CREBBP and colorectal carcinoma: We used wild‐type p53‐positive (HCT116wt) and p53‐negative (HCT116Δp53) human CRC cell lines, human primary short‐term CRC cell cultures, and patient‐derived CRC organoids to measure cellular responses to the topoisomerase I (TOP1) inhibitor irinotecan in combination with the class I HDACi entinostat (MS‐275) and the CBP/p300 inhibitor CPI‐1612.