Management of acute promyelocytic leukemia: updated recommendations from an expert panel of the European LeukemiaNet

Effective treatment with Gilteritinib-based regimens for FLT3-mutant extramedullary relapse in acute promyelocytic leukemia

OBJECTIVE

Extramedullary relapse (EMR) is rare in acute promyelocytic leukemia (APL) and, there is a lack of information on its management. Current practices for EMR in APL are always to adopt strategies from other subtypes of Acute lymphoblastic leukemia (ALL) and Acute myeloid leukemia (AML). Gilteritinib, a highly selective FLT3 inhibitor, has demonstrated a remarkable effect on EMR in FLT3-mutant AML. Therefore, it is worthwhile exploring if FLT3 mutation can be a therapeutic target and assessing the efficacy of Gilteritinib on FLT3-mutant EMR in APL.

METHODS

We described three cases of FLT3-mutant EMR in APL, comprising two isolated EMR cases and one systemic relapse. The patients underwent treatment with Gilteritinib-based regimens based on FLT3 mutation.

RESULTS

All three patients achieved complete regression of EMR, and no signs of tumor lysis syndrome during Gilteritinib-based therapy, only patient 1 showed mild granulocytopenia. They all maintained molecular complete remission (mCR) during the follow-up period.

CONCLUSIONS

The Gilteritinib-based regimen shows a high and sustained therapeutic effect with minimal adverse effects, and provides a valuable experience for further evaluation in EMR APL patients.

Prognosis influence of additional chromosome abnormalities in newly diagnosed acute promyelocytic leukemia with t(15;17)(q24;q21)

OBJECTIVES

In patients with acute promyelocytic leukemia (APL), additional chromosomal abnormalities (ACAs) are prognostic indicators. However, the clinical features of ACAs were not systematically reported in Chinese patients. Therefore, we enrolled a large cohort of APLs to demonstrate the clinical characteristics and prognostic value of ACAs.

METHODS

268 patients with newly diagnosed APL with t(15;17)(q24;q21) were retrospectively enrolled, and their clinical characteristics and the predictive value of ACAs were assessed between patients with the presence and absence of ACAs.

RESULTS

APL patients with and without ACAs did not differ significantly in their clinical features or treatment response and clinical outcomes like overall survival (OS) and disease-free survival (DFS). It appeared to be substantially associated with worse OS in APL patients with trisomy 8, which was the most common ACA, although DFS was unaffected. Interestingly, the presence of ACAs or trisomy 8 affected OS and DFS in the subgroup of patients aged ≥60 years; by contrast, ACAs had no effect on OS or DFS in any treatment subgroup (ATRA + ATO/RIF or ATRA + ATO/RIF + CH or ATRA + CH), except for the ATRA + ATO/RIF + CH treatment subgroup, where their impact on DFS was less favorable.

CONCLUSIONS

Our results suggested that OS and DFS were unaffected by ACAs. Nonetheless, in the subgroup of patients older than 60, the existence of ACAs or trisomy 8 appeared to impact OS and DFS negatively. Individuals with t(15;17) alone had a higher DFS and were more susceptible to ATRA + ATO/RIF + CH than individuals with t(15;17) ACAs.

Outcome of Patients With Relapsed Acute Promyelocytic Leukemia

BACKGROUND

The outcome of patients with acute promyelocytic leukemia (APL) has improved significantly since the introduction of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) as APL therapies. The optimal therapy for APL relapse is believed to require autologous or allogeneic stem cell transplantation (SCT) based on historical experience.

STUDY AIMS

To evaluate the outcome of patients with relapsed APL before and after the era of ATRA-ATO.

PATIENTS AND METHODS

We reviewed 61 patients with relapsed APL treated from November 1991 to June 2023; 31 patients (51%) received modern therapy with the combination of ATRA and ATO with and without idarubicin and gemtuzumab ozogamicin (GO).

RESULTS

Overall, 56 patients (92%) achieved CR after the first salvage therapy; 20 patients received SCT (10 autologous SCT;10 allogeneic SCT). With a median follow-up time of 138 months, the median survival durations were 32 months and 164 months with historical therapy vs. modern (ATRA-ATO) therapy (P = .035); the 5-year survival rates were 44% vs. 71%. With a 10-month landmark analysis, the median survival durations were 102 months vs. not reached, and the 5-year survival rates were 57% and 70% without SCT vs. with SCT (P = .193). The survival benefit with SCT was more prominent in the historical therapy era. However, patients who received the modern combination therapy of ATRA-ATO with and without idarubicin and GO had similar outcomes without vs. with SCT (P = .848).

CONCLUSION

The combination of ATRA-ATO (+/- GO and idarubicin) is a highly effective salvage therapy in relapsed APL. The use of SCT may not be needed after first relapse-second remission but may be considered in subsequent relapses.

Efficacy of Autologous and Allogeneic Hematopoietic Cell Transplantation in Adults with Acute Promyelocytic Leukemia: Results of a Systematic Review and Meta-Analysis

Despite therapeutic advances for acute promyelocytic leukemia (APL) with the emergence of all-trans retinoic acid, arsenic trioxide, and gemtuzumab-ozogamycin, approximately 10% of patients still experience disease relapse, typically occurring within 24 to 36 months following completion of front-line treatment. Traditionally, both allogeneic (allo) and autologous (auto) hematopoietic cell transplantation (HCT) have been considered reasonable treatment options for relapsed APL; however, no randomized controlled studies have been conducted comparing allo-HCT and auto-HCT in patients with relapsed APL. We performed a systematic review/meta-analysis to assess the totality of evidence pertaining to allo-HCT or auto-HCT in relapsed APL. Our search identified 1158 references, of which 23 met our inclusion criteria. While acknowledging the limitations of comparing these 2 treatment modalities indirectly, based on results from separate meta-analyses, it appears that pooled rates of event-free survival (71% versus 54%), progression-free survival (63% versus 43%), and overall survival (82% versus 58%) are higher after auto-HCT. This difference can be explained in part by the higher risk of pooled nonrelapse mortality (NRM) in patients undergoing allo-HCT (29% versus 5%), owing to inherent risks associated with this modality. In the absence of a randomized prospective clinical trial comparing allo-HCT and auto-HCT, our results show that both modalities are acceptable in patients with relapsed APL. The higher pooled NRM rate with allo-HCT is an important consideration when choosing this option. Additionally, the comparable pooled relapse rate for auto-HCT and allo-HCT (24% versus 23%) provides a rationale for evaluating post-HCT consolidative strategies to mitigate this risk.

Management of hematological patients requiring emergency chemotherapy in the intensive care unit

Hematological malignancies may require rapid-onset treatment because of their short doubling time, notably observed in acute leukemias and specific high-grade lymphomas. Furthermore, in targeted onco-hematological scenarios, chemotherapy is deemed necessary as an emergency measure when facing short-term, life-threatening complications associated with highly chemosensitive hematological malignancies. The risks inherent in the disease itself, or in the initiation of treatment, may then require admission to the intensive care unit (ICU) to optimize monitoring and initial management protocols. Hyperleukocytosis and leukostasis in acute leukemias, tumor lysis syndrome, and disseminated intravascular coagulation are the most frequent onco-hematological complications requiring the implementation of emergency chemotherapy in the ICU. Chemotherapy must also be started urgently in secondary hemophagocytic lymphohistiocytosis. Tumor-induced microangiopathic hemolytic anemia and plasma hyperviscosity due to malignant monoclonal gammopathy represent infrequent yet substantial indications for emergency chemotherapy. In all cases, the administration of emergency chemotherapy in the ICU requires close collaboration between intensivists and hematology specialists. In this review, we provide valuable insights that aid in the identification and treatment of patients requiring emergency chemotherapy in the ICU, offering diagnostic tools and guidance for their overall initial management.

