Management of patients with acute promyelocytic leukemia

Research progress on gene mutations and drug resistance in leukemia

Leukemia is a type of blood cancer characterized by the uncontrolled growth of abnormal cells in the bone marrow, which replace normal blood cells and disrupt normal blood cell function. Timely and personalized interventions are crucial for disease management and improving survival rates. However, many patients experience relapse following conventional chemotherapy, and increasing treatment intensity often fails to improve outcomes due to mutated gene-induced drug resistance in leukemia cells. This article analyzes the association of gene mutations and drug resistance in leukemia. It explores genetic abnormalities in leukemia, highlighting recently identified mutations affecting signaling pathways, cell apoptosis, epigenetic regulation, histone modification, and splicing mechanisms. Additionally, the article discusses therapeutic strategies such as molecular targeting of gene mutations, alternative pathway targeting, and immunotherapy in leukemia. These approaches aim to combat specific drug-resistant mutations, providing potential avenues to mitigate leukemia relapse. Future research with these strategies holds promise for advancing leukemia treatment and addressing the challenges of drug-resistant mutations to improve patient outcomes.

The clinical characteristics and implications of acute kidney injury during induction therapy for acute promyelocytic leukemia

Background

Dual induction with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has made acute promyelocytic leukemia (APL) a curable disease. However, differentiation syndrome (DS) can be a life-threatening complication of induction therapy. It is considered to result from a severe systemic inflammatory response mediated by increased expression of cytokines, chemokines, and adhesion molecules on differentiating blast cells. The kidney, as a vital organ rich in the capillary endothelium, could be targeted by differentiating blasts in DS. Acute kidney injury (AKI) is a rare but severe consequence of DS secondary to ATRA and ATO induction and can result in renal failure and early mortality. Nevertheless, its clinical characteristics and impact on APL prognosis have yet to be elucidated.

Objectives

The aim of this study was to describe the clinical characteristics of DS-related AKI in patients with APL and its impact on patient prognosis.

Methods

This was a retrospective study from a single center in a real-world setting. APL patients who developed AKI during ATRA- and ATO-based induction were included. The patients' clinical/laboratory data and outcome information were retrieved from the electronic medical records.

Results

From January 2011 to March 2024, a total of 26 out of 572 (4.5%) APL patients were identified as having AKI during dual induction. Among them, eight patients received continuous renal replacement therapy, and 3/8 patients experienced early death (ED), which was defined as death within 3 months of diagnosis. Among the five non-ED patients, three did not recover from renal function and were still dialysis-dependent during the follow-up. The estimated 2-year overall survival rate for all patients was 42%, and the ED rate was 30.8%. Survival analysis revealed that a greater tumor burden, a rapidly increasing WBC count, worse coagulation parameters, and persistent renal dysfunction were associated with a more adverse prognosis.

Conclusion

AKI is a rare but severe complication of DS in the ATRA + ATO dual-induction era of APL. It is associated with a high ED rate and dismal long-term survival. Some patients develop irreversible renal dysfunction and become dialysis-dependent after leukemia remission. Thus, the management of AKI in APL patients is still a clinical challenge, and a deeper understanding of its pathogenesis, along with multidisciplinary efforts, is needed.

Diagnosis and typing of leukemia using a single peripheral blood cell through deep learning

Leukemia is highly heterogeneous, meaning that different types of leukemia require different treatments and have different prognoses. Current clinical diagnostic and typing tests are complex and time-consuming. In particular, all of these tests rely on bone marrow aspiration, which is invasive and leads to poor patient compliance, exacerbating treatment delays. Morphological analysis of peripheral blood cells (PBC) is still primarily used to distinguish between benign and malignant hematologic disorders, but it remains a challenge to diagnose and type these diseases solely by direct observation of peripheral blood(PB) smears by human experts. In this study, we apply a segmentation-based enhanced residual network that uses progressive multigranularity training with jigsaw patches. It is trained on a self-built annotated dataset of 21,208 images from 237 patients, including five types of benign white blood cells(WBCs) and eight types of leukemic cells. The network is not only able to discriminate between benign and malignant cells, but also to typify leukemia using a single peripheral blood cell. The network effectively differentiated acute promyelocytic leukemia (APL) from other types of acute myeloid leukemia (non-APL), achieving a precision rate of 89.34%, a recall rate of 97.37%, and an F1 score of 93.18% for APL. In contrast, for non-APL cases, the model achieved a precision rate of 92.86%, but a recall rate of 74.63% and an F1 score of 82.75%. In addition, the model discriminates acute lymphoblastic leukemia(ALL) with the Ph chromosome from those without. This approach could improve patient compliance and enable faster and more accurate typing of leukemias for early diagnosis and treatment to improve survival.

Induction treatments with and without addition of one dose anthracycline to all-trans retinoid acid and arsenic in pediatric non-high-risk acute promyelocytic leukemia: study protocol for a randomized controlled trial

BACKGROUND

The treatment of all-trans retinoic acid (ATRA) and arsenical agent has revolutionarily improved the prognosis of acute promyelocytic leukemia (APL) both in adults and children. Nevertheless, coagulation disorder and differentiation syndrome (DS) are the main causes of early death in APL patients. Early chemotherapy to reduce leukocytes during induction is an important measure to reduce complications and mortality. However, the incidence of hyperleukocytosis (WBC > 10 × 109/L) was significantly higher in pediatric patients without chemotherapy than in adults. Although ATRA plus arsenic is the standard therapy for non-high-risk adult patients, it remains controversial whether chemotherapy is necessary for induction therapy in pediatric APL.

METHODS

This study was designed as a multicenter randomized controlled trial. Children with APL were randomly assigned into experimental group (ATRA-RIF plus chemotherapy) and control group (ATRA-RIF). The experimental group was treated with ATRA-RIF plus chemotherapy for induction, while the control group was treated with ATRA-RIF alone. In addition, both groups received the same regimen of ATRA-RIF plus chemotherapy for consolidation and maintenance.

DISCUSSION

This trial aims to compare the efficacy of ATRA-RIF plus chemotherapy versus ATRA-RIF in pediatric non-high-risk patients with APL to demonstrate that chemotherapy during induction therapy can reduce the incidence of complications such as hyperleukocytosis and DS, thereby reducing mortality.

TRIAL REGISTRATION

Chinese Clinical Trials Registry, ID: ChiCTR2000038877. Registered on October 8, 2020, https://www.chictr.org.cn/showproj.html?proj=60733 . V1.0 date 08/01/2020.

Risk factors and remaining challenges in the treatment of acute promyelocytic leukemia

The treatment of acute promyelocytic leukemia (APL) has evolved with the introduction of all-trans retinoic acid (ATRA) and subsequent arsenic trioxide (ATO), particularly in standard-risk APL with an initial white blood cell count (WBC) < 10,000/μL, where a high cure rate can now be achieved. However, for some patients with risk factors, early death or relapse remains a concern. Insights from the analysis of patients treated with ATRA and chemotherapy have identified risk factors such as WBC, surface antigens, complex karyotypes, FLT3 and other genetic mutations, p73 isoforms, variant rearrangements, and drug resistance mutations. However, in the ATRA + ATO era, the significance of these risk factors is changing. This article provides a comprehensive review of APL risk factors, taking into account the treatment approach, and explores the challenges associated with APL treatments.

Leucocytosis during all-trans retinoic acid and arsenic trioxide treatment in acute promyelocytic leukaemia

In patients with acute promyelocytic leukaemia (APL), differentiation syndrome (DS) is a life-threatening complication caused by the differentiating effect of all-trans retinoic acid (ATRA) and/or arsenic trioxide (ATO). Leucocytosis is frequently observed during induction therapy for APL and is intimately associated with the development of DS and its severity. The management of DS is particularly important due to the high likelihood of excellent outcomes for APL patients who successfully complete induction therapy. Commentary on: Cicconi et al. Leukocytosis during induction therapy with all-trans-retinoic acid and arsenic trioxide in acute promyelocytic leukemia predicts for differentiation syndrome and treatment-related complications. Br J Haematol 2024; 205:1727-1733.

Pregnancy and neonatal outcomes in 25 pregnant women diagnosed with new-onset acute myeloid leukemia during pregnancy

PURPOSE

The aim was to analyze the pregnancy and neonatal outcomes of pregnant women with new- onset acute myeloid leukemia (AML) diagnosed during pregnancy.

METHODS

In this retrospective study 25 pregnant women who were diagnosed with new-onset AML during pregnancy from January 2010 to January 2021 were enrolled.

