Infusion-related hypersensitivity reactions during natalizumab treatment

Abstract

As with many biologic therapeutics, hypersensitivity reactions occurred during natalizumab treatment in the AFFIRM study.1 These hypersensitivity reactions included all events reported as hypersensitivity, allergic reaction, or anaphylactic/anaphylactoid by the investigator as well as any report of urticaria, allergic dermatitis, or hives. If a hypersensitivity reaction was observed, natalizumab was immediately discontinued and the patient was not retreated (per protocol). Twenty-five (4%) patients in the natalizumab-treated group experienced 27 hypersensitivity reactions (table); two patients were redosed after experiencing a hypersensitivity reaction; therefore, there were two protocol violations. Fifteen of these 27 hypersensitivity reactions occurred by the second infusion and an additional eight occurred between the third and seventh infusions. Eight hypersensitivity reactions were reported as serious adverse events (seven in the natalizumab group and one in the placebo group). The incidence of serious systemic hypersensitivity reactions, classified as anaphylactoid or anaphylactic reactions, was <1%. Seventeen of the 25 (68%) natalizumab patients with hypersensitivity reactions, which included all the patients with serious systemic reactions, were persistently positive for antibodies to natalizumab. In the SENTINEL study, 11 (1.9%) natalizumab-treated patients experienced hypersensitivity reactions; however, no anaphylactic or anaphylactoid reactions were observed.2 View this table: Table Hypersensitivity reactions in the AFFIRM study Treatment of hypersensitivity reactions was at the discretion of …