Early predictor for differentiation syndrome in newly diagnosed acute promyelocytic leukaemia patients treated with single-agent arsenic trioxide

Differentiation syndrome (DS) is the second leading cause of death in acute promyelocytic leukaemia (APL) patients. Few studies have tested predictors of DS events. This study aimed to identify optimized predictors of DS events related to APL. The data of 298 consecutive patients who were newly diagnosed with APL between December 2012 and June 2023 were retrospectively investigated. A systematic review of computer-based patient medical records was conducted to obtain clinical data, including baseline characteristics, routine blood examination findings, biochemical indices and clinical manifestations of DS. Among the 298 patients, 158 were classified into the no-DS group, while 140 had DS. Compared with those of patients without DS, the peripheral blast count, age, and WBC count at each time point were significantly different in patients with DS (P < 0.05 for all time points). Generalized linear mixed models (GLMMs) revealed that WBC Double (Coeff. 0.442, P = 0.000) and WBCPeak (Coeff. 0.879, P = 0.000) were independent risk factors for DS. The frequencies of clinical manifestations of unexplained fever (P = 0.003), dyspnoea (P = 0.002), weight gain of more than 5 kg (P = 0.006), pleural effusion (P = 0.001), pulmonary infiltrates (P < 0.001), pericardial effusion (P = 0.002) and renal failure (P = 0.006) were considerably lower in moderate DS patients than in severe DS patients. The WBCDouble occurs earlier than the WBCpeak occurrence, so WBC Double might be a new indicator of DS.

Attempts to Improve Lipophilic Drugs' Solubility and Bioavailability: A Focus on Fenretinide

The development of numerous drugs is often arrested at clinical testing stages, due to their unfavorable biopharmaceutical characteristics. It is the case of fenretinide (4-HPR), a second-generation retinoid, that demonstrated promising in vitro cytotoxic activity against several cancer cell lines. Unfortunately, response rates in early clinical trials with 4-HPR did not confirm the in vitro findings, mainly due to the low bioavailability of the oral capsular formulation that was initially developed. Capsular 4-HPR provided variable and insufficient drug plasma levels attributable to the high hepatic first-pass effect and poor drug water solubility. To improve 4-HPR bioavailability, several approaches have been put forward and tested in preclinical and early-phase clinical trials, demonstrating generally improved plasma levels and minimal systemic toxicities, but also modest antitumor efficacy. The challenge is thus currently still far from being met. To redirect the diminished interest of pharmaceutical companies toward 4-HPR and promote its further clinical development, this manuscript reviewed the attempts made so far by researchers to enhance 4-HPR bioavailability. A comparison of the available data was performed, and future directions were proposed.

Drug repurposing for cancer therapy

Cancer, a complex and multifactorial disease, presents a significant challenge to global health. Despite significant advances in surgical, radiotherapeutic and immunological approaches, which have improved cancer treatment outcomes, drug therapy continues to serve as a key therapeutic strategy. However, the clinical efficacy of drug therapy is often constrained by drug resistance and severe toxic side effects, and thus there remains a critical need to develop novel cancer therapeutics. One promising strategy that has received widespread attention in recent years is drug repurposing: the identification of new applications for existing, clinically approved drugs. Drug repurposing possesses several inherent advantages in the context of cancer treatment since repurposed drugs are typically cost-effective, proven to be safe, and can significantly expedite the drug development process due to their already established safety profiles. In light of this, the present review offers a comprehensive overview of the various methods employed in drug repurposing, specifically focusing on the repurposing of drugs to treat cancer. We describe the antitumor properties of candidate drugs, and discuss in detail how they target both the hallmarks of cancer in tumor cells and the surrounding tumor microenvironment. In addition, we examine the innovative strategy of integrating drug repurposing with nanotechnology to enhance topical drug delivery. We also emphasize the critical role that repurposed drugs can play when used as part of a combination therapy regimen. To conclude, we outline the challenges associated with repurposing drugs and consider the future prospects of these repurposed drugs transitioning into clinical application.

Central venous catheters do not increase the hemorrhagic risk in acute promyelocytic leukemia patients during induction therapy

In acute promyelocytic leukemia (APL), hemorrhage, particularly intracranial hemorrhage, is the most common cause of early death. A central venous catheter (CVC) may provide a greater guarantee of safety and comfort to APL patients. However, CVCs have seldom been attempted in APL patients during induction therapy because of concerns about increasing the risk of hemorrhagic complications after this invasive procedure. To evaluate the hemorrhagic risk after CVC placement in APL patients during induction therapy, we retrospectively analyzed 95 newly diagnosed patients with APL from January 2010 to December 2022. Among these patients, 39 patients in the CVC group and 56 patients in the non-CVC group were included. Laboratory and clinical parameters of the two groups were collected and compared. There were no significant differences in median platelet, fibrinogen (Fbg), D-dimer, prothrombin time (PT), white blood count (WBC) and hemoglobin (Hb) between the CVC and non-CVC groups on the first day of the visit (day 0) and the following days (day 4, day 7, day 11, day 14, day 18 and day 21) (p = 0.382, p = 0.805, p = 0.456, p = 0.902, p = 0.901 and p = 0.097, respectively). The consumption of transfused platelets and Fbg was not significantly different between the CVC group and non-CVC group (5.0 vs. 4.5 units, p = 0.34, and 6.8 vs. 6.0, p = 0.36, respectively). The last day of platelet and Fbg transfusion was also not significantly different (21 vs. 19, p = 0.238 and 7.5 vs. 8.5, p = 0.684, respectively). The incidences of total hemorrhagic events and hemorrhagic death were lower in the CVC group than in the non-CVC group (17.9% vs. 37.5%, p = 0.04 and 0% vs. 16.1%, p = 0.01, respectively). The 30-day survival rate was not significantly different (92.3% vs. 82.1%, respectively, p = 0.145) for the CVC group compared with the non-CVC group. Our study suggested that CVCs did not increase the hemorrhagic risk in APL patients during induction therapy and that a CVC should be considered in this type of clinical situation.

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.

The ISTH DIC-score predicts early mortality in patients with non-promyelocitic acute myeloid leukemia

Coagulation disorders frequently complicate the clinical course of acute myeloid leukemia (AML) patients. This study examined the frequency and prognostic significance, with regards of early mortality, of the presence of overt disseminated intravascular coagulation (DIC) at AML diagnosis and its correlation with clinical and biological characteristics. A retrospective analysis of 351 newly diagnosed non-promyelocytic AML patients was conducted, utilizing the 2018 ISTH DIC-Score criteria to evaluate the presence of overt DIC at AML onset. The study cohort had a median age of 65 years with a predominance of male gender (59 %). Overt DIC was present in 21 % of cases and was associated with advanced age, comorbidities, poor performance status, hyperleukocytosis, LDH levels, NPM1 mutations, expression of CD33 and CD4, and lack of expression of CD34. With a median follow-up of 72 months (3-147 months), the 6-year overall survival (OS) was 17.4 %, with patients having overt DIC showing significantly poorer outcomes (7.2 % compared to 20.3 % of those without DIC, p < 0.001). Patients with overt DIC showed markedly high early mortality rates at 30 (42.5 % vs 8 %), 60 (49.3 % vs 16.9 %), and 120 days (64.4 % vs 25.6 %) from disease onset. In multivariate analysis overt DIC retained its independent prognostic value for early mortality. In conclusion, the prevalence and clinical relevance of DIC in non-promyelocytic AML is not negligible, underlining its potential as an unfavorable prognostic marker. In newly diagnosed patients with AML, early recognition and measure to counteract coagulation disturbances might help mitigate the elevated mortality risk associated with DIC.

A systematic review and meta-analysis of recombinant human soluble thrombomodulin for the treatment of DIC associated with hematological malignancies

BACKGROUND

Recombinant human soluble thrombomodulin (rhTM) is commonly used in Japan to treat disseminated intravascular coagulation (DIC), but its efficacy compared with other anticoagulants is unclear. We conducted a systematic review and meta-analysis to investigate this issue in DIC patients with hematological malignancies.

METHODS

We searched PubMed, Cochrane, and Scopus for prospective and retrospective studies evaluating the efficacy and safety of rhTM in DIC patients with hematological malignancies between April 2008 and April 2023. We performed a systematic review and meta-analysis evaluating recovery from DIC, hemorrhagic adverse events (AEs), and overall survival (OS).

RESULTS

We analyzed one prospective (64 patients) and seven retrospective studies (209 patients). Use of rhTM was associated with a higher rate of recovery from DIC (OR: 2.25 [1.09-4.63] and 1.98 [1.12-3.50] in prospective and retrospective studies, respectively; same order below) and fewer hemorrhagic AEs (OR: 0.83 [0.30-2.30] and 0.21 [0.08-0.57]). rhTM did not improve OS (OR: 1.06 [0.42-2.66] and 1.72 [0.87-3.39]), although the incidence of hemorrhagic death was lower in the rhTM group (0 of 94 patients).

