JAK/STAT pathway inhibition overcomes IL7-induced glucocorticoid resistance in a subset of human T-cell acute lymphoblastic leukemias

How I treat ETP-ALL in children

ABSTRACT

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a unique subtype of immature T-cell ALL that was initially associated with a dramatically inferior prognosis compared with non-ETP T-cell ALL (Not-ETP) when it was first described in 2009. Analyses of larger patient cohorts treated with more contemporary regimens, however, have shown minimal survival differences between ETP and Not-ETP. In this manuscript, we use representative cases to explore therapeutic advances and address common clinical questions regarding the management of children, adolescents, and young adults with ETP-ALL. We describe our recommended treatment approach for a child or adolescent with newly diagnosed ETP-ALL, with an emphasis on the prognostic significance of induction failure and detectable minimal residual disease and the role of hematopoietic stem cell transplant in first remission. We discuss the interplay between the ETP immunophenotype and genomic markers of immaturity in T-cell ALL. Finally, we review novel therapeutic approaches that should be considered when managing relapsed or refractory ETP-ALL.

Amyloid beta-induced signalling in leptomeningeal cells and its impact on astrocyte response

The pathological signature of Alzheimer's disease (AD) includes the accumulation of toxic protein aggregates, mainly consisting of amyloid beta (Aβ). Recent strides in fundamental research underscore the pivotal role of waste clearance mechanisms in the brain suggesting it may be an early indication of early onset AD. This study delves into the involvement of leptomeningeal cells (LMCs), crucial components forming integral barriers within the clearance system, in the context of AD. We examined the inflammatory cytokine responses of LMCs in the presence of Aβ, alongside assessments of LMC growth response, viability, oxidative stress, and changes in vimentin expression. The LMCs showed no changes in growth, viability, oxidative stress, or vimentin expression in the presence of Aβ, indicating that LMCs are less susceptible to Aβ damage compared to other CNS cells. However, LMCs exhibited a unique pro-inflammatory response to Aβ when compared to an LPS inflammatory control, showing an mRNA expression of pro-inflammatory cytokines such IL-6, IL-10 and IL-33 but no changes in IL-1α and IL-1β. Furthermore, LMCs influenced the astrocyte response to Aβ, as conditioned media from Aβ-treated LMCs was observed to downregulate somatic S100β in astrocytes. We also investigated whether the JAK/STAT3 pathway was involved in the Aβ response of the LMCs, as this pathway has been shown to be activated in astrocytes and neurons in the presence of Aβ. JAK/STAT3 activation was assessed through phosphorylated STAT3, revealing that JAK/STAT3 was not active in the cells when in the presence of Aβ. However, when JAK1 and JAK2 were inhibited, cytokine protein levels of IL7, IL10, IL15 and IL33 levels, which had shown alteration when LMCs were treated with Aβ, returned to base levels. This indicates that although JAK1/STAT3 and JAK2/STAT3 are not the direct pathway for Aβ response in LMCs, JAK1 and JAK2 may still play a role in regulating cytokine levels, potentially through indirect means or crosstalk. Overall, our findings reveal that LMCs are resilient to Aβ toxicity and suggest that JAK1/STAT3 and JAK2/STAT3 does not play a central role in the inflammatory response, providing new insights into the cellular mechanisms underlying AD.

Ruxolitinib plus steroids for acute graft versus host disease: a multicenter, randomized, phase 3 trial

Newly diagnosed patients with high-risk acute graft-versus-host disease (aGVHD) often experience poor clinical outcomes and low complete remission rates. Ruxolitinib with corticosteroids showed promising efficacy in improving response and failure free survival in our phase I study. This study (ClinicalTrials.gov: NCT04061876) sought to evaluate the safety and effectiveness of combining ruxolitinib (RUX, 5 mg/day) with corticosteroids (1 mg/kg/day methylprednisolone, RUX/steroids combined group) versus using methylprednisolone alone (2 mg/kg/day, steroids-only group). Newly diagnosed patients with intermediate- or high-risk aGVHD were included, with risk levels classified by either the Minnesota aGVHD Risk Score or biomarker assessment. Patients were randomized in a ratio of 1:1 into 2 groups: 99 patients received RUX combined with methylprednisolone, while the other 99 received methylprednisolone alone as the initial treatment. The RUX/steroids group showed a significantly higher overall response rate (ORR) on day 28 (92.9%) compared to the steroids-only group (70.7%, Odds Ratio [OR] = 5.8; 95% Confidence Interval [CI], 2.4-14.0; P < 0.001). Similarly, the ORR on day 56 was higher in the RUX/steroids group (85.9% vs. 46.5%; OR = 7.07; 95% CI, 3.36-15.75; P < 0.001). Additionally, the 18-month failure-free survival was significantly better in the RUX/steroids group (57.2%) compared to the steroids-only group (33.3%; Hazard Ratio = 0.46; 95% CI, 0.31-0.68; P < 0.001). Adverse events (AEs) frequencies were comparable between both groups, with the exception of fewer grade 4 AEs in the RUX/steroids group (26.3% vs. 50.5% P = 0.005). To our knowledge, this study is the first prospective, randomized controlled trial to demonstrate that adding ruxolitinib to the standard methylprednisolone regimen provides an effective and safe first-line treatment for newly diagnosed high-risk acute GVHD.

Investigation on the mechanism of androsta-4,6,8,14-tetraene-3,11,16-trione against acute lymphoblastic leukemia

Steroids are potential anti-leukemia agents, and Epigynum auritum is a Yunnan folk medicine with high levels of androsterone, pregnane, and steroid derivatives. However, the underlying therapeutic mechanism of androsta-4,6,8,14-tetraene-3,11,16-trione (ATT), an androsterone isolated from Epigynum auritum, is not yet clear. This study aimed to explore the anti-leukemia mechanism of ATT using molecular biology, network pharmacology, and molecular docking technology. The cell viability results showed that ATT had an anti-proliferation effect in acute lymphoblastic leukemia cells (CEM/C1, MOLT-4, Jurkat, BALL-1, Nalm-6, and RS4;11). Further studies showed that ATT reduced the mitochondrial membrane potential in B-cell acute lymphoblastic leukemia cell lines (BALL-1, Nalm-6, and RS4;11) and induced cell cycle arrest in MOLT-4 and BALL-1. ATT induced BALL-1 cell apoptosis by activating Caspase 3/7 activity and causing DNA fragmentation. Network pharmacology results suggested that ATT exerts its anti-leukemia activity via the PI3K/Akt signaling pathway. In addition, molecular docking analysis showed that ATT had high scores in docking with PTGS2, NR3C1, and AR. Western blotting results showed that ATT reduced the relative protein level of P-PI3K and P-Akt, thereby increasing the relative level of pro-apoptosis protein Bax and reducing the relative level of anti-apoptosis protein Bcl-2, the apoptosis downstream protein pro-caspase3, and cell proliferation-related proteins (P-GSK3B and CyclinD1). In conclusion, these results demonstrated that ATT could be a potential candidate drug with apoptosis-induction and cell cycle arrest effects for further investigation in acute lymphoblastic leukemia therapy.

Glucocorticoid Therapy in Acute Lymphoblastic Leukemia: Navigating Short-Term and Long-Term Effects and Optimal Regimen Selection

PURPOSE OF REVIEW

Glucocorticoids are a mainstay in acute lymphoblastic leukemia treatment and lack of early response is predictive for overall disease prognosis. Given the vital position of glucocorticoids and well known long and short-term side effects associated with differing glucocorticoids, we aim to highlight the wide breadth of historical and more contemporary data to describe the current landscape of glucocorticoid use in this arena.

RECENT FINDINGS

Emerging studies aim to overcome issues such as steroid resistance and to optimize the antileukemic effects of glucocorticoids while aiming to mitigate the risks and side effects associated with their exposure. Glucocorticoids have and likely always will be a fundamental component of acute lymphoblastic leukemia treatment and understanding how to navigate short- and long-term effects and how to optimize regimens is at the heart of continued treatment success.

