A case of pembrolizumab induced distal renal tubular acidosis

Abstract

Immunotherapy has become a mainstay therapeutic in a variety of malignancies. Checkpoint inhibitors are used to enhance the endogenous immune response to target malignancy. The primary targets of checkpoint inhibitors include programed cell death receptor 1 (PD-1), programed cell death ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4). Despite clinical benefits, immune checkpoint inhibitors are associated with side effects termed immune-related adverse events (irAEs). We report a case of the PD-1 inhibitor (pembrolizumab) causing severe distal renal tubular acidosis (RTA). The patient presented with altered mental status and was found to have a severe non-anion gap metabolic acidosis after other potential etiologies were ruled out. We review the etiology of immune checkpoint inhibitor-induced RTA and review the case reports that have been described in the literature.