BRIEF REPORT: Immune checkpoint inhibitor associated pericarditis

Abstract

Side effects of immune checkpoint inhibitors, termed immune-related adverse events (irAEs), are relatively common but immune checkpoint inhibitor mediated cardiotoxicity are rare, although can be serious and potentially fatal. Pericarditis is an infrequent cardiac toxicity of immunotherapy and predisposing factors remain unknown. Here we report 3 patients with non-small cell lung cancer who developed pericarditis during therapy with PD-1/PD-L1 +/− CTLA-4 inhibitors. We review the clinical presentation of these 3 cases and histopathologic findings from autopsies from the first 2 patients and a pericardial sampling that has been obtained from a pericardial window procedure in the 3^rd patient, who recovered from the pericarditis episode. We also discuss the potential mechanisms, as well as what is known about pericarditis secondary to irAEs.

INTRODUCTION:

Despite remarkable progress made in the treatment of several advanced cancers since the introduction of immune checkpoint inhibitors, immune-related adverse events [irAEs]) associated with unrestrained modulation of the immune system remains a challenge.

Cardiotoxicity is potentially a fatal complication associated with immunotherapy. Myocarditis with clinical presentations ranging from asymptomatic cardiac biomarker elevation to heart failure, arrhythmia, cardiac fibrosis, cardiogenic shock and pericarditis have been reported in clinical trials and as post marketing experience with immunotherapy^1-6. Pericarditis is an infrequent cardiac toxicity of immunotherapy, and predisposing factors remain unknown. Thus far in the literature few cases have been described with pericardial effusion and/or pericarditis⁷.

In this brief report we describe 3 patients with non-small cell lung cancer (NSCLC) who developed pericarditis during therapy with PD-1/PD-L1 +/− CTLA-4 inhibitors. Tissue and associated clinic-pathological information was used after approval from the Yale Human Investigation Committee (protocol #9505008219)

CASE PRESENTATION:

Case 1: A 72 year-old man with hypertension, coronary artery disease and metastatic KRAS-mutant lung adenocarcinoma presented to the hospital with cardiac tamponade and in cardiac arrest. His lung cancer was diagnosed one year previously and progressed on standard chemotherapy. He received radiation to the right hilar mass (figure 1.A) and was enrolled in a clinical trial with an anti-PD-L1 monoclonal antibody associated with a marked clinical and radiological response (Figure 1.B and 1.C). His death was 78 days after starting therapy in a clinical trial with an anti-PD-L1 therapy. Autopsy revealed widespread tumor necrosis in all primary and metastatic sites with the exception of residual viable tumor in the left adrenal gland. The epicardial surface was covered by a hemorrhagic fibrinous exudate (Figure 2).

Figure 1.

A) Radiation fields for palliative right hilum radiation; 1.B and 1.C) Imaging studies by positron emission tomography, B) Pretreatment and C) after 4 cycle of therapy, with marked clinical response, for case #1

Figure 2.

A) Fibrinous pericarditis adherent to the parietal (reflected superiorly) and visceral pericardium, 2.B) Bread-loaf sections of the formalin-fixed heart showing a fibrinous, hemorrhagic exudate covering the heart and epicardial fat (green arrow). The epicardial surface is covered by a fibrinous exudate measuring 4-5mm in thickness, representing a classic “bread and butter” pericarditis.

Case 2: A 65 year-old woman with type 2 diabetes mellitus, hypertension and metastatic recurrent lung adenocarcinoma presented to a local hospital, while she was being treated with anti-CTLA4 and anti-PD1 therapy as part of a clinical trial, with loss of consciousness and hypotension. Work up revealed cardiac tamponade. The patient was intubated and underwent a pericardial window procedure with drainage of 1 liter of blood fluid from the pericardial space which did not reveal malignant cells. She noted to have elevated cardiac enzymes and decreased left ventricular function. A pacemaker was placed due to cardiac arrhythmias. Post procedure, she had limited improvement in her metal status, and a brain MRI showed multiple subacute infarcts without hemorrhage. She had no significant neurological recovery and was transferred to inpatient hospice 13 days after the pericardial window procedure. She expired five days later. Preexisting hypertension was her only comorbid condition.

