This blog appeared earlier on Nature Biotechnology and Bioengineering Community in the behind-the-paper series of our recent Nature Biotechnology paper Engineered phage with antibacterial CRISPR–Cas selectively reduce E. coli burden in mice. While cancer treatment continues to advance and survival rates for people with hematological malignancies are increasing, the chemotherapeutic regimens that are frequently used in this immunocompromised population cause bone marrow suppression and gastrointestinal mucositis with associated increased intestinal permeability.