Central nervous system involvement at first relapse in patients with acute promyelocytic leukemia treated with all-trans retinoic acid and anthracycline monochemotherapy without intrathecal prophylaxis

The treatment of acute promyelocytic leukemia in 2023: Paradigm, advances, and future directions

The transformation of acute promyelocytic leukemia (APL) from an often fatal to highly curable cancer with long-term survival exceeding 90% is one of the greatest and most inspiring successes in oncology. A deeper understanding of the pathogenesis of APL heralded the introduction of highly effective therapies targeting the mutant protein that drives the disease, leading to the chemotherapy-free approach to cure almost all patients. In this review, we discuss the paradigm of treatment of APL in 2023, reinforce the high risk of early death without prompt initiation of treatment at first clinical suspicion, and dedicate a special focus to novel agents and future directions to improve cure rates and quality of life in patients affected by APL.

An effective and chemotherapy-free strategy of all-trans retinoic acid and arsenic trioxide for acute promyelocytic leukemia in all risk groups (APL15 trial)

The combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has been demonstrated to have comparable effectiveness or better to ATRA and chemotherapy (CHT) in non-high-risk acute promyelocytic leukemia (APL). However, the efficacy of ATRA-ATO compared to ATRA-ATO plus CHT in high-risk APL remains unknown. Here we performed a randomized multi-center non-inferiority phase III study to compare the efficacy of ATRA-ATO and ATRA-ATO plus CHT in newly diagnosed all-risk APL to address this question. Patients were assigned to receive ATRA-ATO for induction, consolidation, and maintenance or ATRA-ATO plus CHT for induction followed by three cycles of consolidation therapy, and maintenance therapy with ATRA-ATO. In the non-CHT group, hydroxyurea was used to control leukocytosis. A total of 128 patients were treated. The complete remission rate was 97% in both groups. The 2-year disease-free, event-free survival rates in the non-CHT group and CHT group in all-risk patients were 98% vs 97%, and 95% vs 92%, respectively (P = 0.62 and P = 0.39, respectively). And they were 94% vs 87%, and 85% vs 78% in the high-risk patients (P = 0.52 and P = 0.44, respectively). This study demonstrated that ATRA-ATO had the same efficacy as the ATRA-ATO plus CHT in the treatment of patients with all-risk APL.

Treatment for relapsed acute promyelocytic leukemia

The advent of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has significantly improved the outcomes of acute promyelocytic leukemia (APL); nevertheless, a small fraction of patients still experience relapse. Due to the infrequency of APL relapse coupled with the rapid change in the therapeutic landscape, there are limited available data regarding the treatment of relapsed APL. In this situation, however, ATO-based therapy has been shown to result in high rates of hematological and molecular complete remission (CR). Autologous hematopoietic cell transplantation (HCT) is considered the postremission therapy of choice when patients achieve molecular CR, whereas recent studies have suggested that molecular CR is not prerequisite for the success of autologous HCT. Allogeneic HCT can be reserved for selected patients, i.e., those who cannot achieve CR and those who relapse after autologous HCT, because of high toxicities and the expectation of highly favorable outcomes with autologous HCT during CR. For patients who are ineligible for HCT, prolonged administration of ATRA + ATO would be a viable option. To further refine the therapy for patients with relapsed APL, it is imperative to aggregate clinical data of patients who relapse after the ATRA + ATO frontline therapy within the framework of national and international collaboration.

Central nervous system recurrence in a patient treated for acute promyelocytic leukemia, resulting in sideroblastic anemia: A case report

BACKGROUND

Previous cases that have been stated in this article have displayed that around 1% to 7% of patients that have been treated with chemotherapy for acute promyelocytic leukemia developed myelodysplastic syndrome or acute myeloid leukemia. One can see that’s why this case presentation of a 60-year-old man that had a good response to acute promyelocytic leukemia treatment, that later presented with a central nervous system recurrence of acute promyelocytic leukemia and acquired sideroblastic anemia (a form of myelodysplasia) from treatment is a unique case report.

