Targeted therapies mainly target some unique biological markers or important proteins or enzymes in signaling channels in tumor cells, blocking key receptors in the process of tumor development and correcting their abnormal pathophysiological processes. Since these drugs have the characteristics of targeting and non-cytotoxicity, and mainly play a regulatory and stabilizing role on tumor cells, they are very different from cytotoxic drugs in terms of mechanism of action and manifestation of toxic and side effects, etc. In order to distinguish them from traditional cytotoxic drugs, they are called cell proliferation inhibitors. In order to distinguish them from traditional cytotoxic drugs, these drugs are called cytoproliferative inhibitors. A common analogy has been made to call targeted therapeutic drugs as “laser-guided bombs” and cytotoxic drugs as “cluster bombs”, which means that the former have a clearer target, while the latter have more extensive damage to normal human tissues and organs other than tumor tissues. The damage of the latter is more extensive to normal tissues and organs of human body other than tumor tissues. Targeted tumor therapy has made significant clinical progress in just a few years, and is the most active research area in medical oncology treatment. Targeted therapies have made breakthroughs not only in some relatively rare drug-resistant tumors, but also in the treatment of common tumors, leading to new improvements in the efficacy of some tumors over conventional chemotherapy. cetuximab (C225), an EGFR monoclonal antibody, is used in the first-line treatment of advanced colorectal disease. Not only that, some drugs have been used in the first-line treatment of advanced patients (e.g. bevacizumab in combination with chemotherapy for the first-line treatment of advanced non-small cell lung cancer, and in combination with chemotherapy for the first-line treatment of advanced colorectal cancer), and trastuzumab has been successfully used in the adjuvant treatment of Her-2-positive breast cancer. Targeted therapy, with its specificity and targeting, will play an increasingly important role in tumor treatment. The main targeted therapies are: 1. Antibody therapy At present, antibody therapy is mostly used in the treatment of hematological tumors and has achieved some good results, but there are still problems in solid tumors, as it is difficult for the therapeutic antibody to enter the interior of solid tumors, so the efficacy of treating large solid tumors is still not very satisfactory. Gene therapy and viral therapy are mainly due to the following problems of vectors: ① not specifically targeting tumor cells; ② low efficient expression of therapeutic genes in tumor cells, which is not enough to kill tumors. 3.Inhibition of neovascularization At present, there are many neovascularization inhibitory factors in clinical trials, and these inhibitory factors have no obvious toxic side effects, but because the mechanism of neovascularization is far more complicated than people think, most of the neovascularization inhibitory factors are not clinically effective. However, because the mechanism of neovascularization is more complicated than people think, most of the neovascularization inhibitors are not effective. It provides a new way of thinking for the treatment of tumors: inhibiting angiogenesis and thus starving tumor cells to death. He believes that if solid tumors are not supplied with enough essential nutrients by new blood vessels, their growth will hardly exceed 1~2mm3. The generation of new blood vessels is a complex process. The endothelial cells that constitute the vessel wall have a strong potential to divide and proliferate, and are activated by certain cytokines to produce matrix metalloproteinase (MMP), which degrades the extracellular matrix components, and the endothelial cells then further invade the matrix and divide and proliferate. The generation of new blood vessels is strictly regulated by the sophisticated regulation of certain stimulating and inhibiting factors. On this basis, it is possible to kill tumors by interfering with the formation of blood vessels. So if we want to inhibit tumor angiogenesis, we mainly start from inhibiting the role of angiogenic factors and strengthening the efficacy of angiogenic inhibitory factors. 4.Targeting tumor stem cells Tumor stem cells have been proven in leukemia, breast cancer and glioma at present. Although tumor stem cells account for only a very small number of tumors, they are most likely the root cause of tumorigenesis, drug resistance, recurrence and metastasis. Scientists hope to discover the characteristic antigen expression of tumor stem cells so that monoclonal antibodies can be designed to kill it, but the odds of this are unlikely. The greater possibility currently comes from the feasibility of blocking this pathway through small molecule drugs, as tumor stem cells signal transduction is different from that within normal stem cells. 5.Targeting tumor cell signaling pathway The occurrence and development of tumor is closely related to one of the signaling pathways such as cell proliferation and apoptosis. One of the most important molecules in signaling is the protein tyrosine kinase, and the development of targeted drugs for the latter has become one of the research hotspots for anti-cancer drugs. Small molecules that have been approved by the US FDA can specifically kill tumor cells. Various targeted therapeutic agents are being actively explored in different tumor trials, combinations with different chemotherapy regimens, maintenance therapy, sequential therapy, and combination targeted therapy. In addition to the familiar classes, various drugs with new mechanisms of action are being investigated. Most monoclonal antibody-based targeted therapeutics have low efficiency when used alone, and even those that are effective often develop secondary drug resistance. This is partly due to the complexity and heterogeneity of the pathophysiological mechanisms of tumors, as the same disease is the result of the interaction of multiple factors, and may vary from patient to patient and from patient to patient at different stages of the disease. Therefore, currently monoclonal antibody-based targeted therapeutic agents are often used in combination with cytotoxic drugs or in combination with other targeted drugs. Tumors tend to have fewer molecular biological abnormalities when the load is small in the early stage of development, and pushing targeted therapeutic agents to adjuvant therapy is a direction of clinical research in recent years, which requires an accurate understanding of early molecular events of the disease. In addition, exploring effective efficacy predictors and selecting appropriate patients for targeted therapy can also relatively improve the effectiveness of targeted therapy.