The U.S. Food and Drug Administration has expanded the approval of Gleevec® (imatinib mesylate) to include the adjuvant (post-surgery) treatment of Kit-positive gastrointestinal stromal tumors in adults.
Gastrointestinal stromal tumors (GIST) are a relatively rare but aggressive type of soft-tissue sarcoma. These cancers are most commonly found in the stomach or small intestine.
It is estimated that there are between 4,500–6,000 cases of GIST diagnosed annually in the United States. More than 90% of these cases are Kit-positive, meaning that the cancers contain a particular protein (Kit) that contributes to cancer growth.
Early GIST, or GIST that has not spread to distant sites in the body, is often treated initially with surgery to remove the cancer. Unfortunately, the risk of recurrence is high, and GIST remains relatively resistant to chemotherapy and/or radiation therapy. Targeted drugs that inhibit the Kit protein, such as Gleevec, offer an important new approach to treating these cancers.
Gleevec was first approved in 2001 for the treatment of Philadelphia chromosome-positive chronic myelogenous leukemia. Since that time it has been approved for several other uses, including the treatment of Kit-positive GIST that cannot be surgically removed or that has metastasized (spread to other parts of the body).
The study that led to the approval of Gleevec for adjuvant (post-surgery) treatment of GIST was a Phase III clinical trial that involved more than 700 patients. After surgery to remove the cancer, patients were assigned to receive either Gleevec (400 mg/day) or placebo.
After a median follow-up of 14 months, 8.4% of patients treated with Gleevec had experienced a cancer recurrence or death compared with 19.8% of patients treated with placebo. Gleevec was generally well tolerated. The most frequent adverse reactions were diarrhea, fatigue, nausea, edema, decreased hemoglobin, rash, vomiting, and abdominal pain.
This study suggested that Gleevec significantly reduces the risk of cancer recurrence after surgical removal of Kit-positive GIST, and Gleevec is now approved for this purpose.
Reference: Novartis media release. Glivec receives US approval as first treatment to reduce risk of cancer returning in patients with gastrointestinal stromal tumors. Available at: http://www.novartis.com/newsroom/media-releases/en/2008/1279094.shtml. Accessed December 23, 2008.