Case 3: A 57 year-old man with metastatic lung adenocarcinoma presented with dyspnea, orthopnea, and bilateral lower extremity edema while on therapy with anti-PD-L1 therapy. 98 days after the first dose of immunotherapy, he was found to have cardiac tamponade and underwent a pericardial window procedure with full recovery. Post procedure he was rechallanged with the same immunotherapy. While he did not have any dose limiting toxicities, he experienced progressive disease and discontinued therapy 3 months after his clinical presentation with pericarditis (further details of the clinical presentation including laboratory results and imaging studies are available in table 1-2 and suppl table 1-3)

Table 1:

Clinical characteristics of 3 patients

Case #	Age	Sex	Histology	Smoking status	Molecular profile	Comorbid problems	TNM stage (AJCC 8th edition)	Preexisting cardiac risk factors	Clinical symptoms at presentation	Sites of disease
1	73	M	Adeno Carcinoma	Former smoker (20pack/year)	KRAS G12C mutant	-Hashimoto's thyroiditis -Hypertension - Coronary artery disease (with coronary artery stents) -Chronic Obstructive Pulmonary Disease	T4N2M1c	-Coronary artery disease -Hypertension	-Dyspnea, -Hypotension -Hypoxia	bilateral lungs, liver, spleen, pancreas, adrenal, peritoneum, osseous metastasis
2	65	F	Adeno Carcinoma	Former smoker (30 pack/year)	No driver mutation detected	-Type 2 Diabetes Mellitus -Hypertension	T4N3M1c	-Hypertension	-Loss of consciousness -Hypotension	bilateral lungs, bone, periportal and peripancreatic lymph nodes
3	57	M	Adeno Carcinoma	Former smoker (20 pack/year)	No driver mutation detected	No relevant past medical history	T3N1M1c	None	-Dyspnea, -Orthopnea, -Bilateral lower extremity edema	Bilateral lung nodules, , abdominal LNs, liver and osseous metastasis

Table 2:

Treatment history and response data for 3 patient

Case #	Prior therapies	Prior Radiation therapy (RT)	Type of immune checkpoint inhibitor (ICI)	Time elapsed betwee n last dose of thoraci c RT and initiatio n of ICI	Best response to ICI	Length of time on PD-1/PD- L1 therapy until development of pericarditis	Other irAEs	Therapy and Outcome	Histopathologic findings
1	Carboplatin + Pemetrexed + Bevacizumab × 3 cycles	Palliative RT to the right lung hilum (30 Gy) and right hip	PD-L1 inhibitor	14 days	Partial response (RECIST v1.1)	78 days	None	Presented with cardiac tamponade, and had cardiac arrest, did not respond to resuscitation and died	Complete pathologic response in hilar, carinal lymph nodes, right upper lobe of liver and pancreas, residual viable tumor identified in the left adrenal gland Cytology negative for malignant cells in pericardial effusion
2	Carboplatin + Pemetrexed × 6 cycles followed by Pemetrexed maintenance	Palliative RT (44Gy) to Right lung upper lobe	PD-L1 inhibitor + CTLA-4 inhibitor	145 days	Partial response (RECIST v1.1)	131 days	Grade 2 hypothyroidism (day 42)	Received pericardial drainage and pacemaker for arrhythmias, experienced further clinical decline and died 13 days after her presentation	Complete pathologic response in bilateral lung, periportal and peripancreatic LNs, only residual disease limited to thyroid gland (contiguous dissemination)
3	Cisplatin + Pemetrexed + Multikinase TKI × 6 cycles, followed by Pemetrexed + TKI	No prior RT	PD-L1 inhibitor	N/A	Stable disease	98 days*	None	Received pericardial window, with symptomatic improvement, PD after further 3 months of therapy with no additional toxicity after reintroduction.

