A case report of mesalazine alleviating diarrhea in a patient with nasopharyngeal cancer after tislelizumab treatment

Immunotherapy has become a significant research focus for cancer treatment in recent years because it can generate enduring immunological responses and has promising therapeutic potential. Nevertheless, excessive stimulation of the immune system may adversely affect healthy organs, which can lead to immune-related toxicities, including gastrointestinal, pulmonary, hepatic, and dermatological toxicities. Among them, gastrointestinal toxicity induced by the immune response is the most common. Immune-associated enteritis has an incidence rate of 8%-27% and is one of the most prevalent forms of gastrointestinal toxicity. Tislelizumab is an approved first-line treatment for individuals with recurrent or metastatic nasopharyngeal cancer functioning as an inhibitor of PD-1. Here, we report a patient with nasopharyngeal carcinoma who developed bloody stools and diarrhea after two cycles of tislelizumab. Abdominal CT revealed intestinal wall thickening with inflammatory exudation. Congestion, edema, and mucosal punctate ulcers were discovered during the colonoscopy. Histopathology confirmed active mucosal inflammation. The initial treatment with loperamide, bifidobacterium tetrad, and norfloxacin failed, but the symptoms improved significantly after switching to metronidazole, mesalazine, and methylprednisolone. This article reviewed a case of immunological enteritis triggered by tislelizumab, demonstrating that mesalazine can markedly alleviate the symptoms of immune-associated enteritis, aiming to enhance future clinical efforts regarding tislelizumab-induced immunological enteritis.