First successful desensitization with Abemaciclib in an adult patient with breast cancer: A case report

• Merve Hörmet İğde ^[1] ; Şule Çelik Kamacı ^[1] ; Pelin Korkmaz ^[1] ; İlkim Deniz Toprak ^[2] ; Özdemir Can Tüzer ^[3] ; Osman Ozan Yeğit ^[1] ; Derya Ünal ^[1] ; Semra Demir ^[1] ; Aslı Gelincik ^[1]
  1. [1] Department of Clinical Immunology and Allergy, Faculty of Medicine,Istanbul University, Istanbul, Turkiye
  2. [2] Clinical Immunology and Allergy, Umraniye Training and Research Hospital, Istanbul, Turkiye
  3. [3] Clinical Immunology and Allergy, Haydarpasa Numune Training and Research Hospital, Istanbul, Turkiye

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• Localización: Allergologia et immunopathologia: International journal for clinical and investigate allergology and clinical immunology, ISSN-e 1578-1267, ISSN 0301-0546, Vol. 53, Nº. 6, 2025, págs. 146-148
• Idioma: inglés
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  • Abemaciclib, a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor, is an effective targeted therapy for hormone receptor-positive (HR+), HER2-negative, advanced or metastatic breast cancer. While nonimmediate hypersensitivity reactions (NIHRs) have been reported, no imme-diate hypersensitivity reactions (IHRs) to abemaciclib have been documented to date. Here, we report the first successful desensitization protocol for a patient who developed IHR to abemaciclib. A 75-year-old female with stage II breast cancer underwent a partial mastec-tomy followed by chemotherapy. Abemaciclib was initiated as part of adjuvant treatment. One hour after the third dose, she presented to the emergency department with lip swelling and urticaria. Symptoms resolved following the administration of intravenous methylprednis-olone (0.5 mg/kg) and maleate pheniramine (45.5 mg/mL). Skin prick testing with abemaciclib was negative; however, a drug provocation test led to recurrence of urticaria at a cumula-tive dose of 150 mg. Given the clinical necessity of abemaciclib and the lack of alternatives, a 12-step desensitization protocol was implemented using 300 mg of abemaciclib dissolved in 100 mL of distilled water. The protocol was completed over 4 h, with no complications observed during the procedure or in the subsequent 3-month follow-up. The patient contin-ued abemaciclib at 300 mg/day without recurrence of symptoms. This case highlights the importance of drug desensitization in oncology, particularly in patients for whom no alterna-tive therapies are available.