How we prevent and treat differentiation syndrome in patients with acute promyelocytic leukemia

Complications and Toxicities Associated with Cancer Therapies in the Intensive Care Unit

Advances in the management of hematologic malignancies and solid tumors have given rise to diverse modalities to treat cancer other than cytotoxic chemotherapy, including targeted therapies, immunotherapies, and cellular therapies. Currently, there are over 175 FDA-approved antineoplastic agents in the United States, many with a diverse and profound toxicity profile. Complications of antineoplastic therapy may result in the need for intensive care unit (ICU) admission to provide acute symptom management. Accordingly, ICU providers caring for cancer patients should have a working knowledge of the toxicities and complications associated with antineoplastic therapy.

Acute promyelocytic leukemia (APL): remaining challenges towards a cure for all

The application of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has revolutionized the treatment of acute promyelocytic leukemia (APL). More than 80-90% of patients are expected to be cured with a combination of ATRA, ATO and/or chemotherapy. In this review, we focus on the remaining obstacles to a cure for all patients with APL. We review the issue of early death and coagulopathy and discuss the particular challenges in the care of patients with high-risk APL and patients with relapsed APL. We also give recommendations and highlight ongoing efforts to improve the persistently high early death rate and the outcomes of high risk and relapsed APL patients.

Rate of differentiation syndrome in patients based on timing of initial all-trans retinoic acid administration

All-trans-retinoic acid (ATRA) is the standard of care for the management of acute promyelocytic leukemia (APL), but can be associated with differentiation syndrome (DS). Over a seven-year period, we sought to determine the impact of ATRA initiation time on the development of DS. ATRA administration time had no impact on DS occurrence (p = =0.13), APL risk (p = =0.28) or regimen received (p = =0.1). Patients with higher mean body mass index (BMI) were more likely to develop moderate or severe DS (p = =0.02). Early treatment of APL is essential and maybe strongly considered in patients with elevated BMI.

Differentiation syndrome in acute promyelocytic leukaemia

Acute promyelocytic leukaemia differentiation syndrome (APL DS) is seen when patients with APL are treated with all-trans retinoic acid (ATRA) and/or arsenic trioxide (ATO). Presenting symptoms are varied but frequently include dyspnoea, unexplained fever, weight gain >5 kg, unexplained hypotension, acute renal failure and a chest radiograph demonstrating pulmonary infiltrates or pleural or pericardial effusion. Immediate treatment with steroids at the first clinical suspicion is recommended and ATRA/ATO should be stopped in severe cases or if there is no response to treatment. The utility of steroid prophylaxis in order to prevent APL DS is less certain. Here we provide a detailed review of the pathogenesis, clinical signs and symptoms as well as management and prophylaxis strategies of APL DS.

Autophagy: New Insights into Mechanisms of Action and Resistance of Treatment in Acute Promyelocytic leukemia

Autophagy is one of the main cellular catabolic pathways controlling a variety of physiological processes, including those involved in self-renewal, differentiation and death. While acute promyelocytic leukemia (APL) cells manifest low levels of expression of autophagy genes associated with reduced autophagy activity, the introduction of all-trans retinoid acid (ATRA)-a differentiating agent currently used in clinical settings-restores autophagy in these cells. ATRA-induced autophagy is involved in granulocytes differentiation through a mechanism that involves among others the degradation of the PML-RARα oncoprotein. Arsenic trioxide (ATO) is another anti-cancer agent that promotes autophagy-dependent clearance of promyelocytic leukemia retinoic acid receptor alpha gene (PML-RARα) in APL cells. Hence, enhancing autophagy may have therapeutic benefits in maturation-resistant APL cells. However, the role of autophagy in response to APL therapy is not so simple, because some autophagy proteins have been shown to play a pro-survival role upon ATRA and ATO treatment, and both agents can activate ETosis, a type of cell death mediated by the release of neutrophil extracellular traps (ETs). This review highlights recent findings on the impact of autophagy on the mechanisms of action of ATRA and ATO in APL cells. We also discuss the potential role of autophagy in the development of resistance to treatment, and of differentiation syndrome in APL.

Acute Promyelocytic Leukemia: A History over 60 Years-From the Most Malignant to the most Curable Form of Acute Leukemia

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML) that is cytogenetically characterized by a balanced reciprocal translocation between chromosomes 15 and 17, which results in the fusion of the promyelocytic leukemia (PML) and retinoic acid receptor alpha (RARα) genes. Because patients with APL present a tendency for severe bleeding, often resulting in an early fatal course, APL was historically considered to be one of the most fatal forms of acute leukemia. However, therapeutic advances, including anthracycline- and cytarabine-based chemotherapy, have significantly improved the outcomes of APL patients. Due to the further introduction of all-trans retinoic acid (ATRA) and-more recently-the development of arsenic trioxide (ATO)-containing regimens, APL is currently the most curable form of AML in adults. Treatment with these new agents has introduced the concept of cure through targeted therapy. With the advent of revolutionary ATRA-ATO combination therapies, chemotherapy can now be safely omitted from the treatment of low-risk APL patients. In this article, we review the six-decade history of APL, from its initial characterization to the era of chemotherapy-free ATRA-ATO, a model of cancer-targeted therapy.

Unrecognized fluid overload during induction therapy increases morbidity in patients with acute promyelocytic leukemia

BACKGROUND

The combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has proven to be the most effective therapy for patients with acute promyelocytic leukemia (APL). The majority of the morbidity and mortality from APL therapy occur during the induction phase. The objective of the current study was to identify the risk factors associated with transfer to the intensive care unit (ICU) and endotracheal intubation during induction therapy in patients with APL.

METHODS

The authors analyzed the clinical characteristics of 187 patients with newly diagnosed APL who were treated with ATRA and ATO with or without gemtuzumab ozogamicin. The authors documented the percentage change in body weight from baseline to the maximum recorded weight during induction or to the day of ICU transfer.

