Clinical Study Protocol for the Treatment of ND-AML and RR-AML With KMT2A Gene Abnormalities Using VHEA.

This study is a multicenter, single-arm, open-label clinical trial aimed at evaluating the efficacy and safety of the VHEA（Venetoclax with Homoharringtonine，Etoposide，Cytarabine）regimen in the treatment of newly diagnosed and relapsed/refractory acute myeloid leukemia (AML) with MLL gene abnormalities.

Leukemia is a malignant tumor of the blood system that seriously endangers human health, ranking among the top 10 in the mortality rate of malignant tumors in all age groups in China. Acute myeloid leukemia (AML) is a malignant clonal blood system disease originating from hematopoietic stem and progenitor cells, accounting for about 35% of newly diagnosed leukemia cases each year and 80% of adult leukemia cases. The overall prognosis is poor, with approximately 10-40% of newly diagnosed AML patients unable to achieve CR, and over 50% of AML patients eventually relapse. Especially in AML with KMT2A gene abnormalities, the conventional "3+7" chemotherapy regimen has a low remission rate and a high relapse rate.

Chromosomal translocations include the Mixed Lineage Leukemia gene (MLL), also known as the KMT2A gene, which produces various MLL fusion genes, including AF4, AF6, AF9, AF10, ENL, ELL, and AF1q. Currently, more than 70 MLL fusion genes have been reported. MLL gene abnormalities associated with leukemia account for 5% to 10% of all acute leukemias, and MLL-related leukemia has a poor prognosis. There is currently no standard treatment regimen for MLL-related AML with good efficacy. Current treatment options include conventional chemotherapy, targeted epigenetic and DNA damage response therapies. Conventional chemotherapy includes regimens composed of anthracyclines, cytarabine, and etoposide, followed by consolidation therapy with allogeneic hematopoietic stem cell transplantation, but the efficacy is still unsatisfactory.

Based on preliminary data from our institution, there have been a total of 30 cases of AML with MLL gene abnormalities since 2016, accounting for approximately 12% of all AML cases. Among these, 14 cases received initial induction chemotherapy using the standard "3+7" regimen, with only 4 cases achieving complete remission (28.6%), 3 cases achieving partial remission (21.4%), and 7 cases showing no response (50%). Five cases received induction chemotherapy using a priming regimen, but none achieved remission. Additionally, 11 patients either refused chemotherapy or sought treatment at other hospitals, indicating that conventional chemotherapy regimens do not yield satisfactory results in AML patients with MLL gene abnormalities. Therefore, it is of great clinical significance to explore more effective chemotherapy regimens for MLL gene abnormality-associated acute leukemia.

Venetoclax has demonstrated anti-tumor activity in various hematologic malignancies. In November 2018, the U.S. Food and Drug Administration (FDA) approved the use of Venetoclax in combination with hypomethylating agents (HMAs) or low-dose cytarabine for newly diagnosed AML patients aged 75 years and older who are unfit for intensive chemotherapy. According to the 2021 NCCN guidelines, Venetoclax in combination with HMAs or low-dose cytarabine is an important treatment strategy for both newly diagnosed elderly AML patients and relapsed/refractory AML patients who are not suitable for intensive chemotherapy. Recent exploratory studies have also been conducted on the use of Venetoclax in combination with hypomethylating therapy in newly diagnosed and relapsed/refractory AML with KMT2A gene rearrangement. These studies found that Venetoclax in combination with decitabine or azacitidine achieved an overall response rate (ORR) of 83% and a complete response/complete response with incomplete hematologic recovery (CR/CRi) of 75% in newly diagnosed AML with KMT2A gene rearrangement. However, in relapsed/refractory AML with KMT2A rearrangement, the ORR and CR/CRi were only 17% and 8%, respectively.

Homoharringtonine (HHT) is widely used for the treatment of myeloid leukemia. HHT promotes apoptosis and inhibits autophagy in CML cells by activating ERK phosphorylation and inhibiting Akt phosphorylation. Bcl-2 protein is an apoptosis inhibitor that plays an important regulatory role in cell apoptosis. NFκB is a nuclear transcription factor present in cells that regulates κ immunoglobulin and has anti-apoptotic effects. HHT significantly inhibits the expression of NFκB and Bcl-2 protein, ultimately leading to cell apoptosis.

Venetoclax has been widely used in various hematological malignancies, but the short duration of sustained remission and the occurrence of resistance are the main problems currently. The mechanisms of Venetoclax resistance mainly include the activation of selective dependence on the Bcl-2 anti-apoptotic protein family and kinase mutations, among which other members of the Bcl-2 family, including BCL2-A1, MCL-1, and BCL-XL, have been proven to be key factors leading to primary or acquired resistance to Venetoclax. Recent studies have shown that Venetoclax has synergistic inhibition of AML cell proliferation with Homoharringtonine, reduces mitochondrial membrane potential, promotes AML cell apoptosis, and exhibits time-dependent and concentration-dependent effects. Venetoclax with Homoharringtonine can synergistically promote apoptosis of AML cell lines and primary cells by inhibiting the activation of the MAPK/ERK, PI3K/AKT, and P53 signaling pathways. Therefore, based on this, we propose that Venetoclax with Homoharringtonine, Etoposide, and Cytarabine may be an effective treatment option for newly diagnosed and relapsed/refractory AML with MLL gene abnormalities.

This study will include AML patients with newly diagnosed or relapsed refractory MALL gene abnormalities. The VHEA regimen will be used for induction, followed by one consolidation cycle after achieving CRh/CRi/MLFS. If patients have a PR/NR, VHEA will be continued for induction therapy until disease remission. After achieving remission, patients who are willing and meet the criteria will undergo transplantation. If transplantation is not performed, consolidation chemotherapy will be continued until disease progression.

Specific treatment plan: VHEA Venetoclax 100 mg d1，200 mg d2，400 mg d3-14； homoharringtoine, HHT 2 mg/m2，qd，d1-7； Etoposide 0.1 g，qd，d1-5； Cytarabine 100 mg/m2，qd，d1-7