Introduction:Ventoclax-based combinations have emerged as a new standard of care for patients with acute myeloid leukemia (AML) who are not suitable for intense chemotherapy. Not all patients respond to these treatments, and those who do may relapse. MDM2 inhibitors are promising therapeutics for treating TP53 wild-type tumors, including most de novo AML cases, with numerous compounds currently in pre-clinical and clinical evaluation. However, clinical trials of MDM2 inhibitors have shown modest and variable clinical activity. Functional genomic data showed that monocytic leukemia (FAB M4/M5) is resistant to venetoclax-based therapies and MDM2 inhibitors. Notably, venetoclax and an MDM2 inhibitor, idasanutlin, demonstrated a strong positive correlation in the Beat AML cohort.
We hypothesize that upregulation of certain myeloid transcription factors in monocytic leukemia may confer intrinsic resistance to BCL2 and MDM2 inhibitors, while certain environmental cues upregulated in these cells may confer extrinsic drug resistance. Additionally, there may be crosstalk between these intrinsic and extrinsic mechanisms.
Methods: We performed differential expression gene (DEG) analysis of transcription factors (TFs) between M4/M5 and M0/M1 samples in the Beat AML and TCGA AML cohort. We overexpressed seven myeloid TFs (SPI1, CEBPB, CEBPD, JUNB, IRF8, KLF4, and MAFB) that are upregulated in M4/M5 and performed competitive drug assays. We treated M4/M5 and M0/M1 samples with venetoclax and idasanutlin, in the presence of a panel of myeloid cytokines and measured cell viabilities. A Luminex assay on monocyte supernatants from M4/M5 and M0/M1 AML samples were conducted to identify dysregulated cytokines. Furthermore, RNAseq DEG and immunoblot analysis were performed on CEBPB-overexpressing cell lines and IL-1-treated AML samples to elucidate the underlying mechanisms.
Results: CEBPB overexpression conferred drug resistance to a broad range of BH3 mimetics, venetoclax combinations, and MDM2 inhibitors. RNA-seq and immunoblot analyses demonstrated that CEBPB overexpression downregulated CASP3, CASP6, BCL2, and TP53 pathway targets (CDKN1A, PMAIP1, BBC3, BMF, TP53), while upregulated MCL1, BCL2A1, and the NF-κB/IL-1/TNF pathway at transcription and/or translation levels. Phenotyping analysis showed that CEBPB overexpression drives myelo/monocytic differentiation. In accordance, CEBPB expression in primary AML correlates with drug responses of idasanutlin, venetoclax, and many venetoclax combinations. Additionally, primary monocytic leukemia expresses significantly higher levels of IL-1/TNF family genes, BCL2A1, and reduced CASP3, CASP6, and BCL2.
Abnormal monocytes, but not granulocytes, T cells, or blasts from M4/M5 leukemia, extrinsically protect leukemia blasts from venetoclax and MDM2 inhibition by secreting elevated IL-1 and TNFα. IL-1β/TNFα treatment drove myelo/monocytic differentiation and up-regulated inflammatory cytokines, including an autoregulatory loop, as well as a number of cytokine receptors, such as IL1R1, TNFRSF1R, TNFRSF2R, and CSF2RB. Remarkably, IL-1α/IL-1β and TNFα uniquely upregulated CEBPB expression in M4/M5 cells and protected them from apoptosis induced by venetoclax and MDM2 inhibitors. Conversely, TNFα treatment induced augmented extrinsic apoptosis in M0/M1 leukemia cells.
Interestingly, treatment with venetoclax and idasanutlin led to a feedback upregulation of CEBPB, IL-1β, and/or TNFα, along with their respective receptors, and promoted myelomonocytic differentiation.
IL-1/TNFα antagonists or an IRAK inhibitor alone did not kill leukemia cells, but they showed synergistic cytotoxicity when combined with venetoclax and idasanutlin.
