analysis encompassed the incidence of eosinophilia, baseline disease characteristics, treatment modalities, peak eosinophil counts, associated symptoms, diagnostic procedures, management strategies, disease course, and prognostic implications.

RESULTS

A total of 308 patients were included. Eosinophilia was present in 21.4%, and there was no association with gender, age, histologic type, stage, or BRAF mutation status. The median time interval from treatment initiation to the eosinophilia onset was 56 days, the median eosinophil count at first presentation was 0.70 × 109/L, and the maximum eosinophil count was 1.02 × 109/L. The rate of eosinophilia was significantly higher in patients treated with nivolumab plus bempegaldesleukin (50.0%), followed by nivolumab plus ipilimumab (21.7%). Symptomatic patients and/or patients with hypereosinophilia were assessed for organ involvement and for the identification of the cause of eosinophilia. Patients requiring medical intervention were managed with corticosteroids or antihistamines. Eosinophilia relapsed in 31.8% when rechallenged. While non-significant, there was a numeric trend for longer overall survival in patients with eosinophilia (42.6 vs. 27.9 months, p = 0.178).

CONCLUSIONS

This study marks the first comprehensive approach of the relationship between the type of immunotherapy and the incidence of eosinophilia in melanoma patients. It also delves into the patients' baseline characteristics, diagnostic assessment, management, and prognosis, providing useful guidance for physicians treating patients with ICIs.

Squamous Cell Carcinoma with Prominent Eosinophils

Eosinophils are often encountered in the stroma and peritumoral microenvironment of squamous cell carcinomas. Because eosinophils are readily identified on routine hematoxylin and eosin stained sections, researchers have explored multiple ways in which identifying the extent of eosinophil infiltration on routine biopsy and excisional specimens might provide diagnostic and prognostic information. We review the literature on this evolving topic.

The ascendancy of eosinophil counts in non-small cell lung cancer: a potential marker for predicting response and survival under nivolumab treatment

Lung cancer is the leading cause of cancer-related death globally and is often diagnosed at an advanced stage. Nivolumab represents a significant advancement for treating advanced non-small cell lung cancer (NSCLC). However, the absence of reliable biomarkers predicting treatment response hinders personalized therapy. Eosinophils play a notable role in cancer biology, particularly when treated with immune checkpoint inhibitors. Eosinophils can infiltrate tumor tissues, directly interacting with tumor cells or modifying the tumor microenvironment. This study aims to assess the potential of PD-L1 expression and peripheral blood eosinophil count in predicting treatment response and patient survival. This retrospective cohort study was conducted in three major cancer centers in Turkey, including 174 advanced NSCLC patients who had progressed after chemotherapy between July 2019 and November 2023. Demographic and clinical data, PD-L1 levels, and eosinophil counts were analyzed using SPSS 27.0. Survival analyses were performed with Kaplan-Meier and Cox regression models. Increased peripheral blood eosinophil count was positively associated with response to Nivolumab treatment and overall survival. Among treatment responders, 54.1% had eosinophil levels between 100-499 cells/mm3 before treatment, increasing to 70.8% post-treatment. In patients with high PD-L1 positivity (>50%), eosinophil levels averaged 266.0 cells/mm3, with improved survival outcomes (mean survival: 24.06 months, median: 20.0 months). Non-responders had a mean survival of 19.05 months and a median survival of 15.2 months. Peripheral eosinophil count appears to be a potential biomarker for predicting response to Nivolumab treatment and survival in NSCLC patients. Combined evaluation of eosinophil count and PD-L1 expression may enhance personalized treatment strategies. Further validation in prospective, randomized studies is necessary.

Targeted inhibition of the IL5 axis for immune checkpoint inhibitors eosinophilic-induced adverse events

Given the broad implementation of immune checkpoint inhibitors (ICI) for cancer therapy, we encounter a variety of immune-related adverse events (irAE) including immune-related blood eosinophilia. Eosinophilia demonstrated a potential positive predictive marker for a beneficial clinical response to ICI. However, there are reports of eosinophil-induced adverse events (Eo-irAE) with organ dysfunction requiring initiation of oral glucocorticoid therapy and discontinuation of ICI.We aim to assess the efficacy and safety of interleukin (IL) 5-axis inhibition in Eo-irAE secondary to ICI therapy.We present three cases of Eo-irAE referred to our allergy and clinical immunology unit at Hadassah Hebrew University Medical Center following therapy with pembrolizumab and nivolumab, monoclonal antibodies that target the programmed cell death 1 (PD-1) receptor, for two cases of melanoma and one metastatic non-small cell lung carcinoma. Following informed consent and committee approval, two patients were treated with 1-3 doses of mepolizumab, 100 mg, monoclonal IgG1 kappa anti-IL-5 antibody, and one patient received up-to-date 9 doses of benralizumab, 30 mg, monoclonal IgG1 kappa antibody directed against the alpha chain of the interleukin-5 receptor, both administered subcutaneously. Patients were carefully followed and treatment response was assessed by physical examinations and laboratory tests.Hypereosinophilia at the level of 2300-8000 K/UL was observed 8-12 months following therapy accompanied by symptoms of dyspnea, arthralgia, myalgia, fasciitis, 'morphea'-like lesions, fatigue, abdominal discomfort, pruritus, and chest pain. ICI discontinuation did not improve symptoms, two patients were resistant to glucocorticoids and therefore biological treatment was initiated to inhibit the IL5 axis. Patients demonstrated rapid clinical response and a decrease in peripheral blood eosinophil levels with long-term symptoms remission. There were no signals of negative impacts, such as tumor progression following IL5 axis inhibition.Eosinophilia secondary to ICI therapy can lead to organ dysfunction. Discontinuation of ICI might not be effective and symptoms may be refractory to steroid therapy hence targeted inhibition of the IL5 axis should be considered.

