Fourth-line rescue treatment ripretinib of advanced small intestine gastrointestinal stromal tumors who achieved partial response: a case report.

Background: With the advances in gastrointestinal stromal tumors (GISTs) research and the development of new immunotherapy drugs, the emergence of targeted drugs has greatly changed the diagnosis and treatment of GISTs and benefited more GIST patients. However, drug resistance has become increasingly challenging with the widespread application of targeted therapy in GIST patients. Based on the currently available evidence, the United States Food and Drug Administration (US FDA) has approved sunitinib as a second-line therapy and regorafenib as a third-line therapy, and research and development of more molecularly-targeted drugs are underway. Case Description: A middle-aged male patient was diagnosed with advanced small intestine GIST. Following the resection (R2) of tumors in the small intestine and pelvis, the patient received first-, second-, and third-line adjuvant therapies. However, follow-up examinations indicated progressive disease (PD). Ripretinib was then administered as the fourth-line therapy, and partial response (PR) was achieved 6 months later. To the best of our knowledge, this is a rare case in which the fourth-line adjuvant therapy for GIST achieved significant efficacy after unsuccessful systematic first-, second-, and third-line therapies. Conclusions: Imatinib, as the first-choice targeted therapy for advanced GISTs, has achieved notable clinical efficacy. After localized tumor progression on imatinib, second-line sunitinib may be applied. Third-line regorafenib therapy can be used in patients with GISTs who have failed both imatinib and sunitinib. In our current case, the patient experienced PD after regorafenib administration, and a satisfactory efficacy was obtained following the use of ripretinib. For patients with GISTs, after the failure of imatinib, sunitinib, and regorafenib, ripretinib may achieve a good therapeutic effect as a new targeted drug. Ripretinib is currently approved for use as a fourth-line or higher therapy in advanced GISTs, However, the ultimate place of ripretinib in metastatic or advanced GIST remains under investigation. This case achieved the therapeutic effect of PR through the treatment of repatinib, and there were no other obvious side effects except hair loss. Our findings may inform clinical decision-making regarding the treatment of GISTs. Keywords: Gastrointestinal stromal tumor (GIST); imatinib; ripretinib; case report.