RESULTS

A total of 18 patients (10%) who initiated therapy with ATRA and ATO on a regular hospital floor required transfer to the ICU after a median of 12 days of induction therapy. The median volume of transfusions was 4350 mL (range, 60-30,750 mL). The volume of transfusions was the main factor associated with the risk of ICU transfer (odds ratio, 4.1; P < .001). Of the 18 patients transferred to the ICU, 10 patients (5%) required intubation. An increase in the total volume of transfusions, increase in weight ≥10% during induction therapy, and a plasma albumin level ≤3.2 g/dL at the time of diagnosis were found to be associated with an increased risk of endotracheal intubation.

CONCLUSIONS

Large volumes of blood product transfusions and unrecognized fluid overload during induction are associated with ICU transfer and endotracheal intubation in patients with APL. These can be prevented by limiting the amount of transfusions, careful monitoring for subtle signs of fluid overload, and early intervention with aggressive diuretic therapy.

The simpler, the better: oral arsenic for acute promyelocytic leukemia

Arsenic trioxide and all-trans retinoic acid have become the frontline treatments for patients with acute promyelocytic leukemia (APL). Despite the long wait for an oral arsenic drug, a commercially available agent, realgar-indigo naturalis formula (RIF), was not launched in China until 2009. Since then, over 5000 APL patients have been treated with oral RIF in China. Oral arsenic not only shows a clinical efficacy comparable to that of IV formulations but also displays a better safety profile, improved quality of life, and lower medical costs for patients. The promising results promote incorporating an outpatient postremission therapy model into clinical practice for both low-risk and high-risk APL patients in China. In this review, we discuss the evolution of oral arsenic RIF in the treatment of APL, with a special focus on how to address the related complications during induction therapy.

Role of arsenic (+3 oxidation state) methyltransferase in arsenic mediated APL treatment: an in vitro investigation

Arsenic (+3 oxidation state) methyltransferase (AS3MT) is a key enzyme responsible for arsenic metabolism in humans, which facilitates conversion of arsenic trioxide (As2O3) to more reactive metabolites such as monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII). However, it is unclear whether the biotransformation of arsenic by AS3MT contributes to the promotion of acute promyelocytic leukemia (APL) therapy. In order to understand the probable role of AS3MT in APL patients, we evaluated the effects of arsenite (iAsIII) and three mixed arsenicals (i.e., iAsIII, MMAIII and DMAIII, to mimic active arsenic species in the blood) on NB4 cell differentiation and apoptosis. Although the mixed arsenicals exhibited about 2 fold less effect on the induction of NB4 cell differentiation and PML-RARα fusion protein degradation, they showed 5 times stronger ability to induce apoptosis when compared with iAsIII. More importantly, the proliferation of NB4 cells was significantly (p < 0.05) inhibited in a transwell system co-cultured with AS3MT-transfected HepG2 cells after exposure to iAsIII, suggesting that the generation of methylated metabolites restrained cell proliferation. These findings indicate that the therapeutic efficacy of As2O3 (i.e., iAsIII) in APL patients is probably associated with the production of methylated arsenic metabolites (i.e., MMAIII and DMAIII) by AS3MT.

Predictors of early hemorrhage in acute promyelocytic leukemia

Fatal hemorrhage is the most common cause of induction failure and death among patients with acute promyelocytic leukemia (APL). However, there remains no established means of hemorrhagic risk stratification in APL. In this single center retrospective study of 43 patients treated for APL group-based trajectory modeling was used to identify laboratory trends associated with major bleeding. Bleeding risk was significantly associated with particular trends in white blood cell count (WBC) and lactate dehydrogenase level (LDH). Specifically, patients who presented with high WBC and/or LDH, and whose WBC and/or LDH then proceeded to uptrend during the initial days of induction, were significantly more likely to experience major bleeding (p = .0111 and p = .0143, respectively). Additionally, there appeared to be a temporal association between WBC and LDH trends and major bleeding events. Among nonlaboratory variables, differentiation syndrome (DS) was significantly associated with major bleeding (p = .00149).

Current Therapeutic Results and Treatment Options for Older Patients with Relapsed Acute Myeloid Leukemia

Considerable progress has been made in the treatment of acute myeloid leukemia (AML). However, current therapeutic results are still unsatisfactory in untreated high-risk patients and poorer in those with primary refractory or relapsed disease. In older patients, reluctance by clinicians to treat unfit patients, higher AML cell resistance related to more frequent adverse karyotype and/or precedent myelodysplastic syndrome, and preferential involvement of chemorefractory early hemopoietic precursors in the pathogenesis of the disease further account for poor prognosis, with median survival lower than six months. A general agreement exists concerning the administration of aggressive salvage therapy in young adults followed by allogeneic stem cell transplantation; on the contrary, different therapeutic approaches varying in intensity, from conventional salvage chemotherapy based on intermediate⁻high-dose cytarabine to best supportive care, are currently considered in the relapsed, older AML patient population. Either patients' characteristics or physicians' attitudes count toward the process of clinical decision making. In addition, several new drugs with clinical activity described as "promising" in uncontrolled single-arm studies failed to improve long-term outcomes when tested in larger randomized clinical trials. Recently, new agents have been approved and are expected to consistently improve the clinical outcome for selected genomic subgroups, and research is in progress in other molecular settings. While relapsed AML remains a tremendous challenge to both patients and clinicians, knowledge of the molecular pathogenesis of the disease is fast in progress, potentially leading to personalized therapy in most patients.

