P-0018: Severe neutropenia following a single infliximab infusion in a child with Crohn disease

Infliximab is highly efficacious in the treatment of pediatric and adult Crohn Disease.v,vi. Randomized-controlled trial data indicate that it has a role in the treatment of ulcerative colitis in adult patientsvii and it is currently being evaluated in pediatric ulcerative colitis patients in a prospective open label trialviii. Recognized adverse events associated with infliximab therapy include infusion reactions and skin eruptions, often psoriasiform in nature. Infectious complications include the reactivation of tuberculosis. Blood dyscrasias, seen in association with infliximab therapy, are uncommon. We report the development of profound neutropenia, subsequent to a single infliximab infusion for steroid-refractory ulcerative colitis, in an 8-year old boy. His neutrophil count prior to the infliximab (5mg/kg) therapy was 3.45 × 109/L. Although he had an excellent clinical response to the single infusion, he was found to have severe neutropenia (0.03 × 109/L) prior to the second, scheduled infusion, which was subsequently withheld. He was asymptomatic. Despite extensive investigations including a bone marrow examination, no other underlying cause was identified. We believe that the profound neutropenia developed as a consequence of infliximabinduced autoimmune destruction of neutrophils. A similar experience has been described in an adult Crohn disease patient who developed neutropenia (0.5 × 109/L) following the second infliximab infusion. This adult patient was found to be positive for granulocyte-bound-antibodies and neutrophil-specific-bound antibodies and developed similar episodes of neutropenia following subsequent infusions.ix It is our opinion that a similar mechanism was responsible for the neutropenia in our patient. To the best of our knowledge, this is the first report of profound neutropenia in a pediatric patient following an infliximab infusion. It highlights the need for ongoing hematological surveillance in all patients prior to infliximab therapy.