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2	KIT Mutational Status Predicts Clinical Response to Glivec in Patients With Metastatic GIST What is the frequency of KIT mutations in GIST? Screening by denaturing HPLC Are GIST-associated mutations sensitive to imatinib in vitro? What is the relationship of KIT mutations to drug response? Conclusions
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5	Mutations Observed In The KIT Gene
6	Detection of KIT Gene Mutations Extract DNA from paraffin-embedded tissue Amplify by PCR Look for presence of mutations by denaturing HPLC (Transgenomics WAVE system) Confirm mutations by direct sequencing
7	"147 patients enrolled" 147 patients enrolled Tumor DNA successfully analyzed from 121 patients (82%) Exons 9, 11, 13 & 17 analyzed for all samples 86% of tumors contained a mutation No tumor contained more than one mutation
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13	"All GIST-associated KIT mutations appear..." All GIST-associated KIT mutations appear sensitive to imatinib mesylate in vitro. Do KIT mutations impact drug response in patients?
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17	Conclusions KIT genotype in malignant GISTs predicts the likelihood of response and overall survival in patients treated with imatinib mesylate Exon 11 mutations are favourable No differences noted among subtypes of exon 11 mutations (e.g. deletion vs point mutation) KIT genotype correlates with PET response
18	Conclusions (cont.) KIT exon 9 mutant isoforms are drug sensitive in vitro, but tumors with this mutation appear less responsive in patients Exon 9 mutations are found only in small bowel and colonic GISTs Preliminary data suggest differences in downstream signaling intermediates (J. Fletcher & M. Heinrich)
19	Conclusions (cont.) There is heterogeneity in the group of tumors lacking KIT gene mutations One patient in this group had a partial response to imatinib mesylate Analysis of patients in the Phase III trial (745 pts enrolled) will begin shortly Analyses of GISTs with primary and secondary resistance are underway
20	Clinical Application of KIT Gene Mutation Screening Assays are becoming available in laboratories in Europe, Australia and the U.S. Caveats for cases reported as “wild-type” Sensitivity may depend on screening methodology (and experience) Some “wild-type” tumors may still respond OHSU Molecular Diagnostics Lab offers HPLC-based screening for mutations in exons 9 and 11 We are happy to help other labs interested in adopting this technology for clinical testing
21	Acknowledgements Heinrich Laboratory Diana Griffith Cecily Wait Kevin Yee Ajia Town Kathleen Kemmer Laura McGreevey Corless Laboratory Andrea Haley Linda Jauron-Mills Carolyn Gendron Jonathan Fletcher George Demetri Charles Blanke Brian Druker Novartis Pharma AG GIST/STI Consortium (DFCI, OHSU, FCCC, Univ. of Helsinki, Novartis Pharma)