Immune checkpoint inhibitor-induced diarrhea and colitis: an overview

Immune checkpoint inhibitors (ICIs) have emerged as an integral component of the management of various cancers and have contributed to significant improvements in overall survival. Most available ICIs target anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA4), and anti-programmed cell death 1/programmed cell death ligand 1 (anti-PD1/PDL1). Gastrointestinal immune-related adverse events remain a common complication of ICIs. The predominant manifestations include diarrhea and colitis, which often manifest concurrently as immune-mediated diarrhea and colitis (IMDC). Risk factors for developing these side effects include baseline gut microbiota, preexisting autoimmune disorders, such as inflammatory bowel disease, and type of neoplasm. The hallmark symptom of colitis is diarrhea which may be accompanied by mucus or blood in stools. Patients may also experience abdominal pain, fever, vomiting, and nausea. If not treated rapidly, ICI-induced colitis can lead to serious life-threatening complications. Current management is based on corticosteroids as first-line, and immunosuppressants like infliximab or vedolizumab for refractory cases. Microbiota transplantation and specific cytokines and lymphocyte replication inhibitors are being investigated. Optimal patient care requires maintaining a balance between treatment toxicity and efficacy, hence the aim of this review is to enhance readers' comprehension of the gastrointestinal adverse events associated with ICIs, particularly IMDC. In addition to identifying the risk factors, we discuss the incidence, clinical presentation, workup, and management options of IMDC.

Acute Eosinophilic Pneumonia Induced by Immune Checkpoint Inhibitor and Anti-TIGIT Therapy

BACKGROUND Immune checkpoint inhibitors (ICIs) have been linked to various immune-related adverse events, including pneumonitis, necessitating early recognition and potential treatment discontinuation. Acute eosinophilic pneumonia (AEP) induced by ICIs, particularly with no reported cases involving anti-TIGIT therapy, is rare. This report describes a case of AEP following treatment with pembrolizumab and anti-TIGIT therapy. CASE REPORT A 46-year-old woman with lung adenoid cystic carcinoma and chronic hypoxemic respiratory failure on long-term oxygen therapy presented with fever, cough, and shortness of breath. She underwent left pneumonectomy and radiation therapy at diagnosis 9 years earlier. She was participating in a clinical trial using pembrolizumab and anti-TIGIT EOS-448, due to cancer progression. After starting therapy, she developed stable peripheral eosinophilia and a skin rash, suggestive of a drug reaction. On admission, she was in acute-on-chronic hypoxemic respiratory failure, febrile, with an elevated eosinophil count and new multifocal infiltrates in the right lung. Despite broad antibiotics coverage for pneumonia, she developed worsening respiratory symptoms and eosinophilia. She was then empirically started on intravenous methylprednisolone for acute eosinophilic pneumonia without confirmatory bronchoscopy as she was at high risk with her previous pneumonectomy. She subsequently had rapid improvement in her symptoms. CONCLUSIONS AEP should be considered in patients treated with ICIs who develop immune-related adverse effects. Although bronchoscopy findings are part of AEP's diagnostic criteria, this case underscores the importance of clinical judgment in the prompt initiation of steroids, even without confirmatory bronchoscopy, in rapidly progressing cases. The role of anti-TIGIT therapy in this context remains uncertain.

Pembrolizumab-induced asthma exacerbation with hypereosinophilia and elevated interleukin-5 in endometrial cancer: A case report

Pembrolizumab is an anti-programmed cell death-1 (PD-1) antibody used to treat various cancer types. Treatments with such immune checkpoint inhibitors cause immune-related adverse events. However, airway inflammation caused by immune-related adverse events has rarely been reported. A 54-year-old woman with endometrial cancer experienced asthma exacerbation, and increased blood eosinophil counts 3 months after pembrolizumab administration. Although asthma exacerbation improved, the resumption of pembrolizumab caused the recurrence of dry cough and hypereosinophilia. The discontinuation of pembrolizumab improved her symptoms. Serum interleukin-5 levels increased during pembrolizumab treatment but decreased upon discontinuation. The blockade of PD-1 and its ligand may exacerbate asthma through eosinophilic inflammation.

