Sargramostim, granulocyte–macrophage colony-stimulating factor, a hematopoietic growth factor, stimulates cells of the intestinal innate immune system. Preliminary studies suggest sargramostim may have activity in Crohn's disease. To evaluate this novel therapeutic approach, we conducted a randomized, placebo-controlled trial.

Using a 2:1 ratio, we randomly assigned 124 patients with moderate-to-severe active Crohn's disease to receive 6 μg of sargramostim per kilogram per day or placebo subcutaneously for 56 days. Antibiotics and aminosalicylates were allowed; immunosuppressants and glucocorticoids were prohibited. The primary end point was a clinical response, defined by a decrease from baseline of at least 70 points in the Crohn's Disease Activity Index (CDAI) at the end of treatment (day 57). Other end points included changes in disease severity and the health-related quality of life and adverse events.

There was no significant difference in the rate of the primary end point of a clinical response defined by a decrease of at least 70 points in the CDAI score on day 57 between the sargramostim and placebo groups (54 percent vs. 44 percent, P=0.28). However, significantly more patients in the sargramostim group than in the placebo group reached the secondary end points of a clinical response defined by a decrease from baseline of at least 100 points in the CDAI score on day 57 (48 percent vs. 26 percent, P=0.01) and of remission, defined by a CDAI score of 150 points or less on day 57 (40 percent vs. 19 percent, P=0.01). The rates of either type of clinical response and of remission were significantly higher in the sargramostim group than in the placebo group on day 29 of treatment and 30 days after treatment. The sargramostim group also had significant improvements in the quality of life. Mild-to-moderate injection-site reactions and bone pain were more common in the sargramostim group, and three patients in this group had serious adverse events possibly or probably related to treatment.

This study was negative for the primary end point, but findings for the secondary end points suggest that sargramostim therapy decreased disease severity and improved the quality of life in patients with active Crohn's disease.