Sanofi presented preclinical data on the in vivo CAR-T platform, which modifies T cells directly in the patient's body.[1] The platform uses mRNA and lipid nanoplasts (LNPs) for targeted delivery to CD8+ T cells, enabling transient CAR expression without permanent DNA alteration.[2] In laboratory tests, CAR expression lasts for more than 14 days, allowing repeated dosing.[1] In mouse models, a single intravenous dose of 0.01 mg/kg resulted in greater than 95% depletion of B cells.[1] A 30-fold expansion of in vivo CAR-T cells, potent antitumor activity, and effective responses after single or multiple doses were observed.[1] This platform is designed to treat hematological malignancies such as B-cell tumors and minimize expression in off-target cells.[2] The research was presented at the annual meeting of the American Society of Hematology (ASH).[1]