D1.387 - Long-term Follow-up Outcomes of Patients Undergoing Desensitization for Non-Immediate Hypersensitivity Reactions Associated with Lenalidomide

Lenalidomide is used in the treatment of various hematological diseases. However, lenalidomide associated non-immediate hypersensitivity reactions (HSRs), may limit its continued use. In patients for whom no effective alternative therapy is available, drug desensitization may represent the only viable option. Several desensitization protocols for lenalidomide have been reported in the literature. Nevertheless, data on the long-term follow-up outcomes of patients undergoing lenalidomide desensitization remain limited. We aimed to evaluate the long-term outcomes of 26 patients who underwent a 16-day slow lenalidomide desensitization protocol previously described by our group.

Patients who underwent desensitization were included in this study. Detailed demographic and clinical characteristics, as well as selected laboratory parameters, were recorded. The current clinical status of patients was assessed through outpatient follow-up visits.

Among the 26 patients, fourteen (53.8%) were male; the median age was 63 years (IQR:56.7–69.5). HSRs developed at a median of 12.5 days (IQR:3.0–28.0) after the initiation of lenalidomide. Diagnoses included maculopapular eruption (n=16), delayed urticaria (n=7), eczematous dermatitis (n=2), and drug rash with eosinophilia and systemic symptoms (DRESS, n=1). Despite the presence of DRESS, desensitization was cautiously undertaken in a single patient due to mild disease severity and an essential treatment indication.Desensitization could not be completed in four patients(15.4%) due to persistent HSRs.In three patients(11.5%),the protocol was successfully completed over 23, 35, and 47 days, respectively, with the addition of antihistamines and/or systemic corticosteroids after reactions that occurred on day 11.Among the 22 patients(84.6%) who successfully completed desensitization, the median duration of lenalidomide use after desensitization was 12 months(IQR:5–22).During follow-up, no drug-related HSRs were observed.Treatment was discontinued in 18 patients due to disease progression or other adverse effects of drug, while four patients continued treatment for 4, 4, 7, and 14 months, respectively.

A 16-day slow lenalidomide desensitization protocol, representing the shortest protocol reported to date, was effective and well tolerated, with no recurrence of HSRs during the long-term follow-up.This approach may offer a practical option in clinical practice and could potentially be extended to delayed-type HSRs associated with other oral agents.