Clinical and translational attributes of immune-related adverse events

With immune checkpoint inhibitors (ICIs) becoming the mainstay of treatment for many cancers, managing their immune-related adverse events (irAEs) has become an important part of oncological care. This Review covers the clinical presentation of irAEs and crucial aspects of reversibility, fatality and long-term sequelae, with special attention to irAEs in specific patient populations, such as those with autoimmune diseases. In addition, the genetic basis of irAEs, along with cellular and humoral responses to ICI therapy, are discussed. Detrimental effects of empirically used high-dose steroids and second-line immunosuppression, including impaired ICI effectiveness, call for more tailored irAE-treatment strategies. We discuss open therapeutic challenges and propose potential avenues to accelerate personalized management strategies and optimize outcomes.

Role of eosinophilia in patients with recurrent/metastatic head and neck squamous cell carcinoma treated with nivolumab: Prediction of immune-related adverse events and favorable outcome

INTRODUCTION

Immune-related adverse events (irAEs) are prognostic factors for patients on nivolumab. However, predictors of irAEs have not yet been identified. We aimed to investigate the predictors of irAEs occurrence and nivolumab discontinuation due to irAEs.

METHODS

Sixty-two patients with recurrent/metastatic head and neck squamous cell carcinoma received nivolumab therapy between June 2017 and December 2020. Treatment outcome was compared between the groups with or without irAEs. The irAE (+) group was further divided by nivolumab discontinuation. Progression-free survival (PFS) and overall survival (OS) were compared between the groups. Predictors of irAE occurrence were analyzed.

RESULTS

Twenty-one patients (33.9%) developed irAEs, and six (28.6%) discontinued nivolumab due to severe irAEs. The irAE (+) group had significantly longer PFS and OS than the irAE (-) group (median PFS, 12.7 vs. 1.9 months; median OS, 33.1 vs. 12.8 months). The treatment outcomes in the discontinuation group were comparable to those in the non-discontinuation group. The maximum absolute eosinophil count (AEC) during nivolumab therapy was significantly higher in the irAE (+) group than in the irAE (-) group (548.8 vs. 182) and higher in the discontinuation group than in the non-discontinuation group (729.3 vs. 368.6). The receiver operating characteristic curve showed that the maximum AEC had a moderate-to-high accuracy for predicting irAE occurrence (area under the curve [AUC], 0.757) and nivolumab discontinuation (AUC, 0.893).

DISCUSSION

Monitoring AEC during nivolumab therapy may be useful in predicting irAE occurrence, nivolumab discontinuation, and disease prognosis.

A Curious Case of Gastrointestinal Eosinophilia Induced by Treatment With Immune Checkpoint Inhibitors

Immune checkpoint inhibitors have revolutionized oncologic treatment. However, they are linked to various side effects,¹ a rare one being gastrointestinal eosinophilia. We present a patient with malignant melanoma treated with nivolumab. She underwent upper endoscopy 6 months later which showed a duodenal ulcer and linear furrows of her esophagus. Biopsies of the esophagus, stomach, and duodenum were consistent with eosinophilic infiltration. Repeat endoscopy after nivolumab discontinuation revealed near-complete resolution of eosinophilia in the stomach and duodenum, with lingering eosinophilia in the esophagus. The purpose of this report was to increase awareness of gastrointestinal eosinophilia associated with checkpoint inhibitors.

The multidisciplinary approach to eosinophilia

Eosinophilic granulocytes are normally present in low numbers in the bloodstream. Patients with an increased number of eosinophilic granulocytes in the differential count (eosinophilia) are common and can pose a clinical challenge because conditions with eosinophilia occur in all medical specialties. The diagnostic approach must be guided by a thorough medical history, supported by specific tests to guide individualized treatment. Neoplastic (primary) eosinophilia is identified by one of several unique acquired genetic causes. In contrast, reactive (secondary) eosinophilia is associated with a cytokine stimulus in a specific disease, while idiopathic eosinophilia is a diagnosis by exclusion. Rational treatment is disease-directed in secondary cases and has paved the way for targeted treatment against the driver in primary eosinophilia, whereas idiopathic cases are treated as needed by principles in eosinophilia originating from clonal drivers. The vast majority of patients are diagnosed with secondary eosinophilia and are managed by the relevant specialty-e.g., rheumatology, allergy, dermatology, gastroenterology, pulmonary medicine, hematology, or infectious disease. The overlap in symptoms and the risk of irreversible organ involvement in eosinophilia, irrespective of the cause, warrants that patients without a diagnostic clarification or who do not respond to adequate treatment should be referred to a multidisciplinary function anchored in a hematology department for evaluation. This review presents the pathophysiology, manifestations, differential diagnosis, diagnostic workup, and management of (adult) patients with eosinophilia. The purpose is to place eosinophilia in a clinical context, and therefore justify and inspire the establishment of a multidisciplinary team of experts from diagnostic and clinical specialties at the regional level to support the second opinion. The target patient population requires highly specialized laboratory analysis and therapy and occasionally has severe eosinophil-induced organ dysfunction. An added value of a centralized, clinical function is to serve as a platform for education and research to further improve the management of patients with eosinophilia. Primary and idiopathic eosinophilia are key topics in the review, which also address current research and discusses outstanding issues in the field.