CASE SUMMARY

The presence of central nervous system relapse in acute promyelocytic leukemia patients is very unlikely compared to recurring mainly in the bone marrow. It is also uncommon to be diagnosed with sideroblastic anemia (form of myelodysplastic syndrome) as a result from treatment for acute promyelocytic leukemia. This case report highlights the detection, treatment/maintenance with idarubicin, all-trans-retinoic-acid, arsenic trioxide, methotrexate, 6-mercaptopurine, and ommaya reservoir intrathecal methotrexate administration in a patient that had central nervous system relapse of acute promyelocytic leukemia and acquired sideroblastic anemia.

CONCLUSION

In essence, first time relapse concerning the central nervous system in treated acute promyelocytic leukemia patients who had a good response to therapy is very uncommon. The acquirement of a myelodysplastic syndrome such as ringed sideroblastic anemia is also rare regarding this patient population. Although such cases are infrequent, this case report represents a unique insight of the detection, treatment, and maintenance of a 60-year-old man diagnosed with acute promyelocytic leukemia, resulting in the acquirement of sideroblastic anemia and central nervous system relapse.

Assessment of Arsenic Trioxide and All-trans Retinoic Acid for the Treatment of Pediatric Acute Promyelocytic Leukemia: A Report From the Children's Oncology Group AAML1331 Trial

Importance

All-trans retinoic acid (ATRA) and arsenic trioxide therapy without the use of maintenance therapy has been found to be beneficial for the treatment of adults with standard-risk acute promyelocytic leukemia (APL). However, it is unclear whether similar regimens are safe and beneficial for the treatment of high-risk APL or pediatric patients with standard-risk APL.

Objective

To assess whether treatment with an ATRA and arsenic trioxide-based regimen is safe and allows for the elimination or substantial reduction of chemotherapy use among pediatric patients with standard-risk or high-risk APL, respectively.

Design, Setting, and Participants

The Children's Oncology Group AAML1331 study is a nonrandomized, noninferiority trial that examined survival outcomes among 154 pediatric patients with APL compared with a historical control group of patients with APL from the AAML0631 study. Patients aged 1 to 21 years were enrolled at 85 pediatric oncology centers (members of the Children's Oncology Group) in Australia, Canada, and the US from June 29, 2015, to May 7, 2019, with follow-up until October 31, 2020. All patients had newly diagnosed APL and were stratified into standard-risk APL (white blood cell count <10 000/μL) and high-risk APL (white blood cell count ≥10 000/μL) cohorts.

Interventions

All patients received ATRA and arsenic trioxide continuously during induction therapy and intermittently during 4 consolidation cycles. Patients with high-risk APL received 4 doses of idarubicin during induction therapy only. The duration of therapy was approximately 9 months, and no maintenance therapy was administered.

Main Outcomes and Measures

Event-free survival (EFS) at 2 years after diagnosis.

Results

Among 154 patients (median age, 14.4 years [range, 1.1-21.7 years]; 81 male participants [52.6%]) included in the analysis, 98 patients (63.6%) had standard-risk APL, and 56 patients (36.4%) had high-risk APL. The median follow-up duration was 24.7 months (range, 0-49.5 months) for patients with standard-risk APL and 22.8 months (range, 0-47.7 months) for patients with high-risk APL. Patients with standard-risk APL had a 2-year EFS rate of 98.0% and an overall survival rate of 99.0%; adverse events included 1 early death during induction therapy and 1 relapse. Patients with high-risk APL had a 2-year EFS rate of 96.4% and an overall survival rate of 100%; adverse events included 2 relapses and 0 deaths. These outcomes met predefined noninferiority criteria (noninferiority margin of 10% among those with standard-risk APL and 14.5% among those with high-risk APL).

Conclusions and Relevance

In this nonrandomized, noninferiority trial, pediatric patients with standard-risk APL who received treatment with a chemotherapy-free ATRA and arsenic trioxide regimen experienced positive outcomes. Patients with high-risk APL also had positive outcomes when treated with a novel ATRA and arsenic trioxide-based regimen that included 4 doses of idarubicin during induction therapy only and no maintenance therapy. The 2-year EFS estimates were noninferior to the historical comparator group, and advantages of the regimen included shorter treatment duration, lower exposure to anthracycline and intrathecal chemotherapy, and fewer days hospitalized.

