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GIST

(P 191) EFFICACY OF SYSTEMIC PALLIATIVE THERAPIES IN PATIENTS WITH ADVANCED GASTROINTESTINAL STROMAL TUMORS (GIST) PREVIOUSLY TREATED WITH ADJUVANT IMATINIB - REAL-WORLD CLINICAL PRACTICE DATA

    Author(s)

  • Katarzyna E. Kisielewska, MD, PhD (she/her/hers)

    Medical Oncologist
    Maria Sklodowska-Curie National Research Institute of Oncology
    Warsaw, Mazowieckie, Poland

    • Co-Author(s)

  • AK

    Anna Klimczak, MD

    Maria Sklodowska-Curie National Research Institute of Oncology
    Warsaw, Mazowieckie, Poland

  • PS

    Paweł Sobczuk, MD, PhD

    Medical Oncologist
    Maria Sklodowska-Curie National Research Institute of Oncology
    Warsaw, Mazowieckie, Poland

  • Piotr Rutkowski, MD, PhD

    Head of Department of Soft Tissue/Bone Sarcoma and Melanoma
    Maria Sklodowska-Curie National Research Institute of Oncology
    Warsaw, Mazowieckie, Poland

Objective: Imatinib has revolutionized the management of patients (pts) with GIST, both in adjuvant and advanced settings; however, many patients treated with adjuvant imatinib ultimately relapse during or after completion of therapy. Data on efficacy of palliative systemic therapy in this group remain limited. This study aimed to evaluate the outcomes of palliative treatment in patients with GIST previously treated with adjuvant imatinib.

Methods: We conducted a retrospective analysis of pts with advanced GIST who received palliative treatment after adjuvant therapy at reference center between 2004 and 2025. Data included clinic-pathologic data, and survival outcomes: progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and disease control rate (DCR).

Results: 54 pts were included; (46.3% female, median age 60.9 years). Primary tumors were mostly located in the small intestine (57.4%) or stomach (31.5%). KIT mutations were found in 85.2%; exon 11 in 78.7%, exon 9 in 19.1%. Median DFS on adjuvant imatinib was 46.3 months. Recurrence occurred during adjuvant treatment in 20.4% (11) and within one year of its completion in 46.3% (25).
In 1st line, 88.9% pts received imatinib, and 11.1% sunitinib. Median PFS was 37.9 months (95%CI: 23.7-44.9), with ORR 27.8% and DCR 72.2%. No significant differences in PFS were observed between imatinib- and sunitinib-treated patients (36.4 vs 44.6 months; p = 0.87), imatinib dose, or between mutation subgroups.
2nd and 3rd line therapy were administered to 50% and 22.2% pts. Imatinib 800 mg was offered to 55.5%, while sunitinib to 29.6% pts in 2nd line. PFS in 2nd and 3rd line therapy was 8.7 (95CI: 5.00-NR) and 9.0 (95%CI: 5.73-NR) months, respectively. In 2nd line 11.1% achieved ORR, while in later lines, SD remained the best observed response (57.1% in 3rd, 33.3% in 4th). Median OS on palliative treatment was 8.5 years (95%CI: 5.80-NR); 5-year OS was 39.8%.

Conclusion: Palliative treatment with imatinib and sunitinib remains effective in patients with recurrent GIST after adjuvant imatinib. Outcomes align with those in TKI-naïve populations. Patients who have disease recurrence after completion of adjuvant imatinib can be effectively treated with reinduction of imatinib.