Use of the
iron chelator deferiprone for treatment of
iron overload in
thalassemia patients is associated with concerns over
agranulocytosis, which requires weekly absolute neutrophil counts (ANC). Here, we analyze all episodes of
agranulocytosis (n = 161) and
neutropenia (n = 250) during
deferiprone use in clinical trials (CT) and postmarketing surveillance programs (PMSP). Rates of
agranulocytosis and
neutropenia in CT were 1.5% and 5.5%, respectively. Of the
agranulocytosis cases, 61% occurred during the first 6 months of
therapy and 78% during the first year. These events appeared to be independent of dose, and occurred three times more often in females than males. Their duration was not significantly shortened by use of
G-CSF. No patient with baseline
neutropenia (n = 12) developed
agranulocytosis during treatment, which raises questions about the validity of prior
neutropenia as a
contraindication to use. Only 1/7 novel
neutropenia cases in CT progressed to
agranulocytosis with continued treatment, indicating that
neutropenia does not necessarily lead to
agranulocytosis. The
agranulocytosis fatality rate was 0% in CT and 15/143 (11%) in PMSP. Rechallenge with
deferiprone produced
agranulocytosis in 75% of patients in whom the event had already occurred, and in 10% with previous
neutropenia. Weekly ANC monitoring allows early detection and interruption of
therapy, but does not prevent
agranulocytosis from occurring. Its relevance appears to decrease after the first year of
therapy, when
agranulocytosis occurs less often. Based upon analysis of data collected over the past 20 years, it appears that patient education may be the key to minimizing
agranulocytosis-associated risks during
deferiprone therapy. Am. J. Hematol. 91:1026-1031, 2016. © 2016 The Authors. American Journal of Hematology Published by Wiley Periodicals, Inc.