Osteonecrosis of the jaw associated with ustekinumab in the treatment of Crohn's disease

MRONJ is a well-known side effect of antiresorptive and antiangiogenic drug treatment. Crohn's disease involves pro-inflammatory interleukins IL-12 and IL-23. Ustekinumab is a targeted therapy antagonist of the p40 subunit of IL-12 and -23 indicated in the treatment of immune-mediated inflammatory diseases. A 72-year-old man with Crohn's disease developed MRONJ after being treated with ustekinumab for four years. The patient presented with bone exposure three months after the extraction of two mandibular teeth. He had no known predisposing factors and never received ARDs. The patient underwent surgical treatment, and ustekinumab treatment was suspended for six months. No recurrence of MRONJ was detected after 12 months. Although the new definition of MRONJ excludes antiangiogenic molecules, tyrosine kinase inhibitors, and mTOR inhibitors alone, some cases have been reported with ustekinumab. This report highlights the possibility of MRONJ occurring when taking ustekinumab for Crohn's disease, even without being treated with antiresorptive drugs.