Montemurro M, et al. - The researchers designed this study to investigate the long-term outcome of dasatinib first-line treatment in patients with histologically proven, tyrosine kinase inhibitor (TKI)-naïve, ¹⁸F-fluorodeoxyglucose positron emission tomography coupled to computed tomography (FDG-PET/CT)-positive gastrointestinal stromal tumors (GIST). Among these patients, dasatinib was found to produced high metabolic response rates.

Methods

• The researchers designed this 2-stage, phase 2 trial investigating dasatinib 2 × 70 mg per day in patients with histologically proven, TKI-naïve, FDG-PET/CT-positive GIST.
• FDG-PET/CT response was the primary endpoint.

Results

• Forty-seven patients were enrolled among 52 planned patients from January 2008 to November 2011, when the trial was terminated because of slow accrual.
• Forty-two patients (24 men and 18 women) were eligible; the median patient age was 61 years.
• In this study, performance status was 0 in 29 patients and 1 in 13 patients.
• The median follow-up was 67.2 months.
• The reasons for patients going off trial included elective surgery (n = 8), following 26 cycles as per protocol (n = 5), disease progression (n = 14), toxicity (n = 7), and other reasons (n = 5); and 3 patients died (2 had discontinued drug and 1 was still receiving drug).
• Grade 4 toxicity was reported in 5% and grade 3 toxicity in 48% of patients.
• The toxicity was most often gastrointestinal or pulmonary.
• In 25% of cycles, dose was interrupted or reduced.
• At 4 weeks, the FDG-PET/CT response rate (complete plus partial responses) was 74% (95% confidence interval, 56%-85%; 14 patients had a complete response, 17 had a partial response, 6 had stable disease, 3 had progressive disease, and 2 were not evaluable).
• Observations revealed median progression-free survival of 13.6 months, however, the median overall survival was not reached.