Immunex Corp. moved quickly last week to counter bad news on the use of certain colony stimulating factors in older patients with acute non-lymphocytic leukemia (acute myelogenous leukemia), with a statement emphasizing positive results of its Leukine GM-CSF, which is awaiting FDA approval to speed neutrophil recovery in AML patients after chemotherapy.

In studies reported in the New England Journal of Medicine (NEJM), Schering-Plough's E. coli-derived GM-CSF, and Chugai/Rhône-Poulenc Rorer's G-CSF, despite being safe and accelerating neutrophil recovery, both failed to alter mortality rates in AML in older patients