Successful treatment of disseminated intravascular coagulation by recombinant human soluble thrombomodulin in patients with acute myeloid leukemia

Disseminated intravascular coagulation (DIC) is a life-threatening condition that frequently occurs in patients with hematologic malignancies. Currently, recombinant human soluble thrombomodulin (rTM) is a therapeutic DIC drug that is manufactured and sold in Japan only. We evaluated the efficacy of rTM compared to that of gabexate mesilate (GM), which was previously used routinely for treating DIC in Japan, in patients with acute myeloid leukemia (AML). This retrospective study enrolled 43 AML patients, including 17 with acute promyelocytic leukemia (APL), that was complicated with DIC. DIC resolution rates in non-APL AML and rTM-treated APL patients were 68.4% and 81.8%, respectively. In non-APL AML patients, the duration of rTM administration was significantly shorter than that of GM (7 vs 11 days), suggesting that rTM could improve DIC earlier than GM, although rTM was used in patients with more severe DIC. Moreover, treatment with rTM significantly improved DIC score, fibrinogen, fibrin/fibrinogen degradation product (FDP), and prothrombin time (PT) ratio. Conversely, treatment with GM only improved the DIC score and FDP. In APL patients, the duration of rTM administration was also significantly shorter than that of GM. No severe side effects associated with the progression of bleeding were observed during rTM administration. These findings suggest that rTM is safe, and its anti-DIC effects are more prompt than GM for treating AML patients with DIC.

Basophil-lineage commitment in acute promyelocytic leukemia predicts for severe bleeding after starting therapy

Severe hemorrhagic events occur in a significant fraction of acute promyelocytic leukemia patients, either at presentation and/or early after starting therapy, leading to treatment failure and early deaths. However, identification of independent predictors for high-risk of severe bleeding at diagnosis, remains a challenge. Here, we investigated the immunophenotype of bone marrow leukemic cells from 109 newly diagnosed acute promyelocytic leukemia patients, particularly focusing on the identification of basophil-related features, and their potential association with severe bleeding episodes and patient overall survival.From all phenotypes investigated on leukemic cells, expression of the CD203c and/or CD22 basophil-associated markers showed the strongest association with the occurrence and severity of bleeding (p ≤ 0.007); moreover, aberrant expression of CD7, coexpression of CD34⁺/CD7⁺ and lack of CD71 was also more frequently found among patients with (mild and severe) bleeding at baseline and/or after starting treatment (p ≤ 0.009). Multivariate analysis showed that CD203c expression (hazard ratio: 26.4; p = 0.003) and older age (hazard ratio: 5.4; p = 0.03) were the best independent predictors for cumulative incidence of severe bleeding after starting therapy. In addition, CD203c expression on leukemic cells (hazard ratio: 4.4; p = 0.01), low fibrinogen levels (hazard ratio: 8.8; p = 0.001), older age (hazard ratio: 9.0; p = 0.002), and high leukocyte count (hazard ratio: 5.6; p = 0.02) were the most informative independent predictors for overall survival.In summary, our results show that the presence of basophil-associated phenotypic characteristics on leukemic cells from acute promyelocytic leukemia patients at diagnosis is a powerful independent predictor for severe bleeding and overall survival, which might contribute in the future to (early) risk-adapted therapy decisions.

Bradycardia during Induction Therapy with All-trans Retinoic Acid in Patients with Acute Promyelocytic Leukemia: Case Report and Literature Review

A 41-year-old man with newly diagnosed acute promyelocytic leukemia (APL) received induction chemotherapy, containing all-trans retinoic acid (ATRA), idarubicin, and arsenic trioxide. On the 11th day of therapy, he experienced complete atrioventricular (AV) block; therefore, ATRA and arsenic trioxide were immediately postponed. His heart rate partially recovered, and ATRA was rechallenged with a half dose. However, complete AV block as well as differentiation syndrome recurred on the next day. ATRA was immediately discontinued, and a temporary pacemaker was inserted. Two days after discontinuing ATRA, AV block gradually improved, and ATRA was uneventfully rechallenged again. The Naranjo adverse drug reaction probability scale was 7 for ATRA, suggesting it was the probable cause of arrhythmia. A literature search identified 6 other cases of bradycardia during ATRA therapy, and all of them occurred during APL induction therapy, with onset ranging from 4 days to 25 days. Therefore, monitoring vital signs and performing electrocardiogram are highly recommended during the first month of induction therapy with ATRA. ATRA should be discontinued if complete AV block occurs. Rechallenging with ATRA can be considered in fully recovered and clinically stable patients.

The role of enasidenib in the treatment of mutant IDH2 acute myeloid leukemia

Recurrent mutations affecting cellular metabolism and epigenetic regulation are implicated in the pathogenesis of acute myeloid leukemia (AML). Isocitrate dehydrogenase 2 (IDH2) gene mutations are described in 12% of patients with AML and 5% of patients with myelodysplastic syndromes. IDH2 enzyme is involved in the Krebs cycle, catalyzing α-ketoglutarate from isocitrate. Mutant IDH2 enzymes acquire a neomorphic enzymatic activity with the ability to produce 2-hydroxyglutarate from α-ketoglutarate, inhibiting multiple α-ketoglutarate-dependent dioxygenase reactions; leading to aberrant DNA hypermethylation and differentiation block in myeloid precursors and ultimately promoting leukemogenesis. Enasidenib (formerly AG-221) is an oral small molecule selective targeted inhibitor of the mutant IDH2 enzyme, approved in August 2017 by the United States Food and Drug Administration for the treatment of patients with relapsed or refractory (R/R) IDH2-mutated AML. Preclinical studies showed the effectiveness of enasidenib in inhibiting the production of 2-hydroxyglutarate with high potency, and alleviating the mutant IDH2-induced differentiation block. In the original AG221-001 phase I/II trial, patients with R/R AML were treated with enasidenib single agent therapy at escalating doses up to 650 mg daily, with the 100 mg dose level identified to be safe and effective for further evaluation. Overall, 113 patients were treated in the dose-escalation and 126 in the dose-expansion cohorts. The overall response rate for R/R patients was 40%, including a complete remission of 19%. At a median follow up of 7.7 months, the median overall survival was 9.3 months, and reached 19.7 months in responders. Enasidenib was well tolerated, although adverse events of clinical interest include indirect hyperbilirubinemia and IDH-inhibitor-induced differentiation syndrome, which can be life threatening if not identified and treated promptly. Ongoing clinical trials evaluating enasidenib in combination with intensive chemotherapy and hypomethylating agents in newly diagnosed AML, and in rational combinations for R/R AML patients are underway.

