Interruption of imatinib in advanced gastrointestinal stromal tumor after prolonged imatinib maintenance in the absence of gross tumor lesions

• Published in: Gastric cancer : official journal of the International Gastric Cancer Association and the Japanese Gastric Cancer Association Vol. 26; no. 4; pp. 604 - 613
• Main Authors: Kang, Yoon-Koo, Kim, Hyung-Don, Kim, Hyun Jin, Park, Young Soo, Beck, Mo-Youl, Ryu, Min-Hee
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.07.2023; Springer Nature B.V
• Subjects: Abdominal Surgery; Cancer Research; Cancer therapies; Clinical outcomes; Disease control; Gastric cancer; Gastroenterology; Gastrointestinal cancer; Gastrointestinal diseases; Imatinib; Inhibitor drugs; Lesions; Medicine; Medicine & Public Health; Metastases; Metastasis; Oncology; Original Article; Patients; Remission; Remission (Medicine); Surgical Oncology; Survival; Survival analysis; Tumors; Imatinib; Treatment interruption; Gastrointestinal stromal tumor; Local treatment
• ISSN: 1436-3291; 1436-3305
• DOI: 10.1007/s10120-023-01377-2

Background Current guidelines recommend indefinite imatinib treatment for advanced gastrointestinal stromal tumor (GIST) patients. Imatinib-refractory progression-free survival (PFS) and overall survival were previously reported not to differ between GIST patients who interrupted imatinib and those who did not. Methods Clinical outcomes of 77 consecutive patients with recurrent or metastatic GIST who interrupted imatinib treatment after maintaining years of imatinib treatment in the absence of gross tumor lesions were retrospectively analyzed. Associations between clinical factors and progression-free survival (PFS) following imatinib interruption were analyzed. Results The median time from the absence of gross tumor lesions to imatinib interruption was 61.5 months. Since imatinib interruption, the median PFS was 19.6 months, and 4 patients (26.3%) remained progression-free for longer than 5 years. Among the patients who had progressive disease following the interruption, imatinib re-introduction led to an 88.6% objective response rate and a 100% disease control rate. Complete removal of the initial gross tumor lesion(s) and complete removal of the residual gross tumor lesion(s) by local treatment (vs. no local treatment or residual lesions after local treatment) were independently associated with favorable PFS. Conclusion Interruption of imatinib following prolonged maintenance in the absence of gross tumor lesions led to disease progression in the majority of cases. However, re-introduction of imatinib resulted in effective tumor control. Unmaintained remission seems to be possible in some patients with metastatic or recurrent GIST after a prolonged remission with imatinib if there is complete removal of any gross tumor lesions.