Hematology covers a broad spectrum of indications with very heterogeneous disease patterns. Accordingly, intensive research is being carried out to provide patients with effective treatment. Rarer diseases are examined just as closely as more common effects. The goal is the same for all research focuses: long-term survival with a good quality of life.
Acute myeloid leukemia (AML) is a clonal disease of hematopoietic stem and progenitor cells (HSPC) that leads to an expansion of undifferentiated progenitor cells. The development and progression of the disease is driven by leukemia stem cells (LSCs). Similar to HSPCs, LSCs interact in the bone marrow (BM) microenvironment with different cell types, including BM stromal cells, endothelial cells and also immune cells. However, LSCs efficiently evade elimination by the immune system by expressing immune inhibitory molecules or downregulating important immunological recognition pathways. It has recently been documented that CD8+ T cells infiltrating the bone marrow in AML patients have suppressed gene expression and impaired function. Although CD4+ T cells play a key role in regulating the adaptive immune system, their functional role and associated signaling in leukemia patients is poorly understood. The aim of one study was to characterize BM-infiltrating CD4+ T cells and to investigate their interaction with LSCs and CD8+ T cells [1]. The transcriptome of precisely defined populations of LSCs/HSCs and progenitor cells as well as matching immune cells (CD8+ or CD4+ T-cell lymphocytes) from the BM of 30 newly diagnosed AML patients (different risk categories) and seven controls was analyzed. Subsequently, numerous tens of thousands of predictive networks were modeled using unbiased correlation analysis to identify potential links between genes expressed in the leukemia stem/progenitor fraction and corresponding immune cells in all AML risk groups and controls. The discovered immune-dependent dysregulated signaling pathways in CD4+ T cells and their possible connections with the other cell groups investigated were functionally verified.
In contrast to the CD8+ T cells that infiltrate the peritoneal cavity and show a suppressed gene expression pattern, transcriptomic analysis of peritoneal infiltrating CD4+ T cells in AML revealed activation of immune-related pathways with a skew towards TH1 polarization and a lack of TH9 immunophenotype. Unbiased comprehensive correlation network modeling was performed to investigate potential interactions of CD4+ T cells with primed AML LSCs, progenitors and CD8+ T cells in the BM. Within all mapped networks, a node was defined as a gene expressed in one of the cell populations studied, and a node (highly correlated) was a gene in a cell that significantly correlated with more than 15 different genes in the other cell type. The IL9 gene has been identified as a potential hub in AML LSCs that regulates CD4+ T cells infiltrating the bone marrow. Functional validations showed that IL-9 produced by AML LSCs can epigenetically activate CD4+ T cells in the bone marrow. IL-9R signaling in CD4+ T cells activated JAK/STAT signaling and increased histone methylation. CD4+ T cells activated by IL-9 produced various cytokines such as tumor necrosis factor (TNF)-α and interferon (IFN)-gamma. IFN-gamma secreted by activated CD4+ T cells significantly increased the colony forming ability of AML-LSCs. Blocking JAK/STAT signaling or silencing key regulatory genes for histone methylation (lysine methyltransferase 2A, KMT2A & lysine methyltransferase 2E, KMT2E) decreased activation/proliferation of CD4+ T cells and decreased production of TNF-α and IFN-gamma. According to the researchers, the results indicate that AML-LSCs activate the CD4+ T lymphocytes infiltrating the bone marrow by releasing IL-9. IL9R signaling in CD4+ T cells leads to JAK/STAT signaling and increased histone methylation, resulting in effector cell differentiation and production of IFN-gamma, which in turn enlarges LSCs and contributes to disease progression.
TKI therapy in older patients with Ph+ ALL
Outcomes in younger patients with Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL) were improved by tyrosine kinase inhibitors (TKIs) with pediatric therapy and stem cell transplantation (SCT). In older patients, the choice of TKI, the need for chemotherapy and antibody therapies is still under discussion. New data from Phase II studies are now available [2]. The German Multicenter Center Study Group for Adult ALL (GMALL ) aimed to establish and evaluate standard therapies for older patients with Ph+ ALL (>55 years).
GMALL has conducted a study followed by a registry study based on standard recommendations with prospective documentation in the GMALL registry. The strategies have been modified over the years. The basic framework included: pre-phase (Dexa, Cyclo), induction I (Dexa, VCR, Idarubicine), induction II (Cyclo, ARAC), consolidation cycles (C) with HDMTX (± E.coli ASP), HDAraC (formerly: VM26), re-induction (VCR, Idarubicine, Cyclo, AraC), ± rituximab in CD20+, i.th. Prophylaxis and maintenance (6-MP/MTX). Induction was replaced by imatinib (Ima) only (group 1), Ima was added to standard induction (group 2) or combined with VCR/Dexa only (group 3). In addition, MRD-based modification of TKIs was recommended in group 3 for all patients with MRD>10-4 after C II.
305 patients from 105 institutions were included between 2007 and 2022. The CR rate by indication was 87% with 6% early death (ED) and 7% failure or partial remission. CR rates were 88%, 87% and 81% in patients aged 56-65, 66-75 and ≥76 years with ED rates of 4%, 5% and 19%, respectively. Group 2 comprised only 15 patients and was not included in the comparison. With a median follow-up time of 1.6 years, overall survival (OS) in the overall cohort after 1, 3 and 5 years was 72%, 45% and 34% respectively. 34% or with a median OS of 2.6 years. In 259 CR patients, the duration of remission was 76%, 40% and 27% after 1, 3 and 5 years respectively. The OS correlated strongly with age and was very poor in patients over 75 years of age. Overall, only 29% of all CR patients received an allogeneic SCT in CR1. SCT patients showed a 3/5-year OS of 67%/55%. The OS after SCT compared to no SCT was significantly better for SCT (68% vs. 44%). With this age-adjusted regimen, which included a low-chemo indication with Ima followed by pediatric C treatment, an adequate CR rate was achieved up to the age of 75 years.