RESULTS

A total of 4, 13 and 8 pregnant women with new-onset AML were diagnosed during the first, second, and third trimesters, respectively. Twelve of the 25 pregnant women underwent therapeutic abortion and 13 gave birth (9 preterm and 4 full-term newborns). The gestational age at initial clinical manifestations (13.4 ± 3.7 vs. 27.7 ± 5.6 weeks, P < 0.01) and diagnosis (16.9 ± 4.4 vs. 29.7 ± 5.5 weeks, P < 0.01) was lower in the pregnant women who underwent therapeutic abortion than in those who gave birth. Eighty-four percent (21/25) of the pregnant women with new-onset AML during pregnancy survived and were in remission and all the newborns were born alive. Three of the 13 newborns were exposed to chemotherapy, but no congenital malformations were observed. Eight newborns were admitted to the neonatal intensive care unit (NICU), and all recovered. The complete blood counts and biochemical examinations of the 8 newborns were normal.

CONCLUSIONS

New-onset AML during an earlier stage of pregnancy may increase the risk of poor pregnancy outcomes. The neonatal outcomes of pregnant women with new-onset AML during pregnancy are good with proper treatment.

In Vivo Chemical Screening in Zebrafish Embryos Identified FDA-Approved Drugs That Induce Differentiation of Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is characterized by the abnormal proliferation and differentiation arrest of myeloid progenitor cells. The clinical treatment of AML remains challenging. Promoting AML cell differentiation is a valid strategy, but effective differentiation drugs are lacking for most types of AML. In this study, we generated Tg(drl:hoxa9) zebrafish, in which hoxa9 overexpression was driven in hematopoietic cells and myeloid differentiation arrest was exhibited. Using Tg(drl:hoxa9) embryos, we performed chemical screening and identified four FDA-approved drugs, ethacrynic acid, khellin, oxcarbazepine, and alendronate, that efficiently restored myeloid differentiation. The four drugs also induced AML cell differentiation, with ethacrynic acid being the most effective. By an RNA-seq analysis, we found that during differentiation, ethacrynic acid activated the IL-17 and MAPK signaling pathways, which are known to promote granulopoiesis. Furthermore, we found that ethacrynic acid enhanced all-trans retinoic acid (ATRA)-induced differentiation, and both types of signaling converged on the IL-17/MAPK pathways. Inhibiting the IL-17/MAPK pathways impaired ethacrynic acid and ATRA-induced differentiation. In addition, we showed that ethacrynic acid is less toxic to embryogenesis and less disruptive to normal hematopoiesis than ATRA. Thus, the combination of ethacrynic acid and ATRA may have broader clinical applications. In conclusion, through zebrafish-aided screening, our study identified four drugs that can be repurposed to induce AML differentiation, thus providing new agents for AML therapy.

Role of reactive oxygen species in myelodysplastic syndromes

Reactive oxygen species (ROS) serve as typical metabolic byproducts of aerobic life and play a pivotal role in redox reactions and signal transduction pathways. Contingent upon their concentration, ROS production not only initiates or stimulates tumorigenesis but also causes oxidative stress (OS) and triggers cellular apoptosis. Mounting literature supports the view that ROS are closely interwoven with the pathogenesis of a cluster of diseases, particularly those involving cell proliferation and differentiation, such as myelodysplastic syndromes (MDS) and chronic/acute myeloid leukemia (CML/AML). OS caused by excessive ROS at physiological levels is likely to affect the functions of hematopoietic stem cells, such as cell growth and self-renewal, which may contribute to defective hematopoiesis. We review herein the eminent role of ROS in the hematological niche and their profound influence on the progress of MDS. We also highlight that targeting ROS is a practical and reliable tactic for MDS therapy.

Natural products as potential drug treatments for acute promyelocytic leukemia

Acute promyelocytic leukemia (APL), which was once considered one of the deadliest types of leukemia, has become a curable malignancy since the introduction of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) as clinical treatments. ATO, which has become the first-line therapeutic agent for APL, is derived from the natural mineral product arsenic, exemplifying an important role of natural products in the treatment of APL. Many other natural products, ranging from small-molecule compounds to herbal extracts, have also demonstrated great potential for the treatment and adjuvant therapy of APL. In this review, we summarize the natural products and representative components that have demonstrated biological activity for the treatment of APL. We also discuss future directions in better exploring their medicinal value, which may provide a reference for subsequent new drug development and combination therapy programs.

Identification of a novel fusion gene, RARA::ANKRD34C, in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a specific subtype of acute myeloid leukemia that is distinguished by the chromosomal translocation t(15;17)(q24;q21), which leads to the fusion of the promyelocytic leukemia (PML) gene with the retinoic acid receptor alpha (RARA). Recently, we identified a novel fusion gene in APL, RARA::ankyrin repeat domain 34C (ANKRD34C), identified its functions by morphological, cytogenetic, molecular biological and multiplex fluorescence in situ hybridization analyses, and demonstrated the potential therapeutic effect clinically and experimentally of all-trans retinoic acid (ATRA); the findings have important implications for the diagnosis and treatment of atypical APL.

Gaillardin exerts potent antileukemic effects on HL-60 cells and intensifies arsenic trioxide cytotoxicity: Providing new insight into sesquiterpene lactones in leukaemia treatment

The use of all-trans retinoic acid and arsenic trioxide resulted in favourable therapeutic responses in standard-risk acute promyelocytic leukaemia (APL) patients. However, resistance to these agents has made treating the high-risk subgroup more problematic, and possible side effects limit their clinical dosages. Numerous studies have proven the cytotoxic properties of Gaillardin, one of the Inula oculus-christi-derived sesquiterpene lactones. Due to the adverse effects of arsenic trioxide on the high-risk subgroup of APL patients, we aimed to assess the cytotoxic effect of Gaillardin on HL-60 cells as a single or combined-form approach. The results of the trypan blue and MTT assays outlined the potent cytotoxic properties of Gaillardin. The flow cytometric analysis and the mRNA expression levels revealed that Gaillardin attenuated the proliferative capacity of HL-60 cells through cell cycle arrest and induced apoptosis via reactive oxygen species generation. Moreover, the results of synergistic experiments indicated that this sesquiterpene lactone sensitizes HL-60 cells to the cytotoxic effects of arsenic trioxide. Taken together, the findings of the present investigation highlighted the antileukemic characteristics of Gaillardin by inducing G1 cell cycle arrest and triggering apoptosis. Gaillardin acts as an antileukemic metabolite against HL-60 cells and this study provides new insight into treating APL patients, especially in the high-risk subgroup.

Retinoic Acid Action in Cumulus Cells: Implications for Oocyte Development and In Vitro Fertilization

In the field of human in vitro fertilization (IVF), selecting the best oocyte for freezing or embryo for transfer remains an important focus of clinical practice. Although several techniques are and have been used for this goal, results have generally not been favorable and/or are invasive such that damage to some embryos occurs, resulting in a reduced number of healthy births. Therefore, the search continues for non-invasive oocyte and embryo quality markers that signal the development of high-quality embryos. Multiple studies indicate the important positive effects of retinoic acid (RA) on oocyte maturation and function. We previously showed that a high follicular fluid (FF) RA concentration at the time of oocyte retrieval in IVF protocols was associated with oocytes, giving rise to the highest quality embryos, and that cumulus granulosa cells (CGCs) are the primary source of follicle RA synthesis. Data also demonstrated that connexin-43 (Cx43), the main connexin that forms gap junctions in CGCs, is regulated by RA and that RA induces a rapid increase in gap junction communication. Here, we hypothesize that CGC RA plays a causal role in oocyte competency through its action on Cx43 and, as such, may serve as a biomarker of oocyte competence. Multiple studies have demonstrated the requirement for Cx43 in CGCs for the normal progression of folliculogenesis, and that the increased expression of this connexin is linked to the improved developmental competence of the oocyte. The data have shown that RA can up-regulate gap junction intercellular communication (GJIC) in the cumulus-oocyte complex via a non-genomic mechanism that results in the dephosphorylation of Cx43 and enhanced GJIC. Recognizing the positive role played by gap junctions in CGCs in oocyte development and the regulation of Cx43 by RA, the findings have highlighted the possibility that CGC RA levels may serve as a non-invasive indicator for selecting high-quality oocytes for IVF procedures. In addition, the data suggest that the manipulation of Cx43 with retinoid compounds could provide new pharmacological approaches to improve IVF outcomes in cases of failed implantation, recurrent miscarriage, or in certain diseases that are characterized by reduced fecundity, such as endometriosis.

