ペムブロリズマブの最終投与から17週後に脳炎を発症し，自然軽快した1例

Spontaneous Remission of Encephalitis that Developed 17 Weeks After the Last Dose of Pembrolizumab: A Case Report

症例は73歳の男性である。多発転移を伴う肺腺癌に対しペムブロリズマブを含む化学療法を施行したが，薬剤性肺障害を発症したため治療を中断した。ペムブロリズマブを最終投与した17週後に意識障害と右片麻痺を呈する脳炎を発症したが，症状は徐々に自然軽快し，発症3週間後には消失した。免疫チェックポイント阻害薬の投与後に遅発性に脳炎を発症する例は稀である。また，重篤な脳炎症状が後遺症を残すことなく自然消失した例を本例では初めて詳細に報告した。

Abstract

We present a 73-year-old man with a history of lung adenocarcinoma and multiple metastases. He was treated with chemotherapy, including pembrolizumab, but treatment was interrupted due to concurrent drug-induced lung injury. Seventeen weeks after the last dose of pembrolizumab, he developed encephalitis, presenting with a disturbance of consciousness and right hemiplegia. However, his symptoms gradually improved spontaneously and disappeared three weeks after their onset. Late-onset encephalitis after the administration of immune checkpoint inhibitors is rare. In addition, this is the first report of a case in which severe encephalitis recovered spontaneously without leaving sequelae.

(Received April 7, 2023; Accepted July 4, 2023; Published October 1, 2023)