DNA damage reaction in AML
Myeloid malignancies, including myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML), are characterized by the accumulation of genetic alterations. Failure of DNA damage response (DDR) mechanisms may be one of the underlying mechanisms for the development and progression of these diseases. Therefore, the investigation of changes in the gene expression profile of DNA damage response genes is of particular importance. The aim of one study was therefore to investigate possible changes in the gene expression profile of DNA damage response genes in patients with de novo AML and MDS as a mechanism of resistance to genotoxic stress and resistance to genotoxic stress and possible treatment resistance [3].
The cell lines Kasumi-1 with t(8;21) and MV4-11 (biphenotypic B-myelomonocytic leukemia) were treated either with idarubicin (0.1μΜ ) for six hours or with cytarabine (1μΜ ) for 48 hours. Dead cells were removed from the drug-treated cells using an appropriate commercial kit. Gene expression profiling by PCR array analysis was performed in triplicate after RNA extraction from untreated, chemotherapy-treated and live cells after chemotherapy exposure. Gene expression associated with the human DNA damage signaling pathway was assessed and analyzed using the RT2 Profiler PCR Array data analysis tool. In addition, mononuclear cells were isolated from bone marrow of lymphoma patients serving as controls, de novo AML patients and low-risk MDS patients. Total RNA was isolated and quantified, and cDNA was synthesized.
The following genes were upregulated more than twofold in living cells of leukemic cell lines after treatment with both drugs: PPP1R15A, CDKN1A and GADD45G genes in both live cell lines, GADD45A in live MV4-11 cells and EXO1 in live Kasumi cells. CDKN1A and GADD45A were downregulated in MDS patients compared to controls and AML. GADD45G was downregulated in AML patients compared to controls and MDS. PPP1R15A was upregulated in AML compared to controls, while it was downregulated in MDS. A sub-analysis of the expression of all five genes in AML, in which responders to induction chemotherapy were compared with non-responders, revealed a tendency towards higher PPP1R15A expression in non-responders compared with responders.
The results indicate a dysregulation of DNA damage and repair pathways in AML and MDS. It is known that upregulation of GADD45G in response to DNA damage triggers apoptosis, differentiation and growth arrest and increases the sensitivity of AML cells to chemotherapeutic agents. Its downregulation in AML may be related to chemoresistance. CDKN1A and GADD45A induce apoptosis via the p53/TP53 and p38-JNK pathways, respectively. Their downregulation in MDS may represent a compensatory mechanism for the increased apoptosis that characterizes low-risk MDS. PPP1R15A preserves the transcription factor eIF-2A/EIF2S1 in its active state, thereby promoting protein synthesis and facilitating cell recovery from stress. The upregulation of PPP1R15A in AML, which is more pronounced in non-responders to induction chemotherapy, could be a mechanism of resistance, while the downregulation of PPP1R15A in MDS is consistent with increased apoptosis.
MCL prognosis factors
Mantle cell lymphoma (MCL) is a subtype of non-Hodgkin’s lymphoma with a very heterogeneous clinical course. Paired-box 5 (PAX5), the regulator of B-cell differentiation and growth, is abnormally expressed in various types of cancer. However, the clear link between PAX5 changes and the prognosis of MCL patients still needs to be investigated further. The aim of a study is to investigate the role of PAX5 expression in MCL patients and to establish a novel risk scoring system for clinical risk assessment in MCL [4]. The clinical characteristics and laboratory data of 82 MCL patients were analyzed in detail. It was shown that in MCL patients, PAX5 positivity was associated with shorter overall survival (OS) and could therefore be identified as an independent prognostic factor. Survival analysis of other clinical characteristics showed that a high risk score, a Mantle Cell Lymphoma International Prognostic Index (MIPI), a high ECOG score (≥2), splenomegaly and a high β 2-MG score (≥2.65 mg/L) were correlated with poorer OS. In addition, the elevated β 2-MG and advanced MIPI score were associated with positive PAX5 expression. In MCL patients with positive PAX5 expression, β 2-MG (≥2.65 mg/L), splenomegaly, Ki67 positive rate (≥30%) and LDH (≥202 U/L) were correlated with poorer OS. The novel risk scoring system called MIPI-SP was introduced and showed a better prognostic value for OS with an area under the ROC curve (AUC) of 0.770 than the MIPI score with an AUC of 0.698.
Congress: 28th Annual Congress of the European Hematology Association (EHA) 2023
Literature:
- Radpour R, Riether C, Ochsenbein A: IL-9 secreted by leukemia stem cells indurces the epigenetic activation of BM-infiltrating CD4+ T-Cells in acute myeloid leukemia. HemaSphere 2023; 7(S3): 59-60.
- Lang F, Pfeifer H, Raffel S et al. Outcome of older patients (>55 yrs) with newly diagnosed PH/BCR:ABL positive ALL prospectively treated according to pediatric-based, age-adapted gmall protocolls. HemaSphere 2023; 7(S3): 34-35.
- Bouchla A, Delikonstantinou G, Loupis T, et al: Differential gene expression profile in DNA damage signaling pathways, in de novo acute myeloid leukemia and low-risk MDS patients. HemaSphere 2023; 7(S3): 3418-3419.
- Zhang X, Han, Y, Nie Y, et al: PAX5 aberrant expression incorporated in MIPI-SP risk scoring system exhibits additive value in mantle cell lymphoma. HemaSphere 2023; 7(S3): 4324-4325.
InFo ONKOLOGIE & HÄMATOLOGIE 2023; 11(5): 26-27 (published on 2.11.23, ahead of print)
