Acute lymphoblastic leukemia (ALL) results from a clonal expansion of abnormal lymphoid progenitors of B cell (BCP-ALL) or T cell (T-ALL) origin that invade bone marrow, peripheral blood, and extramedullary sites. Leukemic cells, apart from their oncogene-driven ability to proliferate and avoid differentiation, also change the phenotype and function of innate and adaptive immune cells, leading to escape from the immune surveillance. In this review, we provide an overview of the genetic heterogeneity and treatment of BCP- and T-ALL. We outline the interactions of leukemic cells in the bone marrow microenvironment, mainly with mesenchymal stem cells and immune cells. We describe the mechanisms by which ALL cells escape from immune recognition and elimination by the immune system. We focus on the alterations in ALL cells, such as overexpression of ligands for various inhibitory receptors, including anti-phagocytic receptors on macrophages, NK cell inhibitory receptors, as well as T cell immune checkpoints. In addition, we describe how developing leukemia shapes the bone marrow microenvironment and alters the function of immune cells. Finally, we emphasize that an immunosuppressive microenvironment can reduce the efficacy of chemo- and immunotherapy and provide examples of preclinical studies showing strategies for improving ALL treatment by targeting these immunosuppressive interactions.
B-cell malignancies are a heterogeneous group of hematological neoplasms derived from cells at different stages of B-cell development. Recent studies revealed that dysregulated redox metabolism is one of the factors contributing to the pathogenesis and progression of B-cell malignancies. Elevated levels of oxidative stress markers usually correlate with the advanced stage of various B-cell malignancies. In the complex tumor microenvironment, reactive oxygen species affect not only malignant cells but also bystander cells, including immune cells. Importantly, malignant cells, due to genetic dysregulation, are able to adapt to the increased demands for energy and reducing equivalents via metabolic reprogramming and upregulation of antioxidants. The immune cells, however, are more sensitive to oxidative imbalance. This may cause their dysfunction, leading to immune evasion and tumor progression. On the other hand, the already imbalanced redox homeostasis renders malignant B-cells particularly sensitive to further elevation of reactive oxygen species. Indeed, targeting antioxidant systems has already presented anti-leukemic efficacy in preclinical models. Moreover, the prooxidant treatment that triggers immunogenic cell death has been utilized to generate autologous anti-leukemic vaccines. In this article, we review novel research on the dual role of the reactive oxygen species in B-cell malignancies. We highlight the mechanisms of maintaining redox homeostasis by malignant B-cells along with the antioxidant shield provided by the microenvironment. We summarize current findings regarding therapeutic targeting of redox metabolism in B-cell malignancies. We also discuss how the oxidative stress affects antitumor immune response and how excessive reactive oxygens species influence anticancer prooxidant treatments and immunotherapies.
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.
B-cell acute lymphoblastic leukemia (B-ALL) is a malignancy caused by accumulation of immature B cells. Advances in the field, especially in genomic studies and new treatment development, significantly improved the prognosis of B-ALL over the last decades. However, the B-ALL subtype harboring Philadelphia chromosome t(9;22)(q34;q11) (Ph+ B-ALL) still remains a therapeutic challenge despite available targeted treatment with tyrosine kinase inhibitors (TKIs). The novel therapeutic regimens for adult B-ALL often include rituximab (RTX) - a monoclonal anti-CD20 antibody - for patients with >20% CD20+ blasts. Moreover, drug combinations including approved TKIs and antibodies are being tested in clinical trials. Since some TKIs display immune effector cell inhibition, investigating their immunomodulatory effects in the context of combined chemo-immunotherapies is clinically relevant for the rational combination design. We found that blasts isolated from Ph+ B-ALL patients showed the highest CD20 expression on mRNA level among defined B-ALL genetic subtypes. As Ph+ CD20+ patients may be qualified for treatment with TKIs along with RTX, this result prompted the need of investigating the effects of TKIs on immune effectors. We therefore compared how first-, second- and third-generation TKIs (imatinib, dasatinib, nilotinib, bosutinib, ponatinib) and allosteric inhibitor asciminib recently approved for the treatment of chronic myeloid leukemia (CML) affect innate and antibody-mediated cytotoxicity. B-ALL cell lines, patient-derived lymphoblasts propagated in NSG mice (primografts) and ex vivo whole blood assays were used for testing the efficacy of effector cell-mediated mechanisms in the presence of TKIs. The TKIs were compared in NK-cell based natural cytotoxicity tests, antibody-dependent cytotoxicity (ADCC) tests and phagocytosis assays with monocyte-derived macrophages. Dasatinib was also tested using whole blood ex vivo ADCC assays before and after administration of the TKI. Out of six tested TKIs, asciminib presented the most favorable profile, causing slight or no effector cell inhibition in both innate and antibody-mediated responses. In contrast, dasatinib significantly decreased the immune cells activity in all tests, reducing natural and RTX-mediated cytotoxicity of NK cells against B-ALL blasts. Dasatinib and ponatinib significantly inhibited in vitro phagocytosis of primograft B-ALL cells. To a lesser extent, cytotoxicity and phagocytosis were suppressed by imatinib, bosutinib and nilotinib. Importantly, we confirmed that the orally administered dasatinib impairs the NK cell activity in patients’ blood. Our findings indicate that the TKIs differentially impact RTX-mediated effector mechanisms. The novel, allosteric TKI asciminib could be preferentially used in combination with RTX-based immunotherapy. This work was supported by the Polish National Science Centre grant 2019/35/B/NZ5/01428 and by the Ministry of Education and Science within “Regional Initiative of Excellence” program 013/RID/2018/19." Citation Format: Krzysztof Domka, Martyna Poprzeczko, Zuzanna Urbanska, Lukasz Komorowski, Agata Pastorczak, Klaudyna Fidyt, Agnieszka Dabkowska, Mieszko Lachota, Magdalena Winiarska, Karolina Siudakowska, Elzbieta Patkowska, Łukasz Sędek, Bartosz Perkowski, Beata Krzymieniewska, Malgorzata Firczuk. Optimizing the therapeutic potential of tyrosine kinase inhibitors in chemo-immunotherapy of B-cell acute lymphoblastic leukemia involving rituximab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3324.
