CML,Blast Phase

Study on the Efficacy and Safety of a Reduced-Toxicity Conditioning Regimen Containing Thiotepa and Melphalan in Patients with Blast Phase Chronic Myeloid Leukemia

Even in the TKI era, the outcoms of patients with blast phase is still poor.The response rate to conventional intensive chemotherapy is only 12.5% and the 5-year survival rate is 0 for patients with myeloid blast crsis. The response rate of TKI monotherapy is about 50% and the response rate is further improved when combined TKI and chemotherapy for patients with lymphoid blast crsis. The induction remission rate of chemotherapy alone for patients with Ph-positive acute lymphoblastic leukemia is 50-60%, and the remission rate increases to more than 95% when combined with TKI. Therefore, the application of TKI for patients in the blast crisis phase is of great significance. Olverembatinib is the only third-generation TKI drug approved in the Chinese mainland at present. Preclinical research data show that olverembatinib has a significant inhibitory effect on wild-type and mutant ABL resistant to the first and second-generation TKIs, as well as some complex mutations resistant to ponatinib. Phase I and II clinical studies have shown that for CML patients in the chronic and accelerated phases with resistance or intolerance to various TKIs, with or without T315I mutations, there are significant hematological and molecular responses and survival benefits. Olverembatinib can also inhibit many other kinases related to tumors. In vitro studies have shown that olverembatinib downregulates MCL-1 expression and acts synergistically with BCL-2 inhibitors to induce apoptosis of AML cells. Preclinical studies have shown that venetoclax has a synergistic effect with TKIs. It upregulates apoptosis-inducing proteins, downregulates anti-apoptotic protein MCL1, inhibits the anti-apoptotic activity of BCL-XL, induces apoptosis of Ph+ cells, overcomes TKI resistance, and eliminates CML leukemia stem cells. A large amount of evidence indicates that DNA hypermethylation plays an important role in the progression of CML, and abnormal DNA methylation is associated with progression to the accelerated and blast crisis phases and resistance to TKIs.Domestic scholars have reported successful cases of combined treatment with TKI, venetoclax, and demethylating agent azacitidine for CML patients with lymphoid blast crisis. Therefore, we designed this study to explore the efficacy and safety of olverembatinib, venetoclax, and azacitidine in the treatment of CML patients in the blast crisis phase.