ATR and cancer: Based on promising early clinical trial results in other cancer types,44, 45, 46, 47, 48, 49 more extensive testing using inhibitors of ATR (AZD6738) and WEE1 (AZD1775) was performed on 15 PDCLs defined as high and low replication stress based on the replication stress signature score (Figure 3A and Supplementary Figure 3).