Exploring the potential of histone demethylase inhibition in multi-therapeutic approaches for cancer treatment

Histone demethylases play a critical role in gene transcription regulation and have been implicated in cancer. Numerous reports have highlighted the overexpression of histone demethylases, such as LSD1 and JmjC, in various malignant tumor tissues, identifying them as effective therapeutic targets for cancer treatment. Despite many histone demethylase inhibitors entering clinical trials, their clinical efficacy has been limited. Therefore, combination therapies based on histone demethylase inhibitors, along with other modulators like dual-acting inhibitors, have gained significant attention and made notable progress in recent years. In this review, we provide an overview of recent advances in drug discovery targeting histone demethylases, focusing specifically on drug combination therapy and histone demethylases-targeting dual inhibitors. We discuss the rational design, pharmacodynamics, pharmacokinetics, and clinical status of these approaches. Additionally, we summarize the co-crystal structures of LSD1 inhibitors and their target proteins as well as describe the corresponding binding interactions. Finally, we also provided the challenges and future directions for utilizing histone demethylases in cancer therapy, such as PROTACs and molecular glue etc.

Targeting DHODH reveals therapeutic opportunities in ATRA-resistant acute promyelocytic leukemia

Although all-trans retinoic acid (ATRA)-induced differentiation has transformed acute promyelocytic leukemia (APL) from the most fatal to the most curable hematological disease, resistance to ATRA in high-risk APL patients remains a clinical challenge. In this paper, we discovered that dihydroorotate dehydrogenase (DHODH) inhibition overcame ATRA resistance. 416, a potent DHODH inhibitor previously obtained in our group, inhibited the occurrence of APL in cells and model mice. Excitingly, 416 effectively overcame ATRA resistance in vitro and in vivo by inducing apoptosis and differentiation. Further mechanistic studies showed that PML/RARα lost the regulation of Bcl-2 and c-Myc in NB4-R1 cells, which probably contributed to ATRA resistance. Notably, 416 maintained its Bcl-2 and c-Myc down-regulation effect in NB4-R1 cells and overcome ATRA resistance by inhibiting DHODH. In conclusion, our study highlights the potential of 416 for APL therapy and overcoming ATRA resistance, supporting the further development of DHODH inhibitors for clinical use in refractory and relapsed APL.

A giant thrombus in the right atrium of a patient with acute promyelocytic leukemia M3

Acute promyelocytic leukemia is a special type of acute myeloid leukemia. Patients with this disease are at high risk of complications. Right atrial thrombosis is a rare but potentially serious complication. A 55-month-old girl with acute promyelocytic leukemia M3 was in her last phase of treatment. Radiologic examination revealed an echo structure in the right atrium that was still present after 6 weeks of anticoagulation treatment with enoxaparin. Cardiac surgery was performed to remove the mass, which was found to be a calcified thrombus. Although this is a rare occurrence, recognition of the possibility of a calcified thrombus may minimize misdiagnosis and allow surgical retrieval if the thrombus is sufficiently large.

Successful Management of Acute Promyelocytic Leukemia in a Patient Who Presented With Acute Ischemic Stroke on Top of Subdural Hematoma

Acute promyelocytic leukemia (APL), a distinct subtype of acute myelogenous leukemia (AML), is commonly associated with a heightened risk of bleeding due to coagulopathy. Thrombotic events, although less frequent, have also been linked to APL. However, the occurrence of ischemic stroke as an initial presentation of APL, particularly concomitant with central nervous system (CNS) bleeding, is exceedingly rare. The combination of these two complications is not reported in APL patients and is anticipated to carry a high mortality rate even with treatment. In this report, we describe the case of a young female patient with no significant medical history, who presented with decreased consciousness and recurrent seizures. Brain magnetic resonance imaging (MRI) revealed the simultaneous occurrence of acute ischemic stroke and acute-on-chronic subdural hematoma. The subsequent bone marrow biopsy confirmed the diagnosis of APL, displaying the characteristic positive promyelocytic leukemia (PML)-retinoic acid receptor alpha (RARA) t(15;17) translocation. The patient was promptly initiated on a high-risk AML-M3 protocol, coupled with supportive treatment through platelet transfusion. Remarkably, a favorable response to treatment was observed, and a marked improvement in her neurological parameters was observed within 2 weeks duration of treatment. Subsequent assessment through a bone marrow biopsy one month later revealed complete remission, with the PML-RARA fusion gene becoming negative following a single course of consolidation therapy.

Additional cytogenetic abnormalities in patients with newly diagnosed acute promyelocytic leukemia predict inferior event-free survival

BACKGROUND

The innovative combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has established a new chapter of curative approach in acute promyelocytic leukemia (APL). The disease characteristics and prognostic influence of additional cytogenetic abnormalities (ACA) in APL with modern therapeutic strategy need to be elucidated.

METHODS

In the present study, we retrospectively investigated disease features and prognostic power of ACA in 171 APL patients treated with ATRA-ATO-containing regimens.

RESULTS

Patients with ACA had markedly decreased hemoglobin levels than that without ACA (p = 0.021). Risk stratification in the ACA group was significantly worse than that in the non-ACA group (p = 0.032). With a median follow-up period of 62.0 months, worse event-free survival (EFS) was demonstrated in patients harboring ACA. Multivariate analysis showed that ACA was an independent adverse factor for EFS (p = 0.033). By further subgroup analysis, in CD34 and CD56 negative APL, patients harboring ACA had inferior EFS (p = 0.017; p = 0.037).

CONCLUSIONS

To sum up, ACA remains the independent prognostic value for EFS, we should build risk-adapted therapeutic strategies in the long-term management of APL when such abnormalities are detected.

Differentiation syndrome and coagulation disorder - comparison between treatment with oral and intravenous arsenics in pediatric acute promyelocytic leukemia

Realgar-Indigo naturalis formula (RIF), with A₄S₄ as a major ingredient, is an oral arsenic used in China to treat pediatric acute promyelocytic leukemia (APL). The efficacy of RIF is similar to that of arsenic trioxide (ATO). However, the effects of these two arsenicals on differentiation syndrome (DS) and coagulation disorders, the two main life-threatening events in children with APL, remain unclear. We retrospectively analyzed 68 consecutive children with APL from South China Children Leukemia Group-APL (SCCLG-APL) study. Patients received all-trans retinoic acid (ATRA) on day 1 of induction therapy. ATO 0.16 mg/kg day or RIF 135 mg/kg·day was administrated on day 5, while mitoxantrone was administered on day 3 (non-high-risk) or days 2-4 (high-risk). The incidences of DS were 3.0% and 5.7% in ATO (n = 33) and RIF (n = 35) arms (p = 0.590), and 10.3% and 0% in patients with and without differentiation-related hyperleukocytosis (p = 0.04), respectively. Moreover, in patients with differentiation-related hyperleukocytosis, the incidence of DS was not significantly different between ATO and RIF arms. The dynamic changes of leukocyte count between arms were not statistically different. However, patients with leukocyte count > 2.61 × 10⁹/L or percentage of promyelocytes in peripheral blood > 26.5% tended to develop hyperleukocytosis. The improvement of coagulation indexes in ATO and RIF arms was similar, with fibrinogen and prothrombin time having the quickest recovery rate. This study showed that the incidence of DS and recovery of coagulopathy are similar when treating pediatric APL with RIF or ATO.

Targeting HDAC3 to overcome the resistance to ATRA or arsenic in acute promyelocytic leukemia through ubiquitination and degradation of PML-RARα

Acute promyelocytic leukemia (APL) is driven by the oncoprotein PML-RARα, which recruits corepressor complexes, including histone deacetylases (HDACs), to suppress cell differentiation and promote APL initiation. All-trans retinoic acid (ATRA) combined with arsenic trioxide (ATO) or chemotherapy highly improves the prognosis of APL patients. However, refractoriness to ATRA and ATO may occur, which leads to relapsed disease in a group of patients. Here, we report that HDAC3 was highly expressed in the APL subtype of AML, and the protein level of HDAC3 was positively associated with PML-RARα. Mechanistically, we found that HDAC3 deacetylated PML-RARα at lysine 394, which reduced PIAS1-mediated PML-RARα SUMOylation and subsequent RNF4-induced ubiquitylation. HDAC3 inhibition promoted PML-RARα ubiquitylation and degradation and reduced the expression of PML-RARα in both wild-type and ATRA- or ATO-resistant APL cells. Furthermore, genetic or pharmacological inhibition of HDAC3 induced differentiation, apoptosis, and decreased cellular self-renewal of APL cells, including primary leukemia cells from patients with resistant APL. Using both cell line- and patient-derived xenograft models, we demonstrated that treatment with an HDAC3 inhibitor or combination of ATRA/ATO reduced APL progression. In conclusion, our study identifies the role of HDAC3 as a positive regulator of the PML-RARα oncoprotein by deacetylating PML-RARα and suggests that targeting HDAC3 could be a promising strategy to treat relapsed/refractory APL.

Improvement of Early Death in Acute Promyelocytic Leukemia: A Population-Based Analysis

BACKGROUND

Early death is a major factor of treatment failure in acute promyelocytic leukemia (APL), however, the recent trends in the incidence of early death based on the population-level are not clear. Hence, this study is aimed at describing the incidence, recent trends, causes and characteristics of early death in APL based on the real world.