A first-in-human study of the fibroblast activation protein-targeted, 4-1BB agonist RO7122290 in patients with advanced solid tumors

This first-in-human study evaluated RO7122290, a bispecific fusion protein carrying a split trimeric 4-1BB (CD137) ligand and a fibroblast activation protein α (FAP) binding site that costimulates T cells for improved tumor cell killing in FAP-expressing tumors. Patients with advanced or metastatic solid tumors received escalating weekly intravenous doses of RO7122290 as a single agent (n = 65) or in combination with a 1200-milligram fixed dose of the anti-programmed death-ligand 1 (anti-PD-L1) antibody atezolizumab given every 3 weeks (n = 50), across a tested RO7122290 dose range of 5 to 2000 milligrams and 45 to 2000 milligrams, respectively. Three dose-limiting toxicities were reported, two at different RO7122290 single-agent doses (grade 3 febrile neutropenia and grade 3 cytokine release syndrome) and one for the combination (grade 3 pneumonitis). No maximum tolerated dose was identified. The pharmacokinetic profile of RO7122290 suggested nonlinearity in elimination. The observed changes in peripheral and tissue pharmacodynamic (PD) biomarkers were consistent with the postulated mechanism of action. Treatment-induced PD changes included an increase in proliferating and activated T cells in peripheral blood both in the single-agent and combination arms. Increased infiltration of intratumoral CD8⁺ and Ki67⁺CD8⁺ T cells was observed for both treatment regimens, accompanied by the up-regulation of T cell activation genes and gene signatures. Eleven patients experienced a complete or partial response, six of whom were confirmed to be immune checkpoint inhibitor naive. These results support further evaluation of RO7122290 in combination with atezolizumab or other immune-oncology agents for the treatment of solid tumors.

French guidelines for the etiological workup of eosinophilia and the management of hypereosinophilic syndromes

Eosinophilic-related clinical manifestations are protean and the underlying conditions underpinning eosinophilia are highly diverse. The etiological workup of unexplained eosinophilia/hypereosinophilia can be challenging, and can lead sometimes to extensive, inappropriate, costly and/or invasive investigations. To date, guidelines for the etiological workup and management of eosinophilia are mainly issued by hematologists, and thus mostly cover the scope of clonal hypereosinophilic syndromes (HES). Here, thanks to an extensive literature review, and thanks to the joint work of a large panel of experts involving physicians from both adult and pediatric medicine and from various subspecialties (as well as a representative of a patients' association representative), we provide recommendations for both the step-by step diagnostic workup of eosinophilia (whether unexplained or within specific contexts) as well as the management and follow-up of the full spectrum of eosinophilic disorders (including clonal, reactive, lymphocytic and idiopathic HES, as well as single-organ diseases). Didactic prescription summaries intended to facilitate the prescription of eosinophil-targeted drugs are also provided, as are practical diagnostic and therapeutic algorithms. Lastly, this set of recommendations also includes a summary intended for general practitioners, as well as an overview of the therapeutic patient education program set up by the French reference center for HES. Further updates will be mandatory as new validated information emerges.

Predictive Biomarkers for Immune-Related Endocrinopathies following Immune Checkpoint Inhibitors Treatment

In recent years, in the context of the increase in the life expectancy of cancer patients, special attention has been given to immunotherapy and, indeed, to immune checkpoint inhibitors. The use of immune checkpoint inhibitors has increased rapidly, and approximately 40% of cancer patients are eligible for this treatment. Although their impact is valuable on cancer treatment, immune checkpoint inhibitors come with side effects, known as immune-related adverse effects. These can affect many systems, including cutaneous, musculoskeletal, cardiovascular, gastrointestinal, endocrine, neural, and pulmonary systems. In this review, we focus on immune-related endocrinopathies that affect around 10% of all treated patients. Endocrine dysfunctions can manifest as hypophysitis, thyroid dysfunction, hypoparathyroidism, insulin-deficient diabetes mellitus, and primary adrenal insufficiency. Currently, there are multiple ongoing clinical trials that aim to identify possible predictive biomarkers for immune-related adverse effects. The design of those clinical trials relies on collecting a variety of biological specimens (tissue biopsy, blood, plasma, saliva, and stool) at baseline and regular intervals during treatment. In this review, we present the predictive biomarkers (such as antibodies, hormones, cytokines, human leukocyte antigens, and eosinophils) that could potentially be utilized in clinical practice in order to predict adverse effects and manage them appropriately.

