PHASE I II TRIAL OF PIXY321 (GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR INTERLEUKIN-3 FUSION PROTEIN) FOR TREATMENT OF INHERITED AND ACQUIRED MARROW FAILURE SYNDROMES/

Fourteen paediatric patients with advanced amegakaryocytic thrombocyto penia (AMT) or other bone marrow (BM) failure syndromes were enrolled on one of two phase I/II dose escalation studies of PIXY321. PIXY321 w as administered subcutaneously in doses ranging from 250 to 750 mg/m(2 )/d. No dose-limiting toxicity was observed. Peak absolute neutrophil count (ANC) was higher than baseline in all patients. Most transfusion -independent patients demonstrated elevation in haematocrit and/or pla telet count. Trilineage haemopoietic responsiveness was evident in the three transfusion-independent patients. In these paediatric populatio ns PIXY321 is well tolerated and merits consideration as a potential t herapy.