Surgical resection of residual disease in initially inoperable imatinib-resistant/intolerant gastrointestinal stromal tumor treated with sunitinib.

AIM: Sunitinib malate therapy in inoperable and/or metastatic gastrointestinal stromal tumor (GIST) resistant to imatinib mesylate may facilitate surgical removal of residual disease. We explored this possibility in the course of treating patients as part of a treatment-use trial, the objective of which was to provide access to sunitinib treatment.
METHODS: Four patients with inoperable and/or metastatic GIST resistant to imatinib who had responded to sunitinib therapy administered at a starting dose of 50 mg daily in 6-week cycles of 4 weeks on treatment followed by 2 weeks off underwent surgical removal of residual disease. Disease progression on or clinical response to treatment was defined based on Response Evaluation Criteria in Solid Tumors.
RESULTS: In three of four cases it was possible to perform macroscopically complete resection of residual disease, resulting in surgical complete clinical responses, two with durations of 13 months. The fourth patient achieved a dramatic partial response to sunitinib that required emergency surgical resection of the necrotic tumor mass, with the partial response having been maintained for 15 months. In all cases, viable GIST cells were detected histologically in the resection specimens, and sunitinib treatment was resumed post-surgery. None of the patients experienced any postoperative complications during 13-16 months of follow-up.
CONCLUSIONS: Combining sunitinib treatment with surgical removal of residual disease may allow selected imatinib-resistant GIST patients who have shown a favorable response to sunitinib to achieve complete and sustained remission or durable control of previously progressive disease beyond that expected for sunitinib treatment alone.