Hematologic malignancies following immune checkpoint inhibition for solid tumors

Immune checkpoint inhibition (ICI) can induce durable responses in patients with advanced malignancies. Three cases of hematological neoplasia following ICI for solid tumors have been reported to date. We present five patients treated at our tertiary referral center between 2017 and 2021 who developed chronic myeloid leukemia (two patients), acute myeloid leukemia, myelodysplastic syndrome and chronic eosinophilic leukemia during or after anti-PD-1-based treatment. Molecular analyses were performed on pre-ICI samples to identify baseline variants in myeloid genes. We hypothesize that PD-1 blockade might accelerate progression to overt myeloid malignancies and discuss potential underlying mechanisms.

Strongyloides —An uncommon cause of eosinophilia whilst on durvalumab

Background

In malignancy, eosinophils have been shown to play an important role in the tumour micro‐environment. Increasingly, development of eosinophilia with immune checkpoint inhibitor (ICI) use is thought to be predictive of prognosis and development of immune‐related adverse events. However, there are many other causes for developing eosinophilia which can contribute to the difficulties in diagnosis and management.

Case

Here, we present a case of Strongyloides parasitic infection as an uncommon differential for eosinophilia in a patient with lung cancer receiving a PDL‐1 ICI, durvalumab, in Australia.

Conclusion

This case highlights the complexities exploring the multiple potential causes of eosinophilia and the subsequent management, to allow safe continuation of ICI.

Blood Eosinophils Are Associated with Efficacy of Targeted Therapy in Patients with Advanced Melanoma

Background: Eosinophils appear to contribute to the efficacy of immunotherapy and their frequency was suggested as a predictive biomarker. Whether this observation could be transferred to patients treated with targeted therapy remains unknown. Methods: Blood and serum samples of healthy controls and 216 patients with advanced melanoma were prospectively and retrospectively collected. Freshly isolated eosinophils were phenotypically characterized by flow cytometry and co-cultured in vitro with melanoma cells to assess cytotoxicity. Soluble serum markers and peripheral blood counts were used for correlative studies. Results: Eosinophil-mediated cytotoxicity towards melanoma cells, as well as phenotypic characteristics, were similar when comparing healthy donors and patients. However, high relative pre-treatment eosinophil counts were significantly associated with response to MAPKi (p = 0.013). Eosinophil-mediated cytotoxicity towards melanoma cells is dose-dependent and requires proximity of eosinophils and their target in vitro. Treatment with targeted therapy in the presence of eosinophils results in an additive tumoricidal effect. Additionally, melanoma cells affected eosinophil phenotype upon co-culture. Conclusion: High pre-treatment eosinophil counts in advanced melanoma patients were associated with a significantly improved response to MAPKi. Functionally, eosinophils show potent cytotoxicity towards melanoma cells, which can be reinforced by MAPKi. Further studies are needed to unravel the molecular mechanisms of our observations.

Eosinophils and Lung Cancer: From Bench to Bedside

Eosinophils are rare, multifunctional granulocytes. Their growth, survival, and tissue migration mainly depend on interleukin (IL)-5 in physiological conditions and on IL-5 and IL-33 in inflammatory conditions. Preclinical evidence supports an immunological role for eosinophils as innate immune cells and as agents of the adaptive immune response. In addition to these data, several reports show a link between the outcomes of patients treated with immune checkpoint inhibitors (ICI) for advanced cancers and blood eosinophilia. In this review, we present, in the context of non-small cell lung cancer (NSCLC), the biological properties of eosinophils and their roles in homeostatic and pathological conditions, with a focus on their pro- and anti-tumorigenic effects. We examine the possible explanations for blood eosinophilia during NSCLC treatment with ICI. In particular, we discuss the value of eosinophils as a potential prognostic and predictive biomarker, highlighting the need for stronger clinical data. Finally, we conclude with perspectives on clinical and translational research topics on this subject.

Eosinophil counts can be a predictive marker of immune checkpoint inhibitor-induced secondary adrenal insufficiency: a retrospective cohort study

Immune checkpoint inhibitors (ICIs) treatment can result in endocrine immune-related adverse events (irAEs), including pituitary dysfunction. Quick diagnosis of secondary adrenal insufficiency (AI) is challenging because no universal definition of ICI-induced secondary AI has been agreed. The aim of this study was to clarify the clinical features of ICI-induced secondary AI that can be used for screening in standard clinical practice. This retrospective study was performed using the medical records of patients who received ICIs at Hirosaki University Hospital between 1 September 2014 and 31 January 2021. Longitudinal clinical data of patients who developed AI were analyzed and compared with the data of thyroid irAEs. Regression analysis showed a significant correlation between ICI-induced secondary AI and absolute or relative eosinophil counts at pre-onset of AI, as well as differences or rate of increase in eosinophil counts at baseline and at pre-onset. Absolute eosinophil counts > 198.36/µL or relative eosinophil counts > 5.6% at pre-onset, and a difference of 65.25/µL or a rate of eosinophil count increase of 1.97 between the baseline and at pre-onset showed the best sensitivity and specificity. This is the first report to demonstrate that eosinophil counts can be a predictor of ICI-induced secondary AI.

