Safety outcomes of low versus high dose imatinib mesylate in patients with advanced, metastatic, or nonresectable gastrointestinal stromal tumors: A systematic review.

BACKGROUND AND OBJECTIVES

Gastrointestinal stromal tumors (GIST) are a rare cancer where tumors grow along the gastrointestinal tract. While treatment options aim towards surgical resection, some patients present with advanced metastatic and/or nonresectable diseases. The tyrosine kinase inhibitor imatinib mesylate is approved for this indication. However, dose escalation from 400 to 600 mg/d or 800 mg/d is allowed. The present study systematically evaluates the safety outcomes, particularly the incidence of grade ⩾ 3 adverse events (AEs) with low dose compared with high dose imatinib in these patients.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines were utilized to identify relevant studies through the PubMed, Cochrane Library, and Ovid databases and included randomized and non-randomized clinical trials comparing a low dose intervention of imatinib 400 mg/d with a high dose comparator of 600 or 800 mg/d in patients with histologically confirmed advanced metastatic and/or nonresectable GIST. Four studies were reviewed regarding study summaries and patient characteristics, patient demographics, and risk of bias, with a main emphasis on the evaluation of both efficacy outcomes and safety outcomes.

RESULTS

Three of the four studies did not provide significant differences in response outcomes; however, all four studies reported a higher incidence of grade ⩾ 3 AEs in the high dose imatinib groups. Individual study reports of more high dose patients experiencing a grade ⩾ 3 event ranged from 0.6% to 19.8%, while combined low and high dose patient arms revealed a 17.1% difference favoring a high dose patient event. A sub-analysis of the three most frequently occurring categories, blood and lymphatic system disorders, gastrointestinal disorders, and general disorders and administration site conditions each revealed more high dose patients experiencing said category events compared to those low dose counterparts.

CONCLUSION

Low dose imatinib provides clinically meaningful response and demonstrated better tolerability with less frequently reported reactions. This evidence supports further research into the maintenance of 400 mg/d for this patient population compared to a dose escalation.