Treatment patterns in patients with advanced gastrointestinal stromal tumor in Japan: An administrative claims database study.

811 Background: Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract. Tyrosine kinase inhibitors, including imatinib, sunitinib, and regorafenib, and the HSP90 inhibitor, pimitespib have been approved for advanced GIST in Japan, but few studies have examined the nationwide trend in treatment patterns. This study aimed to evaluate the real-world treatment patterns for advanced GIST in Japan. Methods: This retrospective cohort study used the Japanese hospital-based administrative claims database provided by Medical Data Vision Co., Ltd. (Tokyo, Japan). Patients diagnosed with advanced GIST according to ICD-10 codes who received any approved standard drug in Japan, such as imatinib, sunitinib, regorafenib, or pimitespib (Approved in June 2022) between July 2013 and March 2023 were included. The primary endpoint was the proportion of patients with GIST who were treated with each approved standard drug. Secondary endpoints included treatment patterns, time to treatment failure (TTF), overall survival, adverse events, and the proportion of patients who underwent surgical intervention for GIST while taking standard drugs. Results: This study included 2702 patients with advanced GIST. The median age was 70.0 years, 17% of the patients were ≥80 years, and 59% were male. The most common primary tumor sites were the stomach (37%), small intestine (25%) and large intestine (12%). The proportions of patients with GIST treated with imatinib, sunitinib, regorafenib, and pimitespib were 94% (2536 patients), 26% (702 patients), 14% (376 patients) and 1% (37 patients), respectively. The most common first-line regimen was imatinib (2485/2702 patients; 92%), second-line regimen was sunitinib (560/672 patients; 83%), third-line regimen was regorafenib (200/317 patients; 63%), and fourth-line regimen was imatinib (55/119 patients; 46%). The median TTF was 30.4 months (95% CI 27.4–32.9) with imatinib, 6.4 months (95% CI 5.6–7.7) with sunitinib, 5.2 months (95% CI 4.4–6.2) with regorafenib and 2.5 months (95% CI 1.7–3.1) with pimitespib. The proportions of patients who underwent surgical intervention for GIST was 15% (403/2702 patients), and curative surgery was 10% (273/2702 patients). Conclusions: This is the first real-world study to provide insights into the patient characteristics and current treatment patterns for advanced GIST in Japan. The treatment patterns are consistent with the Japanese Clinical Practice Guidelines.