MATERIALS AND METHODS

APL patients diagnosed from 1986 to 2015 in the Surveillance, Epidemiology, and End Results (SEER) dataset were enrolled, and categorized based on gender, age, year of diagnosis, race, marital status, resident county and socioeconomic status (SES). The risk factors for all-cause and acute myelocytic leukemia (AML) specific early death were determined by univariate and multivariate logistic regression analyses, and stratified analysis was conducted by age.

RESULTS

Overall, 3212 APL patients were included in analysis between 1986 and 2015, of which a total of 683 (21.3%) patients were noted for early death. Significant differences were recognized for patient distribution by age, year of diagnosis, marital status, and SES. The early death rate of APL patients diagnosed during 2006-2015 was significantly lower than that of the early stage, but this trend was not evident in juvenile patients. At the same time, older age, and lower SES score were independent risk factors for early death in the multivariate analysis.

CONCLUSION

We established that the early death trend in APL has decreased over the past few years, but the early death rate remains high, especially in older patients and those with lower SES.

Pyrrolidine Dithiocarbamate Enhances the Cytotoxic Effect of Arsenic Trioxide on Acute Promyelocytic Leukemia Cells

BACKGROUND

More than 95% patients with acute promyelocytic leukemia (APL) carry the PML-RARα fusion oncoprotein. Arsenic trioxide (ATO) is an efficacious therapeutic agent for APL, and the mechanism involves the binding with PML and degradation of PML-RARα protein. Pyrrolidine dithiocarbamate (PDTC) demonstrates the function of facilitating the cytotoxic effect of ATO.

PURPOSE

To investigate whether PDTC is potential to enhance the cytotoxic effect of ATO to APL cells by acting on PML-RARα oncoproteins.

METHODS

Inhibitory effects of drugs on cell viability were examined by CCK-8 test, and apoptosis was evaluated by flow cytometry. Western blotting and immunofluorescence assays were used to explore the mechanism.

RESULTS

PDTC improved the effect of ATO on inhibiting proliferation of NB4 cells in vitro. Further, PDTC-ATO promoted apoptosis and cell cycle arrest in NB4 cells. The expression of caspase- 3 and Bcl-2 was reduced in PDTC-ATO-treated NB4 cells, while cleaved caspase-3 and Bax was up-regulated. Furthermore, less PML-RARα expression were found in PDTC-ATO-treated NB4 cells than that in NB4 cells treated with ATO singly. Laser confocal microscopy showed that protein colocalization of PML and RARα was disrupted more significantly by PDTC-ATO treatment than that with ATO monotherapy.

CONCLUSION

In conclusion, PDTC enhanced the cytotoxic effect of ATO on APL, and the mechanism was, at least in part, related to the promotion of ATO-induced degradation of PML-RARα fusion protein via forming a complex PDTC-ATO.

Realgar (As4S4), a traditional Chinese medicine, induces acute promyelocytic leukemia cell death via the Bcl-2/Bax/Cyt-C/AIF signaling pathway in vitro

Acute promyelocytic leukemia (APL) is a specific subtype of acute myelogenous leukemia (AML) characterized by the proliferation of abnormal promyelocytes. Realgar, a Chinese medicine containing arsenic, can be taken orally. Traditional Chinese medicine physicians have employed realgar to treat APL for over a thousand years. Therefore, realgar may be a promising candidate for the treatment of APL. Nevertheless, the underlying mechanism behind realgar therapy is largely unclear. The present study aimed to investigate the effect of realgar on cell death in the APL cell line (NB4) in vitro and to elucidate the underlying mechanism. In this study, after APL cells were treated with different concentrations of realgar, the cell survival rate, apoptotic assay, morphological changes, ATP levels and cell cycle arrest were assessed. The expression of Bcl-2, Bax, Cytochrome C (Cyt-C) and apoptosis-inducing factor (AIF) at the mRNA and protein levels were also measured by immunofluorescence, quantitative PCR (qPCR) and Western blotting. We found that realgar could significantly inhibit APL cell proliferation and cell death in a time- and dose-dependent manner. Realgar effectively decreased the ATP levels in APL cells. Realgar also induced APL cell cycle arrest at the S and G2/M phases. Following realgar treatment, the mRNA and protein levels of Bcl-2 were significantly downregulated, whereas the levels of Bax, Cyt-C, and AIF were significantly upregulated. In summary, realgar can induce APL cell death via the Bcl-2/Bax/Cyt-C/AIF signaling pathway, suggesting that realgar may be an effective therapeutic for APL.

Coagulation Abnormalities and Risk Assessment in Acute Promyelocytic Leukemia: An Experience From a Resource-Constraint Country

Introduction

The objective of the study was to assess the impact of coagulopathy in risk-stratified acute promyelocytic leukemia (APML) patients irrespective of bleeding manifestation.

Patients and methods

This was a cross-sectional study design conducted at the National Institute of Blood Diseases and Bone Marrow Transplantation (NIBD & BMT) from November 2019 to December 2021. A total of 62 patients between three years to 74 years of age of either gender and treatment-naive cases of APML were included in the study. Morphological diagnosis was made on bone marrow samples, and confirmation was done by karyotyping/fluorescence in situ hybridization (FISH) and/or polymerase chain reaction (PCR). Complete blood count (CBC), prothrombin time (PT), activated partial thromboplastin time (APTT), D-dimer, and fibrinogen levels were done for bleeding risk assessment. Cases other than APML and cases on treatment were excluded from the study.

Results

A total of 85 APML patients were registered at our institute. Among them, 62 (73%) were included in the analysis as per the inclusion criteria of the study. The median age was 32 (3-74) years, with a male predominance of 34 (55%). According to the Sanz score, 18 (29%) patients were noted to have low risk; however, 22 (35.4%) patients were found to have an intermediate-risk disease and 22 (35.4%) patients had high-risk disease. There was positive bleeding history among 44 (71%) patients, followed by fever in 28 (45%) patients. Raised PT, APTT, and D-dimer were found in 46 (74%), 38 (61%), and 52(83.8%) patients, respectively. Low fibrinogen levels were observed among 16 (26%) patients. The association of risk stratification and bleeding history with CBC and coagulation parameters was observed. Platelet count and total leucocyte count were noted to be significantly associated with risk stratification. However, there was no association observed between the rest of the parameters with risk stratification and bleeding.

Conclusion

The results of our study suggest that regardless of bleeding symptoms, coagulation parameters must be investigated at the time of diagnosis in patients with suspected APML, and in addition to all-trans-retinoic acid (ATRA), transfusion of fresh frozen plasma should be done. It has clinical value, and adding it to the algorithm of treatment would be beneficial to the patients in the developing world, where resources are already meager.

PRMT5-mediated RNF4 methylation promotes therapeutic resistance of APL cells to As2O3 by stabilizing oncoprotein PML-RARα

Acute promyelocytic leukemia (APL) is a hematological malignancy driven by the oncoprotein PML-RARα, which can be treated with arsenic trioxide (As2O3) or/and all-trans retinoic acid. The protein arginine methyltransferase 5 (PRMT5) is involved in tumorigenesis. However, little is known about the biological function and therapeutic potential of PRMT5 in APL. Here, we show that PRMT5 is highly expressed in APL patients. PRMT5 promotes APL by interacting with PML-RARα and suppressing its ubiquitination and degradation. Mechanistically, PRMT5 attenuates the interaction between PML-RARα and its ubiquitin E3 ligase RNF4 by methylating RNF4 at Arg164. Notably, As2O3 treatment triggers the dissociation of PRMT5 from PML nuclear bodies, attenuating RNF4 methylation and promoting RNF4-mediated PML-RARα ubiquitination and degradation. Moreover, knockdown of PRMT5 and pharmacological inhibition of PRMT5 with the specific inhibitor EPZ015666 significantly inhibit APL cells growth. The combination of EPZ015666 with As2O3 shows synergistic effects on As2O3-induced differentiation of bone marrow cells from APL mice, as well as on apoptosis and differentiation of primary APL cells from APL patients. These findings provide mechanistic insight into the function of PRMT5 in APL pathogenesis and demonstrate that inhibition of PRMT5, alone or in combination with As2O3, might be a promising therapeutic strategy against APL.

Arsenic trioxide induces proteasome dependent TBLR1-RARα degradation to improve leukemia eradication through cell differentiation enhancement

Background: Acute promyelocytic leukemia (APL) mainly harbors PML-RARα fusion gene, which is sensitive to all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) treatment. However, APL harboring other RARα fusion genes exhibit different drug sensitivity. Here, we investigated the role and mechanism of TBLR1-RARα, a rare RARα fusion gene, on ATO treatment in leukemia cells.