Cell dynamics during differentiation therapy with all-trans retinoic acid in acute promyelocytic leukemia

The introduction of all-trans retinoic acid (ATRA) has made acute promyelocytic leukemia (APL) a curable disease; however, early death prior to the completion of treatment remains a problem. In quantitative evaluation of response to ATRA treatment, lymphocytes must be excluded as they do not originally have t(15;17). We categorized peripheral blood leukocytes by nuclear morphology into polymorphonuclear cells (PMNs) comprising segmented granulocytes, and non-polymorphonuclear cells (NPMs) which includes lymphocytes, monocytes, band cells, and immature myeloid cells. We consecutively evaluated the ratio of t(15;17)-positive cells using fluorescence in situ hybridization in eight newly diagnosed patients with APL. We confirmed the differentiation of APL cells until cytogenetic complete remission; the association of a decrease of t(15;17)-positive NPMs and an increase of t(15;17)-positive PMNs was followed by a decrease of t(15;17)-positive PMNs. The kinetic pattern of t(15;17)-positive NPMs and PMNs was consistent in most patients, irrespective of leukocyte counts at diagnosis, additional chromosomal changes, and ATRA with or without chemotherapies. Kinetic analysis enables us to evaluate treatment response and the recovery of normal hematopoiesis in individuals.

Dexamethasone in hyperleukocytic acute myeloid leukemia

Patients with acute myeloid leukemia and a high white blood cell count are at increased risk of early death and relapse. Because mediators of inflammation contribute to leukostasis and chemoresistance, dexamethasone added to chemotherapy could improve outcomes. This retrospective study evaluated the impact of adding or not adding dexamethasone to chemotherapy in a cohort of 160 patients with at least 50×10⁹ white blood cells. In silico studies, primary samples, leukemic cell lines, and xenograft mouse models were used to explore the antileukemic activity of dexamethasone. There was no difference with respect to induction death rate, response, and infections between the 60 patients in the dexamethasone group and the 100 patients in the no dexamethasone group. Multivariate analysis showed that dexamethasone was significantly associated with improved relapse incidence (adjusted sub-HR: 0.30; 95% CI: 0.14–0.62; P=0.001), disease-free survival (adjusted HR: 0.50; 95% CI: 0.29–0.84; P=0.010), event-free survival (adjusted HR: 0.35; 95% CI: 0.21–0.58; P<0.001), and overall survival (adjusted HR: 0.41; 95% CI: 0.22–0.79; P=0.007). In a co-culture system, dexamethasone reduced the frequency of leukemic long-term culture initiating cells by 38% and enhanced the cytotoxicity of doxorubicin and cytarabine. In a patient-derived xenograft model treated with cytarabine, chemoresistant cells were enriched in genes of the inflammatory response modulated by dexamethasone. Dexamethasone also demonstrated antileukemic activity in NPM1-mutated samples. Dexamethasone may improve the outcome of acute myeloid leukemia patients receiving intensive chemotherapy. This effect could be due to the modulation of inflammatory chemoresistance pathways and to a specific activity in acute myeloid leukemia with NPM1 mutation.

Selenite promotes all-trans retinoic acid-induced maturation of acute promyelocytic leukemia cells

Selective targeting of the PML/RARα oncoprotein demonstrates a successful molecular targeted therapy in acute promyelocytic leukemia (APL) with a typical t(15:17) chromosomal translocation. The zinc-thiolate coordination is critical for structural stability of zinc finger proteins, including the PML moiety of PML/RARα. Based on the known interaction of redox-active selenium compounds with thiolate ligands of zinc, we herein have investigated the abrogatory effects of selenite alone or in combination with all-trans retinoic acid on PML/RARα and the possible effects on differentiation in these cells. At pharmacological concentrations, selenite inhibited the proliferation and survival of APL originated NB4 cells. In combination with ATRA, it potentiated the differentiation of NB4 cells without any differentiating effects of its own as a single agent. Concordant with our hypothesis, PML/RARα oncoprotein expression was completely abrogated by selenite. Increased expression of RARα, PU.1 and FOXO3A transcription factors in the combined treatment suggested the plausible basis for increased differentiation in these cells. We show that selenite at clinically achievable dose targets PML/RARα oncoprotein for degradation and potentiates differentiation of promyelocytic leukemic cells in combination with ATRA. The present investigation reveals the hitherto unknown potential of selenite in targeted abrogation of PML/RARα in APL cells with prospective therapeutic value.

Case report: Purulent transformation of granulocytic sarcoma: An unusual pattern of differentiation in acute promyelocytic leukemia

RATIONALE

Acute promyelocytic leukemia (APL) is a curable subtype of acute myeloid leukemia. APL is currently treated with combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) resulting in the induction of apoptosis and differentiation of the leukemic cells. Differentiation syndrome (so-called ATRA syndrome) is the main life-threatening complication of induction therapy with these differentiating agents.

PATIENT CONCERNS

Herein, we report the case of a 49-year-old woman diagnosed with APL with, concomitantly, a bulky cutaneous lesion of 10 cm diameter with a red-to-purple background and a necrotic center, localized on her abdomen.

DIAGNOSES

After 10 days of treatment, the cutaneous lesion became purulent. Fluorescence in situ hybridization (FISH) analysis performed on this pus confirmed the presence of malignant features in the involved granulocytes proving their origin from the differentiation of leukemic APL cells, as all the analyzed nuclei showed 2 promyelocytic leukemia (PML)-retinoic acid receptor-a (RARA) fusions signals.

INTERVENTION

The association by ATRA and ATO was continued.

OUTCOME

Eventually, the evolution was favorable with healing in three weeks.

