Successful Rechallenge With Pembrolizumab After a Grade 3 Infusion Reaction With a Far Slower Infusion Rate and Premedication: A Case Report

Patients who experience grade 3 and 4 infusion reactions during pembrolizumab treatment should discontinue treatment, per the prescribing guidelines. We report a case of successful rechallenge with pembrolizumab after a grade 3 infusion reaction with a slow infusion rate and premedication. A Japanese woman in her 60s with recurrent endometrial cancer was treated using a combination of pembrolizumab and lenvatinib. During the second cycle of pembrolizumab treatment, delayed and recurrent grade 3 infusion reactions associated with systematic flushes and elevated body temperature occurred. Pembrolizumab rechallenge was performed, accompanied by the administration of premedication (histamine receptor inhibitors and acetaminophen) and reduction of the infusion rate. The flow rate was reduced to 25% of the normal rate, followed by a 50% reduction of the normal infusion rate; no recurrence of the infusion reaction was noted. Proper management of severe-grade infusion reactions may allow the continuation of pembrolizumab treatment, thereby improving patient prognosis.