Potent, p53-independent induction of NOXA sensitizes MLL-rearranged B-cell acute lymphoblastic leukemia cells to venetoclax

Abstract

The prognosis for B-cell precursor acute lymphoblastic leukemia patients with Mixed-Lineage Leukemia (MLL) gene rearrangements (MLLr BCP-ALL) is still extremely poor. Inhibition of anti-apoptotic protein BCL-2 with venetoclax emerged as a promising strategy for this subtype of BCP-ALL, however, lack of sufficient responses in preclinical models and the possibility of developing resistance exclude using venetoclax as monotherapy. Herein, we aimed to uncover potential mechanisms responsible for limited venetoclax activity in MLLr BCP-ALL and to identify drugs that could be used in combination therapy. Using RNA-seq, we observed that long-term exposure to venetoclax in vivo in a patient-derived xenograft model leads to downregulation of several tumor protein 53 (TP53)-related genes. Interestingly, auranofin, a thioredoxin reductase inhibitor, sensitized MLLr BCP-ALL to venetoclax in various in vitro and in vivo models, independently of the p53 pathway functionality. Synergistic activity of these drugs resulted from auranofin-mediated upregulation of NOXA pro-apoptotic protein and potent induction of apoptotic cell death. More specifically, we observed that auranofin orchestrates upregulation of the NOXA-encoding gene Phorbol-12-Myristate-13-Acetate-Induced Protein 1 (PMAIP1) associated with chromatin remodeling and increased transcriptional accessibility. Altogether, these results present an efficacious drug combination that could be considered for the treatment of MLLr BCP-ALL patients, including those with TP53 mutations.

Venetoclax Use in Paediatric Haemato-Oncology Centres in Poland: A 2022 Survey

“…KMT2A::AF4 directly regulates BCL2 gene expression by promoting increased H3K79me2/3 levels in the BCL2 gene vicinity leading to a BH3-dependance in KMT2A -rearranged leukaemia [ 24 ]. Other pre-clinical reports also point to venetoclax activity in KMT2A -rearranged ALL [ 27 , 29 ]. The same study also demonstrated high BCL2 expression in hypodiploid BCP-ALL but the consequences were not studied in more detail [ 24 ].…”

“…This is consistent with efforts from several pre-clinical studies that highlighted genetic backgrounds associated with high BH3-dependance and BH3 mimetic sensitivity. Thus far, in the setting of ALL and to a lesser extent in AML, the pre-clinical experimental data have pointed to several molecular subtypes which may display therapeutically applicable venetoclax vulnerabilities [ 21 , 24 , 25 , 26 , 27 , 28 , 29 ].…”

“…BH3 mimetics, and in particular venetoclax, were also highlighted as potential interventions to target specific vulnerabilities in some aggressive molecular subtypes of ALL, including hypodiploid, KMT2A -rearranged or ALL with TCF3::HLF fusion, or early T-precursor (ETP)-ALL that are associated with poor or very poor outcomes. With respect to TCF3::HLF subtype venetoclax vulnerability, while striking, this is only a correlative link without mechanistic explanation, whereas KMT2A rearrangements seem to be due to epigenetic regulation of the expression of BCL2 via histone modifications [ 21 , 24 , 25 , 26 , 27 , 28 , 29 ].…”

Histone deacetylase inhibition sensitizes p53-deficient B-cell precursor acute lymphoblastic leukemia to chemotherapy

“…PMAIP1 (NOXA) induction was not affected by p53 loss, consistent with the notion that this gene, apart from being a p53 target, can mediate apoptosis in a p53-independent manner in hematologic malignancies. 11 To test whether romidepsin may act to (re)activate p53 target genes and thereby induce apoptosis, we performed GSEA, again using the MSigDB hallmark gene set collection which includes gene sets that cover p53 pathway or apoptosis, comparing both romidepsin-only versus control treatment and combination versus cytarabine-only treatment (normalized enrichment scores, P values and false discovery rate q values of HALLMARK_APOPTOSIS and HALLMARK_P53_PATHWAY are shown in Online Supplementary Table S3). We found significantly enhanced apoptosis in three out of four models for both comparisons (non-significant enrichment of RCH-ACV wild-type for romidepsin versus control, normalized enrichment score 1.23, P=0.133; and Nalm6 wild-type near significant in combination versus cytarabine, normalized enrichment score 1.31, P=0.06).…”

Combined BCL-2 and PI3K/AKT Pathway Inhibition in KMT2A-Rearranged Acute B-Lymphoblastic Leukemia Cells

“…The first published phase I study to evaluate co-administration of VEN, navitoclax, and chemotherapy demonstrated encouraging results [ 9 ]. Despite notable efficacy, dose limitation as well as primary and secondary resistance to VEN monotherapy highlight the need for rational combination strategies to consistently modulate apoptotic processes in malignant cells [ 6 , 10 , 11 ].…”