Delayed natalizumab allergy seen in patient with multiple sclerosis


NEW YORK–

Although most hypersensitive reactions to natalizumab (Tysabri) occur within hours of the first dose, such responses may be delayed, according to a case report by German researchers.

In Archives of Neurology, Dr. Markus Krumbholz of Ludwig Maximilian University, Munich, and colleagues report on a 23-year-old man with relapsing-remitting multiple sclerosis (MS).

Eight hours after his second infusion of natalizumab he collapsed, developed a fever, arthralgias (1) , urticarial (2)  exanthema (3) , and a swollen lower lip.

The patient had had no history of allergic reactions and his concomitant medication had not changed over the previous weeks. After excluding an underlying infection, the researchers treated the man with oral prednisone for 2 days. All symptoms subsequently resolved.

He tested positively for anti-natalizumab antibodies 5 weeks after his initial treatment with the agent and exhibited persistent antibody titers 8 and 12 weeks later. The researchers diagnosed a delayed allergic reaction and switched his therapy to mitoxantrone.

Thus, Dr. Krumbholz and his associates advise, "patients and treating physicians should be aware that delayed hypersensitivity reactions, such as serum sickness, can develop during treatment with natalizumab."

"If unusual symptoms consistent with an allergic reaction occur during the first days after infusion, patients should contact their neurologists to initiate appropriate medical treatment," they conclude.