Methods: By constructing two cell models of leukemia cell line HL-60 and U937 with overexpressed TBLR1-RARα, we detected the cell differentiation in the two cell models after ATO treatment by flow cytometry and Wright staining. Meanwhile, cell viability, colony formation and apoptosis were also determined after ATO treatment.

Results: We found that TBLR1-RARα enhanced ATO-induced apoptosis and cell proliferation inhibition. Besides, TBLR1-RARα also promoted ATO-induced cell differentiation. Furthermore, we found that the mitochondrial caspase pathway was involved in the apoptosis induced by ATO treatment in TBLR1-RARα positive leukemia cells. Moreover, ATO mediated TBLR1-RARα protein degradation via proteasome pathway, which accounts for the transcriptional activation of RARα target gene and is further involved in cell differentiation of TBLR1-RARα positive leukemia cells.

Conclusions: Our study provides evidence that TBLR1-RARα positive APL patients may benefit from ATO treatment, thereby improving the appropriate management in TBLR1-RARα positive APL.

Circulating lnc-LOC as a novel noninvasive biomarker in the treatment surveillance of acute promyelocytic leukaemia

BACKGROUND

Acute promyelocytic leukaemia (APL) is a unique subtype of acute myeloid leukaemia (AML) characterized by haematopoietic failure caused by the accumulation of abnormal promyelocytic cells in bone marrow (BM). However, indispensable BM biopsy frequently afflicts patients in leukaemia surveillance, which increases the burden on patients and reduces compliance. This study aimed to explore whether the novel circulating long noncoding RNA LOC100506453 (lnc-LOC) could be a target in diagnosis, assess the treatment response and supervise the minimal residual disease (MRD) of APL, thereby blazing a trail in noninvasive lncRNA biomarkers of APL.

METHODS

Our study comprised 100 patients (40 with APL and 60 with non-APL AML) and 60 healthy donors. BM and peripheral blood (PB) sample collection was accomplished from APL patients at diagnosis and postinduction. Quantitative real-time PCR (qRT-PCR) was conducted to evaluate lnc-LOC expression. A receiver operating characteristic (ROC) analysis was implemented to analyse the value of lnc-LOC in the diagnosis of APL and treatment monitoring. For statistical analysis, the Mann-Whitney U test, a t test, and Spearman's rank correlation test were utilized.

RESULTS

Our results showed that BM lnc-LOC expression was significantly different between APL and healthy donors and non-APL AML. lnc-LOC was drastically downregulated in APL patients' BM after undergoing induction therapy. Lnc-LOC was upregulated in APL cell lines and downregulated after all-trans retinoic acid (ATRA)-induced myeloid differentiation, preliminarily verifying that lnc-LOC has the potential to be considered a treatment monitoring biomarker. PB lnc-LOC was positively correlated with BM lnc-LOC in APL patients, non-APL AML patients and healthy donors and decreased sharply after complete remission (CR). However, upregulated lnc-LOC was manifested in relapsed-refractory patients. A positive correlation was revealed between PB lnc-LOC and PML-RARα transcript levels in BM samples. Furthermore, we observed a positive correlation between PB lnc-LOC and BM lnc-LOC expression in APL patients, suggesting that lnc-LOC can be utilized as a noninvasive biomarker for MRD surveillance.

CONCLUSIONS

Our study demonstrated that PB lnc-LOC might serve as a novel noninvasive biomarker in the treatment surveillance of APL, and it innovated the investigation and application of newly found lncRNAs in APL noninvasive biomarkers used in diagnosis and detection.

Role of cardiolipins, mitochondria, and autophagy in the differentiation process activated by all-trans retinoic acid in acute promyelocytic leukemia

The role played by lipids in the process of granulocytic differentiation activated by all-trans retinoic acid (ATRA) in Acute-Promyelocytic-Leukemia (APL) blasts is unknown. The process of granulocytic differentiation activated by ATRA in APL blasts is recapitulated in the NB4 cell-line, which is characterized by expression of the pathogenic PML-RARα fusion protein. In the present study, we used the NB4 model to define the effects exerted by ATRA on lipid homeostasis. Using a high-throughput lipidomic approach, we demonstrate that exposure of the APL-derived NB4 cell-line to ATRA causes an early reduction in the amounts of cardiolipins, a major lipid component of the mitochondrial membranes. The decrease in the levels of cardiolipins results in a concomitant inhibition of mitochondrial activity. These ATRA-dependent effects are causally involved in the granulocytic maturation process. In fact, the ATRA-induced decrease of cardiolipins and the concomitant dysfunction of mitochondria precede the differentiation of retinoid-sensitive NB4 cells and the two phenomena are not observed in the retinoid-resistant NB4.306 counterparts. In addition, ethanolamine induced rescue of the mitochondrial dysfunction activated by cardiolipin deficiency inhibits ATRA-dependent granulocytic differentiation and induction of the associated autophagic process. The RNA-seq studies performed in parental NB4 cells and a NB4-derived cell population, characterized by silencing of the autophagy mediator, ATG5, provide insights into the mechanisms underlying the differentiating action of ATRA. The results indicate that ATRA causes a significant down-regulation of CRLS1 (Cardiolipin-synthase-1) and LPCAT1 (Lysophosphatidylcholine-Acyltransferase-1) mRNAs which code for two enzymes catalyzing the last steps of cardiolipin synthesis. ATRA-dependent down-regulation of CRLS1 and LPCAT1 mRNAs is functionally relevant, as it is accompanied by a significant decrease in the amounts of the corresponding proteins. Furthermore, the decrease in CRLS1 and LPCAT1 levels requires activation of the autophagic process, as down-regulation of the two proteins is blocked in ATG5-silenced NB4-shATG5 cells.

Acute leukemia in pregnancy: a single institutional experience with 21 cases at 10 years and a review of the literature

INTRODUCTION

Acute leukemia (AL) occurring in pregnancy is extremely rare, and its treatment is a clinical dilemma.

METHODS

We retrospectively reviewed the medical records of our hospital from 2010 to 2019.

RESULTS

Twenty-one patients were diagnosed with AL during pregnancy. Of whom, eighteen had acute myeloid leukemia, and 3 had acute lymphoblastic leukemia. Six, eight and seven patients were diagnosed during the first, second, and third trimester, respectively. Six of the 21 patients experienced therapeutic abortion and 1 had spontaneous abortion, whereas 9 gave birth to healthy babies (4 through vaginal deliveries and 5 with Caesarean sections). Four babies had been exposed to chemotherapeutic agents, but no congenital malformations were observed. Sixteen patients received chemotherapy, while 4 patients died before chemotherapy and one was discharged after refusing chemotherapy. The complete remission rate of the 10 patients who began chemotherapy immediately after diagnosis was 80%, compared with 66.7% in the 6 patients who started chemotherapy after abortion or delivery. Three remain alive.

CONCLUSIONS

In general, initiation of chemotherapy as early as possible may increase the CR rate. Combined with literature data, we proposed that, for patients diagnosed in early and late stages of pregnancy (>30 weeks), elective termination or induced delivery before chemotherapy may be a good choice for better maternal (and fetal) outcome.KEY MESSAGESAcute leukaemia diagnosed in pregnancy is extremely rare, and its treatment is a clinical dilemma.In general, initiation of chemotherapy as early as possible may increase the CR rate.For patients who are diagnosed in the first trimester or late stage of pregnancy (>30 weeks), elective termination or induced delivery before starting chemotherapy may be a good choice for better maternal (and fetal) outcome.

Based on Activation of p62-Keap1-Nrf2 Pathway, Hesperidin Protects Arsenic-Trioxide-Induced Cardiotoxicity in Mice

Background: Hesperidin (HES) is a flavonoid glycoside found in the tangerine peel and has antioxidant properties. Arsenic trioxide (ATO) is an anti-tumour drug; however, its serious cardiotoxicity limits its clinical application. In addition, the protection of HES against ATO-induced cardiotoxicity has not been explored.

Objective: The study aims to investigate and identify the underlying effect and mechanism of HES on ATO-induced cardiotoxicity.

Methods: Fifty mice were randomly assigned to five groups. Mice were orally given HES:100 or 300 mg/kg/day concurrently and given ATO intraperitoneal injections: 7.5 mg/kg/day for 1 week. Blood and heart tissues were collected for examination. Evaluated in serum was the levels of creatine kinase (CK), lactate dehydrogenase (LDH) and cardiac troponin I (cTnI). In addition, evaluated in heart tissues were the levels of reactive oxygen species (ROS), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), catalase (CAT), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), Caspase-3, cleaved-Caspase-3, p62, Kelch-like ECH-associated protein 1 (Keap1), and nuclear factor erythroid 2-related factor 2 (Nrf2). The heart tissues were also examined for histopathology and mitochondrial ultrastructure.