The IL-7R antagonist lusvertikimab reduces leukemic burden in xenograft ALL via antibody-dependent cellular phagocytosis

ABSTRACT

Acute lymphoblastic leukemia (ALL) arises from the uncontrolled proliferation of B-cell precursors (BCP-ALL) or T cells (T-ALL). Current treatment protocols obtain high cure rates in children but are based on toxic polychemotherapy. Novel therapies are urgently needed, especially in relapsed/refractory (R/R) disease, high-risk (HR) leukemias and T-ALL, in which immunotherapy approaches remain scarce. Although the interleukin-7 receptor (IL-7R) plays a pivotal role in ALL development, no IL-7R-targeting immunotherapy has yet reached clinical application in ALL. The IL-7Rα chain (CD127)-targeting IgG4 antibody lusvertikimab (LUSV; formerly OSE-127) is a full antagonist of the IL-7R pathway, showing a good safety profile in healthy volunteers. Here, we show that ∼85% of ALL cases express surface CD127. We demonstrate significant in vivo efficacy of LUSV immunotherapy in a heterogeneous cohort of BCP- and T-ALL patient-derived xenografts (PDX) in minimal residual disease (MRD) and overt leukemia models, including R/R and HR leukemias. Importantly, LUSV was particularly effective when combined with polychemotherapy in a phase 2-like PDX study with CD127high samples leading to MRD-negativity in >50% of mice treated with combination therapy. Mechanistically, LUSV targeted ALL cells via a dual mode of action comprising direct IL-7R antagonistic activity and induction of macrophage-mediated antibody-dependent cellular phagocytosis (ADCP). LUSV-mediated in vitro ADCP levels significantly correlated with CD127 expression levels and the reduction of leukemia burden upon treatment of PDX animals in vivo. Altogether, through its dual mode of action and good safety profile, LUSV may represent a novel immunotherapy option for any CD127+ ALL, particularly in combination with standard-of-care polychemotherapy.

PELI2 regulates early B-cell progenitor differentiation and related leukemia via the IL-7R expression

Little is known about the transition mechanisms that govern early lymphoid lineage progenitors from common lymphoid progenitors (CLP). Pellino2 (PELI2) is a newly discovered E3 ubiquitin ligase, which plays important roles in inflammation and the immune system. However, the physiological and molecular roles of PELI2 in the differentiation of immune cells are largely unknown. Here, by using a conditional knockout mouse model, we demonstrated that PELI2 is required for early B-cell development and stressed hematopoiesis. PELI2 interacted with and stabilized PU.1 via K63-polyubiquitination to regulate IL-7R expression. The defects of B-cell development induced by PELI2 deletion were restored by overexpression of PU.1. Similarly, PELI2 promoted TCF3 protein stability via K63-polyubiquitination to regulate IL-7R expression, which is required for the proliferation of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cells. These results underscore the significance of PELI2 in both normal B lymphopoiesis and malignant B-cell acute lymphoblastic leukemia via the regulation of IL-7R expression, providing a potential therapeutic approach for BCP-ALL.

Deciphering JAK/STAT signaling pathway: A multifaceted approach to tumorigenesis, progression and therapeutic interventions

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, essential for cellular communication, orchestrates a myriad of physiological and pathological processes. Recently, the intricate association between the pathway's dysregulation and the progression of malignant tumors has garnered increasing attention. Nevertheless, there is no systematic summary detailing the anticancer effects of molecules targeting the JAK/STAT pathway in the context of tumor progression. This review offers a comprehensive overview of pharmaceutical agents targeting the JAK/STAT pathway, encompassing phytochemicals, synthetic drugs, and biomolecules. These agents can manifest their anticancer effects through various mechanisms, including inhibiting proliferation, inducing apoptosis, suppressing tumor metastasis, and angiogenesis. Notably, we emphasize the clinical challenges of drug resistance while spotlighting the potential of integrating JAK/STAT inhibitors with other therapies as a transformative approach in cancer treatment. Moreover, this review delves into the avant-garde strategy of employing nanocarriers to enhance the solubility and bioavailability of anticancer drugs, significantly amplifying their therapeutic prowess. Through this academic exploration of the multifaceted roles of the JAK/STAT pathway in the cancer milieu, we aim to sketch a visionary trajectory for future oncological interventions.

Prognostic significance of ETP phenotype and minimal residual disease in T-ALL: a Children's Oncology Group study

The early thymic precursor (ETP) immunophenotype was previously reported to confer poor outcome in T-cell acute lymphoblastic leukemia (T-ALL). Between 2009 and 2014, 1256 newly diagnosed children and young adults enrolled in Children's Oncology Group (COG) AALL0434 were assessed for ETP status and minimal residual disease (MRD) using flow cytometry at a central reference laboratory. The subject phenotypes were categorized as ETP (n = 145; 11.5%), near-ETP (n = 209; 16.7%), or non-ETP (n = 902; 71.8%). Despite higher rates of induction failure for ETP (6.2%) and near-ETP (6.2%) than non-ETP (1.2%; P < .0001), all 3 groups showed excellent 5-year event-free survival (EFS) and overall survival (OS): ETP (80.4% ± 3.9% and 86.8 ± 3.4%, respectively), near-ETP (81.1% ± 3.3% and 89.6% ± 2.6%, respectively), and non-ETP (85.3% ± 1.4% and 90.0% ± 1.2%, respectively; P = .1679 and P = .3297, respectively). There was no difference in EFS or OS for subjects with a day-29 MRD <0.01% vs 0.01% to 0.1%. However, day-29 MRD ≥0.1% was associated with inferior EFS and OS for patients with near-ETP and non-ETP, but not for those with ETP. For subjects with day-29 MRD ≥1%, end-consolidation MRD ≥0.01% was a striking predictor of inferior EFS (80.9% ± 4.1% vs 52.4% ± 8.1%, respectively; P = .0001). When considered as a single variable, subjects with all 3 T-ALL phenotypes had similar outcomes and subjects with persistent postinduction disease had inferior outcomes, regardless of their ETP phenotype. This clinical trial was registered at AALL0434 as #NCT00408005.

Developing Targeted Therapies for T Cell Acute Lymphoblastic Leukemia/Lymphoma

PURPOSE OF REVIEW

Largely, treatment advances in relapsed and/or refractory acute lymphoblastic leukemia (ALL) have been made in B cell disease leaving T cell ALL reliant upon high-intensity chemotherapy. Recent advances in the understanding of the biology of T-ALL and the improvement in immunotherapies have led to new therapeutic pathways to target and exploit. Here, we review the more promising pathways that are able to be targeted and other therapeutic possibilities for T-ALL.

RECENT FINDINGS

Preclinical models and early-phase clinical trials have shown promising results in some case in the treatment of T-ALL. Targeting many different pathways could lead to the next advancement in the treatment of relapsed and/or refractory disease. Recent advances in cellular therapies have also shown promise in this space. When reviewing the literature as a whole, targeting important pathways and antigens likely will lead to the next advancement in T-ALL survival since intensifying chemotherapy.

Development of constitutively synergistic nanoformulations to enhance chemosensitivity in T-cell leukemia

Advances in multiagent chemotherapy have led to recent improvements in survival for patients with acute lymphoblastic leukemia (ALL); however, a significant fraction do not respond to frontline chemotherapy or later relapse with recurrent disease, after which long-term survival rates remain low. To develop new, effective treatment options for these patients, we conducted a series of high-throughput combination drug screens to identify chemotherapies that synergize in a lineage-specific manner with MRX-2843, a small molecule dual MERTK and FLT3 kinase inhibitor currently in clinical testing for treatment of relapsed/refractory leukemias and solid tumors. Using experimental and computational approaches, we found that MRX-2843 synergized strongly-and in a ratio-dependent manner-with vincristine to inhibit both B-ALL and T-ALL cell line expansion. Based on these findings, we developed multiagent lipid nanoparticle formulations of these drugs that not only delivered defined drug ratios intracellularly in T-ALL, but also improved anti-leukemia activity following drug encapsulation. Synergistic and additive interactions were recapitulated in primary T-ALL patient samples treated with MRX-2843 and vincristine nanoparticle formulations, suggesting their clinical relevance. Moreover, the nanoparticle formulations reduced disease burden and prolonged survival in an orthotopic murine xenograft model of early thymic precursor T-ALL (ETP-ALL), with both agents contributing to therapeutic activity in a dose-dependent manner. In contrast, nanoparticles containing MRX-2843 alone were ineffective in this model. Thus, MRX-2843 increased the sensitivity of ETP-ALL cells to vincristine in vivo. In this context, the additive particles, containing a higher dose of MRX-2843, provided more effective disease control than the synergistic particles. In contrast, particles containing an even higher, antagonistic ratio of MRX-2843 and vincristine were less effective. Thus, both the drug dose and the ratio-dependent interaction between MRX-2843 and vincristine significantly impacted therapeutic activity in vivo. Together, these findings present a systematic approach to high-throughput combination drug screening and multiagent drug delivery that maximizes the therapeutic potential of combined MRX-2843 and vincristine in T-ALL and describe a novel translational agent that could be used to enhance therapeutic responses to vincristine in patients with T-ALL. This broadly generalizable approach could also be applied to develop other constitutively synergistic combination products for the treatment of cancer and other diseases.