LESSONS

This case report therefore highlights the differentiation phenomenon of promyelocytic blasts within promyelocytic sarcoma with the ATRA-ATO combination and the efficacy of this drug association in resolving both the malignant sarcoma and a secondary local infection.

Two cases of differentiation syndrome with ocular manifestations in patients with acute promyelocytic leukaemia treated with all-trans retinoic acid and arsenic trioxide

Purpose

To describe two cases of differentiation syndrome presenting with ocular manifestations including bilateral chorioretinopathy in patients with acute promyelocytic leukaemia treated with all-trans retinoic acid and arsenic trioxide differentiation therapy.

Observations

This observational case series identifies two patients at a single tertiary institution diagnosed with differentiation syndrome with associated ophthalmic involvement. Both patients reported bilateral reduction in visual acuity at days fourteen and ten respectively following initiation of differentiation therapy in addition to developing other systemic manifestations of differentiation syndrome. Both patients received the same chemotherapeutic regimen including both all-trans retinoic acid and arsenic trioxide as well as ten days of routine differentiation syndrome prophylaxis with oral prednisolone. Case 1 presented with bilateral pale yellow sub-retinal lesions concentrated at the posterior poles with ocular coherence tomography (OCT) evidence of bilateral multifocal areas of focal RPE elevation and adhesion to the thickened outer retina with interspersed sub-retinal fluid. Fluorescein angiography revealed areas of early hyperflouresence corresponding to the yellow chorioretinal lesions with late diffuse leakage of fluid into the subretinal space. Case 2 presented with a similar characteristic retinal findings on fundoscopy and optical coherence tomography. Both patients experienced rapid improvement in the visual symptoms and marked resolution of the sub-retinal fluid within seven to fourteen days of onset with excellent long-term visual outcome. Both patients achieved molecular remission after induction and received standard consolidation and maintenance therapy without visual disturbance.

Conclusion and importance

Ocular manifestations of differentiation syndrome have been only recently recognised. We present a case series of two patients with differentiation syndrome with ocular involvement. Common to both presentations was the presence of bilateral reduction in visual acuity with multifocal serous retinal detachment secondary to chorioretinopathy. The visual outcome from both presentations was excellent with rapid normalisation of visual acuity and resolution of the sub-retinal fluid with only the first case having their differentiation therapy temporarily withheld during the acute phase of illness.

Enasidenib, a targeted inhibitor of mutant IDH2 proteins for treatment of relapsed or refractory acute myeloid leukemia

Mutations in IDH2 genes (mIDH2) occur in approximately 12% of patients with acute myeloid leukemia. Enasidenib is an oral, small-molecule inhibitor of mIDH2 proteins. Enasidenib is shown to suppress the oncometabolite, 2-hydroxyglutarate, and promote differentiation of leukemic bone marrow blasts. In a Phase I dose-escalation and expansion study, 40.3% of patients with relapsed/refractory acute myeloid leukemia responded to enasidenib monotherapy, including 19.3% who achieved complete remission and 11% who proceeded to transplant. Median overall survival was 9.3 months. 2-hydroxyglutarate suppression did not predict response and mIDH2 clearance was possible, but not required for response. Patients with ≥6 co-mutations or NRAS co-mutations were less likely to attain a response. Enasidenib was safe and well tolerated with low rates of treatment-related adverse events.

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In vitro studies on the role of recombinant human soluble thrombomodulin in the context of retinoic acid mediated APL differentiation syndrome

Recombinant human soluble thrombomodulin (rTM) is a newly developed anti-coagulant approved for treatment of disseminated intravascular coagulation (DIC) in Japan. rTM exerts anti-inflammatory and cytoprotective functions via its lectin-like and epidermal growth factor-like domains, respectively. In this study, we retrospectively reviewed the treatment of 21 consecutive patients with coagulopathy, complicated by acute promyelocytic leukemia (APL), with all-trans retinoic acid (ATRA) with or without combination with rTM. Surprisingly, none of the 14 rTM-treated patients developed retinoic acid (RA)-related differentiation syndrome (DS). The co-culture of vascular endothelial cell-derived EA.hy926 and APL-derived NB4 cells in the presence of RA increased production of tumor necrosis factor alpha (TNF-α) in culture media, in parallel with activation of p38 mitogen-activated protein kinase and increased levels of intracellular adhesion molecule 1 (ICAM1) in EA.hy926 cells. This was also associated with increased levels of the phosphorylated forms of VE-cadherin and enhanced vascular permeability of EA.hy926 monolayers. Importantly, addition of rTM to this co-culture system inhibited the RA-induced phosphorylation of p38 and VE-cadherin and decreased ICAM1 and vascular permeability in EA.hy926 cells, without a decrease inthe levels of TNF-α. Taken together, use of rTM may be a promising treatment strategy to prevent DS in APL patients who receive ATRA.

The global problem of early deaths in acute promyelocytic leukemia: A strategy to decrease induction mortality in the most curable leukemia

Acute promyelocytic leukemia (APL) is a hyper-acute illness and presents with profound cytopenias in most patients and disseminated intravascular coagulation (DIC). Excellent treatment options are now available with drugs such as all-trans retinoic acid (ATRA), arsenic trioxide (ATO), anthracyclines and cytarabine. The outcome in APL has improved tremendously in the last 50years due to better understanding of the disease, development of effective targeted agents and improvement in supportive care. Carefully selected groups of patients treated in large multi-center trials on a protocol and in experienced centers have shown survival rates in excess of 85%. However population data and other studies show that approximately 30% of patients die during induction. This is an Institutional, national and global problem and remains a pressing and frustrating challenge in APL. While most APL experts are aware of the high rate of early deaths (ED), such awareness is not typically present among general hematologists and oncologists. Our area of focus over the last 7years has been the reduction of ED in both academic and community centers; as a result we have acquired substantial experience in APL induction. Two centers have implemented population-wide prospective trials; Brazil and Georgia/South Carolina, USA with improvement in the ED rate. Both centers used standardized guidelines along with consultative support and sharing of expertise which proved effective and helped to decrease ED. Induction mortality in APL is 30% or greater. We believe ED is largely preventable and population-wide survival can be improved. An effective strategy is to utilize a set of simplified treatment guidelines coupled with support from a group of experts during induction. Treating oncologists in both academic and community hospitals should receive aggressive education about ED and be encouraged to seek advice from a core group of established APL experts. This model could be implemented nationally to improve population-wide survival in this most curable leukemia.