(*trace pericardial effusion noted in an imaging study after 60 days of therapy).

Histopathology Findings:

Case 1: Autopsy examination of the heart revealed that the parietal pericardium was up to 0.4cm thick with the serosal surface being covered by a shaggy, fibrinous, hemorrhagic exudate. There was also a shaggy, fibrinous, hemorrhagic exudate surfacing the pericardium adherent to the epicardium (Fig 2A, B). Microscopically, there was diffuse fibrinous pericarditis with a thick layer of fibrinous tissue adherent to the epicardium of the left and right ventricles, and an inflammatory infiltrate underlying the fibrinous tissue consisting of numerous lymphocytes, some macrophages, and occasional plasma cells. Additionally, there were small collections of lymphocytes, predominantly perivascular, identified within the myocardium of the left and right ventricles. No tumor cells were identified on the pericardial or epicardial surfaces. Immunohistochemical staining of the samples revealed the inflammatory infiltrate beneath the thick fibrinous layer on the epicardium to consist of numerous CD4+and CD8+T-cells in a 1:1 ratio, some CD68+ macrophages, and scattered CD20+ B-cells (Supp. fig.1-3). There were residual viable tumor cells in left adrenal gland, but no viable tumor cells noted in the right hilar and right lower lobe (Supp. fig.4-6)

Case 2: At autopsy, the pericardium was markedly fibrotic and adherent to the anterior chest wall. There was a fibrinous pericarditis, with a mild chronic lymphocytic infiltrate and fibrin deposition. There was no evidence of acute inflammation in the pericardium, and no tumor cells were identified on the pericardial or epicardial surfaces (Supp. fig.7-9).

Case 3: Histopathologic examination of the tissue from the pericardial window procedure revealed fragments of pericardium with fibrosis, hemorrhage, edema, moderate lymphoplasmacytic infiltrate and fibrinous exudate with organization, along with moderate macrophage infiltrate and focal neutrophilic infiltrate. No epicardium was observed (Supp. fig. 10-12).

Translation studies:

In quantitative immunofluorescence analysis the expression of the immune cell markers (Methods for multiplexed TILs, TILs activation and PD-L1/CD68 Immunofluorescence staining and statistical analysis are in supplement) was assessed in 10 field-of-view hotspots for each sample (figure 3). TIL marker expression (CD4, CD8 and CD20) did not differ between primary tumor and toxicity site (Supp. fig.13). Assessment of the macrophage population across sites, revealed a uniformly higher CD68+ expression in the pericarditis samples, compared with baseline tumor biopsies which were obtained prior to immunotherapy (p<0.0001). Notably the CD68 protein expression was also high in available primary tumor samples at the time of toxicity, compared with baseline samples. The expression of PD-L1 in the CD68+ cells was also statistically higher in the pericarditis samples compared with baseline tumor (p<0.0001), with the primary tumor site having the highest PD-L1 expression in macrophages at the time of toxicity (Supp. fig.14). In our study, pericardial tissue samples and pericardial fluid cytology did not reveal malignant cells and there was no positive PD-L1 expression outside the infiltrating immune cells in the pericarditis samples.

Figure 3:

1^st, 2^nd and 3 rd row are macroscopic, H&E and TILs multiplexing images from case 1, 2 and 3 respectively. First column (3.A, 3.F) shows macroscopic images from pericardial sample for case 1, 2; Second column (3.B, 3.G and 3.K) shows H&E images of the pericardial samples x10 magnification), 3^rd column (3.C, 3.H and 3.L) is representing multiplexing with CD 3 (green), granzyme (red) and Ki 67 (blue channel); 4^th column (3.D, 3.I, 3.M)is representing multiplexing with CD4 (green), CD8 (red), CD20 (blue); 5^th column (3.E, 3.J, 3.N) is representing CD68 (green), PD-L1 (red).