Trial Registration

ClinicalTrials.gov Identifier: NCT02339740.

Drug treatment options for acute promyelocytic leukemia

INTRODUCTION

Until the late 1980s, acute promyelocytic leukemia (APL) was the most rapidly fatal leukemia; however, nowadays, it is a curable disease with survival rates exceeding 90-95%. The improvement of APL outcome is mainly due to two agents, which target the typical translocation t(15;17) and its fusion transcript PML-RARα responsible for initiating and maintaining the disease: all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). The story of APL represents a pioneering model for the development of precision medicine and curative chemotherapy-free approaches for acute leukemia.

AREA COVERED

The authors examine the major advances in the treatment of patients with APL focusing on three different eras: 1) the pre-ATRA era; 2) the ATRA era; 3) the ATO era.

EXPERT OPINION

The combination of ATRA and ATO is effective and curative for the majority of APL patients. It has been approved for low/intermediate risk cases while an experimental trial with a minimal addition of chemotherapy for high-risk ones is ongoing. Disease relapse is infrequent and can be cured with ATRA-ATO rechallenging, with or without subsequent transplantation depending on the interval between complete remission and relapse. New therapeutic landscapes contemplate the use of an oral chemo-free ATRA-ATO combination, implementing treatment as outpatient care, thus increasing quality of life and decreasing medical costs.

Leukaemia cutis for clinicians, a literature review

Leukaemia cutis (LC) describes infiltration of the skin by leukaemia cells, resulting in clinically identifiable cutaneous lesions. LC has a wide range of clinical manifestations, which can make it difficult to distinguish LC from other skin changes. In a group of patients, LC can be the first manifestation of leukaemia, therefore skin biopsy is crucial for the diagnosis. In this mini review, we discuss various types of leukaemia most frequently represented in leukaemia cutis, in both children and adults and skin changes in multiple myeloma, focusing on the clinical presentation of LC and prognosis in patients.

Long-term survival in an acute promyelocytic leukemia patient with recurrent granulocytic sarcomas: A case report

RATIONALE

Granulocytic sarcoma (GS) is an extramedullary myeloid tumor composed of immature cells of the granulocytic series. It rarely occurs in acute promyelocytic leukemia (APL). No case of long-term survival in an APL patient with recurrent GS has been reported.

PATIENT CONCERNS

A 54-year-old female patient was diagnosed with APL in 1995 and has been in complete remission (CR) of bone marrow morphology for 24 years; however, recurrent GS occurred successively in ovary, breast, spine, body of sternum, lymph nodes, soft tissues from 2004 to 2019.

DIAGNOSES

The immunohistochemistry confirmed the diagnosis of GS, and fluorescence in situ hybridization (FISH) revealed its origin from APL.

INTERVENTIONS

She received surgery, and had an excellent response to all-trans retinoic acid (ATRA), DA (daunorubicin combined with cytarabine) regimens, and arsenic trioxide (ATO).

OUTCOMES

The patient achieved CR in March 2020 after radiotherapy followed by ATO and ATRA. So far, she is still in follow-up.

LESSONS

It is rare that recurrent GS at multiple sites is involved in APL patient with bone marrow morphology in CR. It is interesting to observe a long-term excellent response to ATRA, chemotherapy and ATO. Although multiple recurrence of GS in patients with APL is rare, the data in this case highlight the need for individualized treatment when such conditions occur.

An unusual headache: CSF negative APML relapse in the brain

Acute Promyelocytic Leukaemia (APML) is a subtype of Acute Myeloid Leukaemia (AML), responsible for around 10% of cases of the disease in adults. Extra medullary disease (EMD) occurs infrequently in APML, but where EMD does occur, the central nervous system is one of the most commonly infiltrated sites. Our case describes a man in his 40s undergoing post-therapy surveillance for APML who presented to follow-up clinic with a headache, which was ultimately found to be caused by a tumour comprised of APML cells. His case presented a diagnostic challenge due to the benign appearances of the lesion on initial computed tomography brain imaging and the non-diagnostic cerebrospinal fluid analysis. The diagnostic difficulties described in our case emphasizes that clinicians working with APML patients must approach new neurological symptoms with a high degree of suspicion to prevent diagnostic delay.

