GATA6 expression with CA19-9 levels as biomarkers in resectable pancreatic adenocarcinoma treated with neoadjuvant modified FOLFIRINOX in the NeoPancONE trial.

772 Background: The increasing use of neoadjuvant systemic therapy for resectable pancreatic adenocarcinoma (rPDAC) highlights the need for biomarkers for patient selection in this setting. High GATA6 expression has been shown to be useful in identifying the classical subtype, compared to the GATA6 low basal-like subtype associated with chemoresistance. GATA6 expression and CA19-9 levels have been evaluated independently as potential biomarkers, with their respective limitations. We therefore sought to assess whether the use of both, in tandem, may enhance their prognostic utility in the phase 2 NeoPancONE trial where CA19-9 levels were not part of exclusion. Methods: Patients with rPDAC were analyzed within four subgroups based on GATA6 ISH (high vs low) and baseline CA19-9 level (≥200 vs