Induction of differentiation therapy: In vitro experiments before the clinical application of ATRA have demonstrated that ATRA can induce differentiation of leukemic cell lines (e.g., HL-60 cells) and APL progenitor cells. The mechanism of action of retinoic acid on tumor cells is different from that of chemotherapeutic drugs. It corrects the abnormalities of coagulation mechanism by promoting the differentiation of APL cells, avoiding the possibility of myelosuppression and induction of DIC caused by chemotherapy, which has led to a major breakthrough in the treatment of leukemia and greatly improved the prognosis of APL. The CR of initial cases with retinoic acid (ATRA) in combination with chemotherapy can reach 70%-80% and most patients can also obtain a high secondary remission rate (CR2) by applying As203 or reapplying retinoic acid (ATRA) with chemotherapy after the first relapse, etc. Therefore, it is generally believed that HSCT is not advocated for patients in first remission: Treatment Although current therapeutic approaches can result in Although current therapies can achieve a high remission rate in APL, the relapse rate is still 25%, and autologous or allogeneic stem cell transplantation is a salvage treatment for these patients. Prior to the clinical application of ATRA, HSCT cured 45% of patients in secondary remission. Recent studies have shown that the application of autologous transplantation after secondary remission is very effective and can reduce the relapse of leukemia resulting in a disease-free survival rate of more than 70%. Domestic and international reports indicate that the 3-year DFS of bone marrow transplantation after CR is over 77%-80%, which is better than the post-CR regimen of chemotherapy alone or chemotherapy combined with ATRA (ATRA) Given that patients in remission from APL have a 5-year survival rate of 50%-70% with chemotherapy, ATRA, and arsenic, and given the treatment-related mortality, HSCT is not necessarily required after the first complete remission of the disease. Treatment is mainly indicated for relapsed patients or patients with persistent PML-RARα fusion gene positivity. However, despite the 15-20% transplant-related mortality, allogeneic HSCT is an important treatment option for patients in second or multiple remissions.