Acute Interstitial Nephritis Induced by Monoclonal Antibodies Targeting Calcitonin Gene-Related Peptide (CGRP)—Unveiling a New Association: A Case Report

Drug-induced acute interstitial nephritis represents an idiosyncratic systemic T-cell-mediated hypersensitivity reaction associated with over 200 different agents, and predicting its occurrence is challenging. Monoclonal antibodies (mAb) that target the calcitonin gene-related peptide (CGRP) (anti-CGRP-mAbs) are among the most promising therapies for migraine treatment, with an increase in prolonged use and a lack of long-term studies. The immunogenicity of biological therapies potentially leads to the production of antidrug antibodies, potentially resulting in hypersensitivity reactions. Here, we report 2 cases of acute interstitial nephritis after more than 15 months of exposure to anti-CGRP-mAb. Both patients responded to corticosteroid therapy and discontinuation of the offending agent, with recovery of kidney function. To our knowledge, this is the first description of acute interstitial nephritis secondary to anti-CGRP-mAbs. Being aware of the possible association between anti-CGRP monoclonal antibodies and interstitial nephritis is critical in the scenario of new therapies for nephrologists.