Venetoclax and Daratumumab combination treatment demonstrates pre-clinical efficacy in mouse models of Acute Myeloid Leukemia

Hematopoietic stem cell aging and leukemia transformation

With aging, hematopoietic stem cells (HSCs) have an impaired ability to regenerate, differentiate, and produce an entire repertoire of mature blood and immune cells. Owing to dysfunctional hematopoiesis, the incidence of hematologic malignancies increases among elderly individuals. Here, we provide an update on HSC-intrinsic and -extrinsic factors and processes that were recently discovered to contribute to the functional decline of HSCs during aging. In addition, we discuss the targets and timing of intervention approaches to maintain HSC function during aging and the extent to which these same targets may prevent or delay transformation to hematologic malignancies.

Targeting CD38 for acute leukemia

Acute leukemia (AL) is a hematological malignancy, and the prognosis of most AL patients hasn’t improved significantly, particularly for relapsed or refractory (R/R) AL. Therefore, new treatments for R/R adult acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) are urgently necessary. Novel developments have been made in AL treatment, including target and immune therapies. CD38 is one of the targets due to its high expression in many hematological malignancies, including multiple myeloma, ALL and a subset of AML. Consequently, targeting CD38 therapies, including CD38 monoclonal antibodies (mAbs), bispecific antibodies, and CAR-T cell therapy, exhibit promising efficacy in treating multiple myeloma without significant toxicity and are being explored in other hematological malignancies and nonhematological diseases. Herein, this review focuses on targeting CD38 therapies in ALL and AML, which demonstrate sound antileukemic effects in acute leukemia and are expected to become effective treatment methods.

Synergistic effect of chidamide and venetoclax on apoptosis in acute myeloid leukemia cells and its mechanism

Background

Acute myeloid leukemia (AML) is a hematological malignancy with a low remission rate and high recurrence rate. Overexpression of the antiapoptotic protein Bcl-2 is associated with a lower overall survival rate in AML patients. Venetoclax (ABT199) is a selective inhibitor of Bcl-2 that has a significant effect in AML, but single-drug resistance often occurs due to the high expression of Mcl-1 protein. Studies have confirmed that chidamide can downregulate the expression levels of Bcl-2 and Mcl-1 and induce apoptosis.

Methods

This study aimed to use AML cell lines and primary cells to study the effects of venetoclax and chidamide combination therapy on AML cell apoptosis, the cell cycle, and changes in related signaling pathways in vitro; establish an AML mouse model to observe the efficacy and survival time of combination therapy in vivo; and analyze the drug effects with multi-omics sequencing technology. The changes in gene and protein expression before and after treatment were examined to clarify the molecular mechanism driving the synergistic effect of the two drugs.

Results

(I) Both venetoclax and chidamide promoted apoptosis in AML cell lines and primary cells in a time- and concentration-dependent manner. The effect was further enhanced when the two drugs were combined, and a synergistic effect was observed (combination index <1). (II) At both the mRNA and protein levels, the expression of Mcl-1 was upregulated by venetoclax and downregulated by chidamide, and the expression of Mcl-1 decreased further after combination treatment. (III) Transcriptome sequencing showed that differentially expressed genes in the combination group compared with the venetoclax monotherapy group were mainly enriched in the PI3K-AKT pathway and JAK2/STAT3 pathway. Moreover, qRT-PCR and Western blot confirmed these results. (IV) The combination therapy group exhibited significantly inhibited disease progression and a prolonged survival time among AML mice.

Conclusions

Chidamide combined with venetoclax synergistically promoted apoptosis in AML cell lines and primary cells by inhibiting activation of the PI3K/AKT pathway and JAK2/STAT3 pathway.