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AND THE ANSWER IS . . .

1

Discussion
Treatment with Flix is generally safe. However, TNF alpha does play a role in a number of inflammatory reactions, both 1) pathogenic and 2) protective against microbial invasion. Therefore, it is not surprising that blocking TNF alpha activity might be associated with an increased predisposition to serious infections. In a series of 500 Crohn's disease patients treated with Flix at the Mayo Clinic, serous adverse events were attributed to Flix in 6% of the cases (1). Infections were the most common serious adverse event (4% of cases), with pneumonia a common locus of such infection. In another report, there were a sizable number of what appears to be reactivation tuberculosis infections (Tbc) in Flix treated patients (2). A more recent report (3) described an increased relative risk for Tbc in rheumatoid arthritis patients treated with FLIX (RR=19.9). These findings have been impressive enough so that many clinicians tuberculin skin test all individuals considered for Flix therapy. Tuberculin-positive patients are either excluded from Flix therapy or are co-treated with modified anti-Tbc therapy if Flix is used.

Flix is a chimeric monoclonal antibody composed of mainly human but some mouse components. Serum sickness like reactions have occurred in 2-3% of those treated with Flix (1). Antibodies against this chimeric antibody appear in a sizable number of Flix treated patients. However, this immune response does not appear to inhibit the efficacy of subsequent Flix infusions in most cases.

Acute infusion reactions have been observed in 4-19% of treated patients. Most reactions are mild although serious anaphylactic reactions have been reported, even though most Crohn's patients receiving Flix were also receiving corticosteroids and/or immunosuppressive therapy at the time (1). Therefore, one cannot count on corticosteroid therapy to prevent all acute infusion reactions to Flix.

References

  1. Gastroenterology 2004; 126:19-31
  2. N Engl J Med 2001; 345:1098-1104
  3. Arthritis Rheum 2003; 48:2122-2127


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