A national register of all patients receiving imatinib treatment for GIST should be maintained. Details could include patient characteristics, dose and duration of treatment, mutational analysis, tumour response rates and survival both with and after discontinuation of imatinib treatment. The response rates of patients who have received escalated doses of imatinib treatment in the context of clinical trials could also be included.
The key dose-response trials for imatinib for metastatic and/or unresectable GIST are still in progress. There are also studies assessing the use of imatinib in patients with metastatic and/or unresectable GIST that have been published in abstract form, and many report interim results.
NICE recommends that further trials be undertaken to evaluate the benefit of maintenance therapy at 400 mg/day for patients with progressive disease, and the response rate of patients after switching to higher doses of imatinib treatment. The effectiveness of dose escalation should be evaluated for patients who do not respond to imatinib treatment at 400 mg/day, and for patients who initially respond to the lower dose but later develop progressive disease. These trials should incorporate measures of health-related quality of life. Information on survival following withdrawal of imatinib treatment should also be collected.
NICE considered that studies should be conducted to assess:
the effectiveness of PET assessment for the measurement of tumour response
the use of mutational analysis to predict individual responses to imatinib treatment.