Emerging Epigenetic and Posttranslational Mechanisms Controlling Resistance to Glucocorticoids in Acute Lymphoblastic Leukemia

Glucocorticoids are extensively used for the treatment of acute lymphoblastic leukemia as they pressure cancer cells to undergo apoptosis. Nevertheless, glucocorticoid partners, modifications, and mechanisms of action are hitherto poorly characterized. This hampers our understanding of therapy resistance, frequently occurring in leukemia despite the current therapeutic combinations using glucocorticoids in acute lymphoblastic leukemia. In this review, we initially cover the traditional view of glucocorticoid resistance and ways of targeting this resistance. We discuss recent progress in our understanding of chromatin and posttranslational properties of the glucocorticoid receptor that might be proven beneficial in our efforts to understand and target therapy resistance. We discuss emerging roles of pathways and proteins such as the lymphocyte-specific kinase that antagonizes glucocorticoid receptor activation and nuclear translocation. In addition, we provide an overview of ongoing therapeutic approaches that sensitize cells to glucocorticoids including small molecule inhibitors and proteolysis-targeting chimeras.

Dasatinib overcomes glucocorticoid resistance in B-cell acute lymphoblastic leukemia

Resistance to glucocorticoids (GC) is associated with an increased risk of relapse in B-cell progenitor acute lymphoblastic leukemia (BCP-ALL). Performing transcriptomic and single-cell proteomic studies in healthy B-cell progenitors, we herein identify coordination between the glucocorticoid receptor pathway with B-cell developmental pathways. Healthy pro-B cells most highly express the glucocorticoid receptor, and this developmental expression is conserved in primary BCP-ALL cells from patients at diagnosis and relapse. In-vitro and in vivo glucocorticoid treatment of primary BCP-ALL cells demonstrate that the interplay between B-cell development and the glucocorticoid pathways is crucial for GC resistance in leukemic cells. Gene set enrichment analysis in BCP-ALL cell lines surviving GC treatment show enrichment of B cell receptor signaling pathways. In addition, primary BCP-ALL cells surviving GC treatment in vitro and in vivo demonstrate a late pre-B cell phenotype with activation of PI3K/mTOR and CREB signaling. Dasatinib, a multi-kinase inhibitor, most effectively targets this active signaling in GC-resistant cells, and when combined with glucocorticoids, results in increased cell death in vitro and decreased leukemic burden and prolonged survival in an in vivo xenograft model. Targeting the active signaling through the addition of dasatinib may represent a therapeutic approach to overcome GC resistance in BCP-ALL.

Beyond Corticoresistance, A Paradoxical Corticosensitivity Induced by Corticosteroid Therapy in Pediatric Acute Lymphoblastic Leukemias

Known as a key effector in relapse of acute lymphoblastic leukemia (ALL), resistance to drug-induced apoptosis, is tightly considered one of the main prognostic factors for the disease. ALL cells are constantly developing cellular strategies to survive and resist therapeutic drugs. Glucocorticoids (GCs) are one of the most important agents used in the treatment of ALL due to their ability to induce cell death. The mechanisms of GC resistance of ALL cells are largely unknown and intense research is currently focused on this topic. Such resistance can involve different cellular and molecular mechanisms, including the modulation of signaling pathways involved in the regulation of proliferation, apoptosis, autophagy, metabolism, epigenetic modifications and tumor suppressors. Recently, several studies point to the paradoxical role of GCs in many survival processes that may lead to therapy-induced resistance in ALL cells, which we called "paradoxical corticosensitivity". In this review, we aim to summarize all findings on cell survival pathways paradoxically activated by GCs with an emphasis on previous and current knowledge on gene expression and signaling pathways.

Venetoclax-Resistant T-ALL Cells Display Distinct Cancer Stem Cell Signatures and Enrichment of Cytokine Signaling

Therapy resistance remains one of the major challenges for cancer treatment that largely limits treatment benefits and patient survival. The underlying mechanisms that lead to therapy resistance are highly complicated because of the specificity to the cancer subtype and therapy. The expression of the anti-apoptotic protein BCL2 has been shown to be deregulated in T-cell acute lymphoblastic leukemia (T-ALL), where different T-ALL cells display a differential response to the BCL2-specific inhibitor venetoclax. In this study, we observed that the expression of anti-apoptotic BCL2 family genes, such as BCL2, BCL2L1, and MCL1, is highly varied in T-ALL patients, and inhibitors targeting proteins coded by these genes display differential responses in T-ALL cell lines. Three T-ALL cell lines (ALL-SIL, MOLT-16, and LOUCY) were highly sensitive to BCL2 inhibition within a panel of cell lines tested. These cell lines displayed differential BCL2 and BCL2L1 expression. Prolonged exposure to venetoclax led to the development of resistance to it in all three sensitive cell lines. To understand how cells developed venetoclax resistance, we monitored the expression of BCL2, BCL2L1, and MCL1 over the treatment period and compared gene expression between resistant cells and parental sensitive cells. We observed a different trend of regulation in terms of BCL2 family gene expression and global gene expression profile including genes reported to be expressed in cancer stem cells. Gene set enrichment analysis (GSEA) showed enrichment of cytokine signaling in all three cell lines which was supported by the phospho-kinase array where STAT5 phosphorylation was found to be elevated in resistant cells. Collectively, our data suggest that venetoclax resistance can be mediated through the enrichment of distinct gene signatures and cytokine signaling pathways.

STAT5 does not drive steroid resistance in T-cell acute lymphoblastic leukemia despite the activation of BCL2 and BCLXL following glucocorticoid treatment

Physiological and pathogenic interleukin-7-receptor (IL7R)-induced signaling provokes glucocorticoid resistance in a subset of patients with pediatric T-cell acute lymphoblastic leukemia (T-ALL). Activation of downstream STAT5 has been suggested to cause steroid resistance through upregulation of anti-apoptotic BCL2, one of its downstream target genes. Here we demonstrate that isolated STAT5 signaling in various T-ALL cell models is insufficient to raise cellular steroid resistance despite upregulation of BCL2 and BCL-XL. Upregulation of anti-apoptotic BCL2 and BCLXL in STAT5-activated T-ALL cells requires steroid-induced activation of NR3C1. For the BCLXL locus, this is facilitated by a concerted action of NR3C1 and activated STAT5 molecules at two STAT5 regulatory sites, whereas for the BCL2 locus this is facilitated by binding of NR3C1 at a STAT5 binding motif. In contrast, STAT5 occupancy at glucocorticoid response elements does not affect the expression of NR3C1 target genes. Strong upregulation of BIM, a NR3C1 pro-apoptotic target gene, upon prednisolone treatment can counterbalance NR3C1/STAT5-induced BCL2 and BCL-XL expression downstream of IL7- induced or pathogenic IL7R signaling. This explains why isolated STAT5 activation does not directly impair the steroid response. Our study suggests that STAT5 activation only contributes to steroid resistance in combination with cellular defects or alternative signaling routes that disable the pro-apoptotic and steroid-induced BIM response.

