Effects of rhGM-CSF on myeloid clonogenic cells in acute myelogenous leukemia patients

Regrowth resistance in cancer: why has it been largely ignored?

In drug-sensitive malignancies, treatment failure is a complex phenomenon resulting from both drug resistance and the rapid regrowth of malignant cells in between cycles of chemotherapy. This phenomenon has been referred to as regrowth resistance, and has been identified as a common impediment to the successful treatment of many neoplastic diseases. This phenomenon has received little attention in the past. The administration of maximally tolerated individual dosages of chemotherapeutic agents, combined with the use of biological response modifiers to slow the regrowth between courses of therapy, would be an effective approach to reduce the regrowth resistance. This also could reduce the emergence of drug resistant clones.

Unexpected remission of acute myeloid leukaemia after GM-CSF

The administration of granulocyte-monocyte colony-stimulating factor (GM-CSF) was associated with complete clinical and haematological response in an adult patient with minimally differentiated acute myeloid leukaemia who presented with pneumonia and moderate neutropenia, but no blast cells in the peripheral blood. The response lasted 9 months. At relapse, a second GM-CSF course resulted in a very good partial remission lasting 5 months, although differences in the kinetics of haemoglobin, neutrophil and platelet recovery were noted. Subsequent recurrences were managed with chemotherapy, a complete remission being obtained twice more and lastly consolidated with myeloablative chemo-radiotherapy supported by a peripheral blood stem cell autograft. This report suggests that GM-CSF should be further investigated as a therapeutic agent in selected cases of AML.