Treatment of Metastatic Gastrointestinal Stromal Tumor with KIT Exon 9 Mutation

This protocol is specific to patients with metastatic gastrointestinal stromal tumor (GIST) harbouring a KIT exon 9 mutation — a molecularly defined subgroup with distinct treatment requirements. The mutation status directly informs both the selection and dosing strategy across treatment lines.

The protocol defines a sequential, evidence-graded systemic therapy strategy for this mutation-specific setting, extending through later lines of treatment. A fourth-line targeted agent is specified for patients who have progressed through earlier therapies. Complete regimen selection, sequencing, and evidence grading are in the full protocol.