Background: Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine that is involved in the differentiation and proliferation of various hematopoietic precursors. It also has been reported to enhance the antitumor activity of various mature effector cells. Previous reports have noted preclinical antitumor activity in a murine model utilizing genetically engineered tumor cells and instances of tumor regression in patients with solid tumors receiving GM-CSF. In the present study, a Phase II trial of human recombinant GM-CSF (GM-CSFrh) in patients with metastatic renal cell carcinoma (RCC) was conducted to investigate further the potential antitumor activity of this cytokine.
Methods: Twenty-six eligible patients with metastatic RCC received 3 microgram/kg of GM-CSFrh subcutaneously for 14 days, with cycles repeated every 28 days.
Results: Two of 26 patients (8%; 95% confidence interval 1-25%) demonstrated partial tumor responses during GM-CSFrh therapy. Both individuals who responded had received prior therapy. A median of three cycles per patient were administered, and toxicity was mild.
Conclusions: GM-CSFrh may mediate tumor regression in patients with metastatic RCC; however, the level of activity in previously treated patients is low.