Desensitization in immediate-type hypersensitivity reactions (HRs) caused by chemotherapeutics is well described and standardized for many drugs. However, there are no standardized protocols in non-immediate HRs.

To evaluate the effectiveness of a 16-day desensitization protocol in the non-immediate HRs induced by lenalidomide.

According to our previously published slow desensitization protocol, we desensitized patients who had experienced non-immediate HRs attributable to lenalidomide. The protocol was started with the 1/100 of the daily-prescribed dose in milligrams of the culprit drug; then the doses were slowly increased to complete the procedure in 16 days. Demographic and clinical features of the patients were further appraised.

Ten patients (mean age was 64.7 ± 10.8 years; 7 male) were successfully desensitized to lenalidomide. The mean reaction time was 7.3 ± 3.9 days in the history, and the reaction types were delayed urticaria (n = 4), eczematous rash (n = 3), and maculopapular eruptions (n = 3). The desensitization was successfully completed in 16 days in 9 patients. In 1 patient, maculopapular eruptions developed on the 11th day, and the patient was treated with corticosteroids. We repeated the previous tolerated dose longer and completed with a slower dose increasement, and the targeted dose was achieved in 35 days.

The 16-day desensitization protocol seemed to be safe and effective in the non-immediate type drug HRs caused by lenalidomide.