Treatment patterns, prescribing decision drivers, and predictors of complete response following disease recurrence in gastrointestinal stromal tumor patients-a chart extract-based approach.

Abstract

The aim of this study was to investigate tumor characteristics, treatment patterns, and outcomes in recurrent KIT + GIST patients treated in a community practice setting. An online tool was used to retrieve data on 410 patients treated with adjuvant imatinib mesylate (IM) for primary resectable KIT + GIST, who discontinued, had a recurrence, and then restarted IM or initiated sunitinib. Tumor characteristics at recurrence, treatment patterns, and factors associated with post-recurrence complete response (CR) achievement were analyzed. About 72.7% of patients did not have surgery post-recurrence as majority of them had unresectable (45%), metastatic (40%), or multifocal tumors (62.4%). Following recurrence, 76.6% of patients were re-started on IM and 23.4% on sunitinib; patients were 7.37 times more likely to re-start IM if initial treatment duration was ≤18months (p < 0.001). Patients were also more likely to re-start IM if recurrence occurred >12months post-discontinuation, or they had a recurrence inside the GI system, lower or unknown Fletcher risk score at primary diagnosis, or lower mitotic rate, (odds ratio (OR) = 3.54, p < 0.001; OR = 2.64, p = 0.006; OR = 2.55, p = 0.007; and OR = 2.45, p = 0.002, respectively). About 22.4% achieved CR; patients were more likely to achieve CR if they had unifocal tumor at recurrence, inside the GI system, of ≤2cm, or had lower mitotic rate (OR = 2.61, p < 0.001; OR = 2.27, p = 0.036; OR = 2.16, p = 0.023, OR = 1.87, p = 0.017, respectively). IM treatment duration at primary diagnosis, time to develop recurrence after IM discontinuation, tumor location, and mitotic rate at recurrence were the main prescribing decision drivers. Tumor characteristics were the most important factor in achieving CR following c-KIT inhibitor retreatment.