This study is designed to evaluate the efficacy and safety of a novel two-tooth endoscopic clip, utilized in a "clip with line" traction configuration, during endoscopic resection procedures (ESD and EFTR) of GIST. The novel clip's dual-tooth design is intended to provide a more secure anchor on the lesion, enabling effective counter-traction when combined with a line. The primary aim is to determine if this method improves submucosal dissection efficiency compared to conventional ESD. A secondary aim is to evaluate the performance of the same clip system for full-thickness or mucosal defect closure.

Endoscopic Submucosal Dissection (ESD) and Endoscopic Full-Thickness Resection (EFTR) are established, minimally invasive techniques for the en-bloc resection of gastrointestinal stromal tumor (GIST). However, a persistent challenge, especially in difficult locations or large lesions, is the lack of sufficient counter-traction, which leads to prolonged procedure times, increased risk of intraoperative bleeding, and potential for incomplete resection due to poor visualization of the submucosal layer. Furthermore, managing large post resection defects or perforations requires reliable and technically feasible endoscopic suturing.

This study introduces a novel two-tooth clip. The device's geometry is hypothesized to provide a stronger, more stable grasp on the targeted tissue compared to standard single-tooth or non-toothed clips. The study will investigate two sequential applications of this clip within a single procedure:

The Traction Phase: A "clip with line" technique will be employed. The novel two-tooth clip will be anchored to the proximal edge of the lesion. A dental line, pre-tied to the clip, will be used by the endoscopist to apply adjustable counter-traction. This is intended to lift the lesion, tauten the submucosal fibers, and clearly expose the dissection plane, thereby simulating the principle of surgical counter-traction.

The Closure Phase: Following lesion resection, the novel two-tooth clip will be utilized to perform a continuous, circumferential closure of the mucosal defect or perforation. The study will assess the technical success rate, time required for complete closure, and the clip's ability to securely approximate tissue layers.

Inclusion Criteria:

• Age ≥ 18 and ≤ 85 years.
• Patients diagnosed with gastric gastrointestinal lesions clinically indicated for ESD or EFTR.
• Lesion size between 2 cm and 5 cm in diameter.
• Willing and able to provide written informed consent.

Exclusion Criteria:

• Lesions with clear evidence of deep submucosal invasion or distant metastasis precluding curative endoscopic resection.
• Severe coagulation dysfunction (international normalized ratio >2.0, platelet count <50,000/µL) or ongoing use of dual antiplatelet therapy/anticoagulants that cannot be appropriately bridged or discontinued per guidelines.
• Severe organ failure (cardiac, renal, hepatic, or respiratory) rendering the patient unsuitable for prolonged sedation or general anesthesia.
• Pregnancy or lactation.
• Prior surgical or endoscopic intervention at the target lesion site that results in significant fibrosis.