Enasidenib in mutant IDH2 relapsed or refractory acute myeloid leukemia

Recurrent mutations in isocitrate dehydrogenase 2 (IDH2) occur in ∼12% of patients with acute myeloid leukemia (AML). Mutated IDH2 proteins neomorphically synthesize 2-hydroxyglutarate resulting in DNA and histone hypermethylation, which leads to blocked cellular differentiation. Enasidenib (AG-221/CC-90007) is a first-in-class, oral, selective inhibitor of mutant-IDH2 enzymes. This first-in-human phase 1/2 study assessed the maximum tolerated dose (MTD), pharmacokinetic and pharmacodynamic profiles, safety, and clinical activity of enasidenib in patients with mutant-IDH2 advanced myeloid malignancies. We assessed safety outcomes for all patients and clinical efficacy in the largest patient subgroup, those with relapsed or refractory AML, from the phase 1 dose-escalation and expansion phases of the study. In the dose-escalation phase, an MTD was not reached at doses ranging from 50 to 650 mg per day. Enasidenib 100 mg once daily was selected for the expansion phase on the basis of pharmacokinetic and pharmacodynamic profiles and demonstrated efficacy. Grade 3 to 4 enasidenib-related adverse events included indirect hyperbilirubinemia (12%) and IDH-inhibitor-associated differentiation syndrome (7%). Among patients with relapsed or refractory AML, overall response rate was 40.3%, with a median response duration of 5.8 months. Responses were associated with cellular differentiation and maturation, typically without evidence of aplasia. Median overall survival among relapsed/refractory patients was 9.3 months, and for the 34 patients (19.3%) who attained complete remission, overall survival was 19.7 months. Continuous daily enasidenib treatment was generally well tolerated and induced hematologic responses in patients for whom prior AML therapy had failed. Inducing differentiation of myeloblasts, not cytotoxicity, seems to drive the clinical efficacy of enasidenib. This trial was registered at www.clinicaltrials.gov as #NCT01915498.

Retinoic acid and arsenic trioxide sensitize acute promyelocytic leukemia cells to ER stress

Retinoic acid (RA) in association with chemotherapy or with arsenic trioxide (ATO) results in high cure rates of acute promyelocytic leukemia (APL). We show that RA-induced differentiation of human leukemic cell lines and primary blasts dramatically increases their sensitivity to endoplasmic reticulum (ER) stress-inducing drugs at doses that are not toxic in the absence of RA. In addition, we demonstrate that the PERK pathway, triggered in response to ER stress, has a major protective role. Moreover, low amounts of pharmacologically induced ER stress are sufficient to strongly increase ATO toxicity. Indeed, in the presence of ER stress, ATO efficiently induced apoptosis in RA-sensitive and RA-resistant APL cell lines, at doses ineffective in the absence of ER stress. Our findings identify the ER stress-related pathways as potential targets in the search for novel therapeutic strategies in AML.

Retinoic acid and arsenic trioxide in the treatment of acute promyelocytic leukemia: current perspectives

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML) with a unique morphological appearance, associated coagulopathy and canonical balanced translocation of genetic material between chromosomes 15 and 17. APL was first described as a distinct subtype of AML in 1957 by Dr Leif Hillestad who recognized the pattern of an acute leukemia associated with fibrinolysis, hypofibrinogenemia and catastrophic hemorrhage. In the intervening years, the characteristic morphology of APL has been described fully with both classical hypergranular and variant microgranular forms. Both are characterized by a balanced translocation between the long arms of chromosomes 15 and 17, [t(15;17)(q24;q21)], giving rise to a unique fusion gene PML-RARA and an abnormal chimeric transcription factor (PML-RARA), which disrupts normal myeloid differentiation programs. The success of current treatments for APL is in marked contrast to the vast majority of patients with non-promyelocytic AML. The overall prognosis in non-promyelocytic AML is poor, and although there has been an improvement in overall survival in patients aged <60 years, only 30%-40% of younger patients are still alive 5 years after diagnosis. APL therapy has diverged from standard AML therapy through the empirical discovery of two agents that directly target the molecular basis of the disease. The evolution of treatment over the last 4 decades to include all-trans retinoic acid and arsenic trioxide, with chemotherapy limited to patients with high-risk disease, has led to complete remission in 90%-100% of patients in trials and rates of overall survival between 86% and 97%.

Targeted Differentiation Therapy with Mutant IDH Inhibitors: Early Experiences and Parallels with Other Differentiation Agents

Somatic mutations in the isocitrate dehydrogenase (IDH) 1 and 2 genes have been described in multiple hematologic and solid tumors, and confer a gain of function, permitting the production of the oncometabolite (R)-2-hydroxyglutarate (2-HG). 2-HG accumulation induces DNA and histone hypermethylation and altered gene expression, ultimately resulting in a block in cellular differentiation. Proof-of-concept preclinical work demonstrated that targeted inhibition of the mutant IDH (mIDH) enzyme is a feasible therapeutic strategy, based on the hypothesis that inhibition of the mIDH enzyme blocks 2-HG production, resulting in an appropriate methylation state and the onset of cellular differentiation. Clinical development programs for targeted inhibitors are underway, and preliminary data in patients with mIDH acute myeloid leukemia suggest that these inhibitors act as differentiation agents. Here we review the use of differentiation agents for the treatment of hematologic and solid tumors and discuss the preclinical and early clinical evidence that mIDH inhibitors mediate antitumor effects through the induction of differentiation.