CONCLUSION

Use of rhTM in patients with hematological malignancy-associated DIC is strongly expected to be effective and safe.

Double Emergency: A Case of Concurrent Heparin-Induced Thrombocytopenia and Acute Promyelocytic Leukemia

A 48-year-old woman presented to the hospital with acute pulmonary embolism in the setting of presumed apixaban failure and was transitioned to heparin. Rapidly progressive pancytopenia prompted workup with suspicion for heparin-induced thrombocytopenia (HIT) as well as peripheral blood smear concerning for acute promyelocytic leukemia (APL). She was emergently started on non-heparin anticoagulation and transferred to start APL-directed treatment. Both HIT and APL were confirmed with serotonin release assay (SRA) and promyelocytic leukemia/retinoic acid receptor alpha (PML-RARA) fusion assay, respectively. We present this case to remark on the novelty of these two acute diseases occurring together. Each of these entities is a hematologic emergency requiring immediate treatment before disease confirmation. We explore the mechanisms by which HIT occurs and outline the parameters for managing APL in the acute setting. Furthermore, this case serves to examine the treatment considerations for needing to carefully balance the thrombotic and hemorrhagic risk of both HIT and APL, which are clinically well-known for coagulopathy. Fortunately, HIT in this patient recovered on anticoagulation without bleeding or worsening thrombosis. Furthermore, following induction and consolidation treatment for APL, she remained negative for residual disease.

History of Developing Acute Promyelocytic Leukemia Treatment and Role of Promyelocytic Leukemia Bodies

The story of acute promyelocytic leukemia (APL) discovery, physiopathology, and treatment is a unique journey, transforming the most aggressive form of leukemia to the most curable. It followed an empirical route fueled by clinical breakthroughs driving major advances in biochemistry and cell biology, including the discovery of PML nuclear bodies (PML NBs) and their central role in APL physiopathology. Beyond APL, PML NBs have emerged as key players in a wide variety of biological functions, including tumor-suppression and SUMO-initiated protein degradation, underscoring their broad importance. The APL story is an example of how clinical observations led to the incremental development of the first targeted leukemia therapy. The understanding of APL pathogenesis and the basis for cure now opens new insights in the treatment of other diseases, especially other acute myeloid leukemias.

SOHO State of the Art Updates and Next Questions: Pre-emptive Therapy at Molecular Measurable Residual Disease Failure in Acute Myeloid Leukemia

Molecular measurable residual disease (MRD, eg, by real-time quantitative polymerase chain reaction, RT-qPCR), is an integral part of response assessment in acute myeloid leukemia (AML) with established prognostic and evolving therapeutic significance. MRD failure can occur through several pathways (namely MRD persistence at the end of treatment at a high level, MRD progression from a low level or MRD re-emergence during follow up; the latter two constitute MRD relapse as defined by the European Leukemia Net) and is clinically actionable, with survival benefit reported in AML subgroups. Selection of pre-emptive therapy at MRD failure relies upon an integrated clinico-molecular assessment and is subset-specific. In acute promyelocytic leukemia, arsenic trioxide-based regimen for MRD failure following frontline treatment with all-trans-retinoic acid plus chemotherapy represents standard of care, while hypomethylating agents (eg, azacitidine), salvage chemotherapy (eg, FLAG-IDA) and venetoclax-based regimens are effective in NPM1-mutated AML. Specific inhibitors of FLT3 have emerging use in FLT3-mutated AML and are associated with minimal toxicity. Furthermore, immunotherapeutic approaches such as donor lymphocyte infusions and interferon-⍺ are efficacious options in the post-allogeneic-HSCT settings. Enrollment into clinical trials with genomic-guided assignment of pre-emptive therapy at MRD failure should be prioritized. Finally, with the emergence of novel agents (eg, menin inhibitors) and approaches (eg, adoptive cellular and immunological therapy), an exciting future lies ahead where a broad array of highly active pre-emptive therapeutic options will likely be clinically applicable to a wide range of AML subsets.

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.

Disseminated Intravascular Coagulation in Acute Promyelocytic Leukemia Patients: A Retrospective Analysis of Outcomes and Healthcare Burden in US Hospitals

Objective

Acute promyelocytic leukemia (APL) is associated with an elevated risk of developing disseminated intravascular coagulation (DIC). The purpose of this study was to assess the outcomes of hospitalizations related to DIC in APL and their impact on healthcare.

Materials and Methods

This study entailed a cross-sectional and retrospective analysis of the US National Inpatient Sample database. We identified adults with APL and categorized them into groups of patients with and without DIC. Our focus areas included in-hospital mortality, length of stay, charges, and complications associated with DIC. Unadjusted odds ratios/coefficients were computed in univariate analysis, followed by adjusted odds ratios (aOR)/coefficients from multivariate analysis that accounted for confounding factors.

Results

Our analysis revealed that APL patients with DIC had a substantially higher aOR for mortality (aOR: 6.68, 95% confidence interval [CI]: 4.76-9.37, p<0.001) and a prolonged length of stay (coefficient: 10.28 days, 95% CI: 8.48-12.09, p<0.001) accompanied by notably elevated total hospital charges (coefficient: $215,512 [95% CI: 177,368-253,656], p<0.001), thereby emphasizing the reality of extended medical care and economic burden. The presence of DIC was associated with increased odds of sepsis, vasopressor support, pneumonia, acute respiratory failure, intubation/mechanical ventilation, and acute kidney injury, reflecting heightened vulnerability to these complications. Patients with DIC demonstrated significantly higher odds ratios for major bleeding, intracranial hemorrhage, gastrointestinal bleeding, red blood cell transfusion, platelet transfusion, fresh frozen plasma transfusion, and cryoprecipitate transfusion, highlighting the pronounced hematological risks posed by DIC.

Conclusion

This study has revealed the significant associations between DIC in APL and various outcomes, underscoring the clinical and economic implications of these conditions. The hematological risks further increase patients’ vulnerability to bleeding events and the need for transfusions.

Cellular hierarchy insights reveal leukemic stem-like cells and early death risk in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) represents a paradigm for targeted differentiation therapy, with a minority of patients experiencing treatment failure and even early death. We here report a comprehensive single-cell analysis of 16 APL patients, uncovering cellular compositions and their impact on all-trans retinoic acid (ATRA) response in vivo and early death. We unveil a cellular differentiation hierarchy within APL blasts, rooted in leukemic stem-like cells. The oncogenic PML/RARα fusion protein exerts branch-specific regulation in the APL trajectory, including stem-like cells. APL cohort analysis establishes an association of leukemic stemness with elevated white blood cell counts and FLT3-ITD mutations. Furthermore, we construct an APL-specific stemness score, which proves effective in assessing early death risk. Finally, we show that ATRA induces differentiation of primitive blasts and patients with early death exhibit distinct stemness-associated transcriptional programs. Our work provides a thorough survey of APL cellular hierarchies, offering insights into cellular dynamics during targeted therapy.

Incidence, risk factors, and outcomes of second neoplasms in patients with acute promyelocytic leukemia: the PETHEMA-PALG experience

The most important challenges in acute promyelocytic leukemia (APL) is preventing early death and reducing long-term events, such as second neoplasms (s-NPLs). We performed a retrospective analysis of 2670 unselected APL patients, treated with PETHEMA "chemotherapy based" and "chemotherapy free" protocols. Only de novo APL patients who achieved complete remission (CR) and completed the three consolidation cycles were enrolled into the analysis. Out of 2670 APL patients, there were 118 (4.4%) who developed s-NPLs with the median latency period (between first CR and diagnosis of s-NPL) of 48.0 months (range 2.8-231.1): 43.3 (range: 2.8-113.9) for s-MDS/AML and 61.7 (range: 7.1-231.1) for solid tumour. The 5-year CI of all s-NPLs was of 4.43% and 10 years of 7.92%. Among s-NPLs, there were 58 cases of s-MDS/AML, 3 cases of other hematological neoplasms, 57 solid tumours and 1 non-identified neoplasm. The most frequent solid tumour was colorectal, lung and breast cancer. Overall, the 2-year OS from diagnosis of s-NPLs was 40.6%, with a median OS of 11.1 months. Multivariate analysis identified age of 35 years (hazard ratio = 0.2584; p < 0.0001) as an independent prognostic factor for s-NPLs. There were no significant differences in CI of s-NPLs at 5 years between chemotherapy-based vs chemotherapy-free regimens (hazard ratio = 1.09; p = 0.932). Larger series with longer follow-up are required to confirm the potential impact of ATO+ATRA regimens to reduce the incidence of s-NPLs after front-line therapy for APL.

