55O - IMADGIST: A randomized study of 6 vs 3 years of adjuvant imatinib in patients with localized GIST at high risk of relapse

Background

Adjuvant imatinib is indicated after complete resection of primary, localized, KIT-positive GIST at high risk of recurrence. A large proportion of these patient relapse after the end of adjuvant imatinib. Whether prolonging adjuvant imatinib beyond 3 years may enable to reduce the risk of GIST recurrence has not been explored in a randomized setting.

Methods

IMADGIST (NCT02260505) is a multicenter open-label, randomized, phase III study evaluating maintenance of imatinib at the last dose routinely taken by the patient in the 3-year period prior to randomization (either 300 or 400 mg/d) compared to Interruption of imatinib treatment (STOP arm) from the day of randomization. Primary endpoint is Disease-Free Survival (DFS). Secondary endpoints include Overall Survival, (OS) Time to Imatinib Resistance, Rate of Complete Response after reintroduction, Safety and Quality of Life. A sample size of 134 patients was calculated to detect an improvement of 15% in 3-year DFS rate (75% vs. 90% in the 3-years and 6-years arms, respectively).

Results

From December 24th, 2014 to April 4th, 2023; 136 patients aged ≥ 18, ECOG PS ≤2, with confirmed diagnosis of localized GIST with documented KIT (CD117) positivity, complete surgical R0 or R1, and a risk of tumor recurrence ≥35% according to National Comprehensive Cancer Network Task Force on GIST (NCCN) risk classification were randomised by 14 French anticancer centers. Sixty five patients were randomized to the 3-year arm vs 71 in the 6 year arm. 63 and 73 patients with moderate ([35-70%]) or high (>70%) NCCN risk, respectively, were included. The final analysis is scheduled for Janaury 31st, 2024. THe results will be presented at the congress.

Conclusions

Data cut of was set to September 30^th, 2023. Statistical analysis is in progress and results will be presented at the time of the congress.

Clinical trial identification

IMADGIST (NCT02260505).

Editorial acknowledgement

none

Legal entity responsible for the study

Centre Léon Bérard.

Funding

Programme Hospitalier de Recherche Clinique & Institut National du Cancer (INCA) & EURACAN.

Disclosure

A. Le Cesne, O. Bouche, M. Toulmonde, E. Bompas, F. Bertucci, L. Chaigneau, B. Landi, M. Pracht, S. Metzger, D. Perol: Financial Interests, Institutional, Research Grant: Novartis. O. Bouche: Financial Interests, Institutional, Research Grant: Novartis. N. Penel: Financial Interests, Institutional, Research Grant, Research grant for clinical trials in sarcoma filed: BAYER HealthCare. M. Brahmi: Financial Interests, Personal, Advisory Board: Bayer; Financial Interests, Personal, Invited Speaker: Amgen, PharmaMar, Deciphera. W. Lahlou: Financial Interests, Personal, Research Grant: Novartis. I.L. Ray-Coquard: Financial Interests, Personal, Advisory Board: Roche, GSK, AstraZeneca, Mersana, Deciphera, Amgen, Oxnea, Merck Sereno, Agenus, Novartis, Macrogenics, Clovis, EQRX, Adaptimmune, Eisai, Sutro, BMS, Adaptimmune, Daiichi Sankyo; Financial Interests, Institutional, Other, COLIBRI translational research: BMS; Financial Interests, Institutional, Advisory Board, translational research NEOPREMBROV trial: MSD; Non-Financial Interests, Personal, Principal Investigator: PAOLA1; Non-Financial Interests, Personal, Other, President: GINECO. J-Y. Blay: Financial Interests, Institutional, Invited Speaker: MSD, MSD, PharmaMar; Financial Interests, Institutional, Advisory Board: Bayer, GSK, Roche; Financial Interests, Personal, Advisory Board: Deciphera; Financial Interests, Personal, Other, member of the supervisory board. No remunerations in 2021 and 2022.: Innate pharma; Financial Interests, Personal, Member of Board of Directors: Transgene; Financial Interests, Institutional, Funding: MSD, BMS, Deciphera; Financial Interests, Institutional, Research Grant: AstraZeneca, Roche, Bayer, GSK, Novartis, OSE pharma. All other authors have declared no conflicts of interest.