Peripheral blood eosinophil count is associated with response to chemoimmunotherapy in metastatic triple-negative breast cancer

Introduction: There is evidence for an association between peripheral blood eosinophil count (PBEC) and response to cancer immunotherapy; however, such data is limited in metastatic triple-negative breast cancer (mTNBC). Patients & methods: This report presents patients (n = 14) who received a combination of durvalumab and paclitaxel for mTNBC (NCT02628132). Results: There was a statistically significant correlation (p = 0.028) between an increase in PBEC (>300/mm³) during treatment and response to the combination therapy. Survival analysis showed a statistically significant association between progression-free survival and increased PBEC, after therapy (p = 0.005). A similar trend existed for overall survival, although it did not reach statistical significance (p = 0.167). Conclusion: This is the first study to report on eosinophilia in mTNBC treated with chemoimmunotherapy and supports a role for eosinophils in immunotherapy for mTNBC.

Eosinophilic Vasculitis and Arteritic Anterior Ischemic Optic Neuropathy Associated With Anti-PD-L1 Therapy

Immune checkpoint inhibitor therapy is frequently associated with immune-related adverse events, which occasionally manifest with visual symptoms. Here, we describe a case of unilateral and sudden-onset painless vision loss in an 82-year-old man with metastatic non-small cell lung cancer receiving immunotherapy with the anti-programmed death-ligand 1 agent atezolizumab. Examination demonstrated a right-sided relative afferent pupillary defect, diffusely swollen optic disc, and delayed choroidal and retinal arterial filling on fundus fluorescein angiography, consistent with an arteritic anterior ischemic optic neuropathy. Histology of an ipsilateral temporal artery biopsy revealed a transmural eosinophilic infiltrate without granulomas, while serology revealed the presence of antineutrophil cytoplasmic antibodies. Peripheral eosinophilia was also noted, which preceded treatment by several months. This report highlights the importance of clinician awareness of immune checkpoint inhibitors and their systemic and ophthalmic complications, which rarely appear to extend to eosinophilic temporal arteritis.

Intestinal Microbiota and Gene Expression Reveal Similarity and Dissimilarity Between Immune-Mediated Colitis and Ulcerative Colitis

Immune checkpoint inhibitors (ICIs) have become the standard of care for several cancers. However, ICI therapy has also been associated with various immune-related adverse events (irAEs). Clinical manifestations of immune-related colitis resemble those of inflammatory bowel diseases such as ulcerative colitis (UC). The composition of the bowel microflora is thought to influence the development of inflammatory bowel disease and irAE colitis. We profiled the gene expressions and microbe compositions of colonic mucosa from patients with solid cancers receiving anti-PD-L1 antibody treatment; we then compared the expression profiles associated with irAE colitis with those associated with UC. The pathway enrichment analysis revealed functional similarities between inflamed regions of irAE colitis and UC. The common enriched pathways included leukocyte extravasation and immune responses, whereas non-inflamed mucosa from patients with irAE colitis was distinct from patients with UC and was characterized by the recruitment of immune cells. A similarity between the microbiota profiles was also identified. A decreased abundance of Bacteroides species was observed in inflamed regions from both irAE colitis and UC based on a microbiota composition analysis of 16S rDNA sequencing. Pathways associated with molecule transport systems, including fatty acids, were enriched in inflamed and non-inflamed irAE colitis and inflamed UC, similar to Piphillin-inferred KEGG pathways. While UC is characterized by local regions of inflammation, ICI treatment extends to non-inflammatory regions of the colonial mucosa where immune cells are reconstituted. This analysis of the similarity and heterogeneity of irAE colitis and UC provides important information for the management of irAE colitis.

Successful management of severe bronchial asthma exacerbated by anti-PD-L1 treatment: A report of two cases

Immune checkpoint inhibitors (ICIs) have been used for various carcinomas. However, immune-related adverse events have been observed. There have been few reports of treatment with biologics for severe bronchial asthma induced by ICI; therefore, their efficacy is unknown. We report two cases of severe bronchial asthma requiring systemic steroid administration while using anti-programmed death-ligand 1 (PD-L1) antibody for advanced non-small-cell lung cancer. The anti-interleukin-5 antibody, mepolizumab, was introduced, resulting in the discontinuation of systemic prednisolone and good asthma control. These reports suggest that treatment with biologics may be effective in severe cases of poorly controlled bronchial asthma during ICI therapy.

