This activation induced cell death (AICD) of CAR T cells is dependent on the level of antigen expression since CAR T cell survival was higher in cell lines with lower GD2 expression. class of attractive antigens for anti-cancer immunotherapy development [4,5]. Multiple TACAs are over-expressed on the surface of cancer cells compared to those on normal cells [6]. In addition, TACAs can be found at high levels on many types of cancer, rendering them intriguing targets for potential broad spectrum anti-cancer immunotherapy [7]. Tremendous efforts have been devoted to the development of anti-cancer vaccines targeting TACAs with Tenovin-1 innovative designs of the antigen structures, the carrier moieties to deliver the antigens to the immune system, as well as incorporation of immune activation elements including LAMC2 adjuvants and cytotoxic T cell epitopes into the vaccine constructs [8C11]. Besides vaccines, chimeric antigen receptor (CAR) T cells and bispecific antibodies (BsAbs) have emerged as appealing immunotherapeutic strategies to combat cancer, as evident from multiple products approved by the FDA [12]. Recently, great progresses have been achieved in the development of CAR T cells and BsAbs targeting two TACAs, i.e., gangliosides GD2 and glycoprotein mucin-1 (MUC1). In this review, we will discuss the advances and challenges in these areas to stimulate further development. 2.?GD2 CAR T cells: going beyond the anti-GD2 monoclonal antibodies Disialoganglioside GD2 is an [16]. With its high expression on tumor cells and importance in tumor development, GD2 was ranked as one of the top antigenic targets for cancer [14,17]. Open in a separate window Figure 1. Structure of the GD2 ganglioside. Monoclonal antibodies against GD2 have achieved clinical success in cancer treatment. Early generation of anti-GD2 cancer immunotherapy utilized murine monoclonal antibodies, 14G2a and 3F8, in patients with melanoma, neuroblastoma, and osteosarcoma [14]. However, due to the mouse origin of these antibodies, significant human anti-mouse antibodies were induced, limiting the dose that can be administered and reducing their anti-tumor efficacy. In addition, administration of these antibodies are associated with side effects such as pain, fever, Tenovin-1 hypertension and urticarial reactions, which limit their wide applications. To overcome these challenges, human-mouse chimeric anti-GD2 monoclonal antibodies have been generated [14,18]. ch14.18 consisting of the variable regions of murine 14G2a mAb fused with the constant regions of human IgG1, has higher antibody-dependent cell-mediated cytotoxicity and longer half-life compared to 14G2a. Further development of humanized anti GD2 antibody, hu3F8 and hu14.18K322A with a K322A mutation of the Fc region to prevent complement fixation, improved their half-lives and tolerable dose. However, in clinical trials, similar side effects as m3F8, including pain and hypertension, were observed. Adoptive transfer of CAR T cells is a promising immunotherapy strategy to treat cancer in an MHC-independent manner. CAR T cells are designed by linking the single-chain variable fragment (scFv) of a monoclonal antibody with the T cell receptor (TCR) -chain transmembrane and cytoplasmic regions. Further development of CAR Ts by the addition of costimulatory signal (CD28) for full activation of these cells has led to 2nd generation of CAR Ts and the third generation includes additional signaling domain (CD27, 4C1BB or OX40) aimed at improving proliferation, survival and cytokine release from the cells. With the high anti-tumor efficacy in acute lymphoblastic leukemia, two anti-CD19 CAR T cell based immunotherapies (KYMRIAH and CARTA) have been approved by FDA. However, applications of CAR T therapy in solid tumors have met with limited successes. Some of the main barriers of CAR T cell therapy include: limited ability of CAR T cells to proliferate, inefficient trafficking of CAR T cells to tumor tissues, limited Tenovin-1 T cell extravasation into solid tumor, and suppressive tumor microenvironment that dampens T cell proliferation and cytokine production[19]. With the importance and targetability of GD2 for solid tumors, anti GD2 CAR T cell immunotherapy has been investigated in.