Delayed immune-related hepatitis after 24 months of pembrolizumab treatment: a case report and literature review

Immune checkpoint inhibitors targeting the programmed cell death protein 1 (PD-1) pathway have revolutionized cancer immunotherapy by enhancing the immune system’s ability to combat cancer cells. However, this innovative approach comes with a distinctive set of challenges, as these therapies can lead to immune-related adverse events (irAEs) due to their mechanism of action. The most common irAEs involve the skin, gastrointestinal tract, liver, endocrine system, and lungs. These events can range from mild skin rashes to severe colitis, pneumonitis, or even autoimmune organ damage. These adverse effects usually appear with an average of 5–15 weeks from the start of treatment depending on the affected organ. This article presents a case report of a delayed related-mediated hepatitis, after 24 months of treatment with pembrolizumab and almost 3 months after its termination, and a review of the scientific literature on cases of delayed immune-related hepatitis caused by anti-PD1. This case highlights the importance of monitoring patients treated with immune checkpoint inhibitors after cessation as a growing number of patients stop treatment due to achieving durable responses.