The goal of this clinical trial is to learn what dose of the drug fampridine can be given safely together with imatinib (Gleevec) in patients with gastrointestinal stromal tumor (GIST) with a DNA mutation in exon 11 of the KIT gene.
The main questions this study aims to answer are:
* What is the maximum dose of fampridine that can be given safely together with imatinib (Gleevec)? * Is the combination of the two drugs efficacious against the tumor?
Participants will:
* Take the drugs before tumor surgery (preoperative treatment) for at least 2 months with the option to continue for a longer period of time if treatment seems safe and effective. * Visit the clinic at the scheduled appointments for checkups and tests.
Provision of written informed consent prior to any screening procedures
Age ≥ 18 years
Having been pathologically confirmed to have a KIT exon 11 mutant gastrointestinal stromal tumor assessed for KIT variant mutations by next generation sequencing
Treatment naïve gastrointestinal stromal tumor
Unwilling or unable to comply with the protocol
KIT exon 9, 13, 14, 17, or 18 mutant gastrointestinal stromal tumor by next generation sequencing.
Non-KIT mutant gastrointestinal stromal tumor
Have residual tumor following surgical debulking