Elevated Eosinophil Count Following Pembrolizumab Treatment for Non-Small Cell Lung Cancer

Immune-related adverse events (IRAEs) are a common yet problematic phenomenon in patients who are treated with immune checkpoint inhibitors (ICIs). Current research efforts have explored the exact pathophysiology of IRAEs in the clinical setting. However, a rare subset of IRAEs that is less highlighted and may cause detrimental effects are hematological IRAEs (heme-IRAEs). Of note, immune-induced eosinophilia itself is a heme-IRAE that is worthy of further investigation.

In this report, we present two cases of advanced staged non-small cell lung cancer (NSCLC) treated with single-agent pembrolizumab, and who subsequently sustained markedly elevated eosinophil counts (EEC) on laboratory findings. The two patients were Caucasian and both were diagnosed with NSCLC, although with differing histologies: a 76-year-old male with adenocarcinoma and a 66-year-old female with squamous cell carcinoma. Programmed death-ligand 1 (PD-L1) expression was detected via immunohistochemistry (IHC) and molecular tumor profiling did not show any actionable oncogenic mutations. Both patients were treatment-naïve and received pembrolizumab as first-line systemic therapy. The male patient, a former heavy smoker, underwent 18 months of pembrolizumab treatment before high eosinophil counts and was diagnosed with immunotherapy-related apoptotic colopathy after colonoscopy. Following pembrolizumab discontinuation, he remains under surveillance with good disease control and does not show any ongoing symptoms. The female patient, a never-smoker, underwent 15 cycles of pembrolizumab before the discontinuation of the treatment after consistently high levels of eosinophil counts. Both patients were treated with systemic corticosteroids after the discontinuation of immunotherapy, and their eosinophil levels returned to normal values. However, the female patient declined any further therapy and expired 24 months after the discontinuation of immunotherapy.

Immune-induced eosinophilia is a rare event and reported in only 2.9% of NSCLC cases. Outcomes in the two patients differed, indicating that further research related to eosinophilia and its causes in the context of varying histologies and clinical profiles of patients is warranted.

Mechanisms Driving Immune-Related Adverse Events in Cancer Patients Treated with Immune Checkpoint Inhibitors

PURPOSE OF REVIEW

In the past decade, immune checkpoint inhibitors (ICIs) have revolutionized the field of cancer treatment. With the continuing rise in the number of cancer patients eligible for ICIs, a corresponding rise in immune-related adverse events (irAEs) is occurring. IrAEs are inflammatory reactions against normal, healthy tissue that occur due to ICI-induced activation of the immune system. Although the exact immune pathogenesis driving irAE development remains unknown, we review the main proposed mechanisms, highlighting how they may inform irAE prediction and treatment.

RECENT FINDINGS

IrAEs are common and diverse, varying in incidence, timing, and severity. The possible mechanisms driving irAEs include (1) activation of cytotoxic T cells; (2) activation of B cells and increased autoantibody production; (3) direct molecular mimicry and off-target toxicity; (4) activation of intracellular signaling and pro-inflammatory cytokine production; and (5) environmental modifiers of immune system activation, including composition of the host gut microbiome. These mechanisms may help identify predictive biomarkers and targeted treatment strategies. IrAEs are driven by multiple components of the immune system. More research is needed to understand their immunopathogenesis so that clinicians across all specialties may more effectively monitor and manage these increasingly common conditions.

Renal Complications Related to Checkpoint Inhibitors: Diagnostic and Therapeutic Strategies

Immune checkpoint inhibitors (ICI) targeting CTLA-4 and the PD-1/PD-L1 axis have unprecedentedly improved global prognosis in several types of cancers. However, they are associated with the occurrence of immune-related adverse events. Despite their low incidence, renal complications can interfere with the oncologic strategy. The breaking of peripheral tolerance and the emergence of auto- or drug-reactive T-cells are the main pathophysiological hypotheses to explain renal complications after ICI exposure. ICIs can induce a large spectrum of renal symptoms with variable severity (from isolated electrolyte disorders to dialysis-dependent acute kidney injury (AKI)) and presentation (acute tubule-interstitial nephritis in >90% of cases and a minority of glomerular diseases). In this review, the current trends in diagnosis and treatment strategies are summarized. The diagnosis of ICI-related renal complications requires special steps to avoid confounding factors, identify known risk factors (lower baseline estimated glomerular filtration rate, proton pump inhibitor use, and combination ICI therapy), and prove ICI causality, even after long-term exposure (weeks to months). A kidney biopsy should be performed as soon as possible. The treatment strategies rely on ICI discontinuation as well as co-medications, corticosteroids for 2 months, and tailored immunosuppressive drugs when renal response is not achieved.

