A case of nivolumab-induced cervical lymphadenopathy in a patient with gastric cancer

Nivolumab is a monoclonal antibody targeting programmed cell death-1 (PD-1) that has been recently shown to exhibit clinical efficacy in patients with gastric cancer. However, various degrees of immune-related adverse events (irAEs) have been reported. We report the case of a 71-year-old male patient diagnosed with gastric cancer with peritoneal metastases. He was treated with nivolumab as third-line chemotherapy. On the 10th day after completing seven cycles of nivolumab treatment, he urgently visited the hospital because of mild left cervical lymphadenopathy. We suspected it to be due to inflammation and initiated treatment with levofloxacin hydrate. However, 3 days later, he was admitted to the emergency room due to exacerbation of his lymphadenopathy. A diagnosis of nivolumab-induced lymphadenopathy was made as the antibiotics were ineffective, and the patient was administered prednisolone (PSL) 20 mg. One day after admission, the pain and swelling of the lymph node greatly lessened, and the following day, the pain gradually disappeared; thereafter, the PSL dose was tapered and nivolumab treatment was resumed. The patient again developed cervical lymphadenopathy approximately 4- 5 days after nivolumab was reintroduced, which disappeared 1 week later. During each episode of lymphadenopathy, he received a dose of 20 mg of PSL for 4 days, which would be eventually tapered to 10 mg without antibiotics and NSAIDs. After 2 months, cervical lymphadenopathy completely disappeared while 10 mg of PSL was continued, which was also eventually tapered off. To our knowledge, this is the first case report of nivolumab-induced lymphadenopathy in a patient with gastric cancer. This case suggested that we should keep in mind that various irAEs may occur during treatment with immune checkpoint inhibitors. It is necessary to ensure the absence of infection and metastasis before treatment and to promptly administer systemic corticosteroids to address them.