Late‑onset immune checkpoint inhibitor‑related pneumonitis after cessation of sintilimab: A case report and literature review.

Immune-related adverse events following treatment with immune checkpoint inhibitors (ICIs) can occur at any time during therapy, with onset occurring most frequently during the first 3 months of treatment. However, they rarely occur after treatment cessation. An awareness of delayed immune-related events following the termination of immunotherapy is paramount for optimal tumour management. The present study reports a case of a 69-year-old male patient with right lung adenocarcinoma. He suffered from psoriasis for ~40 years and was suspected of developing immune checkpoint inhibitor-related pneumonitis (CIP) 6 months after the cessation of treatment with the anti-programmed cell death-1 receptor antibody sintilimab. The present case study is, to the best of our knowledge, the first case of late-onset CIP after the cessation of sintilimab. Subsequently, the report also reviews previously reported cases of late-onset CIP after the cessation of ICI treatment. The present report highlights the finding that CIP can develop, although rarely reported, months or even years after the termination of immunotherapy. Therefore, CIP should always be considered as one of the possibilities and addressed accordingly once the pulmonary infection is ruled out. Careful monitoring, timely diagnosis and administration of corticosteroids are essential in controlling this condition, particularly for patients with pre-existing autoimmune diseases.