Imatinib (Gleevec®) appears to be safe and effective as a neoadjuvant therapy for advanced rectal gastrointestinal stromal tumors (GIST), according to a recently published study in Frontiers.

Although surgical removal remains the standard of care for patients with rectal GIST, surgical treatment in this area is often challenging due to the narrow space of the anatomical size and the great size of the tumors. Therefore, there is a high interest in neoadjuvant therapies capable of reducing tumor size to increase the chance of successful resection with anal preservation.

Most patients with GIST have mutations in either c-kit or platelet-derived growth factor receptor α receptor tyrosine kinases. Imatinib, a tyrosine kinase inhibitor, has already been successfully used to treat GISTs. Although its use has already been recommended by prestigious medical societies, there are still doubts regarding the surgical approach and duration of neoadjuvant therapy.


Continue Reading

Read more about GIST therapies

The authors aimed to compare the outcomes of a group of patients that received neoadjuvant therapy with imatinib and a group that did not. The criteria for administering neoadjuvant therapy included difficulty in obtaining clean margins, difficulty in achieving anal preservation, and risk of tumor rupture. The final decision in each case was made by a multidisciplinary team. 

Patients received a daily dose of 400 mg of imatinib. Treatment was continued until an appropriate response, determined by the attending physician, was detected through imaging studies. Response evaluation was carried out every 3 months.

The study included 58 patients with advanced GIST, of which approximately 55% received neoadjuvant therapy with imatinib. The median tumor size reduction with neoadjuvant therapy was 1.2 cm, with the maximal response being observed a year after treatment initiation, suggesting that the optimal time of neoadjuvant therapy might be 12 months.

Although patients that received imatinib had a higher incidence of preventive ileostomy and a higher rate of low mitotic activity, there was no statistically significant difference in recurrence-free survival or overall survival. There were also no significant differences in intraoperative outcomes.

“Neoadjuvant imatinib therapy is an effective and safe treatment to reduce tumor size for locally advanced rectal GISTs, and achieves similar rates of complete resection and anal preservation without increasing intraoperative or postoperative complications risk,” the authors concluded.

Reference

Li W, Li X, Yu K, et al. Efficacy and safety of neoadjuvant imatinib therapy for patients with locally advanced rectal gastrointestinal stromal tumors: a multi-center cohort study. Front Pharmacol. Published online September 27, 2022. doi:10.3389/fphar.2022.950101