Results: Compared with the ATO group, the HES treatment groups reduced the levels of CK, LDH, cTnI, ROS, MDA, TNF-α, IL-6, Bax, Caspase-3, cleaved-Caspase-3 and Keap1 and enhanced the levels of SOD, GSH, CAT, Bcl-2, p62 and Nrf2.

Conclusions: The results demonstrate that HES protects against ATO-induced cardiotoxicity, through inhibiting oxidative stress, and subsequent inflammation and apoptosis. The underlying results are closely related to the regulation of the p62-Keap1-Nrf2 signalling pathway.

Thioredoxin 1 is required for stress granule assembly upon arsenite-induced oxidative stress

Arsenic is a major water pollutant and health hazard, leading to acute intoxication and, upon chronic exposure, several diseases including cancer development. Arsenic exerts its pronounced cellular toxicity through its trivalent oxide arsenite (ASN), which directly inhibits numerous proteins including Thioredoxin 1 (Trx1), and causes severe oxidative stress. Cells respond to arsenic by inhibition of protein synthesis and subsequent assembly of stress granules (SGs), cytoplasmic condensates of stalled mRNAs, translation factors and RNA-binding proteins. The biological role of SGs is diverse and not completely understood; they are important for regulation of cell signaling and survival under stress conditions, and for adapting de novo protein synthesis to the protein folding capacity during the recovery from stress. In this study, we identified Trx1 as a novel component of SGs. Trx1 is required for the assembly of ASN-induced SGs, but not for SGs induced by energy deprivation or heat shock. Importantly, our results show that Trx1 is essential for cell survival upon acute exposure to ASN, through a mechanism that is independent of translation inhibition.

Novel insights into the impact of the SUMOylation pathway in hematological malignancies (Review)

The small ubiquitin-like modifier (SUMO) system serves an important role in the regulation of protein stability and function. SUMOylation sustains the homeostatic equilibrium of protein function in normal tissues and numerous types of tumor. Accumulating evidence has revealed that SUMO enzymes participate in carcinogenesis via a series of complex cellular or extracellular processes. The present review outlines the physiological characteristics of the SUMOylation pathway and provides examples of SUMOylation participation in different cancer types, including in hematological malignancies (leukemia, lymphoma and myeloma). It has been indicated that the SUMO pathway may influence chromosomal instability, cell cycle progression, apoptosis and chemical drug resistance. The present review also discussed the possible relationship between SUMOylation and carcinogenic mechanisms, and evaluated their potential as biomarkers and therapeutic targets in the diagnosis and treatment of hematological malignancies. Developing and investigating inhibitors of SUMO conjugation in the future may offer promising potential as novel therapeutic strategies.

Arsenic trioxide in pediatric cancer - a case series and review of literature

Arsenic trioxide (ATO) has become an established component of treatment protocols for acute promyelocytic leukemia (APL) with excellent efficacy and no relevant sustained toxicity. Part of its action has been attributed to the inhibition of Hedgehog signaling (Hh) which enables a possible therapeutic approach as many pediatric tumor entities have been associated with increased Hh activity. We retrospectively analyzed 31 patients with refractory and relapsed pediatric cancer who were treated with ATO at the University Children's Hospital of Tuebingen. Additionally a literature review on the clinical and preclinical use of ATO in pediatric cancer treatment was performed.ATO alone as well as combinations with other drugs have proven effective in vitro and in mouse models of various pediatric malignancies. However, only few data on the clinical use of ATO in pediatric patients besides APL exist. In our patient sample, ATO was overall well tolerated in the treatment of various pediatric cancers, even in combination with other cytostatic drugs. Due to distinct tumor entities, differently progressed disease stages and varying co-medication, no clear statement can be made regarding the efficacy of ATO treatment. However, patients with proven Hh activation in molecular tumor profiling surpassed all other patients, who received ATO in an experimental treatment setting, in terms of survival. As molecular profiling of tumors increases and enhanced Hh activity can be detected at an early stage, ATO might expand its clinical use to other pediatric malignancies beyond APL depending on further clinical studies.

Hypoxia enhances the cytotoxic effect of As4S4 on rat ventricular H9c2 cells through activation of ubiquitin-proteasome system

BACKGROUND

As₄S₄ is widely used in Chinese traditional medicine compound. However, based on some recent studies, we found that the cardiotoxicity risk of using As₄S₄ in ischemic heart disease patients may be increased. To study this potential risk, we compared the effects of As₄S₄ on rat ventricular H9c2 cell line with or without hypoxic pretreatment, and to elucidate mechanisms of c-Cbl mediated ubiquitination/degradation of integrin β1.

METHODS

The present study was conducted on rat ventricular H9c2 cell line in the absence or presence of hypoxic pretreatment for 6 h followed by As₄S₄ treatment for 24 h. Following As₄S₄ treatment, cell viability assay, flow cytometric quantification of apoptotic cells, caspase-3 activity assay and DAPI staining were conducted. Western blotting was carried out to detect expressions of ubiquitination related proteins. In addition, the ubiquitination/degradation of integrin β1 and the role of c-Cbl in it was evaluated by immunoprecipitation and immunoblot assay.

RESULTS

The viability of cells with hypoxic pretreatment followed by As₄S₄ treatment was decreased significantly, apoptosis rate and the activity of caspase-3 were increased than As₄S₄ treatment alone. The ubiquitin-proteasome degradation pathway induced by As₄S₄ was further enhanced by hypoxic pretreatment. The results of IP and immunoblot assay showed hypoxic enhanced down-regulation effect of As₄S₄ on integrin β1 probably through c-Cbl activation.

CONCLUSIONS

This study demonstrated that the hypoxia enhanced cytotoxicity of As₄S₄ on H9c2 cells may through increasing the ubiquitin-proteasome degradation of integrin β1 mediated by the E3 ligase c-Cbl. The results provide an important clue that, in patients with ischemic heart disease, use of As₄S₄ may be associated with increased cardiotoxicity. We believe that the results worth to be further illuminated by in vivo and clinical research.

Risk factors of thrombosis in Chinese subjects with acute promyelocytic leukemia

BACKGROUND

Acute promyelocytic leukemia (APL) is a special type of acute myeloid leukemia Thrombosis is at increased risk complication in patients with this disease. However, the risk factors of thrombosis related to Chinese APL patients are not fully understood.

METHODS

In this study, clinical and laboratory data of 44 consecutively Chinese APL patients were collected and analyzed.

RESULTS

One arterial and 6 venous thrombosis occurred in 44 patients, including 22 males and 22 females, with a median age of 44 years (range from 18 to 74 years). The ratio of male and female gender, age, white blood cell count, hemoglobin, platelets, disease risk stratification, CD2, Khorana score, differentiation syndrome (DS) and gene mutation related to prognosis of APL, including DNMT3A, TET2, IDH1, IDH2, NRAS and ASXL1 in the two groups with and without thrombosis were not statistically significant. The detection rate of PAI-1 genotype 4G4G was 71.4% (5/7) in 7 patients with thrombosis, while the detection rate of PAI-1 genotype 4G4G in 37 patients without thrombosis was 8.1% (3/37). The differences between the two groups in WT-1 (P = 0.01), PAI-1 4G4G (P = 0.0009), bcr3 (P = 0.027), CD15 (P = 0.005), and FLT3-ITD mutation (P = 0.0008) were statistically significant. Using multivariate analysis, the risk factors of venous thrombosis in APL were CD15 (P = 0.043), PAI-1 4G4G (P = 0.009), WT-1 (P = 0.043) and FLT3/ITD (P = 0.013), respectively.

CONCLUSION

Our results suggested the PAI-1 gene 4G4G type, CD15, WT-1 and FLT3-ITD mutations excluding DNMT3A, TET2, IDH1/2, NRAS and ASXL1 are risk factors of thrombotic events in Chinese APL patients.

Successful treatment of acute promyelocytic leukemia in a 92-year-old man using all-trans retinoic acid combined with oral arsenic: A case report

RATIONALE

Acute promyelocytic leukemia is a special subtype of acute myeloid leukemia. The incidence of early death and complications is high. An oral regimen of all-trans retinoic acid combined with the realgar-indigo naturalis formula (RIF) without chemotherapy has provided a new strategy for the treatment of these patients.

PATIENT CONCERNS

A 92-year-old male patient was admitted to the hospital due to fatigue and oral bleeding. He had no fever or lung infection. Routine blood test showed white blood cell count 1.0 ×109/L, hemoglobin 100 g/L, and platelets 21 × 109/L. Coagulation function indicated fibrinogen 1.02 g/L and D-dimer 2360 ng/mL. And 28% abnormal promyelocytes were observed in peripheral blood.

DIAGNOSIS

A bone marrow morphologic, immunophenotypic, cytogenetic, and molecular examination was performed. Routine bone marrow examination showed active proliferation of nucleated cells, with promyelocytes accounting for 91%; immunophenotyping revealed an early myeloid cell population, accounting for approximately 82.4% of all cells.

