Abstract Introduction With the increasing use of immune checkpoint inhibitors (ICI), the prevalence of associated adverse events is also rising. We present a rare case of “Triple M syndrome” - a combination of Myasthenia Gravis (MG), Myocarditis, and Myositis in a 77-year-old male as a consequence of immune checkpoint inhibitor therapy. Case Presentation A 77-year-old male with hepatocellular carcinoma, treated with tremelimumab and durvalumab, presented to the ED with new-onset horizontal diplopia and fatigue. Brain imaging ruled out acute stroke. Lab work revealed elevated acetylcholine receptor binding antibody (8.6 nmol/L), creatine kinase (3491 U/L), and troponin (1041 ng/L), raising concern for ICI-related MG, myocarditis, and myositis - Triple M syndrome. Pyridostigmine and prednisone (40 mg daily) were initiated for MG management but was escalated to high-dose steroids for suspected ICI-related toxicities after interdisciplinary discussions with oncology, neurology, and apheresis teams. The patient underwent plasma exchange, but this was complicated by transient hypotension. Given the risk of respiratory compromise from MG exacerbation, he was transferred to the ICU where he required intubation for worsening respiratory mechanics and vasopressor support for presumed distributive shock. Despite additional therapies including abatacept, ruxolitinib, and IVIG, the patient continued to clinically decline. After multiple failed spontaneous breathing trials, goals of care were reevaluated, and the patient was transitioned to comfort measures with palliative extubation. The patient ultimately passed away due to respiratory failure. Discussion The concurrent onset of MG, myocarditis, and myositis posed diagnostic and therapeutic challenges, requiring an interdisciplinary approach. Literature on ICI-induced Triple M is sparse, with few cases reporting such overlap. This case underscores the need for vigilant monitoring of adverse events of immune checkpoint inhibitors and tailored immunosuppressive strategies. This abstract is funded by: None
Nary et al. (Fri,) studied this question.