Clinical analysis of pediatric T-cell acute lymphoblastic leukemia using the MRD-oriented strategy system

Pediatric T-cell acute lymphoblastic leukemia (T-ALL) has historically been associated with a poor prognosis. However, prognostic indicators and methods of treatment used for T-ALL remain controversial. A total of 136 children newly diagnosed with T-ALL between 2005 and 2018 were consecutively enrolled in this study. We assessed the effect of different prognostic factors, such as clinical characteristics, minimal residual disease (MRD), and the role of transplantation in postremission treatment, as the outcomes. Compared with B-ALL patients, patients with T-ALL are generally older, more likely to be male and have a higher white blood cell count. The complete remission (CR) rate was 95.6%, while the 5-year overall survival (OS), event-free survival (EFS), and cumulative incidence of relapse (CIR) were 74.3 ± 3.7%, 71.3 ± 3.9%, and 24.4 ± 3.8%, respectively. In the multivariate analysis, day 33 MRD ≥0.1% and hyperleukocytosis were associated with a significantly worse prognosis in the whole group. Transplantation resulted in a significant survival advantage, compared with chemotherapy, for high-risk (HR) patients (5-year CIR: 15.6 ± 10.2% vs. 55.6 ± 11.7%, P = .029). The prognosis of children with T-ALL was poor, and the MRD on day 33 was found to be an important predictive factor of clinical outcome at our center.

Endothelial cell-leukemia interactions remodel drug responses, uncovering T-ALL vulnerabilities

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive and often incurable disease. To uncover therapeutic vulnerabilities, we first developed T-ALL patient-derived tumor xenografts (PDXs) and exposed PDX cells to a library of 433 clinical-stage compounds in vitro. We identified 39 broadly active drugs with antileukemia activity. Because endothelial cells (ECs) can alter drug responses in T-ALL, we developed an EC/T-ALL coculture system. We found that ECs provide protumorigenic signals and mitigate drug responses in T-ALL PDXs. Whereas ECs broadly rescued several compounds in most models, for some drugs the rescue was restricted to individual PDXs, suggesting unique crosstalk interactions and/or intrinsic tumor features. Mechanistically, cocultured T-ALL cells and ECs underwent bidirectional transcriptomic changes at the single-cell level, highlighting distinct "education signatures." These changes were linked to bidirectional regulation of multiple pathways in T-ALL cells as well as in ECs. Remarkably, in vitro EC-educated T-ALL cells transcriptionally mirrored ex vivo splenic T-ALL at single-cell resolution. Last, 5 effective drugs from the 2 drug screenings were tested in vivo and shown to effectively delay tumor growth and dissemination thus prolonging overall survival. In sum, we developed a T-ALL/EC platform that elucidated leukemia-microenvironment interactions and identified effective compounds and therapeutic vulnerabilities.

T-cell acute lymphoblastic leukemia: promising experimental drugs in clinical development

INTRODUCTION

Despite advances in treatment approaches in acute lymphoblastic leukemia (ALL), the prognosis of adults with newly diagnosed T-ALL remains poor, as well as that of adults and children with relapsed disease. Novel targeted therapies are therefore needed.

AREAS COVERED

This review summarizes promising emerging strategies for the treatment of T-ALL.

EXPERT OPINION

The recent molecular characterization of T-ALL has led to the identification of new therapeutic targets. Small-molecules inhibitors and other targeted therapies have therefore been recently developed and are currently under clinical investigations. Similarly, first studies involving monoclonal antibodies and chimeric antigen receptor (CAR) T cells have shown encouraging results. Improvement of outcome with these novel approaches, eventually combined with current standard chemotherapy, is therefore expected in a near future in T-ALL.

Body mass index during maintenance therapy and relapse risk in children with acute lymphoblastic leukemia: A Children's Oncology Group report

BACKGROUND

Obesity at diagnosis of childhood acute lymphoblastic leukemia (ALL) is associated with greater risk of relapse; whether this association extends to obesity during maintenance is unstudied.

METHODS

This study used data from AALL03N1 to calculate median body mass index (BMI) for 676 children over 6 consecutive months during maintenance therapy; BMI percentile (BMI%ile) were operationalized as normal/underweight (<85%ile), overweight/obese (85%-98%ile), and extreme obesity (≥99%ile). Hazard of relapse was estimated using multivariable proportional subdistributional hazards regression after adjusting for all relevant demographic and clinical predictors.

RESULTS

Median age at study enrollment was 6 years and median length of follow-up was 7.9 years. Overall, 43.3% of the cohort was underweight/normal weight, 44.8% was overweight/obese, and 11.8% had extreme obesity. Cumulative incidence of relapse at 4 years from study enrollment was higher among those with extreme obesity (13.6% ± 4.5%) compared to those with underweight/normal weight (9.0% ± 2.1%). Multivariable analysis revealed that children with extreme obesity had a 2.4-fold (95% confidence interval [CI], 1.1-5.0; p = .01) greater hazard of relapse compared to those who were underweight/normal weight. Overweight/obese patients were at comparable risk to those who were underweight/normal weight (hazard ratio, 0.8; 95% CI, 0.4-1.6). Erythrocyte thioguanine nucleotide (TGN) levels were significantly lower among children with extreme obesity compared to those with underweight/normal weight (141.6 vs. 168.8 pmol/8 × 108 erythrocytes; p = .0002), however, the difference in TGN levels did not explain the greater hazard of relapse among those with extreme obesity.

CONCLUSIONS

Extreme obesity during maintenance therapy is associated with greater hazard of relapse in children with ALL. Underlying mechanisms of this association needs further investigation.

LAY SUMMARY

Findings from this study demonstrate that extreme obesity during maintenance therapy is associated with a greater hazard of relapse among children with acute lymphoblastic leukemia. We show that children with obesity have lower levels of erythrocyte thioguanine nucleotides even after adjusting for adherence to oral chemotherapy. However, these lower levels do not explain the greater hazard of relapse, paving the way for future studies to explore this association.

IL-7 and IL-7R in health and disease: An update through COVID times

The role of IL-7 and IL-7R for normal lymphoid development and an adequately functioning immune system has been recognized for long, with severe immune deficiency and lymphoid leukemia as extreme examples of the consequences of deregulation of the IL-7-IL-7R axis. In this review, we provide an update (focusing on the past couple of years) on IL-7 and IL-7R in health and disease. We highlight the findings on IL-7/IL-7R signaling mechanisms and the, sometimes controversial, impact of IL-7 and its receptor on leukocyte biology, COVID-19, acute lymphoblastic leukemia, and different solid tumors, as well as their relevance as therapeutic tools or targets.

Types of T-cell lymphoma-a cytogenetic perspective

T cell lymphoma, a type of non-Hodgkin lymphomas is a rare form of malignancy with poor outcomes. TCLS are a heterogeneous group of lymphoid malignancies that occur in nodal and extranodal sites. There are two main types of TCLs namely T-lymphoblastic lymphoma/leukemia and Peripheral T-cell lymphomas classified based on clinical manifestations and cytogenetic mutations. The use of advance technology like karyotyping, fluorescent in situ hybridization (FISH), comparative genomic hybridization (CGH) has allowed us to study TCLs in detail and to observe a different biochemical change that occurs in different TCLs allowing us to classify and treat them differently. This review focuses on the different mutations occurring in different TCLs and how they help us distinguish one type from another.

Targeting Leukemia-Initiating Cells and Leukemic Niches: The Next Therapy Station for T-Cell Acute Lymphoblastic Leukemia?

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive subtype of hematological malignancy characterized by its high heterogeneity and potentially life-threatening clinical features. Despite the advances in risk stratification and therapeutic management of T-ALL, patients often suffer from treatment failure and chemotherapy-induced toxicity, calling for greater efforts to improve therapeutic efficacy and safety in the treatment of T-ALL. During the past decades, increasing evidence has shown the indispensable effects of leukemia-initiating cells (LICs) and leukemic niches on T-ALL initiation and progression. These milestones greatly facilitate precision medicine by interfering with the pathways that are associated with LICs and leukemic niches or by targeting themselves directly. Most of these novel agents, either alone or in combination with conventional chemotherapy, have shown promising preclinical results, facilitating them to be further evaluated under clinical trials. In this review, we summarize the latest discoveries in LICs and leukemic niches in terms of T-ALL, with a particular highlight on the current precision medicine. The challenges and future prospects are also discussed.

