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Adjuvant imatinib therapy improved recurrence-free survival after GIST resection
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Patients assigned to adjuvant imatinib to treat primary gastrointestinal stromal tumors after resection had better recurrence-free survival than patients assigned to placebo.
Researchers randomly assigned 354 patients to placebo and 359 patients to 400-mg daily imatinib (Gleevec, Novartis) for one year after surgical resection in a phase-3, double blind trial. Accrual was stopped early because results met the efficacy boundary for recurrence-free survival.
After a median follow-up of 19.7 months, the estimated one-year recurrence-free survival for the imatinib group was 98% (95% CI, 96%-100%) compared with 83% for the placebo group (95% CI, 78%-88%). This translates into an overall HR of 0.35 (95% CI, 0.22-0.53). The researchers noted that recurrence-free survival was better in the imatinib group irrespective of tumor size, but added that there was no difference in OS between the two groups (HR=0.66; 95% CI, 0.22-2.03).
When analyzing only the 682 patients who received at least one dose of placebo or imatinib, the researchers observed that 95% of patients had at least one adverse event. Eighteen percent of the placebo group had grade-3/4 events compared with 31% of patients in the imatinib group. Treatment was stopped early for 184 patients, primarily for adverse events in the imatinib group and for recurrence in the placebo group (P<.0001).
In an accompanying editorial, Peter Hohenberger, MD, a professor in the division of surgical oncology and thoracic surgery at the University of Heidelberg in Germany, noted that imatinib reduced the one-year risk for recurrence by nearly half in patients with primary tumors 10 cm or larger, but showed only marginal improvement for patients with smaller tumors.
He also argued that tumor size was not the most appropriate selection criteria for gastrointestinal stromal tumors and pointed out that the observed improvement in recurrence-free survival did not lead to improvement in OS. “As always with trials investigating a new treatment, criticism is easy,” Hohenberger wrote. “But for some patients, the data from today’s study open the way to receive adequate treatment for undetected metastases.”
DeMatteo RP. Lancet. 2009;doi:10.1016/S0140-6736(09)60500-6.