Background: Venetoclax (VEN), a specific BCL2 inhibitor, exerts anti-leukemic effects in various high-risk (HR) B-ALL subtypes, such as ALL with mixed lineage leukemia (MLL) gene rearrangements (MLLr ALL) (PMID: 26711339), Philadelphia chromosome-positive (Ph+) (PMID 30546081) or hypodiploid B-ALL (PMID 30862722). Nevertheless, despite high rationale for targeting BCL2 in these subtypes of B-ALL, VEN monotherapy is not effective enough to completely eliminate leukemic cells. For this reason identification of other drugs that could sensitize leukemic cells to VEN may become beneficial treatment strategy in HR ALL. Previously, we showed that the enzymes of the thioredoxin system are upregulated in primary B-ALL cells and that auranofin (AUR), a thioredoxin reductase inhibitor, effectively kills leukemic cells in vitro and in vivo. Importantly, elements of the thioredoxin system are not only balancing redox homeostasis within the cells, but may also interact with other pathways, including anti-apoptotic signaling. Considering above, we hypothesized that AUR may potentiate VEN efficacy in HR B-ALL. Methods: To evaluate cytostatic/cytotoxic effects of VEN+AUR combination by MTT assay and propidium iodide (PI)-staining we used HR B-ALL cell lines, including SEM (MLLr ALL), BV-173 (Ph+ ALL) and NALM-16 (hypodiploid ALL). Patient derived xenograft cells (PDX) were generated through long-term propagation of primary B-ALL samples in immune-deficient NSG mice. Ex vivo drug testing in co-culture system was performed using primary bone marrow-derived mesenchymal stem cells (BM-MSC) and murine stromal OP9 cell line. NOXA genomic knockout (KO) in SEM cells was established by CRISPR/Cas9 system. Chromatin accessibility within PMAIP1 gene (encodes for NOXA) was detected using ATAC-seq. Results: We observed that AUR sensitizes HR B-ALL cell lines to VEN, as determined by MTT and PI-staining. Further, we mimicked the bone marrow support of stromal cells towards B-ALL and evaluated its impact on the response to VEN+AUR. For this reason we employed an ex vivo co-culture system of B-ALL PDX cells with primary BM-MSC or an OP9 cell line. In all tested PDX samples representing diagnostic/relapsed MLLr ALL (n=8), Ph+ ALL (n=2) and Ph-like ALL (n=2) we observed synergistic effect of this combination (Fig. 1A). Next, we determined the efficacy of VEN+AUR combination in vivo using a PDX model of MLLr B-ALL. We observed that administration of VEN+AUR diminished the progression of leukemia during a 3 week-long treatment more effectively than any single drug alone, which reflected in longer survival of NSG mice (Fig. 1B). Subsequently, we aimed to uncover the mechanism responsible for the synergistic action of VEN+AUR. In cells treated with both drugs we observed enhanced caspase activation and changes in the levels of BCL2 family proteins involved in apoptotic signaling. In particular, we found that AUR strongly upregulates a pro-apoptotic NOXA protein, both in HR B-ALL cell lines and in MLLr ALL PDX samples (Fig. 1C). To evaluate whether NOXA induction is functionally relevant for the cell death mediated by VEN+AUR, we generated SEM cells with a NOXA genomic KO. Lack of NOXA significantly abolished VEN-single agent as well as VEN+AUR combination cytotoxicity, demonstrating its dependence on NOXA expression (Fig. 1D). We then showed that NOXA is regulated at the transcriptional level, as co-treatment with AUR and the transcription inhibitor, actinomycin D, abolished AUR-mediated NOXA induction at mRNA and protein levels in SEM cells. Additionally, to test whether AUR-treatment itself provokes changes in chromatin accessibility within the NOXA encoding gene (PMAIP1) we performed ATAC-seq. We observed a clear increase in accessibility at PMAIP1 in response to AUR, which correlated with transcriptional induction of NOXA. Moreover, ChIP-qPCR revealed that increased ATAC peaks within PMAIP1 were associated with an increase in H3 lysine 27 acetylation (H3K27ac) - an epigenetic mark associated with open chromatin conformation. Conclusions: Our results demonstrate that FDA-approved drug, AUR, is a promising candidate to be used in combination with VEN for the therapy of HR B-ALL subtypes. Importantly, NOXA induction by AUR plays a central role in the VEN+AUR synergistic cytotoxicity. More studies elucidating the mechanism of NOXA upregulation by AUR are underway. Disclosures Milne: OxStem Oncology (OSO), a subsidiary company of OxStem Ltd.: Other: Founding shareholder .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.