In the light of recent report that CES2, the most efficient carboxyl esterase in activating the prodrug irinotecan into the active metabolite SN-38, predicted the tumor response to irinotecan and neoadjuvant FOLFIRINOX therapy in patients with PDAC [21], we examined the correlation between the loss of MAP4K5 expression and CES2 expression in our patient population. The gene discussed is CES2; the disease is neoplasm.