In vitro bioaccessibility and intestinal transport of retinoic acid in ethyl cellulose-based microparticles and impact of meal co-ingestion

The development of carrier-based delivery systems for oral administration of retinoic acid (RA), that provides its release and absorption at intestinal level, is of major relevance in the treatment of acute promyelocytic leukemia. The aim of this work was to evaluate RA bioaccessibility and intestinal transport on ethyl cellulose (EC)- and EC + polyethylene glycol (ECP)-based microparticles and to understand the impact of meal co-ingestion by applying in vitro assays. RA-loaded microparticles were produced by spray-drying with an encapsulation efficiency higher than 90 % for both formulations. The gastric bioaccessibility of RA (after in vitro static digestion of RA-loaded particles) was lower than 3 % for both types of microparticles, with and without meal co-ingestion. Whereas after intestinal digestion, RA bioaccessibility was significantly higher and affected by the type of microparticles and the presence of meal. The digestion of EC- and ECP-based microparticles without diet enabled a significantly higher bioaccessibility of RA when compared to the one recorded for the co-digestion of these microparticles with diet. Herein, RA bioaccessibility decreased from 84 ± 1 to 24 ± 6 % (p < 0.0001) for microparticles EC and 54 ± 4 to 25 ± 5 % (p < 0.001) for microparticles ECP. Moreover, comparing both types of microparticles, RA bioaccessibility was significantly higher for EC-based microparticles digested without diet (p < 0.0001). At last, the bioaccessibility of RA was similar among EC- and ECP-based microparticles when co-digested with diet. Intestinal transport experiments performed in Caco-2 monolayers evidenced that after 2 h of transport the amount of RA retained in the apical compartment was higher than the amount that reached the basolateral compartment evidencing a slow transport at intestinal level that was higher when RA is spiked in the blank of digestion and the meal digestion samples compared to RA dissolved in HBSS (44 ± 6 (p < 0.01) and 38 ± 1 (p < 0.05) vs 26 ± 2 %, respectively).

Research Progress on the Use of Metformin in Leukemia Treatment

OPINION STATEMENT

Metformin is a first-line drug in the clinical treatment of type 2 diabetes. Its main molecular mechanism involves the activation of adenosine 5'-monophosphate-activated protein kinase (AMPK), which regulates cell energy metabolism. Many clinical studies have shown that metformin can reduce the incidence and mortality of cancer in patients with or without diabetes. In vitro studies also confirmed that metformin can inhibit proliferation, promote apoptosis, and enhance the response of cells to chemical drugs and other anticancer effects on a variety of leukemia cells. In recent years, leukemia has become one of the most common malignant diseases. Although great progress has been made in therapeutic approaches for leukemia, novel drugs and better treatments are still needed to improve the therapeutic efficacy of these treatments. This article reviews the application status and possible mechanism of metformin in the treatment of leukemia to further understand the anticancer mechanism of metformin and expand its clinical application.

Tetraarsenic tetrasulfide triggers ROS-induced apoptosis and ferroptosis in B-cell acute lymphoblastic leukaemia by targeting HK2

PURPOSE

Acute lymphoblastic leukemia (ALL) is the most common type of cancer diagnosed in children. Despite cure rates of higher than 85 %, refractory or relapsed ALL still exhibits a bleak prognosis indicative of the dearth of treatment modalities specific for relapsed or refractory ALL. Prior research has implicated metabolic alterations in leukemia pathogenesis, and literature on the therapeutic efficacy of arsenic compounds targeting metabolic pathways in B-cell acute lymphoblastic leukemia (B-ALL) cells is scarce.

METHODS

A compound extracted from realgar, tetraarsenic tetrasulfide (As4S4), and its antitumor effects on B-ALL were experimentally examined in vitro and in vivo.

RESULTS

As4S4 apparently targets B-ALL cells by inducing specific cellular responses, including apoptosis, G2/M arrest, and ferroptosis. Interestingly, these effects are attributed to reactive oxygen species (ROS) accumulation, and increased ROS levels have been linked to both the mitochondria-dependent caspase cascade and the activation of p53 signaling. The ROS scavenger N-acetylcysteine (NAC) can counteract the effects of As4S4 treatment on Nalm-6 and RS4;11 cells. Specifically, by targeting Hexokinase-2 (HK2), As4S4 induces alterations in mitochondrial membrane potential and disrupts glucose metabolism, leading to ROS accumulation, and was shown to inhibit B-ALL cell proliferation in vitro and in vivo. Intriguingly, overexpression of HK2 can partially desensitize B-ALL cells to As4S4 treatment.

CONCLUSION

Tetraarsenic tetrasulfide can regulate the Warburg effect by controlling HK2 expression, a finding that provides both new mechanistic insight into metabolic alterations and pharmacological evidence for the clinical treatment of B-ALL.

Transcatheter arterial chemoembolization using CalliSpheres beads loaded with arsenic trioxide for unresectable large or huge hepatocellular carcinoma: a prospective study

OBJECTIVES

To determine the safety and efficacy of transcatheter arterial chemoembolization with CalliSpheres® beads loaded with arsenic trioxide (CBATO-TACE) in the first-line treatment of patients with large (5 cm ≤ maximum diameter < 10 cm) or huge (maximum diameter ≥ 10 cm) hepatocellular carcinoma (HCC).

METHODS

Patients were randomly allocated to the CBATO-TACE group and the conventional transcatheter arterial chemoembolization (cTACE) group. The primary endpoint was progression-free survival (PFS). The secondary endpoint was overall survival (OS), treatment response, and treatment-related adverse events (TRAEs). The extrahepatic collateral arteries, liver function, and liver fibrosis after the first TACE were also evaluated.

RESULTS

From September 2018 to September 2020, a total of 207 patients who underwent TACE were consecutively enrolled in this study. The median PFS was 9.5 months (range: 8.0 - 11.0) in the CBATO group, which was significantly longer than that in the cTACE group (6.0 months, range: 4.0-6.0) (p < 0.0001). Patients in the CBATO group had a median OS of 22 months (range: 20.0 - 27.0) compared with 16 months (range: 15.0 - 20.0) in the cTACE group (p = 0.0084). The most common TRAEs were fever (p = 0.043), and nausea and vomiting (p = 0.002), which were more observed in the cTACE group. In addition, the progressive disease time, pulmonary metastasis rate (p = 0.01), the mean number of extrahepatic collateral arteries (p = 0.01), and average number of TACE sessions (p = 0.025) were significantly decreased in the CBATO group.

CONCLUSIONS

CBATO-TACE achieved better therapeutic outcomes and similar safety profile compared to cTACE in large or huge HCC patients. Furthermore, CBATO-TACE was able to reduce extrahepatic collateral arteries production and extrahepatic lung metastasis.

CLINICAL RELEVANCE STATEMENT

Our study showed that CalliSpheres® beads loaded with arsenic trioxide (CBATO-TACE) were effective and safe for the treatment of large and giant HCC. In addition, CBATO-TACE can reduce lateral hepatic branch artery formation and extrahepatic pulmonary metastasis, which provides a new treatment approach for unresectable HCC.

KEY POINTS

• We compare long-term efficacy and safety of transcatheter arterial chemoembolization with CalliSpheres® beads loaded with arsenic trioxide (CBATO-TACE) and conventional transcatheter arterial chemoembolization (cTACE) in patients with large (5 cm ≤ maximum diameter < 10 cm) or huge HCC (maximum diameter ≥ 10 cm). • Compared with cTACE, CBATO-TACE significantly improved therapeutic outcomes, overall survival, and progression-free survival in patients with large or huge HCC. The safety assessment suggested that CBATO-TACE is a safe treatment that improves the quality of life and has good treatment adherence.

