In vitro assessment of the effects of granulocyte-macrophage colony-stimulating factor on primary human tumors and derived lines

One hundred eighty-nine human tumor specimens were tested in a human tumor cloning assay to determine their growth response to human recombinant granulocyte-macrophage colony-stimulating factor. Of these samples 48 were evaluable for response. Growth stimulation to greater than 150% of controls was noted in 1 of 12 lung cancers (8%) and 1 of 14 breast cancers (7%) but in no other instances for an overall rate of 2 of 48 (4.2%). A dose-response effect was not seen with each of the two stimulated samples responding only at the two lowest concentrations tested. In addition, 7 cell lines derived from human tumors were tested using a metabolic CO2 production assay without evidence of growth stimulation. Samples of normal bone marrow displayed the usual dose-dependent stimulation whether grown in agar or assayed metabolically. We conclude that human recombinant granulocyte-macrophage colony-stimulating factor has minimal effect on the growth of the solid tumors tested and that clinical trials to reduce chemotherapy-associated myelo-suppression may proceed without undue concern for enhancement of tumor growth.