Diagnostic and Therapeutic Considerations for Extramedullary Leukemia

PURPOSE OF REVIEW

The purpose of this review is to summarize the current literature on the presentation, diagnosis, and treatment options available for extramedullary (EM) manifestations of leukemia including myeloid sarcoma (MS) and leukemia cutis (LC).

RECENT FINDINGS

Advanced imaging using 18FDG-PET/CT is an effective screening tool for EM manifestations of leukemia. The role of radiation therapy has been more clearly delineated in the treatment of both MS and LC. FDA-approved targeted agents have improved outcomes in patients with AML but have not demonstrated improvements specifically for EM; however, a checkpoint inhibitor, Ipilimumab, holds promise in impacting local control for the treatment of AML-related EM. EM manifestations of leukemia pose significant therapeutic challenges. Treatment of EM is predicated on multiple factors including the presence of concomitant bone marrow involvement, AML-risk classification, and timing of presentation at initial diagnosis or relapse following systemic therapy.

Oral arsenic trioxide, all-trans retinoic acid, and ascorbic acid maintenance after first complete remission in acute promyelocytic leukemia: Long-term results and unique prognostic indicators

BACKGROUND

The role of arsenic trioxide (As₂ O₃ ) in the maintenance of first complete remission (CR1) in acute promyelocytic leukemia (APL) is unclear.

METHODS

A total of 129 consecutive adult patients with APL of all risk categories who achieved CR1 with conventional induction (all-trans retinoic acid [ATRA]/daunorubicin) and consolidation (daunorubicin/cytarabine [induction daunorubicin and consolidation omitted for age ≥70 years]) underwent maintenance comprising ATRA (45 mg/m² /day), oral As₂ O₃ (10 mg/day), and ascorbic acid (1 g/day) (AAA) for 2 weeks every 2 months for 2 years.

RESULTS

Over a 17-year period from August 1, 2002, to July 31, 2019, 63 men and 66 women (median age, 46 years [range, 18-82 years]) received AAA maintenance, which was already completed in 117 patients. At a median follow-up of 100 months (range, 8-215 months), 17 patients (13%) developed first relapse (R1) (hematologic, n = 14; molecular, n = 3) after a median of 19 months (range, 7-96 months) from CR1. Two R1 patients had concomitant central nervous system (CNS) involvement. All patients achieved CR2 with oral As₂ O₃ -based salvage. Five patients had a subsequent relapse and died. Eight patients died of unrelated causes while still in CR1. The 5-year and 10-year rates of relapse-free survival (RFS) were 89% and 85%, respectively. The 5-year and 10-year rates of overall survival (OS) were 94% and 87%, respectively. Multivariate analysis showed that inferior RFS was associated with FLT3-ITD (P = .005) and CNS involvement on presentation (P = .004), and inferior OS was associated with therapy-related APL (P = .03), FLT3-ITD (P = .03), and relapse (P = .03). The safety profile was favorable, with no grade 3/4 organ toxicities.

CONCLUSION

CR1 maintenance with AAA is safe and results in favorable long-term survival in patients with APL.

Central Nervous System Double Relapse of Acute Promyelocytic Leukemia and Acute Myelomonocytic Leukemia

Relapse of acute promyelocytic leukemia (APL) and non-M3-acute myeloid leukemia in the central nervous system (CNS) are rare events. Here, we describe a case of simultaneous relapses of APL and acute myelomonocytic leukemia on the CNS of a patient after allogeneic bone marrow transplant. This extremely unusual case highlights the difficulties that CNS leukemia relapses pose in the post-transplant setting.