Risk stratification for early mortality in newly diagnosed acute promyelocytic leukemia: a multicenter, non-selected, retrospective cohort study

Introduction

Despite the current effective treatments for acute promyelocytic leukemia (APL), early mortality (EM), defined as death within 30 days of presentation, is a major hurdle to long-term survival.

Methods

We performed a multicenter retrospective study to evaluate the incidence and clinical characteristics of EM in patients with newly diagnosed APL and to develop a risk stratification model to predict EM.

Results

We identified 313 eligible patients diagnosed between 2000 and 2021 from five academic hospitals. The median age was 50 years (range 19-94), and 250 (79.9%) patients were <65 years. Most patients (n=274, 87.5%) received their first dose of all-trans retinoic acid (ATRA) within 24 hours of presentation. EM occurred in 41 patients, with a cumulative incidence of 13.1%. The most common cause of EM was intracranial hemorrhage (n=22, 53.6%), and most EMs (31/41, 75.6%) occurred within the first seven days of APL presentation. In a multivariable analysis, we identified three independent factors predicting EM: age ≥65 years (HR, 2.56), white blood cell count ≥8.0 x 109/L (HR, 3.30), and ATRA administration >24 hours of presentation (HR, 2.95). Based on these factors, patients were stratified into three categories with a significantly increasing risk of EM: 4.1% for low risk (54.3%; no risk factors; HR 1), 18.5% for intermediate risk (34.5%; 1 factor; HR 4.81), and 40.5% for high risk (11.2%; 2-3 factors; HR 13.16).

Discussion

The risk of EM is still not negligible in this era of ATRA-based therapies. Our risk model serves as a clinically useful tool to identify high-risk patients for EM who may be candidates for novel treatments and aggressive supportive strategies.

Retinoic acid signaling in development and differentiation commitment and its regulatory topology

Retinoic acid (RA), the derivative of vitamin A/retinol, is a signaling molecule with important implications in health and disease. It is a well-known developmental morphogen that functions mainly through the transcriptional activity of nuclear RA receptors (RARs) and, uncommonly, through other nuclear receptors, including peroxisome proliferator-activated receptors. Intracellular RA is under spatiotemporally fine-tuned regulation by synthesis and degradation processes catalyzed by retinaldehyde dehydrogenases and P450 family enzymes, respectively. In addition to dictating the transcription architecture, RA also impinges on cell functioning through non-genomic mechanisms independent of RAR transcriptional activity. Although RA-based differentiation therapy has achieved impressive success in the treatment of hematologic malignancies, RA also has pro-tumor activity. Here, we highlight the relevance of RA signaling in cell-fate determination, neurogenesis, visual function, inflammatory responses and gametogenesis commitment. Genetic and post-translational modifications of RAR are also discussed. A better understanding of RA signaling will foster the development of precision medicine to improve the defects caused by deregulated RA signaling.

Vitamin C enhances the sensitivity of osteosarcoma to arsenic trioxide via inhibiting aerobic glycolysis

Osteosarcoma (OS) is a common malignant tumor disease in the department of orthopedics, which is prone to the age of adolescents and children under 20 years old. Arsenic trioxide (ATO), an ancient poison, has been reported to play a critical role in a variety of tumor treatments, including OS. However, due to certain poisonous side effects such as cardiotoxicity and hepatotoxicity, clinical application of ATO has been greatly limited. Here we report that low doses of ATO (1 μM) observably reduced the half-effective inhibitory concentration (IC50) of vitamin C on OS cells. Compared with the treatment alone, the synthetic application of vitamin C (VitC, 800 μM) and ATO (1 μM) significantly further inhibited the proliferation, migration, and invasion of OS cells and promoted cell apoptosis in vitro. Meanwhile, we observed that the combined application of VitC and ATO directly suppresses the aerobic glycolysis of OS cells with the decreased production of pyruvate, lactate, and ATP via inhibiting the expression of the critical glycolytic genes (PGK1, PGM1, and LDHA). Moreover, the combination of VitC (200 mg/kg) and ATO (1 mg/kg) with tail vein injection significantly delayed OS growth and migration of nude mice by inhibiting aerobic glycolysis of OS. Thus, our results demonstrate that VitC effectively increases the sensitivity of OS to low concentrations of ATO via inhibiting aerobic glycolysis to alleviate the toxic side effects of high doses of arsenic trioxide, suggesting that synthetic application of VitC and ATO is a promising approach for the clinical treatment of human OS.

Different Isoforms of PML-RARA Chimeric Protein in Patients with Acute Promyelocytic Leukemia: Survival Analysis per Demographic Characteristics, Clinicohematological Parameters, and Cytogenetic Findings

Background & Objective

Acute Promyelocytic Leukemia (APL) is a medical emergency with potentially fatal complications. APL primarily results from a chromosomal translocation (t(15;17)(q22;q21)), leading to the formation of the PML-RARA fusion gene with three possible isoforms. This study aims to investigate the characteristics of Iranian APL patients, the distribution of PML-RARA isoforms, and survival analysis.

Methods

We included 145 consecutive eligible patients in this study. Data were collected through archived documents and phone inquiries, following consent. Subsequently, we analyzed the data using SPSS software version 26.0.

Results

We examined 75 men and 70 women, with a mean age of 34 years (range: 2-78 years). Besides t(15;17) (q22;q21), 45.6% had other chromosomal abnormalities. The prevalence of bcr1 and bcr3 isoforms was 73% and 27%, respectively. bcr3 correlated with higher white blood cell (WBC) counts, additional chromosomal abnormalities, and faster Complete Hematologic Response (CHR). Early death occurred in approximately 36% of all patients. The mean overall survival time was 73.5 months, with 120-month survival rates of 53.8% for all patients and 83.9% for those who achieved CHR. Univariate analysis identified old age, relapse, lower platelet (PLT) counts, higher WBC counts, and leukocytosis as survival risk factors. However, in multivariate analysis, only old age and higher WBC counts were identified as adverse prognostic factors.

Conclusion

In Iranian APL patients, bcr1 predominates, while bcr3 correlates with higher WBC counts, high-risk categorization, additional chromosomal abnormalities, and faster CHR. Survival is negatively impacted by old age, relapse, lower PLT counts, higher WBC counts, and leukocytosis.

How to avoid early mortality in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL), a phenotypically and genotypically unique subtype of acute myeloid leukemia, has seen unprecedented advances in its management since the introduction of all-trans retinoic acid (ATRA) and arsenic trioxide. However, the phenomenal pharmacologic conversion of this once highly fatal disease to one with a long-term survival exceeding 90% among patients who survive induction remains impaired by the significant incidence of early death (ED) reaching 30% in some real-world studies. The key driver for ED in APL is catastrophic hemorrhage with a proclivity for cranial sites. Most EDs in APL are currently considered preventable. Here, we discuss the concept of early death in APL and its characteristics. Importantly, we outline implementable strategies to reduce the incidence of ED. Early recognition of APL underpins these preventive measures as significant delays in the diagnosis increase the likelihood of ED. While early administration of ATRA is often taught to all hematology trainees, this lifesaving intervention is only possible if providers, including those in emergency departments and urgent/immediate care settings, are trained to have a high index of suspicion and competence to recognize the morphologic and clinical characteristics of the disease. Other proposed strategies tackle the complications that can be present at diagnosis or arise during induction therapy and address the issues of expert consultation and protocol adherence in the management of these patients. While some of these measures appear intuitive and others aspirational, widespread adoption could bring about an era of cure for almost every patient with APL.

Long-term outcome of children with acute promyelocytic leukemia: a randomized study of oral versus intravenous arsenic by SCCLG-APL group

Realgar-Indigo naturalis formula (RIF), an oral traditional Chinese medicine mainly containing Realgar (As4S4), is highly effective in treating adult acute promyelocytic leukemia (APL). However, the treatment efficacy and safety of RIF have not been verified in pediatric patients. SCCLG-APL group conducted a multicenter randomized non-inferiority trial to determine whether intravenous arsenic trioxide (ATO) can be substituted by oral RIF in treating pediatric APL. Of 176 eligible patients enrolled, 91 and 85 were randomized to ATO and RIF groups, respectively. Patients were treated with the risk-adapted protocol. Induction, consolidation, and 96-week maintenance treatment contained all-trans-retinoic acid and low-intensity chemotherapy, and either ATO or RIF. The primary endpoint was 5-year event-free survival (EFS). The secondary endpoints were adverse events and hospital days. After a median 6-year follow-up, the 5-year EFS was 97.6% in both groups. However, the RIF group had significantly shorter hospital stays and lower incidence of infection and tended to have less cardiac toxicity. All 4 relapses occurred within 1.5 years after completion of maintenance therapy. No long-term arsenic retentions were observed in either group. Substituting oral RIF for ATO maintains treatment efficacy while reducing hospitalization and adverse events in treating pediatric APL patients, which may be a future treatment strategy for APL.

