Cardiac tamponade during pembrolizumab treatment in a patient with ovarian cancer: a case report.

We present the case of a 39-year-old woman with platinum-resistant ovarian cancer who was treated with pembrolizumab. After five cycles of pembrolizumab treatment, she suddenly developed cardiac tamponade with a pleural effusion. The malignant pericardial and pleural effusion had increased, while the other malignant lesions had diminished in size. After pericardial and pleural drainage, no re-accumulation occurred. Pembrolizumab was continued and the patient did not have tumor progression for > 20 months. In some patients with pembrolizumab-induced cardiac tamponade, continuation of pembrolizumab treatment may be possible if other lesions decrease in size and the pericardial effusion can be controlled after drainage.