HOXD8 hypermethylation as a fully sensitive and specific biomarker for biliary tract cancer detectable in tissue and bile samples
Eleonora Loi, Cesare Zavattari, Alessandro Tommasi, Loredana Moi, Matteo Canale, Agnese Pò, Claudia Sabato, Ana Florencia Vega-Benedetti, Pina Ziranu, Marco Puzzoni, Eleonora Lai, Luca Faloppi, María Rullán, Juan Carrascosa, Irene Amat, Jesús Urmán, María Arechederra, Carmen Berasain, Elisabetta Ferretti, Andrea Casadei‐Gardini, Matías A. Ávila, Sergio Alonso, Mario Scartozzi, Patrizia Zavattari
Abstract
BACKGROUND: Biliary tract cancers (BTC) are rare but highly aggressive tumours with poor prognosis, usually detected at advanced stages. Herein, we aimed at identifying BTC-specific DNA methylation alterations. METHODS: Study design included statistical power and sample size estimation. A genome-wide methylation study of an explorative cohort (50 BTC and ten matched non-tumoral tissue samples) has been performed. BTC-specific altered CpG islands were validated in over 180 samples (174 BTCs and 13 non-tumoral controls). The final biomarkers, selected by a machine-learning approach, were validated in independent tissue (18 BTCs, 14 matched non-tumoral samples) and bile (24 BTCs, five non-tumoral samples) replication series, using droplet digital PCR. RESULTS: We identified and successfully validated BTC-specific DNA methylation alterations in over 200 BTC samples. The two-biomarker panel, selected by an in-house algorithm, showed an AUC > 0.97. The best-performing biomarker (chr2:176993479-176995557), associated with HOXD8, a pivotal gene in cancer-related pathways, achieved 100% sensitivity and specificity in a new series of tissue and bile samples. CONCLUSIONS: We identified a novel fully efficient BTC biomarker, associated with HOXD8 gene, detectable both in tissue and bile by a standardised assay ready-to-use in clinical trials also including samples from non-invasive matrices.