Continuous imatinib therapy in patients with gastrointestinal stromal tumors

Patients with gastrointestinal stromal tumors (GIST) used to have a poor prognosis due to the very low response rate of these tumors to conventional chemotherapy and radiation therapy. However, following the introduction of imatinib as a targeted therapeutic agent with efficacy in GIST, survival outcomes have improved remarkably for patients in the advanced/metastatic and adjuvant settings. Imatinib is now approved for both indications and has become the standard of care for patients with GIST. Despite the mounting evidence demonstrating the clinical benefits of extending imatinib treatment beyond 1 year, the optimal duration of imatinib therapy has not yet been determined. Similarly, whether chronic or extended adjuvant imatinib therapy can further improve clinical outcomes in patients with GIST remains to be determined. In this review, we present recent findings from various clinical trials which indicate that prolonged, uninterrupted imatinib treatment can have durable clinical benefits in patients who underwent resection of primary, operable GIST, as well as patients with advanced, unresectable, or metastatic GIST. We also summarize data showing that treatment interruption can result in disease progression in both the adjuvant and advanced/metastatic settings. Finally, we present evidence from different trials that long-term imatinib therapy is feasible and safe (ie, without cumulative toxicities) in patients with GIST.