Desensitization to an isatuximab allergy in patients with indolent systemic mastocytosis (SM) appears possible, according to a recently published letter to the editor in the Journal of Investigational Allergology and Clinical Immunology.
Isatuximab is a monoclonal antibody intended to treat adults with multiple myeloma. Multiple myeloma can coexist with other hematologic disorders, such as SM. There are reports of patients with indolent SM and concomitant multiple myeloma who developed a strong allergic reaction (anaphylaxis) towards isatuximab with marked mast cell activation. Anaphylaxis involves an excessive immune response from the organism that can lead to airway obstruction, hypotension, shock, and death.
Learn more about SM treatment and care
The authors suggest that desensitization, the process by which the immune system stops reacting against a given antigen, is possible in such patients.
The case involved a 52-year-old woman with multiple myeloma and a history of indolent systemic mastocytosis (ISM). The patient needed to take antihistamines daily to prevent SM-associated symptoms such as flushing and palpitations.
As part of her treatment for multiple myeloma previous to bone marrow transplantation, the patient received isatuximab for 10 days without eventuality. Six months later, the patient received isatuximab once again, developing anaphylaxis symptoms within 15 minutes. Treatment was immediately interrupted, and the patient was stabilized with intravenous steroids.
One year after the episode, the patient presented with a multiple myeloma relapse that required isatuximab treatment. Therefore, the attending physicians developed a desensitization schedule that involved administering 12 small, escalating doses together with an immunosuppressant (dexamethasone), in the course of a day. After four days of desensitization treatment, the patient was able to resume her multiple myeloma treatment without complications.
“This is the second report of RDD to isatuximab,” the authors wrote.” We describe a slightly different but equally successful procedure in a patient with underlying [SM] and previous severe anaphylaxis as additional risk factors.”
