Displayed graphically here are the correlation of KIT genotype and best clinical response for the three most common genotypes in this trial.  The grey area indicates patients with a partial response using >50% shrinkage as the definition of PR. The burgundy indicates patients who had stable disease in response to STI571 therapy.  The sapphire blue bars indicated patients who were non-evaluable or had progressive disease in response to STI571.  Patients with an exon 11 had a 79.2% PR rate compared with a 45.5 PR rate for exon 9 muants GISTs and 18.8% for GISTs without detectable KIT mutation.  The difference for partial response rate in exon 11 vs exon 9 GISTs had a p value of 0.003.  The difference in partial response rate for exon 11 vs exon 9 GISTs had a p value of less than 0.0001.  There was no statisically significant difference in the PR rate between exon 9 and no mutation GISTs—this result may be a result of the small sample sizes for these groups.  PR and SD responses can be combined to yield composite % of patients with clinical benefit from imitnib.  Overall, only 8.6% of patients with an exon 11 mutation fail to have any clinical benefit from STI571 therapy , in contrast 62.5 of no mutation GIST patients have no response to STI571.