Azalea Therapeutics and collaborators published results in Nature demonstrating successful in vivo generation of CAR‑T cells after systemic delivery of gene‑editing particles, producing tumor clearance in mouse models of both solid and hematologic cancers. Researchers used targeted editing to convert endogenous T cells into CAR‑T cells inside the animal rather than manufacturing cells ex vivo. The team—building on work from Jennifer Doudna’s lab and other groups—reports methods to bias editing to the correct cell type and genomic loci to reduce off‑target risks. Investigators described robust antitumor activity in preclinical models and presented methodology intended to minimize accidental editing of non‑T cells. Authors and outside experts emphasized this as an important preclinical milestone for in vivo cell‑engineering approaches, while noting translational hurdles including delivery specificity, safety profiling and regulatory scrutiny before human trials.