Human granulocyte-macrophage colony-stimulating factor modulates in vitro growth in only a minority of continuous human tumour cell lines. EORTC Clonogenic Assay Screening Study Group.

Granulocyte-macrophage colony stimulating factor (GM-CSF) has potential usefulness in a range of clinical conditions, including the treatment of patients with myelosuppression induced by chemotherapy and/or radiotherapy. Prior to any extensive use of this material, however, assessment of its effects on non-haematopoietic tumour cell growth appeared warranted. Accordingly, five laboratories, all members of the EORTC Clonogenic Assay Screening Study Group, have monitored in vitro responses to GM-CSF, using their own individual assay procedures, in a series of 18 human tumour cell lines, predominantly of non-haematopoietic origin, 25 tumour biopsy specimens and samples from five normal bone marrow aspirates. Significant growth stimulation by GM-CSF addition was rare, being absent in all 25 "fresh" ovarian tumour samples tested, but was consistently observed in four of the 18 continuous tumour cell lines tested (1 breast and 3 ovary) and all five normal bone marrow aspirates.