INTERVENTIONS

From February 15, 2020, 25 mg/m2 all-trans retinoic acid was orally administered daily. After the fusion gene result was obtained, oral administration of 60 mg/kg RIF daily began since February 18, 2020. The combination of the 2 agents was given until March 16, 2020. Oral administration of 25 mg/m2 retinoic acid daily began from March 20, 2020 for 2 weeks, and oral administration of 60 mg/kg RIF daily lasted for 4 weeks as the consolidation therapy. During the treatment, the proportion of promyelocytes in peripheral blood, white blood cell count, platelets, coagulation function, liver function, and QT interval were monitored.

OUTCOMES

Oral retinoic acid and oral RIF were given without chemotherapy and the patient achieved bone marrow remission after 1 month, and molecular remission was achieved 2 months later. In the early stage of acute promyelocytic leukemia, combined thrombocytopenia and disseminated intravascular coagulation may develop. Platelet and fresh frozen plasma infusion were proactively given until platelets were stabilized above 30 × 109/L, and the coagulation function returned to normal.

LESSONS

The regimen was safe and effective, and subsequent treatment did not require hospitalization, which helped to improve the patient's quality of life.

A Case of Subacute Brain Hemorrhage and Disseminated Intravascular Coagulation Secondary to Acute Promyelocytic Leukemia in a Pediatric Patient

Acute promyelocytic leukemia (APML), characterized by the reciprocal translocation between chromosomes 15 and 17 [t(15;17)], is a result of proliferation of myeloid cells maturation which is interrupted at the promyelocytic stage. The central, and the most important, distinguishing feature of APML is a predisposition to disseminated intravascular coagulation (DIC). The overall prognosis of APML is very good, with 90% of patients achieving complete remission. We find it important to remind pediatric practitioners, both in the ambulatory and urgent care room settings, of presenting signs and symptoms of leukemia, as well as, up-to-date on management of such fulminant scenarios as DIC. Intracranial hemorrhage (ICH) is one of the commonest, and frequently fulminant complication of APML seen after initiation of induction chemotherapy. We report on a young female presenting with non-specific upper respiratory illness symptoms and recurrent headache, who was found to already have ICH and to be in DIC in the setting of APML at the time of initial evaluation. This case illustrates importance of thorough assessment and prompt consideration of wide differential diagnosis, which became somewhat limited and biased towards web-based telemedicine in the COVID-19 pandemics era.

Disparate roles of retinoid acid signaling molecules in kidney disease

Retinoid acid (RA) is synthesized mainly in the liver and has multiple functions in development, cell differentiation and proliferation, and regulation of inflammation. RA has been used to treat multiple diseases, such as cancer and skin disorders. The kidney is a major organ for RA metabolism, which is altered in the diseased condition. RA is known to have renal-protective effects in multiple animal models of kidney disease. RA has been shown to ameliorate podocyte injury through induction of expression of differentiation markers and regeneration of podocytes from its progenitor cells in animal models of kidney disease. The effects of RA in podocytes are mediated mainly by activation of the cAMP/PKA pathway via RA receptor-α (RARα) and activation of its downstream transcription factor, Kruppel-like factor 15. Screening of RA signaling molecules in human kidney disease has revealed RAR responder protein 1 (RARRES1) as a risk gene for glomerular disease progression. RARRES1, a podocyte-specific growth arrest gene, is regulated by high doses of both RA and TNF-α. Mechanistically, RARRES1 is cleaved by matrix metalloproteinases to generate soluble RARRES1, which then induces podocyte apoptosis through interaction with intracellular RIO kinase 1. Therefore, a high dose of RA may induce podocyte toxicity through upregulation of RARRES1. Based on the current findings, to avoid potential side effects, we propose three strategies to develop future therapies of RA for glomerular disease: 1) develop RARα- and Kruppel-like factor 15-specific agonists, 2) use the combination of a low dose of RAR-α agonist with phosphodiesterase 4 inhibitors, and 3) use a combination of RARα agonist with RARRES1 inhibitors.NEW & NOTEWORTHY Retinoic acid (RA) exerts pleotropic cellular effects, including induction of cell differentiation while inhibiting proliferation and inflammation. These effects are mediated by both RA responsive element-dependent or -independent pathways. In kidneys, RA confers renoprotection by signaling through podocyte RA receptor (RAR)α and activation of cAMP/PKA/Kruppel-like factor 15 pathway to promote podocyte differentiation. Nevertheless, in kidney disease settings, RA can also promote podocyte apoptosis and loss through downstream expression of RAR responder protein 1, a recently described risk factor for glomerular disease progression. These disparate roles of RA underscore the complexity of its effects in kidney homeostasis and disease, and a need to target specific RA-mediated pathways for effective therapeutic treatments against kidney disease progression.

Characteristics and outcome of patients with acute myeloid leukaemia and t(8;16)(p11;p13): results from an International Collaborative Study

In acute myeloid leukaemia (AML) t(8;16)(p11;p13)/MYST3-CREBBP is a very rare abnormality. Previous small series suggested poor outcome. We report on 59 patients with t(8;16) within an international, collaborative study. Median age was 52 (range: 16-75) years. AML was de novo in 58%, therapy-related (t-AML) in 37% and secondary after myelodysplastic syndrome (s-AML) in 5%. Cytogenetics revealed a complex karyotype in 43%. Besides MYST3-CREBBP, whole-genome sequencing on a subset of 10 patients revealed recurrent mutations in ASXL1, BRD3, FLT3, MLH1, POLG, TP53, SAMD4B (n = 3, each), EYS, KRTAP9-1 SPTBN5 (n = 4, each), RUNX1 and TET2 (n = 2, each). Complete remission after intensive chemotherapy was achieved in 84%. Median follow-up was 5·48 years; five-year survival rate was 17%. Patients with s-/t-AML (P = 0·01) and those with complex karyotype (P = 0·04) had an inferior prognosis. Allogeneic haematopoietic cell transplantation (allo-HCT) was performed in 21 (36%) patients, including 15 in first complete remission (CR1). Allo-HCT in CR1 significantly improved survival (P = 0·04); multivariable analysis revealed that allo-HCT in CR1 was effective in de novo AML but not in patients with s-AML/t-AML and less in patients exhibiting a complex karyotype. In summary, outcomes of patients with t(8;16) are dismal with chemotherapy, and may be substantially improved with allo-HCT performed in CR1.

All-trans retinoic acid induces leukemia resistance to NK cell cytotoxicity by down-regulating B7-H6 expression via c-Myc signaling

BACKGROUND

The interaction between activating receptor NKp30 and its major tumor ligand B7-H6 is important for NK cell-mediated tumor rejection. However, the regulation of B7-H6 by tumor therapeutics remains largely unknown. In this study, we investigated the regulation of B7-H6 by all-trans retinoic acid (atRA), a terminal differentiation inducer of tumor cells that is extensively used for clinical leukemia therapy.

METHODS

We investigated the role of NKp30:B7-H6 axis in NK cell-mediated tumor lysis against leukemia cells and the influence of atRA treatment on the cytotoxicity of NK cells using NK cell lines (NK92 and NKG) and leukemia cell lines (U-937 and THP-1). We evaluated the effect of atRA treatment on the expression of B7-H6 using real-time PCR, flow cytometry and western blotting. We used CRISPR/Cas9 to knockdown B7-H6 expression and siRNA to knockdown c-Myc in U-937 cells to evaluate the role of B7-H6 and c-Myc in atRA-induced tumor resistance against NK cells.

RESULTS

NK cell-mediated U-937 cell lysis was mainly dependent on NKp30/B7-H6 interaction. Blockade of B7-H6 by monoclonal antibody significantly impaired NK cytotoxicity. atRA treatment induced U-937 resistance to NK cell cytotoxicity by reducing B7-H6 expression, and showed no effect on NK cytotoxicity against B7-H6 knockdown U-937 cells. Epigenetic modifications, such as DNA methylation and histone deacetylase (HDAC), were not responsible for atRA-mediated B7-H6 down-regulation as inhibitors of these pathways could not restore B7-H6 mRNA expression. On the other hand, atRA treatment reduced c-Myc expression, which in turn inhibited the transcription of B7-H6 on leukemia cells.

CONCLUSION

atRA treatment promotes tumor cell resistance against NK cell-mediated lysis by down-regulating B7-H6 expression via the c-Myc signaling pathway, suggesting that more attention needs to be paid to the immunological adverse effects in the clinical use of atRA treatment.