Immune checkpoint inhibitors-induced nephropathy: a French national survey

Immune checkpoint inhibitors (ICIs), aiming to foster cancer-targeted immune response, proved to be effective in several advanced malignancies at the price of immune-related adverse events affecting various organs, notably the kidneys. Herein, a retrospective descriptive analysis was performed on all biopsy-confirmed cases of ICI-induced nephropathy notified to the French Pharmacovigilance database to date. Data were gathered about patients' characteristics, acute kidney injuries and histopathological features. A total of 63 biopsy-proven cases were included for analysis. Immune-related nephropathy occurred after a mean of 105.5 ± 98.6 (standard deviation) days after the introduction of the ICI. Kidney Disease: Improving Global Outcomes acute kidney injury stage 3 occurred in 36.5% of patients, and the mean peak serum creatinine was 288 µmol/L. Histopathology suggested acute tubule-interstitial nephritis in 52 patients (83%), while signs of acute tubular necrosis were found in 18 (29%) and glomerular involvement in 5 of them (8%). Another immune-related adverse event was documented in 25 patients (39.7%). Patients were treated with corticosteroids in 88.9% of cases. All in all, 27.0% fully recovered, 54.0% partially recovered, 12.7% did not recover. Rechallenge was attempted in 19 patients and one patient relapsed. Three-quarters of patients received a medication known to cause acute tubule-interstitial nephritis. The major limits of this study are those inherent to pharmacovigilance studies, such as its retrospective nature and incomplete data. Although it cannot pretend drawing any pathophysiological conclusion, this study depicts the clinical and histopathological pictures of ICI-induced nephropathies in a large cohort of biopsied patients with all grades of severity.

Programmed cell death-1 blockade in kidney carcinoma may induce eosinophilic granulomatosis with polyangiitis: a case report

Background

Immune checkpoint inhibitors have potential applications in treating various cancers but are associated with immune-related adverse events, such as inflammation, in a wide range of organs; however, allergic inflammation caused by these agents has not been extensively studied.

Case presentation

A 65-year-old man was diagnosed with a kidney neuroendocrine carcinoma. Three months after kidney resection surgery, the tumor cells had metastasized to his liver and lymph nodes. Subsequently, the patient started chemotherapy; however, regardless of treatment, the tumor grew, and the patient experienced a series of adverse effects, such as taste disorder, anorexia, and general fatigue. Finally, he was administered a programmed cell death (PD)-1 inhibitor, nivolumab (biweekly, toal 200 mg/body), which was effective against kidney carcinoma. However, the patient had a bronchial asthma attack at 22 cycles of nivolumab treatment and chest computed tomography (CT) revealed an abnormal bilateral shadow after 37 cycles of nivolumab treatment. Bronchoscopy findings revealed eosinophil infiltration in the lungs along with severe alveolar hemorrhage. Paranasal sinus CT scanning indicated sinusitis and nerve conduction analysis indicated a decrease in his right ulnar nerve conduction velocity. Based on these findings, the patient was diagnosed with eosinophilic granulomatosis with polyangiitis; he was treated with prednisolone, which alleviated his bronchial asthma. To restart nivolumab treatment, the dose of prednisolone was gradually tapered, and the patient was administered a monthly dose of mepolizumab and biweekly dose of nivolumab. To date, there have been no bronchial attacks or CT scan abnormalities upon follow up.

Conclusions

We present a rare case in which a patient with cancer was diagnosed with eosinophilic granulomatosis with polyangiitis following treatment with a PD-1 inhibitor. Blockade of PD-1 and the programmed cell death ligand (PD-L) 1/PD-1 and PD-L2/PD-1 signaling cascade may cause allergic inflammation. Further studies are needed to identify the specific mechanisms underlying allergic inflammation after PD-1 blockade.

Immune-related adverse events in a patient with eosinophilic enteritis treated with immune checkpoint inhibitors (anti-PD-1)

The use of immune checkpoint inhibitors (ICIs) in melanoma patients has significantly improved treatment outcomes. Unfortunately, ICI therapy is associated with specific immune-related adverse events (irAEs). There is limited data on the use of ICIs in patients with autoimmune or allergic diseases, because these patients have typically been excluded from clinical trials. Eosinophilic inflammatory bowel disease (primary eosinophilic gastrointestinal disorders) is a rare condition defined as eosinophilic infiltration in the wall of the gastrointestinal tract in the absence of other known causes of tissue eosinophilia. We present a case of a 51-year-old woman with eosinophilic enteritis who was treated with anti-PD-1 because of metastatic melanoma. The use of anti-PD-1 therapy in a metastatic melanoma patient with a positive history of eosinophilic enteritis resulted in the appearance of many immune-related complications (hypothyroidism, hepatitis, skin lesions, colitis). The patient discontinued anti-PD-1 treatment and glucocorticoid therapy was started. All AEs have resolved without any sequelae, and there are no symptoms of eosinophilic enteritis. Currently, the patient has no complaints, and has no clinical features of recurrence or dissemination of melanoma (April 2020); she remains under constant oncological supervision. The use of anti-PD-1 therapy in a patient with metastatic melanoma and a positive history of eosinophilic enteritis resulted in almost complete remission of melanoma but also the appearance of many immune-related complications, none of which were life-threatening. Patients with eosinophilic enteritis may be eligible for anti-PD-1 therapy; however, they should be closely monitored for the appearance of various irAEs when receiving this therapy.