Acute Promyelocytic Leukemia: Update on the Mechanisms of Leukemogenesis, Resistance and on Innovative Treatment Strategies

This review highlights new findings that have deepened our understanding of the mechanisms of leukemogenesis, therapy and resistance in acute promyelocytic leukemia (APL). Promyelocytic leukemia-retinoic acid receptor α (PML-RARa) sets the cellular landscape of acute promyelocytic leukemia (APL) by repressing the transcription of RARa target genes and disrupting PML-NBs. The RAR receptors control the homeostasis of tissue growth, modeling and regeneration, and PML-NBs are involved in self-renewal of normal and cancer stem cells, DNA damage response, senescence and stress response. The additional somatic mutations in APL mainly involve FLT3, WT1, NRAS, KRAS, ARID1B and ARID1A genes. The treatment outcomes in patients with newly diagnosed APL improved dramatically since the advent of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). ATRA activates the transcription of blocked genes and degrades PML-RARα, while ATO degrades PML-RARa by promoting apoptosis and has a pro-oxidant effect. The resistance to ATRA and ATO may derive from the mutations in the RARa ligand binding domain (LBD) and in the PML-B2 domain of PML-RARa, but such mutations cannot explain the majority of resistances experienced in the clinic, globally accounting for 5-10% of cases. Several studies are ongoing to unravel clonal evolution and resistance, suggesting the therapeutic potential of new retinoid molecules and combinatorial treatments of ATRA or ATO with different drugs acting through alternative mechanisms of action, which may lead to synergistic effects on growth control or the induction of apoptosis in APL cells.

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.

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

Since the comprehensive recommendations for the management of acute promyelocytic leukemia (APL) reported in 2009, several studies have provided important insights, particularly regarding the role of arsenic trioxide (ATO) in frontline therapy. Ten years later, a European LeukemiaNet expert panel has reviewed the recent advances in the management of APL in both frontline and relapse settings in order to develop updated evidence- and expert opinion-based recommendations on the management of this disease. Together with providing current indications on genetic diagnosis, modern risk-adapted frontline therapy, and salvage treatment, the review contains specific recommendations for the identification and management of the most important complications such as the bleeding disorder APL differentiation syndrome, QT prolongation, and other all-trans retinoic acid- and ATO-related toxicities, as well as recommendations for molecular assessment of the response to treatment. Finally, the approach to special situations is also discussed, including management of APL in children, elderly patients, and pregnant women. The most important challenges remaining in APL include early death, which still occurs before and during induction therapy, and optimizing treatment in patients with high-risk disease.

Outcome for pediatric acute promyelocytic leukemia patients at Children's Oncology Group sites on the Leukemia Intergroup Study CALGB 9710 (Alliance)

BACKGROUND

Acute promyelocytic leukemia (APL) is a unique leukemia subtype requiring specialized treatment including all-trans retinoic acid (ATRA). A prior report demonstrated worse outcome among young children <5 years old compared with older children.

METHODS

We evaluated outcomes for pediatric patients (<18 years old; N = 83) with APL treated on North American intergroup study CALGB 9710 at Children's Oncology Group sites. Induction and consolidation included ATRA, cytarabine, and anthracyclines. Patients ≥15 years old were randomized to addition of arsenic trioxide (ATO) consolidation. All patients were randomized to ATRA maintenance with versus without oral chemotherapy.

RESULTS

The estimated 5-year overall survival (OS) rate was 82%, and the event-free survival (EFS) rate was 54%. Seven patients (8.4%) died during induction due to coagulopathy. Maintenance randomization demonstrated that addition of oral chemotherapy to ATRA significantly reduced relapse rate, but difference in EFS did not reach statistical significance (P = 0.12; 5-year rates [95% CI]: 41% [17%-64%] ATRA only vs 72% [56%-88%] ATRA plus chemotherapy). There was no difference (P = 0.93) in EFS for age <5 years versus 5-12.99 years versus 13-17.99 years (5-year rates: 56%, 47%, and 45%, respectively). Among adolescents 15-17.99 years old in the ATO randomization, there was a significantly lower relapse risk at 5 years for those receiving ATO (0% ATO vs 44% no ATO; P = 0.02).

CONCLUSION

Our data demonstrate that intensified ATRA, cytarabine, and anthracycline chemotherapy is effective for pediatric APL including very young patients, but early deaths and relapses remain barriers to cure. Further improvements are likely with incorporation of ATO into pediatric APL regimens.

