An 83-year-old male presented with uncontrolled hyperglycemia and abdominal pain for a week. On the abdomen CT scan, a 3.5 x 2.5 cm sized pancreas body mass invading the common hepatic artery was noticed with intrahepatic, common bile duct dilatation, and small peritoneal nodules. Endoscopic ultrasound-guided fine needle aspiration for pancreatic body mass was conducted, and cytologic diagnosis showed a few clusters of atypical cells, resulting in the diagnosis of adenocarcinoma. Peritoneal carcinomatosis was found in the PET CT. After an overall examination, he was diagnosed with PDAC, cT4N1M1, stage IV. The patient received two cycles of cytotoxic chemotherapy: gemcitabine and albumin-bound paclitaxel. His disease continued to progress, as evidenced by the increasing size of the pancreatic body mass (3.6 x 3.0 cm) and the increased amount of ascites, thereby being determined as a progressive disease according to RECIST 1.1 criteria. Although mFOLFIRINOX could have been used as second-line palliative chemotherapy in the country, the patient's condition would have been intolerable considering his performance status.
Tumor molecular profiling using next-generation sequencing (FoundationOne Liquid CDx) was performed through liquid biopsy with a blood sample from the patient. The patient exhibited microsatellite stability, and the blood tumor mutational burden was 0 Muts/Mb. The genomic findings revealed the mutations of BRAF NVTAP deletion ( Figure 1 ), PTEN G127R, CDKN2A/B p16INK4a V25fs*12, MUTYH splice site 892-2A>G, and TP53 R248Q.  Table 1  summarizes the tier according to ESCAT and VAF each genomic alteration. As mentioned above, BRAF NVTAP deletion is reported as an oncogenic mutation in PDAC. There was a single previous case where dabrafenib was used to target BRAF NVTAP deletion, and the clinical effectiveness of dabrafenib was demonstrated in this mutant (20). We requested and obtained dabrafenib/trametinib from Novartis with the Managed Access Program.
After receiving dabrafenib 150 mg twice a day and trametinib 2 mg once a day for 8 weeks, a radiologic evaluation showed a marked decrease in primary pancreas body mass (50 mm to 36 mm) with improved ascites ( Figure 2 ). Findings were rated as a partial response according to RECIST 1.1 criteria, and it was maintained for 6 months with continued treatment. The toxicities of drugs such as pyrexia, headache, diarrhea, and rash were not noticed. However, unfortunately, the patient died of an outbreak of SARS-CoV-2 infection during treatment.