Myocarditis in Cynomolgus Monkeys Following Treatment with Immune Checkpoint Inhibitors

Abstract

Purpose: Immune checkpoint inhibitors (ICI) targeting PD1, PDL1, or CTLA4 are associated with immunerelated adverse events (irAE) in multiple organ systems including myocarditis. The pathogenesis and early diagnostic markers for ICI-induced myocarditis are poorly understood, and there is currently a lack of laboratory animal model to enhance our understanding. We aimed to develop such a model using cynomolgus monkeys. Experimental Design: Chinese-origin cynomolgus monkeys were dosed intravenously with vehicle or nivolumab 20 mg/kg plus ipilimumab 15 mg/kg once weekly and euthanized on day 29. Results: Multiple organ toxicities were observed in cynomolgus monkeys, and were characterized by loose feces, lymphadenopathy, and mononuclear cell infiltrations of varying severity in heart, colon, kidneys, liver, salivary glands, and endocrine organs. Increased proliferation of CD4 þ and CD8 þ T lymphocytes as well as an increase in activated T cells and central memory T cells in the blood, spleen, and lymph nodes, were observed. Transcriptomic analysis suggested increased migration and activation of T cells and increased phagocytosis and antigen presentation in the heart. Mononuclear cell infiltration in myocardium was comprised primarily of T cells, with lower numbers of macrophages and occasional B cells, and was associated with minimal cardiomyocyte degeneration as well as increases in cardiac troponin-I and NT-pro-BNP. Morphologically, cardiac lesions in our monkey model are similar to the reported ICI myocarditis in humans. Conclusions: We have developed a monkey model characterized by multiple organ toxicities including myocarditis. This model may provide insight into the immune mechanisms and facilitate biomarker identification for ICI-associated irAEs.

Immune Checkpoint Inhibitor-Associated Cardiotoxicity: Current Understanding on Its Mechanism, Diagnosis and Management

“…The mechanism of ICI-related cardiac toxicity is not yet fully understood. Histological analyses of patients and monkey models with ICI-associated myocarditis have revealed that the infiltration of predominant CD4 + /CD8 + T lymphocytes and a few macrophages (CD68 + cells) are the main cause of ICI-associated myocarditis (Johnson et al, 2016a; Ganatra and Neilan, 2018; Ji et al, 2019) ( Figure 1 ). In addition, the expression change of multiple chemokine receptors further proves the enhancement of T cells.…”

“…In addition, the expression change of multiple chemokine receptors further proves the enhancement of T cells. CXCR3–CXCL9/CXCL10 and CCR5/CCL5 are required for T cell activities to upregulate (Tokunaga et al, 2018; Ji et al, 2019). Tumor necrosis factor-α, granzyme B, and interferon-γ are produced by activated T cells, inducing cell death.…”

Uncoupling Therapeutic Efficacy from Immune-Related Adverse Events in Immune Checkpoint Blockade

“…reported extensive inflammation in various organs (heart, hepatic, kidney, large intestine, adrenal medulla, and salivary glands) after ipilimumab and nivolumab treatment of monkeys. Interestingly, the myocarditis reported in monkeys demonstrated morphology, cardiac biomarker variations, and immune cell infiltrates comparable with human ICI-associated myocarditis ( Ji et al., 2019 ).…”

PD-1 inhibitor inducing exosomal miR-34a-5p expression mediates the cross talk between cardiomyocyte and macrophage in immune checkpoint inhibitor–related cardiac dysfunction

“…The histopathological evaluation revealed that macrophages infiltrated in the cardiac tissue after ICIs treatment. 37 Macrophages are important cells that modulate inflammation. Indeed, under some circumstance, macrophages promote inflammation and extend injury, thus leading to cardiac senescence-related injury.…”