A review of in vivo CAR T strategies highlights accelerating investment and early clinical signals as companies race to reprogram T cells inside the patient rather than ex vivo. Integrated viral and non‑integrated lipid nanoparticle platforms are advancing through early trials, with several firms demonstrating tumor clearance in hematologic indications. Big pharma M&A and partnership activity reflects growing confidence in scalability and cost advantages of in vivo approaches. The editorial assesses safety tradeoffs—including insertional mutagenesis risk with integrating vectors and the need for redosing strategies with mRNA approaches—and notes that regulatory expectations will shape trial design. Early movers report responses in multiple myeloma and other blood cancers, but broad adoption will depend on reproducible manufacturing, delivery specificity, and long‑term safety readouts.