Treatment of Acute Promyelocytic Leukemia in Adults

The treatment of acute promyelocytic leukemia (APL) has evolved rapidly in the past two decades after the introduction of highly active drugs, including tretinoin (all- trans-retinoic acid) and arsenic trioxide. It is now possible to treat this disease without the use of traditional cytotoxic chemotherapy. Today’s clinical guidelines include multiple regimens, some of which continue to use cytotoxic chemotherapy. This leaves the practicing oncologist with multiple treatment options when faced with a new case of APL. In an effort to standardize our approach to the treatment of newly diagnosed APL, we sought to develop a set of treatment recommendations at our institution. We identified eight major controversial issues in the treatment of APL. These controversial issues include the optimal dose and schedule of both all- trans-retinoic acid and arsenic trioxide, the optimal regimen for high-risk APL, the need for intrathecal prophylaxis, the use of prophylactic corticosteroids, and the need for maintenance therapy after consolidation. We reviewed the relevant literature and used the Delphi method among the coauthors to reach consensus for recommendations on the basis of the best available data and our own clinical experience. In this clinical review, we present our consensus recommendations, the reasoning behind them, and the grading of the evidence that supports them.

Arsenic trioxide and all-trans retinoic acid (ATRA) treatment for acute promyelocytic leukemia in all risk groups: study protocol for a randomized controlled trial

Background

The treatment of acute promyelocytic leukemia (APL) has been revolutionized in the past two decades by the advent of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). It suggests that non-high-risk APL patients can be cured without chemotherapy. However, ATRA plus chemotherapy is still the standard therapy for the high-risk patients. Central nervous system (CNS) relapse remains a significant cause of treatment failure in high-risk patients. However, increasing the ATO concentration in cerebrospinal fluid (CSF) may reduce CNS relapse in high-risk patients. Mannitol can allow ATO to penetrate the blood-brain barrier (BBB) and reach therapeutically effective levels in the CSF. It is used for the treatment of CNS relapse in patients APL. We compare ATRA-ATO with ATRA-ATO plus chemotherapy in both high-risk and non-high-risk patients with APL.

Methods

This study was designed as a multicenter randomized controlled trial. Patients with APL were randomly assigned into two groups: the ATRA-ATO group (experimental group) and the ATRA-ATO plus chemotherapy group (control group). The experimental group receives therapy with ATRA-ATO for induction, consolidation and maintenance therapy. In the high-risk patients, mannitol will be used with ATO in the consolidation and maintenance therapy. Hydroxyurea will be used in patients who developed leukocytosis in the induction therapy. The control group receives therapy with ATRA-ATO plus chemotherapy for induction and consolidation therapy.

Discussion

In this study, a randomized clinical trial design is described. It aims to compare the efficacy of ATRA-ATO versus ATRA-ATO plus chemotherapy in all-risk patients with APL.

Trial registration

Chinese Clinical Trials Registry, ID: ChiCTR-IPR-15006821. Registered on 27 July 2015.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2812-3) contains supplementary material, which is available to authorized users.

Long-term outcome of relapsed acute promyelocytic leukemia treated with oral arsenic trioxide-based reinduction and maintenance regimens: A 15-year prospective study

BACKGROUND

For patients who have acute promyelocytic leukemia (APL) in second complete remission (CR2), optimal postremission strategies remain undefined.

METHODS

The role of an oral arsenic trioxide (As₂ O₃ )-based regimen in the management of patients who had APL in CR2 was examined.