Acute myeloid leukemia: challenges for diagnosis and treatment in Latin America

OBJECTIVE

to review the current diagnostic and therapeutic landscape of AML in Latin America as a reflection of other low- and middle-income countries and regions of the world. Encompassing both acute promyelocytic and non-promyelocytic disease types.

METHODS

We reviewed the literature and study registries concerning epidemiological features of patients with AML/APL treated in Latin America, as well as evaluated diagnostic and genetic stratification and patient fitness assessment challenges, the importance of early mortality and supportive care capacity, intensive and non-intensive chemotherapy alternatives, consolidation, and maintenance strategies including novel agents and hematopoietic stem cell transplantation.

RESULTS

Although most of the current technologies and treatment options are available in the region, a significant fraction of patients have only limited access to them. In addition, mortality in the first weeks from diagnosis is higher in the region compared to developed countries.

CONCLUSIONS

Disparities in access to technologies, supportive care capacity, and availability of novel agents and HSCT hinder results in our region, reflecting barriers common to other LMICs. Recent developments in the diagnosis and treatment of this disease must be implemented through education, collaborative clinical research, and advocacy to improve outcomes.

A Review of Childhood Acute Myeloid Leukemia: Diagnosis and Novel Treatment

Acute myeloid leukemia (AML) is the second most common hematologic malignancy in children. The incidence of childhood AML is much lower than acute lymphoblastic leukemia (ALL), which makes childhood AML a rare disease in children. The role of genetic abnormalities in AML classification, management, and prognosis prediction is much more important than before. Disease classifications and risk group classifications, such as the WHO classification, the international consensus classification (ICC), and the European LeukemiaNet (ELN) classification, were revised in 2022. The application of the new information in childhood AML will be upcoming in the next few years. The frequency of each genetic abnormality in adult and childhood AML is different; therefore, in this review, we emphasize well-known genetic subtypes in childhood AML, including core-binding factor AML (CBF AML), KMT2Ar (KMT2A/11q23 rearrangement) AML, normal karyotype AML with somatic mutations, unbalanced cytogenetic abnormalities AML, NUP98 11p15/NUP09 rearrangement AML, and acute promyelocytic leukemia (APL). Current risk group classification, the management algorithm in childhood AML, and novel treatment modalities such as targeted therapy, immune therapy, and chimeric antigen receptor (CAR) T-cell therapy are reviewed. Finally, the indications of hematopoietic stem cell transplantation (HSCT) in AML are discussed.

Anti-tumor activity of all-trans retinoic acid in gastric-cancer: gene-networks and molecular mechanisms

BACKGROUND

Gastric-cancer is a heterogeneous type of neoplastic disease and it lacks appropriate therapeutic options. There is an urgent need for the development of innovative pharmacological strategies, particularly in consideration of the potential stratified/personalized treatment of this tumor. All-Trans Retinoic-acid (ATRA) is one of the active metabolites of vitamin-A. This natural compound is the first example of clinically approved cyto-differentiating agent, being used in the treatment of acute promyelocytic leukemia. ATRA may have significant therapeutic potential also in the context of solid tumors, including gastric-cancer. The present study provides pre-clinical evidence supporting the use of ATRA in the treatment of gastric-cancer using high-throughput approaches.

METHODS

We evaluated the anti-proliferative action of ATRA in 27 gastric-cancer cell-lines and tissue-slice cultures from 13 gastric-cancer patients. We performed RNA-sequencing studies in 13 cell-lines exposed to ATRA. We used these and the gastric-cancer RNA-sequencing data of the TCGA/CCLE datasets to conduct multiple computational analyses.

RESULTS

Profiling of our large panel of gastric-cancer cell-lines for their quantitative response to the anti-proliferative effects of ATRA indicate that approximately half of the cell-lines are characterized by sensitivity to the retinoid. The constitutive transcriptomic profiles of these cell-lines permitted the construction of a model consisting of 42 genes, whose expression correlates with ATRA-sensitivity.  The model predicts that 45% of the TCGA gastric-cancers are sensitive to ATRA. RNA-sequencing studies performed in retinoid-treated gastric-cancer cell-lines provide insights into the gene-networks underlying ATRA anti-tumor activity. In addition, our data demonstrate that ATRA exerts significant immune-modulatory effects, which seem to be largely controlled by IRF1 up-regulation. Finally, we provide evidence of a feed-back loop between IRF1 and DHRS3, another gene which is up-regulated by ATRA.

CONCLUSIONS

ATRA is endowed with significant therapeutic potential in the stratified/personalized treatment gastric-cancer. Our data represent the fundaments for the design of clinical trials focusing on the use of ATRA in the personalized treatment of this heterogeneous tumor. Our gene-expression model will permit the development of a predictive tool for the selection of ATRA-sensitive gastric-cancer patients. The immune-regulatory responses activated by ATRA suggest that the retinoid and immune-checkpoint inhibitors constitute rational combinations for the management of gastric-cancer.

Long-term experience in treatment of acute promyelocytic leukemia in Mexican children in a tertiary care hospital

Introduction

Acute promyelocytic leukemia (APL) is a rare myeloid leukemia subtype affecting adult and pediatric populations. APL constitutes 15-20% of all childhood AML in Latin America, compared to 7% in the non-Latino population. This leukemia has unique characteristics, such as its association with chromosomal translocations involving the retinoid acid receptor α (RARA) gene on chromosome 17. In addition, APL is also distinct from other AML subtypes due to its response to all-trans-retinoic acid (ATRA), which induces terminal granulocytic differentiation of blasts. Overall 5-year survival rates are generally reported to be greater than 80%.

Materials and methods

A study was conducted from January 2008 to December 2022 applying the IC-APL 2006 treatment protocol. This case series reports the clinical results of 22 children with APL. In all cases, the diagnosis was made by bone marrow aspiration and evaluation of the t(15:17) or t(11:17) transcripts.

Results

We identified 22 patients with APL, of whom 10 were female and 12 were male. Twelve patients debuted with coagulation abnormalities. The doses of anthracyclines varied according to the risk, with an average of 496.8 mgm2. The cardiological assessment was performed before and after chemotherapy, finding 2/22 patients with moderate sisto-diastolic dysfunction and one with mild pulmonary insufficiency at the end of treatment. There were 6/22 patients with complications related to ATRA treatment, the most frequent being pseudotumor cerebri. All complications were transitory and treated immediately without complications. In this series of cases, an overall survival of 90.6% and a relapse-free survival of 90.6% were recorded. The follow-up mean was 9.1 ± 3.8 years.

Conclusion

APL is a highly curable disease when combined with ATRA and anthracyclines. In this series of cases, good long-term results were observed with the IC-APL 2006 protocol. However, in Latin America, the availability of drugs such as arsenic trioxide as the first line of treatment is an unresolved challenge.

Metformin reduces hepatocarcinogenesis by inducing downregulation of Cyp26a1 and CD8+ T cells

BACKGROUND

Hepatocellular carcinoma (HCC) is a highly heterogeneous cancer with major challenges in both prevention and therapy. Metformin, adenosine monophosphate-activated protein kinase (AMPK) activator, has been suggested to reduce the incidence of HCC when used for patients with diabetes in preclinical and clinical studies. However, the possible effects of metformin and their mechanisms of action in non-diabetic HCC have not been adequately investigated.

METHODS

Fah-/-  mice were used to construct a liver-injury-induced non-diabetic HCC model for exploring hepatocarcinogenesis and therapeutic potential of metformin. Changes in relevant tumour and biochemical indicators were measured. Bulk and single-cell RNA-sequencing analyses were performed to validate the crucial role of proinflammatory/pro-tumour CD8+ T cells. In vitro and in vivo experiments were performed to confirm Cyp26a1-related antitumour mechanisms of metformin.