Modern treatment approaches to adult acute T-lymphoblastic and myeloid/T-lymphoblastic leukemia: from current standards to precision medicine

PURPOSE OF REVIEW

To review the most recent advancements in the management of adult T-cell acute lymphoblastic leukemia (T-ALL), we summarize insights into molecular diagnostics, immunotherapy, targeted therapy and new techniques of drug sensitivity profiling that may support further therapeutic progress in T-ALL subsets.

RECENT FINDINGS

With current induction/consolidation chemotherapy and/or risk-oriented allogeneic stem cell transplantation programs up to 95% adult T-ALL patients achieve a remission and >50% (up to 80% in adolescents and young adults) are cured. The group of patients who fail upfront therapy, between 25% and 40%, is enriched in high-risk characteristics (unfavorable genetics, persistent minimal residual disease) and represents the ideal setting for the study of molecular mechanisms of disease resistance, and consequently explore novel ways of restoration of drug sensitivity and assess patient/subset-specific patterns of drug vulnerability to targeting agents, immunotherapy and cell therapy.

SUMMARY

The emerging evidence supports the contention that precision medicine may soon allow valuable therapeutic chances to adult patients with high-risk T-ALL. The ongoing challenge is to identify the best way to integrate all these new data into the therapeutic path of newly diagnosed patients, with a view to optimize the individual treatment plan and increase the cure rate.

The Role of IL-7 and IL-7R in Cancer Pathophysiology and Immunotherapy

Interleukin-7 (IL-7) is a multipotent cytokine that maintains the homeostasis of the immune system. IL-7 plays a vital role in T-cell development, proliferation, and differentiation, as well as in B cell maturation through the activation of the IL-7 receptor (IL-7R). IL-7 is closely associated with tumor development and has been used in cancer clinical research and therapy. In this review, we first summarize the roles of IL-7 and IL-7Rα and their downstream signaling pathways in immunity and cancer. Furthermore, we summarize and discuss the recent advances in the use of IL-7 and IL-7Rα as cancer immunotherapy tools and highlight their potential for therapeutic applications. This review will help in the development of cancer immunotherapy regimens based on IL-7 and IL-7Rα, and will also advance their exploitation as more effective and safe immunotherapy tools.

Oncogenetic landscape of T-cell lymphoblastic lymphomas compared to T-cell acute lymphoblastic leukemia

In the latest 2016 World Health Organization classification of hematological malignancies, T-cell lymphoblastic lymphoma (T-LBL) and lymphoblastic leukemia (T-ALL) are grouped together into one entity called T-cell lymphoblastic leukemia/lymphoma (T-LBLL). However, the question of whether these entities represent one or two diseases remains. Multiple studies on driver alterations in T-ALL have led to a better understanding of the disease while, so far, little data on genetic profiles in T-LBL is available. We sought to define recurrent genetic alterations in T-LBL and provide a comprehensive comparison with T-ALL. Targeted whole-exome next-generation sequencing of 105 genes, multiplex ligation-dependent probe amplification, and quantitative PCR allowed comprehensive genotype assessment in 818, consecutive, unselected, newly diagnosed patients (342 T-LBL vs. 476 T-ALL). The median age at diagnosis was similar in T-LBL and T-ALL (17 vs. 15 years old, respectively; p = 0.2). Although we found commonly altered signaling pathways and co-occurring mutations, we identified recurrent dissimilarities in actionable gene alterations in T-LBL as compared to T-ALL. HOX abnormalities (TLX1 and TLX3 overexpression) were more frequent in T-ALL (5% of T-LBL vs 13% of T-ALL had TLX1 overexpression; p = 0.04 and 6% of T-LBL vs 17% of T-ALL had TLX3 overexpression; p = 0.006). The PI3K signaling pathway was significantly more frequently altered in T-LBL as compared to T-ALL (33% vs 19%; p < 0.001), especially through PIK3CA alterations (9% vs 2%; p < 0.001) with PIK3CA^H1047 as the most common hotspot. Similarly, T-LBL genotypes were significantly enriched in alterations in genes coding for the EZH2 epigenetic regulator and in TP53 mutations (respectively, 13% vs 8%; p = 0.016 and 7% vs 2%; p < 0.001). This genetic landscape of T-LBLL identifies differential involvement of recurrent alterations in T-LBL as compared to T-ALL, thus contributing to better understanding and management of this rare disease.

Adaptation to Hypoxia May Promote Therapeutic Resistance to Androgen Receptor Inhibition in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) surpasses other BC subtypes as the most challenging to treat due to its lack of traditional BC biomarkers. Nearly 30% of TNBC patients express the androgen receptor (AR), and the blockade of androgen production and AR signaling have been the cornerstones of therapies for AR-positive TNBC. However, the majority of women are resistant to AR-targeted therapy, which is a major impediment to improving outcomes for the AR-positive TNBC subpopulation. The hypoxia signaling cascade is frequently activated in the tumor microenvironment in response to low oxygen levels; activation of the hypoxia signaling cascade allows tumors to survive despite hypoxia-mediated interference with cellular metabolism. The activation of hypoxia signaling networks in TNBC promotes resistance to most anticancer drugs including AR inhibitors. The activation of hypoxia network signaling occurs more frequently in TNBC compared to other BC subtypes. Herein, we examine the (1) interplay between hypoxia signaling networks and AR and (2) whether hypoxia and hypoxic stress adaptive pathways promote the emergence of resistance to therapies that target AR. We also pose the well-supported question, “Can the efficacy of androgen-/AR-targeted treatments be enhanced by co-targeting hypoxia?” By critically examining the evidence and the complex entwinement of these two oncogenic pathways, we argue that the simultaneous targeting of androgen biosynthesis/AR signaling and hypoxia may enhance the sensitivity of AR-positive TNBCs to AR-targeted treatments, derail the emergence of therapy resistance, and improve patient outcomes.

Ruxolitinib-corticosteroid as first-line therapy for newly diagnosed high-risk acute graft versus host disease: study protocol for a multicenter, randomized, phase II controlled trial

BACKGROUND

The response rate of the first-line therapy with corticosteroid for acute graft versus host disease (aGVHD) is about 50%, and steroid-refractory disease is associated with high mortality. The improved response rate to the first-line therapy of newly diagnosed aGVHD patients would result in therapeutic benefits. Ruxolitinib, a selective Janus kinase (JAK) 1/2 inhibitor, has been approved for the treatment of steroid-refractory acute GVHD. The addition of ruxolitinib to the first-line therapy may improve the efficacy of corticosteroids.

METHODS

This investigator-initiated, open-label, multicenter, prospective randomized, and controlled two-arm phase II study compares the efficacy and safety of ruxolitinib combined with 1 mg/kg methylprednisolone versus 2 mg/kg methylprednisolone alone in newly diagnosed aGVHD patients. Patients with intermediate or high-risk aGVHD, as defined by the Minnesota aGVHD high-risk score and biomarker algorithm, are eligible for this study. A total of 198 patients will be randomized at a 1:1 ratio and assigned a GVHD risk (intermediate versus high risk) and disease status before transplantation (complete remission versus no complete remission). The primary endpoint is the overall response rate on day 28, which is defined as an improvement of at least one stage in the severity of aGVHD in one organ without deterioration in any other organ or disappearance of any GVHD signs from all organs without requiring new systemic immunosuppressive treatment. The secondary objectives consist of response time, response duration, overall survival, disease-free survival, non-relapse mortality, failure-free survival, and changes in serum levels of proinflammatory cytokines and GVHD-related biomarkers.

DISCUSSION

This open-label, multicenter, two-arm randomized trial will evaluate whether the addition of ruxolitinib combined with corticosteroid is superior to corticosteroid alone in newly diagnosed high-risk aGVHD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04061876 (version number: 2019.5.18). Registered on July 16, 2019.

