an immune-suppressing drug used to treat
rheumatoid arthritis and Crohn's
disease, is behind 70 reported cases of
tuberculosis (TB) among U.S. patients
who received the medication.
cases, at least four of which were
fatal, were reported to the Food and
Drug Administration between 1998 and May
of this year. Researchers who reviewed
the cases say that the immune-system
protein infliximab suppresses -- called
tumor necrosis factor alpha (TNF-alpha)
-- appears to be key in controlling TB
Around 150,000 people worldwide have
received infliximab infusions since the
drug's approval in 1998. In August,
Malvern, Pennsylvania-based Centocor,
which markets infliximab as Remicade,
announced it was changing the drug's
prescribing information to address the
TB concerns. The revised labeling states
that patients should be tested and
treated for inactive, or latent, TB
prior to infliximab therapy.
Latent TB refers to a chronic, but
symptomless and noncontagious,
infection. Such TB infections are
prevalent throughout the world because
in most people, the immune system is
able to suppress TB bacteria.
Up to 15 million Americans are
estimated to have latent TB infections.
When the immune system is suppressed
-- as it is in patients on infliximab --
latent TB can become active. Active TB
usually attacks the lungs, causing
symptoms such as a severe cough, chest
pain and weight loss. It is spread
through the air from person to person.
The New England Journal of Medicine
October 11, 2001;345:1098-1104