RESULTS

RNA-sequencing analysis showed that chronic liver injury led to significant changes in AMPK-, glucose- and retinol metabolism-related pathways in Fah-/- mice. Metformin prevented the formation of non-diabetic HCC in Fah-/- mice with chronic liver injury. Cyp26a1 ddexpression in hepatocytes was significantly suppressed after metformin treatment. Moreover, downregulation of Cyp26a1 occurred in conjunction with increased levels of all-trans-retinoic acid (atRA), which is involved in the activation of metformin-suppressed hepatocarcinogenesis in Fah-/- mice. In contrast, both CD8+  T-cell infiltration and proinflammatory/pro-tumour cytokines in the liver were significantly upregulated in Fah-/- mice during chronic liver injury, which was notably reversed by either metformin or atRA treatment. Regarding mechanisms, metformin regulated the decrease in Cyp26a1 enzyme expression and increased atRA expression via the AMPK/STAT3/Gadd45β/JNK/c-Jun pathway.

CONCLUSIONS

Metformin inhibits non-diabetic HCC by upregulating atRA levels and downregulating CD8+ T cells. This is the first reporting that the traditional drug metformin regulates the metabolite atRA via the Cyp26a1-involved pathway. The present study provides a potential application of metformin and atRA in non-diabetic HCC.

Predictors of very early death in acute promyelocytic leukemia: a retrospective real-world cohort study

Early death (ED) is still the major obstacle to cure in acute promyelocytic leukemia (APL). Most studies focus on 30-day ED; however, little is known on predictors of death before starting APL treatment (very early death - VED) and on predictors of 7-day ED, the period with most deaths due to thrombohemorrhagic diathesis. We hypothesized whether the severity of the coagulopathy of APL could predict VED and 7-day ED. We also aimed to evaluate other characteristics associated with these outcomes. We undertook a retrospective, single-center observational study including newly diagnosed APL patients admitted to our institution between January 2000 and November 2022. Baseline demographical, clinical, and laboratorial data were collected. Statistical analysis was performed using Stata. One hundred four patients were included. The VED rate was 4.8%. A DIC Score ≥ 7 (p = 0.045), serum creatinine > 1.5 mg/dL (p < 0.001%), a DIC Score ≥ 6 within 24 h (p = 0.009), and mechanical ventilation (p < 0.001) were associated with VED. The 7-day ED rate was 12.5%. High-risk (p = 0.007) and hypogranular APL (p = 0.029), DIC Score at diagnosis (p = 0.047), DIC Score ≥ 7 (p = 0.043), DIC Score ≥ 6 within 24 h (p = 0.025), PT prolongation > 6 s (p = 0.002), and creatinine > 1.5 mg/dL (p = 0.004) were associated with 7-day ED. However, only elevated creatinine emerged as an independent predictor of 7-day ED (OR 21.4; p = 0.008). Our study shows that in patients with APL, an elevated creatinine at diagnosis strongly predicts for 7-day ED. A DIC Score ≥ 7 and a Score that remains ≥ 6 within 24 h and a serum creatinine > 1.5 mg/dL significantly associated with VED.

Deciphering the toxicity-effect relationship and action patterns of traditional Chinese medicines from a smart data perspective: a comprehensive review

In Chinese medicine, the primary considerations revolve around toxicity and effect. The clinical goal is to achieve maximize effect while minimizing toxicity. Nevertheless, both clinical and experimental research has revealed a distinct relationship between these two patterns of action in toxic Traditional Chinese Medicines (TCM). These TCM often exhibit characteristic "double-sided" or "multi-faceted" features under varying pathological conditions, transitioning between effective and toxic roles. This complexity adds a layer of challenge to unraveling the ultimate objectives of Traditional Chinese medicine. To address this complexity, various hypotheses have been proposed to explain the toxicity and effect of Traditional Chinese Medicines. These hypotheses encompass the magic shrapnel theory for effect, the adverse outcome pathway framework, and the indirect toxic theory for toxicity. This review primarily focuses on high-, medium-, and low-toxicity Traditional Chinese Medicines as listed in Chinese Pharmacopoeia. It aims to elucidate the essential intrinsic mechanisms and elements contributing to their toxicity and effectiveness. The critical factors influencing the mechanisms of toxicity and effect are the optimal dosage and duration of TCM administration. However, unraveling the toxic-effect relationships in TCM presents a formidable challenge due to its multi-target and multi-pathway mechanisms of action. We propose the integration of multi-omics technology to comprehensively analyze the fundamental metabolites, mechanisms of action, and toxic effects of TCM. This comprehensive approach can provide valuable insights into the intricate relationship between the effect and toxicity of these TCM.

Association of CDSS score and 60-day mortality in Chinese patients with non-APL acute myeloid leukemia: a retrospective cohort study

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy, and is one of the triggers of DIC, the latter is an essential factor in the early death of patients with AML. However, the timely identification of DIC remains a challenge. The Chinese DIC Scoring System (CDSS) is a common consensus widely used in China; but, there are few reports on its application in patients with AML. We undertake this retrospective cohort study to investigate the association between CDSS score and 60-day mortality. CDSS scores were evaluated after admission. The outcome was all-cause 60-day mortality. Multivariate Cox regression analyses were performed to calculate the adjusted hazard ratio (HR) and the corresponding 95% confidence interval (CI). Survival curves were plotted by Kaplan-Meier and log-rank analyses. Subgroup analyses were stratified by relevant effect covariates. A total of 570 consecutive patients with primary AML were included. We found an association between a 39% increase in 60-day mortality and a 1 point increase in CDSS score (HR = 1.39, 95% CI 1.25-1.54), which was associated with a 189% increase in 60-day mortality in CDSS scores ≥ 6 compared with that in the CDSS scores < 6 (HR = 2.89, 95% CI 1.91-4.38). After adjusting for all potential con-founders, a 27% and a 198% increase were observed (HR = 1.27, 95% CI 1.01-1.61; HR = 2.98, 95% CI 1.24-7.19), respectively. There is association between 60-day mortality and CDSS score in patients with AML. These findings may help hematologists in making informed treatment decisions.

Cytogenetics in the management of acute myeloid leukemia and histiocytic/dendritic cell neoplasms: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Genetic data are becoming increasingly essential in the management of hematological neoplasms as shown by two classifications published in 2022: the 5th edition of the World Health Organization Classification of Hematolymphoid Tumours and the International Consensus Classification of Myeloid Neoplasms and Acute Leukemias. Genetic data are particularly important for acute myeloid leukemias (AMLs) because their boundaries with myelodysplastic neoplasms seem to be gradually blurring. The first objective of this review is to present the latest updates on the most common cytogenetic abnormalities in AMLs while highlighting the pitfalls and difficulties that can be encountered in the event of cryptic or difficult-to-detect karyotype abnormalities. The second objective is to enhance the role of cytogenetics among all the new technologies available in 2023 for the diagnosis and management of AML.

Utility of end of induction bone marrow biopsy and survival outcomes in acute promyelocytic leukemia treated with fixed-dose induction regimen

Significant variations exist related to the end of induction practices in the management of Acute Promyelocytic Leukemia (APL). These variations include all-trans retinoic acid (ATRA)-arsenic trioxide (ATO) in fixed doses versus continuation until hematologic complete remission (CR) and performance versus omission of post-induction bone marrow biopsy to confirm morphological CR. A retrospective chart review was conducted of 61 patients (42 low/intermediate-risk and 19 high-risk) aged ≥ 18 years with newly diagnosed APL treated with fixed duration ATRA-ATO +/- cytoreduction at a tertiary medical center from December 2012 through March 2020. Of the 54 patients with post-induction bone marrow biopsy results, 52 (96%) demonstrated no morphologic evidence of APL while the remaining were equivocal. After 2.6 years median follow-up, no relapses occurred. The estimated 2-year overall survival rate of 95% suggests excellent outcomes with a fixed ATO induction regimen and safe omission of post-induction bone marrow biopsy irrespective of hematologic parameters.