JAK3 mutations and mitochondrial apoptosis resistance in T-cell acute lymphoblastic leukemia

Resistance to mitochondrial apoptosis predicts inferior treatment outcomes in patients with diverse tumor types, including T-cell acute lymphoblastic leukemia (T-ALL). However, the genetic basis for variability in this mitochondrial apoptotic phenotype is poorly understood, preventing its rational therapeutic targeting. Using BH3 profiling and exon sequencing analysis of childhood T-ALL clinical specimens, we found that mitochondrial apoptosis resistance was most strongly associated with activating mutations of JAK3. Mutant JAK3 directly repressed apoptosis in leukemia cells, because its inhibition with mechanistically distinct pharmacologic inhibitors resulted in reversal of mitochondrial apoptotic blockade. Inhibition of JAK3 led to loss of MEK, ERK and BCL2 phosphorylation, and BH3 profiling revealed that JAK3-mutant primary T-ALL patient samples were characterized by a dependence on BCL2. Treatment of JAK3-mutant T-ALL cells with the JAK3 inhibitor tofacitinib in combination with a spectrum of conventional chemotherapeutics revealed synergy with glucocorticoids, in vitro and in vivo. These findings thus provide key insights into the molecular genetics of mitochondrial apoptosis resistance in childhood T-ALL, and a compelling rationale for a clinical trial of JAK3 inhibitors in combination with glucocorticoids for patients with JAK3-mutant T-ALL.

MEF2C opposes Notch in lymphoid lineage decision and drives leukemia in the thymus

Rearrangements that drive ectopic MEF2C expression have recurrently been found in patients with human early thymocyte progenitor acute lymphoblastic leukemia (ETP-ALL). Here, we show high levels of MEF2C expression in patients with ETP-ALL. Using both in vivo and in vitro models of ETP-ALL, we demonstrate that elevated MEF2C expression blocks NOTCH-induced T cell differentiation while promoting a B-lineage program. MEF2C activates a B cell transcriptional program in addition to RUNX1, GATA3, and LMO2; upregulates the IL-7R; and boosts cell survival by upregulation of BCL2. MEF2C and the Notch pathway, therefore, demarcate opposite regulators of B- or T-lineage choices, respectively. Enforced MEF2C expression in mouse or human progenitor cells effectively blocks early T cell differentiation and promotes the development of biphenotypic lymphoid tumors that coexpress CD3 and CD19, resembling human mixed phenotype acute leukemia. Salt-inducible kinase (SIK) inhibitors impair MEF2C activity and alleviate the T cell developmental block. Importantly, this sensitizes cells to prednisolone treatment. Therefore, SIK-inhibiting compounds such as dasatinib are potentially valuable additions to standard chemotherapy for human ETP-ALL.

Overcoming Steroid Resistance in Pediatric Acute Lymphoblastic Leukemia-The State-of-the-Art Knowledge and Future Prospects

Acute lymphoblastic leukemia (ALL) is the most common malignancy among children. Despite the enormous progress in ALL therapy, resulting in achieving a 5-year survival rate of up to 90%, the ambitious goal of reaching a 100% survival rate is still being pursued. A typical ALL treatment includes three phases: remission induction and consolidation and maintenance, preceded by a prednisone prephase. Poor prednisone response (PPR) is defined as the presence of ≥1.0 × 10⁹ blasts/L in the peripheral blood on day eight of therapy and results in significantly frequent relapses and worse outcomes. Hence, identifying risk factors of steroid resistance and finding methods of overcoming that resistance may significantly improve patients' outcomes. A mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK-ERK) pathway seems to be a particularly attractive target, as its activation leads to steroid resistance via a phosphorylating Bcl-2-interacting mediator of cell death (BIM), which is crucial in the steroid-induced cell death. Several mutations causing activation of MAPK-ERK were discovered, notably the interleukin-7 receptor (IL-7R) pathway mutations in T-cell ALL and rat sarcoma virus (Ras) pathway mutations in precursor B-cell ALL. MAPK-ERK pathway inhibitors were demonstrated to enhance the results of dexamethasone therapy in preclinical ALL studies. This report summarizes steroids' mechanism of action, resistance to treatment, and prospects of steroids therapy in pediatric ALL.

DT7 peptide-modified lecithin nanoparticles co-loaded with γ-secretase inhibitor and dexamethasone efficiently inhibit T-cell acute lymphoblastic leukemia and reduce gastrointestinal toxicity

T-cell acute lymphoblastic leukemia (T-ALL) is a serious hematologic malignancy and glucocorticoid resistance is the main recurrent cause for a high relapsed and death rate. Here, we proposed an effective therapeutic regimen of combining gamma-secretase inhibitors (GSIs) with dexamethasone (DEX) to overcome glucocorticoid resistance. Moreover, the bone marrow targeting DT7 peptide-modified lecithin nanoparticles co-loaded with DEX and GSI (TLnp/D&G) were developed to enhance T-ALL cells recognition and endocytosis. In vitro cytotoxicity studies showed that TLnp/D&G significantly inhibited cell survival and promoted apoptosis of T-ALL cells. Mechanically, we found that GSIs promoted DEX-induced cell apoptosis by two main synergetic mechanisms: 1) GSIs significantly upregulated glucocorticoid receptor (GR) expression in T-ALL and restored the glucocorticoid-induced pro-apoptotic response. 2) Both DEX and GSI synergistically inhibited BCL2 and suppressed the survival of T-ALL cells. Furthermore, in vivo studies demonstrated that TLnp/D&G showed high bone marrow accumulation and better antileukemic efficacy both in leukemia bearing models and in systemic Notch1-induced T-ALL models, with excellent biosafety and reduced gastrointestinal toxicity. Overall, our study provides new strategies for the treatment of T-ALL and promising bone marrow targeting systems with high transformation potential.

CASPorter: A Novel Inducible Human CASP1/NALP3/ASC Inflammasome Biosensor

Background

Following our 2015 elucidation of the CASP1/NALP3 inflammasome mechanism of glucocorticoid (GC)-resistance in pediatric acute lymphoblastic leukemia (ALL) patients, we engineered a cell-based CASP1/NALP3 reporter system suitable for high-throughput screening (HTS) of small molecule libraries, with the purpose of identifying compounds capable of inhibiting the CASP1/NALP3 inflammasome and synergizing with GC drugs for the treatment of GC-resistant ALL patients and various autoinflammatory diseases.

Methods

A Dox-controlled system was utilized to induce the expression of the ASC transgene in HEK293 cells while simultaneously overexpressing NLRP3 and CASP1. ASC/CASP1/NALP3 inflammasome complex formation was confirmed by co-immunoprecipitation (co-IP) experiments. Next, a LV fluorescence-based biosensor (CASPorter) was transduced in the HEK293-iASC-NLRP3/CASP1 cell line to monitor the real-time activation of CASP1/NALP3 inflammasome in live cells. The applicability and effectiveness of the CASPorter cell line were tested by co-treatment with Dox and four known CASP1/NLRP3 inhibitors (MCC950, Glyburide, VX-765 and VRT-043198). Inflammasome activation and inhibitions were assessed by Western blotting, fluorescence microscopy and flow cytometry (FC) methods.

Results

Dox treatment significantly induced ASC expression and increased levels of cleaved and catalytically active CASP1, co-IPs further demonstrated that CASP1 was pulled-down with NLRP3 in HEK293-iASC-NLRP3/CASP1 cells after induction of ASC by Dox treatment. In HEK293-iASC-NLRP3/CASP1-CASPorter cell system, cleavage of the CASP1 consensus site (YVAD) in the CASPorter protein after Dox treatment causing excitation/emission of green fluorescence and the 71% GFP+ cell population increase quantified by FC (78.1% vs 6.90%). Dox-induced activation of the NLRP3 inflammasome was dose-dependently inhibited by Dox co-treatment with four known CASP1/NLRP3 inhibitors.

Conclusion

We have established a cell-based CASP1/NLRP3 inflammasome model, utilizing a fluorescence biosensor as readout for qualitatively observing and quantitatively determining the activation of caspase 1 and NLRP3 inflammasomes in living cells and easily define the inhibitory effect of inhibitors with high efficacy.

