A Case of BRAF-V600E-Positive Pulmonary Pleomorphic Carcinoma Successfully Treated With Dabrafenib and Trametinib Administered via a Percutaneous Endoscopic Gastrojejunostomy Tube for Ileus Caused by Small Intestinal Metastasis

Pulmonary pleomorphic carcinoma (PPC) is a rare subtype of non-small cell lung cancer (NSCLC). It has a rapid progression and poor prognosis and is resistant to conventional chemotherapy. The efficacy of molecular-targeted drugs for patients with PPC with targetable driver mutations has been reported. However, most molecular-targeted drugs are administered orally, limiting their application in cases where oral administration is difficult. We report the case of a 78-year-old male patient diagnosed with stage IIA lung cancer. He underwent lobectomy and was pathologically diagnosed with PPC harboring a BRAF-V600E mutation. His lung cancer recurred two months postoperatively with multiple metastases, including those in the small intestine, which caused intussusception and ileus. Because the resected specimen from the small intestinal tumor resembled the histopathological results of the preoperative lung tissue, treatment with dabrafenib and trametinib could be effective. A percutaneous endoscopic gastrojejunostomy (PEG-J) tube was placed on the anal side of the intussusception site to depressurize intragastric pressure, allowing drug administration while decompressing the stomach. Treatment initiated for a few days improved abdominal symptoms, and computed tomography (CT) revealed tumor shrinkage. This is the first reported case of a patient with malignant intestinal obstruction successfully treated with targeted therapy drugs administered via a PEG-J tube, which is a viable method for patients with NSCLC with driver mutations who cannot take oral medications or via a nasogastric tube. Furthermore, therapies targeting driver mutations may be effective for patients with PPC.