The incidence of malignant tumors is increasing worldwide, posing a threat to public health [
1-
3]. Numerous breakthroughs in tumor immunology and biotechnology have been reached recently using various strategies such as nanotechnology, gene therapy and combined formulations [
4-
8]. These advances have provided profound knowledge reserves and technical guidance for tumor immune research and development, allowing tumor immunotherapy to be widely recognized. Immune anti-cancer therapy has shown a fantastic medical breakthrough [
9]. Immunotherapy has become the fourth most effective tumor treatment strategy, following surgery, chemotherapy and radiotherapy [
10]. Several cancer immunotherapies exhibit encouraging potential against cancer. Cell therapy is an immune treatment approach applying culture technology
in vitro to increase immune cells or using genetic modification to enhance the virulence of immune cells and then infusing them back into the human body to fight against diseases [
11]. The therapy utilizes the patient's cells to attack tumor cells and enable the immune system to act like an "anti-cancer drug" [
12],
e.g., certain cell groups are isolated, genetically tailored, initiated and increased to the cell number required for treatment. Several immune cells, such as T cells, NK cells, dendritic cells and regulatory T cells (Tregs), can be redirected to outbreak tumors or boost local immune reply [
13]. CAR-T cell therapy has shown promising potential for cancer treatment. CAR-T cell therapy involves transferring genetic material with specific antigen recognition domains and T cell activation signals into T cells through
in vitro modification. The CAR-T enables T cells not to be limited to major histocompatibility complex (MHC) [
14], but to independently recognize tumor antigens and directly associate with specific antigens on the surface of tumor cells [
15], elevating the ability of the immune system to kill tumor cells. CAR-T cells are widely used in hematological cancer treatment, such as B-cell acute lymphoblastic leukemia (B-ALL) [
16], B-cell non-Hodgkin lymphoma (B-NHL), B-cell chronic lymphoblastic leukemia (B-CLL) [
17] and multiple myeloma (MM) [
18]. CAR-T cell therapy has been proven to have excellent results, eradicating very advanced leukemia and lymphoma and suppressing cancer cells long term. Meanwhile, CAR-T cells targeting CD19 and BCMA antigens have been clinically accepted worldwide. Cell therapy has gradually become one of the routine cancer treatments. Despite these advances, CAR-T cells still face certain significant challenges. CAR-T cells demonstrate compromised efficacy against solid tumors due to the complex interaction between various immune cell subsets, such as inhibition of the tumor microenvironment (TME), heterogeneity of tumor antigens or evasion mechanisms, and many other drug-resistant mechanisms [
19]. Therefore, in the relevant indications of hematology and oncology, T cells are modified to regulate the immune response or kill the infected cells or cancer cells. For instance, CAR-T therapy is designed to improve the efficacy and reduce the toxicity associated with T cell therapy, while increasing patients' compliance to promote the production of CAR-T cells, making CAR-T cell therapy universally applicable and a potentially effective treatment method in cancer. In this review, we summarize the basic structure and evolution process of CAR-T cells. We pay more attention to the difficulties faced by CAR-T therapy and the current progress in designing more effective and CAR-T technology. In addition, we discuss the marketed products and the advance, while introducing the latest approach to break through and overcome the disadvantages of CAR-T cells. Finally, we provide perspectives and insights into CAR-T cell technology in the treatment of hematological malignant tumors and solid tumors.