The FDA approves imatinib after the surgical removal of KIT-positive GISTs.
The FDA granted regular approval for imatinib (Gleevec) for treating patients after the surgical removal of CD117-positive (KIT-positive) gastrointestinal stromal tumors (GISTs).
Upcoming imatinib label updates will include study data that show increased overall patient survival for a 36-month treatment regimen as opposed to the original 12-month standard of care.
Imatinib was initially granted accelerated approval by the FDA in 2002 for patients with advanced or metastatic GIST. In 2008, the FDA again granted an accelerated approval to include patients who were at an increased risk for recurrence after surgical removal of the GIST. That same year, regular approval was granted for patients with metastatic GIST.
The latest approval stems from the results of the SSGXVIII/AIO study, which were first presented at the annual American Society of Clinical Oncologists (ASCO) meeting in June 2011. The open-label, multicenter, randomized phase III study evenly divided 400 patients with KIT-positive GIST into 2 groups to receive imatinib for either 12 months or 36 months. The primary endpoint was recurrence-free survival.
After 54 months of follow-up, study results showed that patients who received imatinib for 36 months were 54% less likely to experience recurrence (hazard ratio [HR] 0.46; 95% CI, 0.32, 0.65, P
< .0001) compared patients who received the drug for 12 months. The study also found that the chance of death as a result of GIST was 55% lower in the group that received imatinib for 36 months (HR 0.45; 95% CI, 0.22, 0.89; P
= .019) compared to the group receiving the drug for 12 months. After 5 years, 92% of patients in the 36-month imatinib group were alive, compared to 81.7% of patients in the 12-month arm of the study.
“I consider [the overall survival rate] a very high figure, remembering that these patients had high-risk GIST, and in historical data, the risk of recurrence is greater than 50%,” said Heikki Joensuu, MD, PhD, professor of oncology, Helsinki University Central Hospital, Finland, at the 2011 ASCO meeting.
Novartis Oncology, which manufactures imatinib under its brand name Gleevec, funded the study. In a statement, Novartis noted that the National Comprehensive Cancer Network updated its guidelines in August 2011 to note that high-risk patients with GIST should be considered for a 3-year regimen of the drug.
“This approval represents another important step in the progress of KIT-positive GIST treatment that began a decade ago when Gleevec was first approved to treat metastatic KIT-positive GIST,” said Hervé Hoppenot, president of Novartis Oncology, in a statement released on Tuesday. “With the significant survival benefit resulting from 3 years of adjuvant treatment, GIST patients now have a more effective regimen to help manage their disease.”