A Study to Investigate the Safety and Efficacy of AT13387, Alone or in Combination With Imatinib, in Patients With GIST

"In part 1 pts will receive AT13387 in combination with imatinib. Up to 5 possible dose levels of AT13387 could be evaluated in combination with imatinib 400 mg daily: 120 mg/m2, 150 mg/m2, 180 mg/m2, 220 mg/m2 and 260 mg/m2. AT13387 IV (in the vein) on day 1, 8 and 15 of each 28 day cycle, until progression or unacceptable toxicity develops, in order to establish the recommended phase II combination dose, which will be used in part 2 and/or part 3 of the study.~In part 2 an additional 6-9pts will be treated.~In part 3, provided that sufficient evidence of anti-tumour effect was observed in part 2 (disease stabilisation or reduction in tumour dimensions by RECIST), then an additional 12pts will be treated with AT13387 in combination with imatinib. Alternatively, if combination treatment is found to have excellent efficacy the randomised phase of the study may start so that 12 pts receive AT13387 on its own (monotherapy) and 12 pts receive AT13387 in combination with imatinib."