Molekulare Reaktionsformen und bildgebende Diagnostik gastro-intestinaler Stromatumoren auf die Therapie mit Tyrosinkinase Inhibitor Imatinib (STI571)
Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, and are generally resistant to chemotherapy and radiation. Most GISTs express the KIT receptor tyrosine kinase protein (CD117) and the signal transduction inhibitor imatinib mesylate can be used for treatment. Immunohistochemic analysis of biopsies from humans during treatment with imatinib were analysed and revealed widespread hemorrhagia but no necrosis. Proliferative cell fraction decreased to nearly zero whereas expression of CD117 remained unchanged. Gadolinium-enhanced MRI allowed us to follow the changes in tumor architecture with cystic areas developing at the center in conjunction with a rim of well-perfused parenchyma only, while no major decrease in size developed. Functional imaging by MRI or PET is required to adequately assess the efficacy of tyrosine kinase inhibitor treatment of GISTs.
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