MT-304

**MT-304** is a first-in-class multi-immune chimeric antigen receptor (CAR) cell therapy developed by CREATE Medicines (formerly Myeloid Therapeutics) using an mRNA-lipid nanoparticle (LNP) platform to program multiple immune cell lineages, including NK cells and myeloid cells, directly in vivo. It targets **HER2** (receptor tyrosine-protein kinase erbB-2) as an antagonist, inducing antitumor activity against HER2-positive solid tumors such as breast cancer. The therapy enables selective activation, flexible CAR expression durability (transient or stable via RNA retrotransposon), repeat dosing with a manageable safety profile, and off-the-shelf scalability, building on clinical validation from prior in vivo CAR programs showing tumor infiltration, immune remodeling, and preliminary efficacy.[1][3]