A Case of Relapsing Aseptic Meningitis under Excellent Tumor Response to Pembrolizumab in Microsatellite Instability-High Recurrent Endometrial Cancer

• This is the first report of aseptic meningitis due to immune checkpoint inhibitor treatment in endometrial cancer. • The meningitis was severe and relapsed multiple times unlike in other reported cases. • Oncologic outcome was excellent after overcoming this severe adverse event.