Nephrotic Syndrome During Ipilimumab Plus Nivolumab Therapy for Sarcomatoid Malignant Pleural Mesothelioma: A Case Report of Nivolumab Rechallenge Without Recurrence of Nephrotic Syndrome.

Immune checkpoint inhibitor (ICI)-associated nephrotic syndrome is a rare immune-related adverse event. When it occurs during combination ICI therapy, identifying the causative agent and determining an appropriate strategy for subsequent ICI rechallenge can be clinically challenging. A 67-year-old man with unresectable sarcomatoid malignant pleural mesothelioma received combination therapy with ipilimumab and nivolumab, resulting in tumor shrinkage. Approximately four months after treatment initiation, he developed nephrotic syndrome characterized by severe proteinuria, hypoalbuminemia, and bilateral pleural effusions. Both ICIs were discontinued, and prednisolone therapy resulted in improvement of nephrotic syndrome. However, tumor regrowth was observed during corticosteroid tapering, and nivolumab monotherapy was selected for rechallenge. Nephrotic syndrome did not recur after nivolumab rechallenge, which was administered with concurrent prednisolone at a tapering dose. This pattern raises the possibility that ipilimumab alone or the combination of ipilimumab and nivolumab contributed to the development of nephrotic syndrome. This case provides clinical insight into the potential contribution of individual ICIs to ICI-associated nephrotic syndrome and into selective ICI rechallenge as a subsequent treatment strategy.