Adjuvant Imatinib or Observation in Patients with Gastrointestinal Stromal Tumors with KIT Exon 9 Mutations1
Published on February 26, 2026, in JAMA Oncology, this international study represents a major collaboration between The Life Raft Group and thirty-five leading cancer centers across the U.S., Europe, and Japan to better understand treatment for gastrointestinal stromal tumors (GIST) with KIT exon 9 mutations. Researchers analyzed outcomes from 367 patients with localized disease at diagnosis who underwent surgery to remove their tumors and examined whether imatinib taken after surgery (adjuvant therapy) improves survival.
The study found that patients who received adjuvant imatinib experienced a significantly longer time before recurrence (recurrence-free survival) and improved overall survival compared with observation alone, particularly among those classified as high risk by modified NIH (mNIH) criteria. Among 257 patients with mNIH high-risk disease receiving imatinib, no significant difference in outcomes was observed between 400 mg/day and 800 mg/day dosing.
These results provide the strongest evidence to date supporting adjuvant imatinib for patients with high-risk KIT exon 9–mutated GIST and clarify that higher dosing may not confer additional benefit in the postoperative setting.
1Napolitano A, Joensuu H, Rothschild S, et al. Adjuvant Imatinib or Observation in Patients With Gastrointestinal Stromal Tumors With KIT Exon 9 Mutations. JAMA Oncol. Published online February 26, 2026. doi:10.1001/jamaoncol.2026.0007
From Denisse Evans, Senior Director of Data Management & Research
The Life Raft Group is excited to share our latest study on adjuvant imatinib in KIT exon 9–mutant GISTs, a biologically distinct subset with reduced sensitivity to standard-dose therapy in advanced disease. In our multinational cohort (35 centers, Europe, US, Japan), we applied time-dependent and causal inference models to assess recurrence-free and overall survival.
🔹 Adjuvant imatinib delays recurrence (HR 0.19 early effect)
🔹 Improves overall survival (HR 0.37)
🔹 Benefit is consistent in mNIH high-risk patients
🔹 No clear difference between 400 mg vs 800 mg daily dosing in high-risk patients
These results reinforce adjuvant imatinib for high-risk KIT exon 9 GIST and highlight the need for prospective studies on optimal dose and duration. LRG GIST Patient Registry data was used as part of this study. I am grateful to the patients and caregivers who contributed their experiences; their participation creates a lasting legacy of knowledge that advances research in rare GIST subtypes.
Special recognition & gratitude to Dr. Andrea Napolitano for his leadership in advancing care for this rare GIST subgroup.
