Gastro-intestinal stromal tumours (GIST) - imatinib

1. Guidance

1.1. Imatinib treatment at 400 mg/day is recommended as first-line management of people with KIT (CD117)-positive unresectable and/or KIT (CD117)-positive metastatic gastro-intestinal stromal tumours (GISTs).

1.2. Continuation with imatinib therapy is recommended only if a response to initial treatment (as defined in Section 1.5) is achieved within 12 weeks.

1.3. Responders should be assessed at intervals of approximately 12 weeks thereafter. Continuation of treatment is recommended at 400 mg/day until the tumour ceases to respond, as defined in Section 1.5.

1.4. An increase in the dose of imatinib is not recommended for people receiving imatinib who develop progressive disease after initially responding (see Section 1.5).

1.5. For the purpose of this guidance, response to imatinib treatment should be assessed on the basis of the results of diagnostic imaging to assess size and density of the tumour(s), patients’ symptoms and other factors, in accordance with the Southwest Oncology Group (SWOG) criteria detailed in Appendix D. For the purpose of this guidance, response to therapy is defined as the SWOG classifications of complete response, partial response or stable disease.

1.6. The use of imatinib should be supervised by cancer specialists with experience in the management of people with unresectable and/or metastatic GISTs.