Differentiation Syndrome in Acute Leukemia: APL and Beyond

Differentiation syndrome (DS) is a frequent and potentially life-threatening clinical syndrome first recognized with the advent of targeted therapeutics for acute promyelocytic leukemia (APL). DS was subsequently observed more broadly with targeted therapeutics for acute myeloid leukemia (AML). DS is typically characterized by fever, dyspnea, hypotension, weight gain, pleural or pericardial effusions, and acute renal failure. The incidence in patients with APL ranges from 2 to 37%, with the wide variation likely attributed to different diagnostic criteria, use of prophylactic treatment, and different treatment regimens. Treatment with corticosteroids +/- cytoreductive therapy should commence as soon as DS is suspected to reduce DS-related morbidity and mortality. The targeted anti-leukemic therapy should be discontinued in patients with severe DS. Here, we discuss the pathogenesis of DS, clinical presentations, diagnostic criteria, management strategies, and implementation of prospective tracking on clinical trials.

Maintenance therapy in acute myeloid leukemia: advances and controversies

The last decade has seen steadfast progress in drug development in acute myeloid leukemia (AML) which has moved progressively towards genomic-based therapy. With these advances, outcomes in AML have improved but remains far from satisfactory. One approach towards preventing relapse in AML is to use maintenance therapy in patients, after attaining remission. Allogeneic hematopoietic stem cell transplantation (HSCT) is an effective post-remission therapy that has been proven to reduce the risk of relapse. However, in patients who are ineligible for HSCT or have a high risk of relapse, other effective measures to prevent relapse are needed. There is also a need for post-HSCT maintenance to reduce relapse in high-risk subsets. Over the last 3 decades maintenance therapy in AML has evolved from the use of chemotherapeutic agents to more targeted therapies and better modulation of the immune system. Unfortunately, improvements in survival outcomes as a result of using these agents have not been consistently demonstrated in clinical trials. To derive the optimum benefit from maintenance therapy the time points of therapy initiation need to be defined and therapy must be selected precisely with respect to the AML genetics and risk stratification, prior treatment exposure, transplant eligibility, expected toxicity and the patient's clinical profile and desires. The far-reaching goal is to facilitate patients with AML in remission to achieve a normal quality of life while improving remission duration and overall survival. The QUAZAR trial was a welcome step towards a safe maintenance drug that is easy to administer and showed survival benefit but leaves many open issues for discussion. In this review we will discuss these issues, highlighting the development of AML maintenance therapies over the last 3 decades.

Cytogenetically Cryptic Acute Promyelocytic Leukemia: A Diagnostic Challenge

Cytogenetically cryptic acute promyelocytic leukemia (APL) is rare, characterized by typical clinical and morphological features, but lacks t(15;17)(q24;q21)/PML::RARA translocation seen in conventional karyotyping or FISH. The prompt diagnosis and treatment of APL are critical due to life-threatening complications associated with this disease. However, cryptic APL cases remain a diagnostic challenge that could mislead the appropriate treatment. We describe four cryptic APL cases and review reported cases in the literature. Reverse transcriptase polymerase chain reaction (RT-PCR) is the most efficient diagnostic modality to detect these cases, and alternative methods are also discussed. This study highlights the importance of using parallel testing methods to diagnose cryptic APL cases accurately and effectively.

Hematopoietic Stem Cell Transplantation in Acute Promyelocytic Leukemia in the Era of All-Trans Retinoic Acid (ATRA) and Arsenic Trioxide (ATO)

Acute promyelocytic leukemia (APL) currently represents one of the malignant hemopathies with the best therapeutic responses, following the introduction of all-trans retinoic acid (ATRA) and subsequently of arsenic trioxide (ATO) treatment. As a result, a large proportion of patients with APL achieve long-term responses after first-line therapy, so performing a hematopoietic stem cell transplant as consolidation of first complete remission (CR) is no longer necessary. Even in the case of relapses, most patients obtain a new remission as a result of therapy with ATO and ATRA, but an effective consolidation treatment is necessary to maintain it. The experience accumulated from studies published in the last two decades shows the effectiveness of hematopoietic stem cell transplantation (HSCT) in improving the outcome of patients who achieve a new CR. Thus, the expert groups recommend transplantation as consolidation therapy in patients with a second CR, with the indication for autologous HSCT in cases with molecular CR and for allogeneic HSCT in patients with the persistence of minimal residual disease (MRD) or with early relapse. However, there is a variety of controversial aspects related to the role of HSCT in APL, ranging from the fact that outcome data are obtained almost exclusively from retrospective studies and historical analyses to questions related to the type of transplantation, the impact of minimal residual disease, conditioning regimens, or the role of other therapeutic options. All these questions justify the need for controlled prospective studies in the following years.

MEK1/2 regulate normal BCR and ABL1 tumor-suppressor functions to dictate ATO response in TKI-resistant Ph+ leukemia

Resistance to tyrosine kinase inhibitors (TKIs) remains a clinical challenge in Ph-positive variants of chronic myeloid leukemia. We provide mechanistic insights into a previously undisclosed MEK1/2/BCR::ABL1/BCR/ABL1-driven signaling loop that may determine the efficacy of arsenic trioxide (ATO) in TKI-resistant leukemic patients. We find that activated MEK1/2 assemble into a pentameric complex with BCR::ABL1, BCR and ABL1 to induce phosphorylation of BCR and BCR::ABL1 at Tyr360 and Tyr177, and ABL1, at Thr735 and Tyr412 residues thus provoking loss of BCR's tumor-suppression functions, enhanced oncogenic activity of BCR::ABL1, cytoplasmic retention of ABL1 and consequently drug resistance. Coherently, pharmacological blockade of MEK1/2 induces dissociation of the pentameric MEK1/2/BCR::ABL1/BCR/ABL1 complex and causes a concurrent BCRY360/Y177, BCR::ABL1Y360/Y177 and cytoplasmic ABL1Y412/T735 dephosphorylation thereby provoking the rescue of the BCR's anti-oncogenic activities, nuclear accumulation of ABL1 with tumor-suppressive functions and consequently, growth inhibition of the leukemic cells and an ATO sensitization via BCR-MYC and ABL1-p73 signaling axes activation. Additionally, the allosteric activation of nuclear ABL1 was consistently found to enhance the anti-leukemic effects of the MEK1/2 inhibitor Mirdametinib, which when combined with ATO, significantly prolonged the survival of mice bearing BCR::ABL1-T315I-induced leukemia. These findings highlight the therapeutic potential of MEK1/2-inhibitors/ATO combination for the treatment of TKI-resistant leukemia.

Prompt Initiation of Conventional Chemotherapy to Avoid Early Death in Patients with Newly Diagnosed Acute Promyelocytic Leukemia

Objective Compared to prospective trials, the early death rate of newly diagnosed acute promyelocytic leukemia (APL) in the real-world clinical setting is higher. However, the early death rate was heterogeneous according to the reported institutes. Thus, the therapeutic approach at each institute may be important for preventing early death. This study evaluated the management strategy for untreated APL in our institute to avoid early death. Methods We identified consecutive 21 patients with untreated APL who received induction therapy including all-trans retinoic acid (ATRA) between July 2007 and December 2021 at the University of Tokyo Hospital. Results As therapeutic approaches, 16 patients (76%) received ATRA administration on the day of admission, and the remaining 5 received ATRA within 4 days from admission. Notably, all patients received conventional chemotherapy added to ATRA at a median of 1 day from admission (range: 0-9 days). As clinical outcomes, no patient died during induction therapy for untreated APL, and all achieved complete molecular remission. Conclusion Compared to the previous nationwide survey, a higher proportion of patients at our institute received conventional chemotherapy in addition to ATRA, and it was initiated more promptly, which may have helped prevent early death.

Management of Acute Promyelocytic Leukemia at Extremes of Age

Tailored treatment with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has revolutionized the outcome of acute promyelocytic leukemia (APL) from a uniformly fatal disease to one of the most curable malignant diseases in humans. Due to its high efficacy, ATO/ATRA is the standard first-line therapy in younger adult, non-high-risk APL patients. However, early death is still a major issue in APL, particularly in older patients. Thus, rapid diagnostics, immediate access to ATRA-based therapy, and supportive care are of utmost importance. Nevertheless, challenging situations occur, particularly in patients excluded from controlled studies with clinical knowledge mainly based on case reports and registries. Besides the treatment of newly diagnosed patients, managing toxicities and complications remains challenging. This review discusses the approach to the treatment of APL in elderly and pediatric patients.