Is there a role for interleukin-3 in Diamond-Blackfan anaemia? Results of a European multicentre study.

Forty patients (nine adults aged 20-54; 31 children aged 1-17) with Diamond-Blackfan anaemia (DBA) were treated with recombinant human interleukin-3 (IL-3) in a European multicentre compassionate-need study. IL-3 was given as a daily subcutaneous injection at a starting dose of 2.5 micrograms/kg, escalating at day 21 to 5 micrograms/kg, and then to 10 micrograms/kg if there was no response, for a total duration of 12 weeks. Three children achieved a significant response, achieving sustained remissions off all therapy. At the time of entry, one was steroid-responsive and transfusion-independent, and two were transfusion-dependent. Two adults had a transient reduction in transfusion requirements, but could not tolerate the complete course of therapy. Eosinophilia was common; neutrophil and platelet counts were unaffected except in three patients in whom previously noted mild thrombocytopenia was transiently exacerbated. Clinical response to IL-3 did not correlate with in vitro culture results. A comparison of individual patient characteristics of our study with previously reported series confirms earlier impressions that patients who have never achieved significant in vivo erythropoiesis in response to steroids or during a spontaneous remission are highly unlikely to respond to IL-3. In contrast, there may be a 50% chance of a sustained remission, off steroids, in children who are steroid-dependent and transfusion-independent at the time of IL-3 therapy, suggesting a possible role for a short course of IL-3 earlier in the treatment of children with steroid-responsive DBA.