Achieving precise temporal control over genome editing is essential for safety but remains a challenge, especially when using small-molecule drugs as external regulators over systems like clustered regularly interspaced short palindromic repeats (CRISPR)-Cas (CRISPR-associated systems). Consequently, controlled therapeutic in situ editing that maintains both precision and efficacy has yet to be demonstrated. Here, we report the PRINCE system, in which nuclease proteins and guide RNAs are both inducible, to deliver programmable nucleases under control more effectively. PRINCE demonstrated temporal precision in human cell cultures over a 2-year period, even after stable genomic integration. The design principles of PRINCE were broadly applicable from CRISPR-Cas9 to a prime editor and also compact programmable nucleases, and the latter platform was named "Little Prince." Upon administration of drug inducers, Little Prince, delivered in a single adeno-associated virus vector in situ to humanized mouse models, ameliorated pathological phenotypes of hypercholesterolemia (average reductions of 45 and 47% in serum total cholesterol and low-density lipoprotein cholesterol, respectively) and neovascular age-related macular degeneration, with significantly reduced lesion size and leakage ( < 0.0001). Last, we demonstrated a consistent and marked reduction in off-target activity across the PRINCE and Little Prince systems in comparison with constitutive editors, with fewer off-target sites and substantially lower editing frequencies, irrespective of nuclease type, delivery method, or genomic target. These results position PRINCE and Little Prince as controlled genome editing platforms with potential for in vivo, particularly in situ, therapeutic applications. P
CRISPR Gene Editing