Low-dose Imatinib Efficacy in a Gastrointestinal Stromal Tumor Patient With KIT Exon 11 W557_K558 Deletion.

Gastrointestinal stromal tumors (GISTs) are rare cancers originating from Cajal's stromal cells in the gastrointestinal tract. The most common driver mutation in these cancers is the KIT mutation. This report presents a case of response to low-dose imatinib in a patient with GIST harboring KIT exon 11 W557_K558 deletion. In June 2023, an 82-year-old male developed perineal pain. Computed tomography (CT) imaging revealed a mass measuring >9 cm, extending from the rectum to the prostate. Submucosal tumor biopsy revealed a tumor with CD117-positive and DOG1-positive spindle-shaped cells leading to a diagnosis of GIST. c-Kit gene mutation analysis detected a W557_K558 deletion in exon 11. Treatment with imatinib (400 mg/day) was initiated in late October 2023 to preserve organ function; the dose was reduced to 300 mg/day after 5 days of treatment and further reduced to 200 mg/day after 10 days, with continued treatment at this dose. The CT performed in January, April, and June 2024 showed that the rectal GIST had shrunk. The blood imatinib concentration remained at approximately 650 ng/ml from January to March 2024 and decreased to 391 ng/ml in May 2024. The response rate of GISTs to imatinib is influenced by genetic mutations. GIST with KIT exon 11 W557_K558 deletion is associated with a high risk of recurrence. In vitro data showed that low-dose imatinib was effective in such cases. Low-dose imatinib is a treatment option for patients with GIST harboring KIT exon 11 W557_K558 deletion who are intolerant to high-dose imatinib.

Suto H ，Kawamura M ，Morita M ，Sakai H ，Onoe T ，Ikeuchi K ，Kajimoto K ，Matsumoto K ... -  《-》

The INSIGHT study: a randomized, Phase III study of ripretinib versus sunitinib for advanced gastrointestinal stromal tumor with KIT exon 11 + 17/18 mutations.

George S ，Blay JY ，Chi P ，Jones RL ，Serrano C ，Somaiah N ，Gelderblom H ，Zalcberg JR ，Reichmann W ，Sprott K ，Cox P ，Sherman ML ，Ruiz-Soto R ，Heinrich MC ，Bauer S ... -  《-》

Genomic Subtypes of GISTs for Stratifying Patient Response to Sunitinib following Imatinib Resistance: A Pooled Analysis and Systematic Review.

Tan S ，Chen P ，Ji J ，Guo S ，Yu D ，Asakawa T ，Zhou Y ，Abe M ，Zong L ... -  《-》

Treatment Access for Gastrointestinal Stromal Tumor in Predominantly Low- and Middle-Income Countries.

Briercheck EL ，Wrigglesworth JM ，Garcia-Gonzalez I ，Scheepers C ，Ong MC ，Venkatesh V ，Stevenson P ，Annamalay AA ，Coffey DG ，Anderson AB ，Garcia-Gonzalez P ，Wagner MJ ... -  《JAMA Network Open》

The HSP90 inhibitor, AT13387, is effective against imatinib-sensitive and -resistant gastrointestinal stromal tumor models.

Smyth T ，Van Looy T ，Curry JE ，Rodriguez-Lopez AM ，Wozniak A ，Zhu M ，Donsky R ，Morgan JG ，Mayeda M ，Fletcher JA ，Schöffski P ，Lyons J ，Thompson NT ，Wallis NG ... -  《-》