During the past years, immunotherapy, targeting immune checkpoint molecules, has led to dramatic advances in oncotherapy, especially in non-small cell lung cancer (NSCLC) treatment (1). However, immune checkpoint inhibitors (ICIs) not only can provide outstandingly durable responses in NSCLC but also is associated with a wide range of immune-related adverse events (irAEs) (2). Although it is still conflicting whether irAEs are accompanied with better treatment outcome (3), these irAEs could be disastrous and extend exposure to immunosuppressive therapies to counteract excessive immune upside risk by ICI therapies (4). Previous studies have reported that irAEs were observed in 51% of patients treated with ICIs (5) and 49% in 623 patients with advanced-stage NSCLC included worldwide (6). Also, among these irAEs, immune-related pneumonitis has been receiving extensive attention owing to its high discontinuation and fatality rate, especially in NSCLC (7). Therefore, the identification of biomarkers to predict irAEs and pneumonitis occurrence owing to ICIs is essential to increase the benefits during ICI treatment.

By eliminating the restraint of T-cell function, ICIs promote T cell-mediated effects on cancers. Nonetheless, they could also enhance the activity of mediators and cell sets that function against host tissues and potentially promote autoimmune activity (3). In addition, cytokines may take a role in the pathophysiology of irAEs. Previous studies determined that the level of interleukin (IL)-17 increased in patients with immunotherapy-associated colitis (8) and that increased levels of IL-17 have been detected in preclinical models of colitis (9). A prospective study reported that baseline IL-6 serum levels were independently correlated with a higher risk of severe toxicity, which thus could be used in the clinic to conduct personalized toxicity monitoring for melanoma patients receiving immunotherapy (10).

The purpose of this present study was to identify easily accessible biomarkers to predict the occurrence of irAEs. Given that these biomarkers in the peripheral blood are easily available and can be highly standardized and undergo repeated evaluations, it is particularly ideal to evaluate these biomarkers. With this project, our team members collected and analyzed the clinical characteristics and peripheral blood biomarkers including blood cells and a set of functionally selected cytokines both at baseline (before ICI treatment) and during dynamic monitoring (with ICI treatment).

Impressive agent activity of various ICIs has led to regulatory approvals for multiple agents in various solid tumor indications (15–19). IrAEs from ICI differ from cytotoxicity or toxicity caused by molecular targeting agents. The time of toxicity may be delayed rather than following periodic patterns such as traditional cytotoxicity. Mechanisms have yet to be determined, and even with the same agent, it is likely to be heterogeneous between patients.

These irAEs are widely distributed in terms of affected organs and severity. Dermatology, endocrinology, neurology, gastrointestinal, respiratory, and musculoskeletal toxicity may occur individually or in constellations. More than two-thirds of cancer immunotherapy-related irAEs cases are ICI related, with three drugs (ipilimumab, nivolumab, and pembrolizumab) accounting for nearly 60% of reported cases (20). A preceding clinical trial reported that patients who were treated with nivolumab alone, ipilimumab alone, or nivolumab plus ipilimumab developed grade 3 or 4 irAEs with a rate of 21%, 28%, and 59%, respectively. Furthermore, four patients passed away owing to severe irAEs (21). Most are self-limiting or addressing immunosuppressants such as corticosteroids. ICI treatment can regularly continue through close supervision to avoid more serious irAEs. However, severe irAEs could be related to a grave decline in function of these organs and quality in daily life, and especially fatal results have been reported.

If these irAEs were early detected and properly dealt with, most of them are moderate and reversible. Therefore, it is essential to look for biomarkers in predicting the incidence of irAEs. Compared with many biomarkers of tumor response, there were fewer investigations of biomarkers of tumor irAEs (22). Previous studies have reported that body composition parameters, such as sex, IL-6, IL-17, CXCL5, blood cell counts, autoantibodies, T-cell repertoire, and gut microbiome were relevant to the occurrence of irAEs. Cytokines were reported as the important effect and messenger molecules in the human immune system (23). They are deeply involved in the immune response to infection and inflammation, preventing or contributing to diseases such as allergies, autoimmunity, and tumors. However, with regard to these cytokines, different cytokines and even the same cytokine may play different roles in predicting the irAEs in different studies (10, 24).