Role of Vitamin A/Retinoic Acid in Regulation of Embryonic and Adult Hematopoiesis

Vitamin A is an essential micronutrient throughout life. Its physiologically active metabolite retinoic acid (RA), acting through nuclear retinoic acid receptors (RARs), is a potent regulator of patterning during embryonic development, as well as being necessary for adult tissue homeostasis. Vitamin A deficiency during pregnancy increases risk of maternal night blindness and anemia and may be a cause of congenital malformations. Childhood Vitamin A deficiency can cause xerophthalmia, lower resistance to infection and increased risk of mortality. RA signaling appears to be essential for expression of genes involved in developmental hematopoiesis, regulating the endothelial/blood cells balance in the yolk sac, promoting the hemogenic program in the aorta-gonad-mesonephros area and stimulating eryrthropoiesis in fetal liver by activating the expression of erythropoietin. In adults, RA signaling regulates differentiation of granulocytes and enhances erythropoiesis. Vitamin A may facilitate iron absorption and metabolism to prevent anemia and plays a key role in mucosal immune responses, modulating the function of regulatory T cells. Furthermore, defective RA/RARα signaling is involved in the pathogenesis of acute promyelocytic leukemia due to a failure in differentiation of promyelocytes. This review focuses on the different roles played by vitamin A/RA signaling in physiological and pathological mouse hematopoiesis duddurring both, embryonic and adult life, and the consequences of vitamin A deficiency for the blood system.

Identification of potential targets for differentiation in human leukemia cells induced by diallyl disulfide

Diallyl disulfide (DADS) is a primary component of garlic, which has chemopreventive potential. We previously found that moderate doses (15-120 µM) of DADS induced apoptosis and G2/M phase cell cycle arrest. In this study, we observed the effect of low doses (8 µM) of DADS on human leukemia HL-60 cells. We found that DADS could inhibit proliferation, migration and invasion in HL-60 cells, and arrested cells at G0/G1 stage. Then, cell differentiation was displayed by morphologic observation, NBT reduction activity and CD11b evaluation of cytometric flow. It showed that DADS induced differentiation, reduced the ability of NBT and increased CD11b expression. Likewise, DADS inhibited xenograft tumor growth and induced differentiation in vivo. In order to make sure how DADS induced differentiation, we compared the protein expression profile of DADS-treated cells with that of untreated control. Using high resolution mass spectrometry, we identified 18 differentially expressed proteins after treatment with DADS, including four upregulated and 14 downregulated proteins. RT-PCR and western blot assay showed that DJ-1, cofilin 1, RhoGDP dissociation inhibitor 2 (RhoGDI2), Calreticulin (CTR) and PCNA were decreased by DADS. These data suggest that the effects of DADS on leukemia may be due to multiple targets for intervention.

Promyelocytic extracellular chromatin exacerbates coagulation and fibrinolysis in acute promyelocytic leukemia

Despite routine treatment of unselected acute promyelocytic leukemia (APL) with all-trans-retinoic acid (ATRA), early death because of hemorrhage remains unacceptably common, and the mechanism underlying this complication remains elusive. We have recently demonstrated that APL cells undergo a novel cell death program, termed ETosis, which involves release of extracellular chromatin. However, the role of promyelocytic extracellular chromatin in APL-associated coagulation remains unclear. Our objectives were to identify the novel role of ATRA-promoted extracellular chromatin in inducing a hypercoagulable and hyperfibrinolytic state in APL and to evaluate its interaction with fibrin and endothelial cells (ECs). Results from a series of coagulation assays have shown that promyelocytic extracellular chromatin increases thrombin and plasmin generation, causes a shortening of plasma clotting time of APL cells, and increases fibrin formation. DNase I but not anti-tissue factor antibody could inhibit these effects. Immunofluorescence staining showed that promyelocytic extracellular chromatin and phosphatidylserine on APL cells provide platforms for fibrin deposition and render clots more resistant to fibrinolysis. Additionally, coincubation assays revealed that promyelocytic extracellular chromatin is cytotoxic to ECs, converting them to a procoagulant phenotype. This cytotoxity was blocked by DNase I by 20% or activated protein C by 31%. Our current results thus delineate the pathogenic role of promyelocytic extracellular chromatin in APL coagulopathy. Furthermore, the remaining coagulation disturbance in high-risk APL patients after ATRA administration may be treatable by intrinsic pathway inhibition via accelerating extracellular chromatin degradation.

Acute promyelocytic leukemia: preventing early complications and late toxicities

Acute promyelocytic leukemia (APL) is a unique subtype of acute myeloid leukemia (AML), which presents with a distinct coagulopathy. Therapeutic advances have made APL one of the true success stories in oncology, transforming this once lethal disease into the most curable form of AML. For many patients, cure will now be achieved without the use of chemotherapy. It is hoped that limiting chemotherapy will reduce mortality even further, particularly among more vulnerable older adults whose survival lagged behind that of younger patients. It should be noted that early death persists in patients with APL and continues to negatively affect survival. Further, among survivors treated with chemotherapy or even arsenic trioxide (ATO), there remains the potential for long-term toxicities that must be monitored. Understanding the management of these issues is an important complement to ensure maximal survival for patients with APL.

[Establishment and assessment of a nomogram for predicting the differentiation syndrome of acute promyelocytic leukemia]

Objective: By analyzing the risk factors for occurrence of differentiation syndrome (DS) during induction therapy in newly-diagnosed acute promyelocytic leukemia (APL) patients, a prediction nomogram for DS was established and the accuracy of this nomogram was validated. Methods: The modeling group was made up of 130 classical APL patients during the period of 1st January 2011 to 31st December 2013. After single factor screening of clinical variables, the logistic regression model was used to identify the final model variables. A nomogram subsequently established by R software was validated by Bootstrap resampling as internal validation. Concordance index (C-index) was used for the accuracy evaluation of the nomogram, and calibration curves were painted to test the actual observation and the nomogram-prediction of occurrence rate of DS. Results: Occurrence rate of DS in 130 APL patients was 30.0%; In multivariate analysis, body mass index (BMI) ≥24 kg/m2 and without using steroids for prevention of DS were identified as independent risk factors. The C-index of the nomogram for predicting DS was 0.818 (95% CI 0.741-0.895). The calibration curves showed good concordance of occurrence rate of DS between nomogram-prediction and actual observation. Conclusion: The nomogram was successfully established as a more accurate and visible tool for predicting the occurrence rate of DS in APL patients.