Sharing and Helping: Regularity and Characteristics of Pathogenesis of a Widely Used Transgene Initiated Murine Acute Promyelocytic Leukemia Model

A transgenic acute promyelocytic leukemia (APL) murine model established by Michael Bishop by cloning a human PML-RARα cDNA into the hMRP8 expression cassette has been widely used in the all-trans retinoid acid and arsenic preparations for the research of APL. However, in the existing literature, the data of regularity and characteristics of the pathogenesis of this model were still missing, which hinder the development of many studies, especially application of new technologies such as single-cell sequencing. Therefore, in this article, we have made up this part of the missing data using an improved APL murine model. We clarified the effects of different inoculation doses on the onset time, latency, morbidity, life span, and proportion of APL cells in peripheral blood (PB), spleen, bone marrow, and so on. The relationship between the proportion of APL cells in the bone marrow, spleen, and PB and organ histological changes was also revealed. These results were a supplement and refinement of this APL model. It would add to the knowledge base of the field and aid in ensuring that accurate models are used for directed interventions. It also provides a great convenience for the researchers who will carry out similar research.

The History of the Chemo-Free Model in the Treatment of Acute Promyelocytic Leukemia

Acute promyelocytic leukemia (APL) has become a highly curable disease after four decades of endeavors. Thanks to the efforts of investigators throughout the world, the chemo-free concept has become a reality for both low- and high-risk patients. All-trans retinoic acid (ATRA) plus arsenic trioxide (ATO) without chemotherapy has become a first-line treatment for newly diagnosed APL and has been adopted in guidelines or expert recommendations from the NCCN and ELN and in China. Though the regimen has achieved great success, challenges still exist. The rate of early death still has not diminished significantly and is a major obstacle to curing all patients. Leukocytosis is the most important factor for ED, and completely abandoning chemotherapy is dangerous for certain patients in practice. To narrow the gap between guidelines and practice, this review aims to examine the history of the chemo-free model for the treatment of APL in the arsenic-alone era (1974-2002) and the arsenic plus ATRA era (2002-present) and provide practical considerations regarding early death.

Administration of all-trans retinoic acid after experimental traumatic brain injury is brain protective

BACKGROUND AND PURPOSE

All-trans retinoic acid (ATRA) is a vitamin A metabolite, important in the developing and mature brain. Pre-injury ATRA administration ameliorates ischaemic brain insults in rodents. This study examined the effects of post-traumatic ATRA treatment in experimental traumatic brain injury (TBI).

EXPERIMENTAL APPROACH

Male adult mice were subjected to the controlled cortical impact model of TBI or sham procedure and killed at 7 or 30 days post-injury (dpi). ATRA (10 mg kg-1, i.p.) was given immediately after the injury and 1, 2 and 3 dpi. Neurological function and sensorimotor coordination were evaluated. Brains were processed for (immuno-) histological, mRNA and protein analyses (qPCR and western blot).

KEY RESULTS

ATRA treatment reduced brain lesion size, reactive astrogliosis and axonal injury at 7 dpi, and hippocampal granule cell layer (GCL) integrity was protected at 7 and 30 dpi, independent of cell proliferation in neurogenic niches and blood-brain barrier damage. Neurological and motor deficits over time and the brain tissue loss at 30 dpi were not affected by ATRA treatment. ATRA decreased gene expression of markers for damage-associated molecular pattern (HMGB1), apoptosis (caspase-3 and Bax), activated microglia (TSPO), and reactive astrogliosis (GFAP, SerpinA3N) at 7 dpi and a subset of markers at 30 dpi (TSPO, GFAP).

CONCLUSION AND IMPLICATIONS

In experimental TBI, post-traumatic ATRA administration exerted brain protective effects, including long-term protection of GCL integrity, but did not affect neurological and motor deficits. Further investigations are required to optimize treatment regimens to enhance ATRA's brain protective effects and improve outcomes.

Myosin light chain kinase is a potential target for hypopharyngeal cancer treatment

Hypopharyngeal cancer is squamous cell carcinoma (SCC) with the worst prognosis among the head and neck cancers. Overall, the 5-year survival rate remains poor although diagnostic imaging, radiation, chemotherapy, and surgical techniques have been improved. The mortality of patients with hypopharyngeal cancer is partly due to an increased likelihood of developing a second primary malignancy and metastasis. In this study, we found that MLCK expression, compared to healthy tissue, was up-regulated in hypopharyngeal tumor tissue. Of particular interest, a low 5-year survival rate was positively correlated with MLCK expression. We hypothesized that MLCK might be a target for hypopharyngeal cancer prognosis and treatment. In order to explore the function of MLCK in the development of cancer, we knockdown MLCK in hypopharyngeal cancer FaDu cells. The results showed that MLCK knockdown reduced the migration and invasion of FaDu cells. 4-amino-2-trifluoromethyl-phenyl retinate (ATPR) is the derivative of all-trans retinoic acid (ATRA), which was able to reduce both MLCK expression and activity in FaDu cells. ATPR induced FaDu cells apoptosis in a dose-dependent manner and also inhibited cell growth both in vivo and in vitro. Further experiments showed that overexpression of MLCK reduced ATPR induced-migration inhibition while increase of ATPR induced apoptosis, which suggested that MLCK was involved in ATPR's anti-cancer function. In conclusion, MLCK is a novel prognostic marker and therapeutic target for hypopharyngeal cancer. By targeting MLCK, ATPR exhibits its potential application in the treatment of this type of cancer.

Crocetin attenuates the oxidative stress, inflammation and apoptosisin arsenic trioxide-induced nephrotoxic rats: Implication of PI3K/AKT pathway

Arsenic trioxide (ATO)-induced renal toxicity through oxidative stress and apoptosis restricts the therapeutic action of acute myelogenous leukemia. Crocetin (Crt) possesses antioxidant and antiapoptosis properties, and has certain renal protective effects, but it has not been reported that it has protective effect on renal injury caused by ATO. The current study explored the effects and mechanisms of Crt on kidney damage induced by ATO. Fifty Sprague-Dawley rats were randomly divided into five groups. Adult rats were given Crt concurrently with ATO for 1 week. On the 8th day, rats were killed and blood and kidney tissues were collected. Histopathological changes were measured, and kidneytissues and serum were used to determine renal function and antioxidant enzyme activity. In addition, the protein expression levels of P-PI3K, PI3K, P-AKT, AKT, CytC, Bax, Bcl-2 and Caspase-3 were determined via western blot analysis. Results revealed ATO induced renal morphological alterations and activated serum BUN and CRE. Compared with the control group, ROS, MDA, IL-1β, TNF-α, protein carbonyls (PC), lipid hydroperoxides (LOOH) and arsenic concentration levels were found to be significantly increased and SOD, CAT, GSH-Px, GSH and total sulphydryl groups (TSH) levels were attenuated in the ATO group. Crt markedly reduced oxidative stress in ATO-induced nephrotoxicity. Further, ATO induced apoptosis by significantly enhancing CytC, Bax and Caspase-3 and inhibiting Bcl-2. Administration with Crt markedly improved the expression of apoptosis factor. Moreover, Crt treatment stimulated the expressions of P-PI3K, PI3K, P-AKT, AKT induced by ATO. This study indicates Crt could prevent renal injury caused by ATO through inhibiting oxidative stress, inflammation and apoptosis, and its mechanism may be related to activation of PI3K/Akt signaling pathway.

Predictors of early death, serious hemorrhage, and differentiation syndrome in Japanese patients with acute promyelocytic leukemia

Significant advancements have been achieved with regard to the outcomes of acute promyelocytic leukemia (APL) patients through the introduction of all-trans retinoic acid; however, early hemorrhagic death and differentiation syndrome remain the major causes of remission induction failure in patients with APL. To investigate early death, serious hemorrhage, and differentiation syndrome during remission induction therapy in terms of incidence, risk factors, influence on outcomes, and prophylactic effects of several new anticoagulants, the results of 344 patients enrolled in the Acute Promyelocytic Leukemia 204 study conducted by the Japan Adult Leukemia Study Group were analyzed. Early death was observed in 16 patients (4.7%), of whom 14 had serious hemorrhage and 2 had differentiation syndrome. Serious hemorrhage and differentiation syndrome of grade 2 or higher were observed in 21 and 54 patients, respectively. Patients who achieved complete remission had a 7-year disease-free survival of 84.8% if they did not experience serious hemorrhage and 40.0% if they experienced serious hemorrhage during remission induction therapy (P = 0.001). Risk factor analyses showed that higher white blood cell count was associated with early death, higher white blood cell count and lower platelet count with serious hemorrhage, and leukocytosis during induction therapy and higher body surface area with differentiation syndrome. In conclusion, these results indicate that patients with such high-risk features may benefit from more intensive supportive care. The hemorrhagic risk was not relieved by the introduction of new anticoagulants. Further studies are required to establish the predictive impact of body surface area on differentiation syndrome. This trial is registered with UMIN-CTR as C000000154 on September 13, 2005.