(P 190) TEMPORAL DECLINE IN PROGRESSION-FREE SURVIVAL, TIME ON MEDICATION, AND OVERALL SURVIVAL IN ADVANCED GASTROINTESTINAL STROMAL TUMOR

Objective: To investigate temporal trends in progression-free survival (PFS), time on medication (TOM), and overall survival (OS) in patients with advanced gastrointestinal stromal tumor (GIST) receiving first-line imatinib (IM).

Methods: We analyzed 1,490 patients with metastatic or inoperable GIST treated with first-line imatinib (IM) from the Life Raft Group Registry. PFS, TOM, and OS were calculated and stratified by year of treatment initiation: 2000–2010, 2011–2017, and 2018–2024. The 2000–2010 cohort was excluded due to limited access to later-line therapies. Kaplan-Meier survival analysis and Cox proportional hazards models were used to compare outcomes across time groups. Time strata were selected using the optimal cutoff method implemented in the survminer package in R. 2010 was identified as the inflection point for OS, and 2017 was the optimal threshold for both PFS and TOM.

Results: Patients who began IM between 2018–2024 experienced significantly shorter PFS and TOM. Median PFS was 40 months for the 2011–2017 group versus 24 months for the 2018–2024 group. The hazard ratio (HR) for PFS was 1.46 (95% CI: 1.16–1.85; p < 0.005), indicating a 46% higher risk of progression. TOM declined in parallel, with a median of 57 months in the 2011–2017 group versus 31 months in the 2018–2024 group (HR 1.80, 95% CI: 1.42–2.29; p < 0.005). Overall survival curves for KIT exon 11 patients also significantly diverged, with worse outcomes in the 2018–2024 group compared to 2010–2017 (p = 0.03). No significant OS differences were observed in other subgroups. Follow-up duration was shorter in the recent cohort, potentially impacting survival estimates.

Conclusion: This study shows a significant decline in PFS, TOM, and OS (KIT exon 11 only) for first-line IM starting in 2018, suggesting reduced treatment durability. Further comparative studies are needed to confirm these findings. Continued real-world monitoring is key to improving care and advancing research.

Temporal Trends in PFS, TOM, and OS for First-Line Imatinib in Advanced GIST