Furthermore, the large numbers of starting cells often required can be difficult or even impossible to obtain for pediatric patients and the time required to manufacture autologous CAR-T cell products is often too long to fight fast growing tumors. The common and devastating solid childhood tumor, neuroblastoma, will be used as a model cancer entity for our three-step approach to improve therapy without raising toxicity. Project A06 aims to (1) allow the use of potent CAR constructs by limiting on-target activity to only tumor cells expressing the neuroblastoma-specific antigens GD2 and L1CAM, (2) reduce risk for rejection and manufacture failure by developing an allogenic CAR-T cell product for these heavily pretreated children suffering from neuroblastoma and (3) prevent tumor escape by armoring CAR-T cells with cytokines to modulate the neuroblastoma tumor microenvironment. In Aim 1, we will use logic-gated CAR-T cells to enhance on-target activity against neuroblastoma cells and reduce toxicity to bystander tissues also expressing targeted antigens. The CAR initiating the cytotoxic re- sponse against the tumor cell and binding a second tumor-specific antigen is only produced when the synthetic Notch (synNotch) receptor binds to the first tumor-specific antigen. In Aim 2, we will generate CAR-T cells from allogeneic instead of autologous T cells to reduce the risk of donor T cell rejection, manufacture failure for severely pretreated children and overly long product generation times. In a step-wise approach, multiple gene- editing steps will start by knocking out B2M to reduce immunogenicity and end by inserting the CAR into the constant region of the TCR alpha chain (TRAC), thus silencing TCR expression and allowing the use of al- logeneic T cells without risking graft-versus-host disease. Aim 3 will armor L1CAM-specific CAR-T cells with synNotch-inducible IL18/IL12 expression to improve CAR-T cell fitness. What we learn about how to improve neuroblastoma-targeting CAR-T cells will render important steps forwarding CAR-T cell therapy for solid tu- mors in general and provide valuable information for the CRC and beyond.