212 Incidence and Outcomes of MRI-confirmed Myocarditis in Patients Receiving Immune Checkpoint Inhibitors for Lung Cancer - A Single Tertiary Centre Experience

Abstract

Introduction Myocarditis is a rare and life-threatening complication of immune checkpoint inhibitors (ICI). Lung cancer patients present a diagnostic conundrum with overlapping symptoms, co-morbidities, treatment toxicity, and tumour burden. Methods We reviewed 612 consecutive lung cancer patients treated with ICI over 5 years at St Bartholomew&apos;s Hospital, UK. Myocarditis was confirmed using cardiovascular magnetic resonance imaging. Results Incidence of myocarditis was 1.1% (n = 7/612). Median age of cases was 69 years (range 54-81), 57% male, 43% current smokers, 14% heart failure with left ventricular ejection fraction (LVEF) 50%, 43% moderate COPD, 43% CKD stage 3, and 0% autoimmunity. All cases had metastatic adenocarcinoma; 3 PDL1-high (>=50%), 1 PDL1-low (1-49%), and 3 KRAS-G12X mutations. 6 patients received a platinum-doublet+PD-1/L1 regimen and 1 pembrolizumab monotherapy. Median presentation was 242 days (range 30-480) from first cycle; median cycle number 8 (range 2-17). All patients had other grade 2-3 ICI toxicities (3 pneumonitis, 2 nephritis, 2 hepatitis, 2 dermatitis, 2 endocrinopathies, 1 myositis, 1 colitis). Dyspnoea was the most common symptom (n = 6/7) followed by fatigue (n = 5/7), oedema (n = 2/7), orthopnoea (n = 2/7), and chest pain (n = 1/7). All patients had elevated hs-Trop-T>=15 ng/L and NTpro-BNP>=500 ng/L. ECG was normal in 43% patients, with T-wave changes (n = 4/7) and sinus tachycardia (n = 3/7) most common. 43% had LVEF<50% on echocardiogram. All patients received corticosteroids (range prednisolone 0.5 mg/kg to methylprednisolone 1 g/day) of which 6 improved clinically. 1 with vasculitis overlap required further immunosuppression. All patients recovered from myocarditis and one was successfully rechallenged with maintenance pembrolizumab under close monitoring. Cardiac biomarkers did not correlate with clinical severity and LVEF. Conclusion In our cohort, myocarditis remains an uncommon but likely under-diagnosed ICI complication. Clinical features and investigation findings are varied, hence clinician vigilance is advised. Further research is required to identify risk factors and improve diagnostic performance to improve outcomes. Disclosure No significant relationships.