(A) Standard approach to manufacturing CD19 CAR T cells. After apheresis, bulk peripheral blood mononuclear cells (PBMCs) undergo stimulation and activation (with CD3/CD28 beads and cytokine supplementation) followed by transduction with a CD19 CAR vector of choice. After expansion, the bulk product is cryopreserved until ready for thaw and clinical use. (B) Manufacturing schema of PLAT-02 (defined formulation) CD19 CAR product. After apheresis, PBMCs undergo positive selection for CD8⁺ and CD4⁺ T cells by using immunomagnetic separation (CliniMACS device, Miltenyi Biotec). After enrichment, CD4 and CD8 T cells are separately activated with CD3/CD28 beads and then transduced with the lentiviral CD19 CAR vector expressing EGFRt in the presence of IL-7/IL-15 (CD4) and IL-15/IL-2 (CD8). The separate cell products undergo positive selection for EGFRt-expressing cells using the CliniMACS device, after which the individual products are cryopreserved until ready for thaw and clinical use.