ATM and neoplasm: Regression is rare in MIA PaCa-2 xenograft studies, but adding gemcitabine (50 mg/kg, IP, once per week) to the 50 mg/kg AZD6738 schedule induced regression in the ATM-KO MIA PaCa-2 tumours (mean volume change after 3 weeks = −17.8%, 95% confidence interval −2.7% to −32.8%) and growth delay in the WT tumours (46% TGI) (Figs. 6b and S5A).