Gene Mutations Related to Glucocorticoid Resistance in Pediatric Acute Lymphoblastic Leukemia

OBJECTIVE

To investigate the correlation between gene mutations and glucocorticoid resistance in pediatric acute lymphoblastic leukemia (ALL).

METHODS

A total of 71 children with ALL admitted to our center between September 2019 and September 2021 were enrolled. DNA obtained from bone marrow or peripheral blood samples at initial diagnosis was used for genetic testing via whole exome sequencing. Meanwhile, patient clinical information was collected. Subsequently, the correlations of gene mutations with clinical features and glucocorticoid resistance were analyzed.

RESULTS

Of the 71 children enrolled, 61 (85.9%) had B-cell ALL (B-ALL) and 10 (14.1%) had T-cell ALL (T-ALL). The five genes with the highest mutation frequency in B-ALL were TTN (24.4%), FLT3 (14.6%), TP53 (14.6%), MUC16 (9.8%), and EPPK1 (9.8%). In contrast, those with the highest frequency in T-ALL were NOTCH1 (54.5%), FBXW7 (27.3%), TTN (27.3%), MUC16 (27.3%), and PHF6 (18.2%). Upon statistical analysis, TTN and NOTCH1 mutations were found to be associated with prednisone resistance. Further, TTN and MUC16 mutations were associated with a lower age at diagnosis, and NOTCH1 mutations were associated with T-ALL in female patients. Leukocyte counts and LDH levels did not differ based on the presence of any common gene mutation, and no association between these gene mutations and overall survival was observed.

CONCLUSIONS

Our study is the first to demonstrate the association between TTN mutation and glucocorticoid resistance in ALL. Our findings could guide strategies for overcoming drug resistance and aid in the development of drug targets.

MAPK-ERK is a central pathway in T-cell acute lymphoblastic leukemia that drives steroid resistance

(Patho-)physiological activation of the IL7-receptor (IL7R) signaling contributes to steroid resistance in pediatric T-cell acute lymphoblastic leukemia (T-ALL). Here, we show that activating IL7R pathway mutations and physiological IL7R signaling activate MAPK-ERK signaling, which provokes steroid resistance by phosphorylation of BIM. By mass spectrometry, we demonstrate that phosphorylated BIM is impaired in binding to BCL2, BCLXL and MCL1, shifting the apoptotic balance toward survival. Treatment with MEK inhibitors abolishes this inactivating phosphorylation of BIM and restores its interaction with anti-apoptotic BCL2-protein family members. Importantly, the MEK inhibitor selumetinib synergizes with steroids in both IL7-dependent and IL7-independent steroid resistant pediatric T-ALL PDX samples. Despite the anti-MAPK-ERK activity of ruxolitinib in IL7-induced signaling and JAK1 mutant cells, ruxolitinib only synergizes with steroid treatment in IL7-dependent steroid resistant PDX samples but not in IL7-independent steroid resistant PDX samples. Our study highlights the central role for MAPK-ERK signaling in steroid resistance in T-ALL patients, and demonstrates the broader application of MEK inhibitors over ruxolitinib to resensitize steroid-resistant T-ALL cells. These findings strongly support the enrollment of T-ALL patients in the current phase I/II SeluDex trial (NCT03705507) and contributes to the optimization and stratification of newly designed T-ALL treatment regimens.

Early T-Cell Precursor Acute Lymphoblastic Leukemia: Diagnosis, Updates in Molecular Pathogenesis, Management, and Novel Therapies

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a distinct subtype of T lymphoblastic leukemia (T-ALL) identified in 2009, due to its unique immunophenotypic and genomic profile. The outcome of patients was poor in earlier studies, and they were prone to have induction failure, with more frequent relapse/refractory disease. Recent advances had been made in discoveries of genetic aberrations and molecular pathogenesis of ETP-ALL. However, the diagnosis and management of ETP-ALL is still challenging. There are limited choices of novel therapies so far. In this review article, it highlighted the diagnostic issue of ETP-ALL, pitfall in diagnosis, and strategy of accurate diagnosis. The review also summarized current understanding of molecular mechanism of leukemogenesis. The emerging role of risk-adapted therapy and allogenic stem cell transplant in optimizing the outcome of patients with ETP-ALL was discussed. Finally, some potential novel therapies were proposed based on the current understanding of molecular pathogenesis.

Elevated REG3α predicts refractory aGVHD in patients who received steroids-ruxolitinib as first-line therapy

We started a single-arm, phase II, open-label, prospective clinical trial using steroids-ruxolitinib as the first-line therapy for intermediate- to high-risk aGVHD (NCT04397367). Here, we report the association of a biomarker panel (sST2, REG3α, sTNFR1, IL-6 and IL-8) with responses to GVHD therapy. The novel first-line therapy for 39 patients with newly diagnosed aGVHD consisted of 1 mg/kg methylprednisolone and 5 mg/day ruxolitinib. The serum concentrations of the biomarkers were prospectively detected at planned time points. Of the 39 patients, the complete response rate at day 28 was 82.05%. In patients who achieved CR, the concentrations of REG3α (P₁₄ = 0.01; P₂₈ = 0.10) and sTNFR1 (P₁₄ = 0.42; P₂₈ = 0.04) declined at day 14 and day 28 compared with the pre-enrolment levels. In refractory patients, the levels of REG3α at day 14 were higher than those pre-enrolment (P = 0.04). REG3α (P = 0.02) was elevated in the refractory patients compared with the patients achieving CR at day 14 after enrolment, while there was no significant difference in the levels of sST2, sTNFR1 or IL-6. Elevated REG3α levels may predict refractory aGVHD after novel first-line therapy with steroids-ruxolitinib.

LncRNA PPM1A-AS Regulate Tumor Development Through Multiple Signal Pathways in T-Cell Acute Lymphoblastic Leukemia

ALL (Acute lymphoblastic leukemia) is the most common pediatric malignancy and T-ALL (T-cell acute lymphoblastic leukemia) comprises about 15% cases. Compared with B-ALL (B-cell acute lymphoblastic leukemia), the prognosis of T-ALL is poorer, the chemotherapy is easier to fail and the relapse rate is higher. Previous studies mainly focused in Notch1-related long non-coding RNAs (lncRNAs) in T-ALL. Here, we intend to investigate lncRNAs involved in T-ALL covering different subtypes. The lncRNA PPM1A-AS was screened out for its significant up-regulation in 10 T-ALL samples of different subtypes than healthy human thymus extracts. Besides, the PPM1A-AS expression levels in 3 T-ALL cell lines are markedly higher than that in CD45⁺ T cells of healthy human. We further demonstrate that PPM1A-AS can promote cell proliferation and inhibit cell apoptosis in vitro and can influence T-ALL growth in vivo. Finally, we verified that PPM1A-AS can regulate core proteins, Notch4, STAT3 and Akt, of 3 important signaling pathways related to T-ALL. These results confirm that lncRNA PPM1A-AS can act as an oncogene in T-ALL and maybe a potential clinical target of patients resistant to current chemotherapy or relapsed cases.

Effect of hypoxia on proliferation and glucocorticoid resistance of T-cell acute lymphoblastic leukaemia

OBJECTIVE

Hypoxia is emerging as a key factor in the biology of leukaemia. Here, we want to clarify the impact of hypoxia on the proliferation of T-cell acute lymphoblastic leukaemia (T-ALL) cells and the response to chemotherapy.

METHODS

T-ALL cells were cultured under normoxic and hypoxic conditions. MTT assay and trypan blue staining technique was used to detect cell viability and proliferation. In vitro sensitivity to glucocorticoid was assessed by IC50. CDI was used to analyze the combined effects of glucocorticoid and hypoxia. Flow cytometry was performed to detect apoptosis and cell cycle. Western blotting was performed to detect the protein expression associated with hypoxia.

