Rhabdomyolysis

Nivolumab is a fully human monoclonal antibody against programmed cell death 1 receptor (PD-1). Acting as an immune checkpoint inhibitor, it has emerged as a promising therapeutic method for advanced malignancy, inducing durable responses in patients with solid tumors. It can be associated to very unusual immune mediated toxicity against multiple tissues. Here, we describe a patient with metastatic clear cell renal cell carcinoma, who received nivolumab as fourth line therapy and experienced muscular weakness and pain secondary to rhabdomyolysis and myasthenia gravis. This case portrays a very uncommon yet potentially fatal side effect of nivolumab, seen in less than 1% of patients across all clinical trials. As immunotherapy evolves and its efficacy is proven in more tumor types, the overall use of this class of drugs will increase and their uncommon side effects may be evident more frequently. To our knowledge, this is the first case of fatal myasthenia gravis reported in a patient with renal cell carcinoma treated with anti-PD1 therapy.