Conclusions: In summary, we have described a positive feedback loop between CEBPB, IL-1/TNFα, and monocytic differentiation in monocytic leukemia that contributes to intrinsic and extrinsic drug resistance against BCL2 and MDM2 inhibitors. This crosstalk and the consequent drug resistance are further reinforced by venetoclax/MDM2 inhibition treatment. Combining venetoclax or idasanutlin with IL-1/TNFα antagonists or an IRAK inhibitor can abrogate the feedback loop and induce synergistic cytotoxic effects, offering promising therapeutic strategies to enhance the treatment efficacy of venetoclax and MDM2 inhibitors for monocytic leukemia.
Disclosures
Druker:Tolero: Other: Co-investigator on clinical trial(s) funded via contract with OHSU.; Gilead: Other: Co-investigator on clinical trial(s) funded via contract with OHSU.; Aileron Therapeutics: Membership on an entity's Board of Directors or advisory committees; Therapy Architects, LLC: Membership on an entity's Board of Directors or advisory committees; CureOne: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: PI or Co-investigator on clinical trial(s) funded via contract with OHSU., Research Funding; AstraZeneca: Other: PI or Co-investigator on clinical trial(s) funded via contract with OHSU.; Enliven Therapeutics: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Research Funding; Oregon Health & Science University: Current Employment, Patents & Royalties: #1518 (exclusive option agreement with CytoImage); #0606/Patent 6958335 (Novartis exclusive license); #2573; #0843; #0996; DNA SEQ: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Other: Co-investigator on clinical trial(s) funded via contract with OHSU.; Celgene: Other: Co-investigator on clinical trial(s) funded via contract with OHSU.; Astellas: Other: Co-investigator on clinical trial(s) funded via contract with OHSU.; Incyte: Other: Co-investigator on clinical trial(s) funded via contract with OHSU.; US Patent and Trademark Office: Patents & Royalties: Patents 6958335 (Novartis exclusive license), 4326534, 7416873, 7592142, 10473667, 10664967, 11049247; Burroughs Wellcome Fund: Membership on an entity's Board of Directors or advisory committees; Syndax: Other: Co-investigator on clinical trial(s) funded via contract with OHSU.; Adela, Inc.: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Amgen: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Beat AML LLC: Membership on an entity's Board of Directors or advisory committees; Cepheid: Membership on an entity's Board of Directors or advisory committees; Nemucore Medical Innovations, Inc.: Membership on an entity's Board of Directors or advisory committees; Multicancer Early Detection (MCED) Consortium: Membership on an entity's Board of Directors or advisory committees; Dana-Farber Cancer Institute: Patents & Royalties: #2063 (licensed exclusively to Merck & Co); and #2524, Research Funding; Labcorp: Membership on an entity's Board of Directors or advisory committees; Iterion Therapeutics: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; GRAIL: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Vincerx Pharma, Inc.: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; VB Therapeutics: Membership on an entity's Board of Directors or advisory committees; The RUNX1 Research Foundation: Membership on an entity's Board of Directors or advisory committees; Recludix Pharma, Inc.: Consultancy, Current holder of stock options in a privately-held company; Blueprint Medicines: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Aptose Biosciences: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Majeti:Kodikaz Therapeutic Solutions: Membership on an entity's Board of Directors or advisory committees; TenSixteen Bio: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Cullgen: Membership on an entity's Board of Directors or advisory committees; 858 Therapeutics: Membership on an entity's Board of Directors or advisory committees; Gilead: Patents & Royalties; Pheast: Current equity holder in private company; MyeloGene: Current equity holder in private company, Current holder of stock options in a privately-held company; Orbital Therapeutics: Current equity holder in private company. Tyner:Incyte: Research Funding; Acerta: Research Funding; Petra: Research Funding; Schrodinger: Research Funding; Tolero: Research Funding; Recludix Pharma: Membership on an entity's Board of Directors or advisory committees; Meryx: Research Funding; Aptose: Research Funding; Genentech: Research Funding; AstraZeneca: Research Funding; Constellation: Research Funding; Kronos: Research Funding.