DISCUSSION:

In contrast to the well-characterized temporal patterns of classic chemotherapy toxicities, the onset and duration of irAEs are unpredictable and predisposing factors for individuals to develop irAEs remain unclear⁸. Nearly all organs can be affected by immune-related toxicities. The case series presented here reports histologically confirmed pericarditis which developed during PD-1/PD-L1 +/− CTLA-4 directed therapies.

Clinical presentation of pericarditis as an irAE can be insidious and asymptomatic, and the time to clinical presentation can be variable. In literature cardiac immune checkpoint inhibitor related cardiac toxicities have been reported to develop at a median of 65 days (range 2-454 days)⁴. With its rare and non-specific presentation, diagnosis can be delayed or missed, which can cause considerable difficulty in obtaining accurate data on incidence and prevalence. For the development of cardiotoxicity secondary to immune checkpoint inhibitors multiple hypothesis are generated from clinical observation and preclinical work. These include off target cross reactivity of affinity-enhanced T cells, targeting an antigen shared by a tumor antigen and a homologous heart tissue, anti-tumor activity in the setting of a malignant pericardial or myocardial involvement⁹. In addition the observations in animal models suggest importance of the CTLA-4 and PD-1 pathways in limiting T cell mediated inflammation in the heart^10,11. The role of PD-1/PD-L1 has been studied in cardiac ischemia-reperfusion injury and myocardial infarction models, which showed increased protein expression of PD-1 and PD-L1 in cardiomyocytes in isolated ischemic-reperfused rat hearts¹². This may be particularly important in patients with preexisting cardiac conditions. Another relevant concern in lung cancer patients is the role of the T cell mediated injury secondary to radiation. In preclinical models it has been shown that PD-1 modulates radiation induced cardiac toxicity through cytotoxic T lymphocytes, and an increased mortality with combination of cardiac irradiation and anti-PD-1 antibody has been observed in animal models¹³. Since in immunotherapy naïve patients, acute pericarditis can be secondary to viral infections or connective tissue disease, immune checkpoint blockade theoretically can flare subclinical presentations of etiologies as well^14,15.

In case 1, one possible etiology for the patient’s fibrinous pericarditis is an exuberant immune response by the CD8-positive cytotoxic T-cells, facilitated by the anti-PDL1 treatment during pericardial inflammation secondary to radiotherapy (case #1 right lung radiation with the overlapping cardiac structures in radiation field (figure 1)). For the same case another consideration is possible contribution of his preexisting cardiac comorbidities. At autopsy the slices of the heart showed impressive left ventricular hypertrophy, probably indicative of sustained hypertension (figure 2.B). Another potential mechanism of the pericardial injury is the anti-tumor response to a metastatic involvement in the pericardium, but in our patient cohort; 2 autopsy cases (case 1 and 2) both in myocardium and in pericardium, in case 3 the pericardium and the smears of the sanguineous fluid in the pericardial cavity did not contain any malignant cells. Mechanisms for immune mediated pericardial damage can be multifactorial, in our series the lower expression of Granzyme B in the pericardium infiltrating T cells suggests that while cytotoxic T-cells may still be involved in toxicity (which is supported by the comparable levels of CD8 expression across sites), the mechanism might differ and may not be granule exocytosis mediated. Other cytokines or even death ligands expressed or released by cytotoxic T-cells like FasL, and TRAIL can play a role in toxicity. Our study assessment of the macrophage population across sites revealed a uniformly higher CD68+ expression in the pericarditis samples. This raises the question of whether PD-1/PD-L1 targeted treatment dysregulates the macrophage function leading to excess activity in specific organs. Cardiotoxicity is a rare but potentially fatal complication associated with immunotherapy, pathogenesis is not well known, and diagnostic criteria are lacking⁴. Prospective studies will be helpful to identify risk factors, mechanism and preventions. Additional caution is needed for patients who have underlying autoimmune disease and/or exposure to radiation therapy prior to immunotherapy. A high index of suspicion and a low threshold for investigation should be applied in cases of cardiovascular symptoms in patients with immune checkpoint therapy.