In order to explore the correlation of these cytokines with irAEs, a set of functionally selected cytokines was detected and analyzed. Among these considered biomarkers, baseline and dynamic levels of IL-10 are known to have a crucial role in anti-inflammatory and immunosuppressive effects and can stratify the risk of irAEs, particularly, higher levels of IL-10, indicating the higher risk of irAEs.

IL-10 is reported as an immunomodulatory cytokine and could be provided by different cell types in humans, such as CD4⁺ T cells, CD8⁺ T cells, B cells, and monocytes (25, 26). Recently, macrophages were expanded to IL-10-producing cells (27, 28) and some non-hematopoietic cells, including epithelial (29) and tumor cells (30). In addition to being provided by the above cells, IL-10 functionally targets diverse cells, resulting in even different paradoxical roles in functions with immunity and cancer. Some studies found that IL-10 induced T cell anergy, while others confirmed that IL-10 could stimulate the proliferation of mature CD8+ T cells and can increase the cytolytic activity of the T cells. The faint effects of IL-10 were reported in NK cells as well. NK cell expression was suppressed by IL-10, although IL-10 can also increase NK cytolytic activity. However, IL-10 promotes the survival of B cells and proliferation as well as differentiation, which have been much clear. In addition, IL-10 has been well-documented to restrain MHC class II expression. In our study, we found that a high level of IL-10 was correlated with activated inflammatory environment in both tumor and normal samples.

To our knowledge, this is the first study to investigate the predictive value of baseline and dynamic plasma IL-10 for irAEs in NSCLC patients. Our results suggested that patients with a high level of baseline IL-10 have a higher risk of irAEs (OR = 5.318, p = 0.030). Also, during ICI treatment, the dynamic change of IL-10 was still associated with the occurrence of irAEs. With regard to pneumonitis as the most frequent event among these irAEs, the baseline level of IL-10 plays a reliable role (OR = 9.969, p = 0.037) in predicting the incidence.

However, there are still some limitations. First, this was a single-center retrospective evaluation, and 67 patients were included in our analysis, suggesting that there may have been information bias that needs to be verified in more large and multicenter cohorts. Second, the exact aspects of irAEs were related to ICI drugs, and the predictive role of IL-10 may need to be verified in these ICI drugs to help clinicians personalize immune-toxicity surveillance. Third, we did not explore what the specific mechanisms IL-10 plays in these patients with irAEs because IL-10 may not only serve as a reliable predictor of irAEs but also serve as target therapy to eliminate or reduce these irAEs.

This study analyzed the correlation of a set of functionally selected blood cytokines and the incidence of irAEs. The multivariate analysis indicated that baseline and dynamic blood IL-10 is a promising biomarker for irAEs. These findings suggested that patients with a high level of IL-10 should be carefully monitored for toxicity during ICI therapy. Further prospective studies in larger cohorts are necessary to validate our results.

The original contributions presented in the study are included in the article/ Supplementary Material . Further inquiries can be directed to the corresponding author.

The studies involving human participants were reviewed and approved by The Ethics Committee of Shanghai Pulmonary Hospital, Tongji University. The patients/participants provided their written informed consent to participate in this study.

HW and XC designed this study and drafted the manuscript. MQ and XL collected the data. FZ, CZ, and LC analyzed the data. CCZ gave critical comments. XC and HW revised the paper. All authors contributed to this article and approved the submitted version.

This study was partly supported by grants from the Shanghai Science and Technology Innovation Action Plan Medical Innovation Research Project (No. 21Y11913600), Shanghai Nature Foundation Project (No. 21ZR1453200), Clinical Research Project of Shanghai Pulmonary Hospital (No. Fk18002), Shanghai Innovative Collaboration Project (No. 2020CXJQ02), National Natural Science Foundation of China (No. 81972169), and Establishment and promotion of multidisciplinary collaborative diagnosis and treatment system for non-infectious diseases in the lungs.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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