Current first- and second-line treatment options in acute promyelocytic leukemia

Outcome of acute promyelocytic leukemia (APL) has remarkably improved during the last 30 years, especially after the identification of PML-RARA oncogene as a key in the pathogenesis of APL and all-trans retinoic acid as therapeutic agent. Arsenic trioxide has been recently demonstrated to be the most effective single antileukemic agent and it has also showed synergistic action when combined with all-trans retinoic acid, decreasing relapse rate especially in low/intermediate-risk settings. Therapeutic advances led to complete remission rates of more than 90%, modifying disease history. In relapse setting, arsenic trioxide-based regimens showed efficacy for the achievement of second molecular complete remission. The most challenging issue in APL management remains the significant early deaths rate, nowadays the principal reason for treatment failure.

Massive Pulmonary Embolism at the Onset of Acute Promyelocytic Leukemia

Life-threatening bleeding is a major and early complication of acute promyelocytic leukemia (APL), but in the last years there is a growing evidence of thromboses in APL. We report the first case of a young woman with dyspnea as the first symptom of APL due to massive pulmonary embolism (PE) successfully treated with thrombolysis for PE and heparin. APL has been processed with a combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) obtaining complete remission.

Current management of newly diagnosed acute promyelocytic leukemia

The management of acute promyelocytic leukemia (APL) has considerably evolved during the past two decades. The advent of all-trans retinoic acid (ATRA) and its inclusion in combinatorial regimens with anthracycline chemotherapy has provided cure rates exceeding 80%; however, this widely adopted approach also conveys significant toxicity including severe myelosuppression and rare occurrence of secondary leukemias. More recently, the advent of arsenic trioxide (ATO) and its use in association with ATRA with or without chemotherapy has further improved patient outcome by allowing to minimize the intensity of chemotherapy, thus reducing serious toxicity while maintaining high anti-leukemic efficacy. The advantage of ATRA-ATO over ATRA chemotherapy has been recently demonstrated in two large randomized trials and this option has now become the new standard of care in low-risk (i.e. non-hyperleukocytic) patients. In light of its rarity, abrupt onset and high risk of early death and due to specific treatment requirements, APL remains a challenging condition that needs to be managed in highly experienced centers. We review here the results of large clinical studies conducted in newly diagnosed APL as well as the recommendations for appropriate diagnosis, prevention and management of the main complications associated with modern treatment of the disease.

Disparities in early death and survival in children, adolescents, and young adults with acute promyelocytic leukemia in California

BACKGROUND

Findings from clinical trials and population-based studies have differed with regard to whether mortality within 30 days of diagnosis (early death) of acute promyelocytic leukemia (APL) has decreased in the era of all-trans retinoic acid and anthracycline-based chemotherapy.

METHODS

Using data from the California Cancer Registry, the authors investigated 7-day and 30-day mortality and survival in 772 patients who were aged birth to 39 years when they were diagnosed with APL during 1988 to 2011. Logistic regression and Cox proportional models were used to examine the association of early death and survival, respectively, with sociodemographic and clinical factors.

RESULTS

The overall 30-day mortality decreased significantly over time, from 26% (1988-1995) to 14% (2004-2011) (P =.004). On multivariable analysis, the odds of 30-day mortality were 3 times as high during 1988 through 1995 than 2004 through 2011 (P =.001). However, 7-day mortality did not improve over time (P =.229). When patients who died within 7 days of diagnosis were excluded, the 30-day mortality during 1996 to 2011 was 3% to 8%, which is similar to levels reported in clinical trials. Higher early death and lower survival were associated with a lack of health insurance (1996-2011) (early death odds ratio, 2.67; P =.031) and Hispanic race/ethnicity (early death odds ratio, 2.13; P =.014). Early death was not found to be associated with age, sex, socioeconomic status, or hospital type. Black patients also experienced worse survival.

CONCLUSIONS

The findings of the current study revealed a decreased 30-day mortality during the all-trans retinoic acid era, but 7-day mortality remained high. Efforts to achieve equal outcomes in young patients with APL should focus on improving access to effective treatment, mainly among uninsured patients and those of Hispanic and black race/ethnicity.

Antiproliferative Activity and in Vivo Toxicity of Double-Point Modified Analogs of 1,25-Dihydroxyergocalciferol

Analogs of 1,25-dihydroxyergocalciferol, modified in the side-chain and in the A-ring, were tested for their antiproliferative activity against a series of human cancer cell lines in vitro and in vivo toxicity. The proliferation inhibition caused by the analogs was higher than that of the parent compounds, while the toxicity, measured as the serum calcium level, was lower. All analogs were able to induce, in HL-60 and MV4-11 leukemic cells, G₀/G₁ cell cycle arrest and differentiation expressed as morphological signs typical for monocytes. The analogs also induced the expression of CD11b and/or CD14 cell-differentiation markers. The most potent analogs, PRI-5105, PRI-5106, PRI-5201 and PRI-5202, were also able to induce vitamin D receptor (VDR) protein expression, mainly in the cytoplasmic fraction of HL-60 or MV4-11 cells. The most active analogs were the 19-nor ones with an extended and rigidified side-chain (PRI-5201 and PRI-5202), as in the former analogs PRI-1906 and PRI-1907. Epimerization at C-24 (PRI-5101) or introduction of an additional hydroxyl at C-23 (PRI-5104) reduced the toxicity of the analog with retained antiproliferative activity.