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Patterns of care, prognosis, and survival of patients with metastatic gastrointestinal stromal tumors (GIST) refractory to first-line imatinib and second-line sunitinib.

10044 Background: Data regarding the management and outcome of metastatic GIST patients (pts) refractory to 1st line imatinib (I) and 2nd sunitinib (S) are limited.


METHODS
Eleven institutions participated in this retrospective study. A preliminary analysis based on the data from 176 pts treated in 9 institutions is presented in this abstract. Final analysis will be presented at the meeting.


RESULTS
Median age was 57 years (range 18-84). Median progression free-survival (PFS) on 1st line I and 2nd line S were 22.4 months (mo) (95% CI: 19.2-26.2) and 8.2 mo (95% CI: 6-10.4), respectively. Pts who were treated with 3rd or 4th line sorafenib (vs other treatment) had significantly higher PFS, although improvement in overall survival (OS) was observed in 4th line only. On univariate analysis, age, performance status ≥2, haemoglobin <10g/dl, albumin < 35g/l and primary mutation on exon 11 or 9 (versus wild-type or PDGFRα mutation) were significantly associated with inferior OS. On multivariate analysis, albumin level (HR=2.2, 95% CI 1.1-4.4; p = 0.03) and mutational status (HR=4.1, 95% CI 1.4-11.9; p = 0.01) were the sole independent predictors of poor OS.


CONCLUSIONS
This collaborative study is the largest one focusing on the management and survival of GIST patients refractory to I and S. Pts more likely to carry secondary mutations seem to have the worst outcome. Rechallenge with I is associated with limited clinical benefit, but appears superior to best supportive care. Sorafenib may provide the best treatment option in case of clinical trial ineligibility, given these data. [Table: see text].