Successful rapid desensitization to zoledronic acid in a multiple myeloma patient.

Background: Multiple myeloma (MM) is a malignancy characterized by the proliferation of abnormal plasma cells in the bone marrow, leading to osteolytic lesions. This condition is accompanied by a serum accumulation of monoclonal immunoglobulin. Zoledronic acid (ZA) is a new-generation bisphosphonate commonly used to prevent bone complications. However, allergic reactions can pose challenges, potentially leading to ZA discontinuation. Thus, rapid desensitization (RD) has been proposed as a solution to continue treatment in patients with severe HR. RD consists in the induction of a temporary state of tolerance by administering increasing doses of the offending medication.

Methods: We present the case of a 57-year-old woman with MM who developed face angioedema, flushing with itching, dizziness and fever to ZA. Thus, an allergy work-up with skin prick test and intradermal test (IDT) with ZA were performed. Subsequently, considering the necessity of maintaining ZA treatment, a 3-dilution, 12-step RD infusion protocol was implemented. Skin tests were also repeated after three RD infusions.

Results: Skin tests showed positive IDT reactions to ZA confirming the hypersensitivity state of the patient to the medication. Then, the patient underwent RD procedures without any HR. Skin tests performed after three RD procedures were deemed negative.

Conclusions: Here, we demonstrate successful management with RD in an MM patient with HR to ZA, providing a valuable therapeutic option for patients experiencing such reactions. The effectiveness of RD to ZA was confirmed by the negative response to skin tests after 3 RD procedures. Nevertheless, further research is needed to refine RD protocols and establish their safety and efficacy for patients with HR to ZA. Standardized in vitro testing may also improve the diagnosis and management of ZA hypersensitivity.