000953 - Successful Oral Desensitization to Pomalidomide in a Patient with Multiple Myeloma and Maculopapular Exanthema

Pomalidomide is an immunomodulatory drug essential for treating relapsed/refractory multiple myeloma. Hypersensitivity reactions can compromise therapeutic options in patients with limited alternatives. We present a case of successful oral desensitization to pomalidomide in a patient who developed a maculopapular exanthema.

A 69-year-old woman with stage III-A multiple myeloma (Durie-Salmon), with no prior allergic history, initiated treatment with dexamethasone 20 mg twice weekly, cyclophosphamide 50 mg daily, and pomalidomide 4 mg daily. Twelve days after starting therapy, she developed a measles-like desquamative eruption affecting the face (malar and frontal regions), neck, and chest, without mucosal involvement or systemic symptoms. Treatment was discontinued, and the reaction resolved with parenteral corticosteroids. Cyclophosphamide was safely reintroduced. Given disease progression on previous lenalidomide and bortezomib therapy, pomalidomide continuation was critical

Allergology workup revealed eosinophil counts unchanged from baseline, total IgE <1 kU/L, baseline tryptase 5 μg/L, normal transaminases, negative HLA-B58:01 and HLA-B15:02, and negative serology for Mycoplasma, EBV, CMV, and HSV-1, -2, and -6.

Premedication with loratadine 10 mg and montelukast 10 mg was administered 48 hours before and on the day of desensitization. A graded oral protocol using four solutions was implemented with 15-minute intervals between doses (Table 1). Vehicle preparation utilized gelified water. Solutions were prepared as described in supplementary material (Table 2)

The desensitization protocol was completed without adverse reactions. The patient continued pomalidomide 4 mg daily at home with excellent tolerance. Given the 21-day treatment cycles with 7-day rest periods, subsequent cycle initiation required repeating the desensitization protocol, which was successfully performed without incidents.

This case adds to the limited but growing literature on successful pomalidomide desensitization. Previous reports have documented successful 10-step desensitization protocols for pomalidomide-induced hypersensitivity reactions, primarily involving cutaneous manifestations similar to our patient. Although hypersensitivity reaction rates in clinical trials range between 1-5%, real-world practice may encounter higher rates, making desensitization protocols increasingly relevant. Our case demonstrates that oral desensitization enables safe therapeutic continuation in patients with limited alternatives, emphasizing the critical role of multidisciplinary collaboration between allergology, pharmacy and oncohematology services in optimizing multiple myeloma treatment outcomes.