RESULTS

Hypoxia of 1% O₂ resulted different impact on cell viability and proliferation to different T-ALL cell lines, reduced, unaffected or induced, according to their different metabolic phenotype. All the cell lines showed an induction of key enzymes in glycolysis pathway following hypoxia exposure, although different effector proteins were induced in different cell lines. In GC-sensitive cells, acute hypoxia made no effect on the IC50 of dexamethasone, but chronic hypoxia may improve cell survival and induce GC resistance. However, acute hypoxia induced a higher GC resistance in GC-resistant T-ALL cells and showed an antagonistic effect while combined with high-dose dexamethasone.

CONCLUSION

T-ALL cells adapt well to hypoxic environment. Hypoxia may influence leukaemic cell proliferation. More importantly, hypoxia contributes to GC resistance in T-ALL blasts, especially in refractory/relapsed T-ALL.

Overexpression of wild-type IL-7Rα promotes T-cell acute lymphoblastic leukemia/lymphoma

Tight regulation of IL-7Rα expression is essential for normal T-cell development. IL-7Rα gain-of-function mutations are known drivers of T-cell acute lymphoblastic leukemia (T-ALL). Although a subset of patients with T-ALL display high IL7R messenger RNA levels and cases with IL7R gains have been reported, the impact of IL-7Rα overexpression, rather than mutational activation, during leukemogenesis remains unclear. In this study, overexpressed IL-7Rα in tetracycline-inducible Il7r transgenic and Rosa26 IL7R knockin mice drove potential thymocyte self-renewal, and thymus hyperplasia related to increased proliferation of T-cell precursors, which subsequently infiltrated lymph nodes, spleen, and bone marrow, ultimately leading to fatal leukemia. The tumors mimicked key features of human T-ALL, including heterogeneity in immunophenotype and genetic subtype between cases, frequent hyperactivation of the PI3K/Akt pathway paralleled by downregulation of p27Kip1 and upregulation of Bcl-2, and gene expression signatures evidencing activation of JAK/STAT, PI3K/Akt/mTOR and Notch signaling. Notably, we also found that established tumors may no longer require high levels of IL-7R expression upon secondary transplantation and progressed in the absence of IL-7, but remain sensitive to inhibitors of IL-7R-mediated signaling ruxolitinib (Jak1), AZD1208 (Pim), dactolisib (PI3K/mTOR), palbociclib (Cdk4/6), and venetoclax (Bcl-2). The relevance of these findings for human disease are highlighted by the fact that samples from patients with T-ALL with high wild-type IL7R expression display a transcriptional signature resembling that of IL-7-stimulated pro-T cells and, critically, of IL7R-mutant cases of T-ALL. Overall, our study demonstrates that high expression of IL-7Rα can promote T-cell tumorigenesis, even in the absence of IL-7Rα mutational activation.

T-Cell Acute Lymphoblastic Leukemia: Biomarkers and Their Clinical Usefulness

T-cell acute lymphoblastic leukemias (T-ALL) are immature lymphoid tumors localizing in the bone marrow, mediastinum, central nervous system, and lymphoid organs. They account for 10-15% of pediatric and about 25% of adult acute lymphoblastic leukemia (ALL) cases. It is a widely heterogeneous disease that is caused by the co-occurrence of multiple genetic abnormalities, which are acquired over time, and once accumulated, lead to full-blown leukemia. Recurrently affected genes deregulate pivotal cell processes, such as cycling (CDKN1B, RB1, TP53), signaling transduction (RAS pathway, IL7R/JAK/STAT, PI3K/AKT), epigenetics (PRC2 members, PHF6), and protein translation (RPL10, CNOT3). A remarkable role is played by NOTCH1 and CDKN2A, as they are altered in more than half of the cases. The activation of the NOTCH1 signaling affects thymocyte specification and development, while CDKN2A haploinsufficiency/inactivation, promotes cell cycle progression. Among recurrently involved oncogenes, a major role is exerted by T-cell-specific transcription factors, whose deregulated expression interferes with normal thymocyte development and causes a stage-specific differentiation arrest. Hence, TAL and/or LMO deregulation is typical of T-ALL with a mature phenotype (sCD3 positive) that of TLX1, NKX2-1, or TLX3, of cortical T-ALL (CD1a positive); HOXA and MEF2C are instead over-expressed in subsets of Early T-cell Precursor (ETP; immature phenotype) and early T-ALL. Among immature T-ALL, genomic alterations, that cause BCL11B transcriptional deregulation, identify a specific genetic subgroup. Although comprehensive cytogenetic and molecular studies have shed light on the genetic background of T-ALL, biomarkers are not currently adopted in the diagnostic workup of T-ALL, and only a limited number of studies have assessed their clinical implications. In this review, we will focus on recurrent T-ALL abnormalities that define specific leukemogenic pathways and on oncogenes/oncosuppressors that can serve as diagnostic biomarkers. Moreover, we will discuss how the complex genomic profile of T-ALL can be used to address and test innovative/targeted therapeutic options.

Current and emerging therapeutic approaches for T-cell acute lymphoblastic leukaemia

T-cell ALL (T-ALL) is an aggressive malignancy of T-cell progenitors. Although survival outcomes in T-ALL have greatly improved over the past 50 years, relapsed and refractory cases remain extremely challenging to treat and those who cannot tolerate intensive treatment continue to have poor outcomes. Furthermore, T-ALL has proven a more challenging immunotherapeutic target than B-ALL. In this review we explore our expanding knowledge of the basic biology of T-ALL and how this is paving the way for repurposing established treatments and the development of novel therapeutic approaches.

Selective drug combination vulnerabilities in STAT3- and TP53-mutant malignant NK cells

Mature natural killer (NK) cell neoplasms are rare but very aggressive types of cancers. With currently available treatments, they have a very poor prognosis and, as such, are an example of group of cancers in which the development of effective precision therapies is needed. Using both short- and long-term drug sensitivity testing, we explored novel ways to target NK-cell neoplasms by combining the clinically approved JAK inhibitor ruxolitinib with other targeted agents. We profiled 7 malignant NK-cell lines in drug sensitivity screens and identified that these exhibit differential drug sensitivities based on their genetic background. In short-term assays, various classes of drugs combined with ruxolitinib seemed highly potent. Strikingly, resistance to most of these combinations emerged rapidly when explored in long-term assays. However, 4 combinations were identified that selectively eradicated the cancer cells and did not allow for development of resistance: ruxolitinib combined with the mouse double-minute 2 homolog (MDM2) inhibitor idasanutlin in STAT3-mutant, TP53 wild-type cell lines; ruxolitinib combined with the farnesyltransferase inhibitor tipifarnib in TP53-mutant cell lines; and ruxolitinib combined with either the glucocorticoid dexamethasone or the myeloid cell leukemia-1 (MCL-1) inhibitor S63845 but both without a clear link to underlying genetic features. In conclusion, using a new drug sensitivity screening approach, we identified drug combinations that selectively target mature NK-cell neoplasms and do not allow for development of resistance, some of which can be applied in a genetically stratified manner.

T-cell lymphoblastic lymphoma and leukemia: different diseases from a common premalignant progenitor?

T-cell lymphoblastic lymphoma (T-LBL) and lymphoblastic leukemia (T-ALL) represent malignancies that arise from the transformation of immature precursor T cells. Similarities in T-LBL and T-ALL have raised the question whether these entities represent 1 disease or reflect 2 different diseases. The genetic profiles of T-ALL have been thoroughly investigated over the last 2 decades, whereas fairly little is known about genetic driver mutations in T-LBL. Nevertheless, the comparison of clinical, immunophenotypic, and molecular observations from independent T-LBL and T-ALL studies lent strength to the theory that T-LBL and T-ALL reflect different presentations of the same disease. Alternatively, T-LBL and T-ALL may simultaneously evolve from a common malignant precursor cell, each having their own specific pathogenic requirements or cellular dependencies that differ among stroma-embedded blasts in lymphoid tissues compared with solitary leukemia cells. This review aims to cluster recent findings with regard to clinical presentation, genetic predisposition, and the acquisition of additional mutations that may give rise to differences in gene expression signatures among T-LBL and T-ALL patients. Improved insight in T-LBL in relation to T-ALL may further help to apply confirmed T-ALL therapies to T-LBL patients.