Gastrointestinal stromal tumors (GISTs) are rare mesenchymal tumors with worse prognosis if arising from the small bowel. Surgery remains the mainstay of treatment for patients with resectable tumors. Imatinib has become the standard treatment in cKIT-positive GISTs with significant morbidity in neoadjuvant, adjuvant, and palliative settings. There are limited data on efficacy and safety of imatinib in dialysis patients, and chemotherapy dosing is challenging in dialysis patients with multiple comorbidities.
A 68-year-old male with a history of orthotopic heart transplantation on sirolimus with prednisone, cardiac allograft vasculopathy, plus ESRD on peritoneal dialysis (PD), presented with lower abdominal pain and fever. Abdominal imaging revealed a right lower quadrant (RLQ) mass with concern for bowel perforation.
Diagnosis and Treatment
The patient underwent exploratory laparoscopy with small bowel resection, excision of the mesenteric small bowel mass, drainage and washout of intraabdominal abscess, removal of PD catheter, and transition to hemodialysis. Pathology revealed a 14.5-cm high-grade GIST with mixed spindle and epithelioid types involving the ileal wall and mesentery, consistent with pT4 primary tumor and stage IIIB disease. Molecular testing was positive for c-KIT and DOG-1 mutations.
After a prolonged recovery, repeat abdominal imaging demonstrated metastatic liver disease and a new RLQ lesion. The patient was started on palliative imatinib 100 mg daily with subsequent increase to 200 mg daily. He was monitored closely for toxicities but reported only mild nausea controlled with ondansetron. Hemodialysis was continued 3 times per week. Follow up scans 3 months later showed improvement in RLQ mass and hepatic lesions. The patient remains on the current dose 15 months after the diagnosis.
To our knowledge, this is the first case of a small intestinal GIST in a heart transplant recipient treated with dose-reduced imatinib with concurrent dialysis and immunosuppression. Treatment decision-making was complex given concern for cardiotoxicity with pre-existing cardiac disease and drug-drug interactions with immunosuppressive agents. While some literature suggests standard dose imatinib with dialysis, no large-scale studies evaluated pharmacokinetics of imatinib with creatinine clearance < 20 mL/min. There is a need for further studies to determine dosing strategies for such patients.