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Blood tests for tumour DNA found a mutation in three quarters of 124 patients with advanced bile duct or gallbladder cancer and a drug-relevant change in about half, showing the approach is feasible when tissue is hard to get.
From January 2015 to February 2018, 124 patients with locally advanced or metastatic biliary tract cancer at the Mayo Clinic underwent circulating tumour DNA testing with a clinically available assay, most (n = 122) on a 73-gene panel; about 70% had intrahepatic disease. 138 samples were included.
Excluding variants of unknown significance, 105 samples (76%) had one or more alterations, with an average of three alterations per sample and a median allelic fraction of 0.52%. Therapeutically relevant alterations were observed in 76 patients (55%), including BRAF mutations, ERBB2 amplifications, FGFR2 fusions, FGFR2 mutations and IDH1 mutations seen in 21% of patients. A different spectrum was observed in patients under 50.
Biliary tumours are often diagnosed on tiny biopsies or brushings, so a blood-based panel that detects HER2 amplification and other targets in half of patients is a practical route to testing, with tissue confirmation where the blood is uninformative.
Shares IDH1 / IDH2, FGFR2, HER2, Biliary tract cancer (cholangiocarcinoma).
Shares JCO Precision Oncology, Circulating tumour DNA (ctDNA), Biliary tract cancer (all types), Liquid biopsy (ctDNA).
Shares Circulating tumour DNA (ctDNA), Liquid biopsy (ctDNA), Biliary tract cancer (cholangiocarcinoma), Gallbladder cancer.
Shares FGFR2, Biliary tract cancer (all types), HER2, Biliary tract cancer (cholangiocarcinoma).
Shares HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2, Gallbladder cancer.
Shares HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2, Biliary tract cancer (cholangiocarcinoma), Gallbladder cancer.
Shares IDH1 / IDH2, FGFR2, HER2, Biliary tract cancer (cholangiocarcinoma).
Shares Circulating tumour DNA (ctDNA), Biliary tract cancer (all types), Biliary tract cancer (cholangiocarcinoma), Gallbladder cancer.