MSI-Highを有する去勢抵抗性前立腺癌に対するペムブロリズマブの使用経験

Abstract

Castration-resistant prostate cancer and multiple lymph node and ventral bladder metastases in an 87 year-old man progressed despite various systemic therapies, including chemotherapy. Because his prostate surgical specimen displayed a microsatellite instability (MSI) -high status, pembrolizumab 200 mg/body treatment was started. After six courses of treatment, his prostate-specific antigen (PSA) level decreased by 83% versus that at treatment initiation (from 408.78 ng/ml to 69.54 ng/ml), and the para-aortic lymph node metastasis was reduced in size on imaging. After 13 courses, his PSA level (462.59 ng/ml) exceeded that at the start of treatment, and progressive disease was detected on imaging. Although case reports of pembrolizumab for MSI-high prostate cancer remain few because of its rarity, it is an important therapeutic option and further clinical research is required.