D3.314 - Rapid desensitization to intravenous risankizumab after anaphylaxis in a patient with Crohn’s disease: a case report

Hypersensitivity reactions to biologics, including anaphylaxis, may restrict treatment options in immune-mediated diseases. Risankizumab, an IL-23p19 inhibitor, is approved for Crohn’s disease (CD). However, no desensitization protocols to intravenous risankizumab after anaphylaxis have been reported.

A 43-year-old woman with moderate-to-severe CD developed an immediate hypersensitivity reaction consistent with anaphylaxis shortly after her first intravenous risankizumab infusion. She was treated with corticosteroids, antihistamines, and intravenous fluids. Due to active disease and lack of alternatives, a 12-step rapid drug desensitization (RDD) protocol with three escalating infusion bags was implemented within 24 hours of the event. Skin testing with risankizumab and excipients (polysorbate 80, PEG, tromethamine) was performed before subsequent infusions.

The first RDD allowed completion of the full 600 mg induction dose without recurrence of anaphylaxis. Skin prick and intradermal tests were negative; however, their predictive value for biologics remains uncertain. A second infusion under RDD protocol was uneventful. During the third infusion, a mild grade I breakthrough reaction (erythema, pruritus, mild pharyngeal irritation) occurred at a low step, was managed with corticosteroids and antihistamines, and did not require treatment interruption. The full dose was successfully administered. No further reactions occurred. Written informed consent for publication of clinical details was obtained.

RDD enabled safe continuation of risankizumab in a patient with CD who experienced anaphylaxis to the first dose. To our knowledge, this represents the first reported successful desensitization to intravenous risankizumab. This case underscores the importance of structured RDD in maintaining access to essential biologic therapies in patients with immediate hypersensitivity reactions.