ワルファリン服用患者におけるニボルマブとイピリムマブ併用によるPT-INRの変動した1症例

抄録

Warfarin (WF) has been reported to interact with various other drugs, but there are no reports of nivolumab or ipilimumab directly interacting with WF. In the current case, a patient taking WF had a prolonged PT and increased INR after combination therapy with nivolumab and ipilimumab. The patient was a 71-year-old man who was started on combination therapy with nivolumab and ipilimumab 2 months after excision of a renal tumor. PT-INR was 2.04 before admission. After combination therapy started, PT-INR increased to 8.58 according to a blood test performed on Day 22. The patient also developed hyperthyroidism, which is an immune-related adverse event (irAE) caused by nivolumab and ipilimumab. PT-INR increases as a result of hyperthyroidism, so the increase in PT-INR in the current patient is presumably due to irAE-induced hyperthyroidism. Thyroid dysfunction due to irAE may cause both hyperthyroidism and hypothyroidism and it may affect the efficacy of WF. PT-INR should be monitored when WF is used in combination with immune checkpoint inhibitors.