RESULTS

Seventy-three patients with APL in first relapse (R1) were studied. Oral As₂ O₃ -based reinduction resulted uniformly in CR2, irrespective of previous As₂ O₃ exposure. All patients received oral As₂ O₃ -based maintenance in CR2. At a median follow-up of 94 months (range, 9-205 months), 43 patients (58.9%) were still in CR2, and 49 (67.1%) had finished the planned 2-year CR2 maintenance with all-trans retinoic acid, oral As₂ O₃ , and ascorbic acid. Reinduction and maintenance treatments were well tolerated. Grade 1 and 2 headache occurred in 20 patients (27.4%). Hepatotoxicity, all in the form of transaminitis, occurred in 35 patients (47.9%; grade 1 and 2, n = 26; grade 3 and 4, n = 9). Three patients had self-limiting QTc prolongation. The 10-year leukemia-free survival rate was 56.8%. Thirty patients developed R2. Oral As₂ O₃ -based reinduction led to CR3 in 27 patients (90%). Post-CR3 strategies included autologous hematopoietic stem cell transplantation and oral As₂ O₃ maintenance. At a post-CR3 follow-up of 30 months (range, 3-166 months), 11 patients were still in CR3. The 5-year and 10-year overall survival rates in the R1 cohort were 79.5% and 67.3%, respectively. Prior receipt of oral As₂ O₃ maintenance in CR1 was the only risk factor for inferior leukemia-free survival. Central nervous system involvement occurred in 15 patients, including 5 who remained alive. Relapse during oral As₂ O₃ therapy was the only significant risk factor for central nervous system involvement.

CONCLUSIONS

For patients with relapsed APL, As₂ O₃ remained effective despite repeated As₂ O₃ exposures. Oral As₂ O₃ maintenance was an effective postremission strategy for CR2. Cancer 2018;124:2316-26. © 2018 American Cancer Society.

Central nervous system involvement of acute promyelocytic leukemia, three case reports

Central nervous system (CNS) involvement of acute promyelocytic leukemia (APL) causes poor prognosis. Our three cases show that CNS can be involved at the first hematological recurrence, but predicting this is difficult. Triple intrathecal treatment and craniospinal irradiation were effective, while arsenic oxide failed to prevent and improve CNS involvement.

Isolated Central Nervous System (CNS) Relapse in Paediatric Acute Promyelocytic Leukaemia: A Systematic Review

INTRODUCTION

Extramedullary disease, as a whole, is rare in Acute Promyelocytic Leukaemia (APML). If at all relapse occurs, following sites are involved: Central Nervous System (CNS), skin, testes, mediastinum, gingiva, and ear. Isolated CNS relapses after complete morphological and molecular remission is rarer particularly in children.

AIM

To review the literature systematically to find out the incidence of isolated CNS relapse in paediatric APML cases.

MATERIALS AND METHODS

A systematic search of major databases (Medline, Pubmed and Google Scholar) was conducted. We included all types of studies that reported about incidence or prevalence of isolated CNS relapse in children upto 18 years of age with APML.

RESULTS

A total of nine studies (with 10 cases of isolated CNS relapse) were included. Majority (70%) was high risk patients, and 60% were ≤six-year-old. Nearly, 50% were having the mean time to relapse <12 months and most (60%) of them were male. The children who died were having shorter time to CNS relapse (around 12 months), and were older (>6 to 18 years).

CONCLUSION

In the present review, disease in the high-risk group, male sex, younger age (≤six-years-old), and Promyelocytic Leukaemia/Retinoic Acid Receptor Alpha (PML-RARA) detection was found to be associated with isolated CNS relapse in children with APML. Cerebrospinal fluid (CSF) examination along with immunophenotyping and Reverse Transcription polymerase Chain Reaction (RT-PCR) for PML-RARA is required for a definite diagnosis and early treatment of patients to improve overall survival.

[Critical roles of matrix metalloproteinases secreted by leukemic cells in the pathogenesis of central nervous system leukemia]

目的

观察白血病细胞分泌的基质金属蛋白酶（MMP）-2和MMP-9对脑微血管内皮细胞（BMVEC）紧密连接蛋白ZO-1、claudin-5、occludin表达及对血脑屏障（BBB）通透性的影响，探讨MMP-2和MMP-9在中枢神经系统白血病（CNSL）发病机制中的作用。

方法

①实时定量PCR检测SHI-1、HL-60、U937细胞MMP-2、MMP-9基因的转录水平；明胶酶谱法检测细胞培养上清中MMP-2和MMP-9蛋白表达；体外穿膜实验观察各白血病细胞株的侵袭能力。②将原代人BMVEC接种于铺有Matrigel胶和纤维黏连蛋白包被的Transwell小室系统中，建立体外BBB模型。将蛋白酶抑制剂GM6001处理或未处理的SHI-1、HL-60、U937细胞或MMP-2/MMP-9基因沉默的SHI-1细胞接种于BBB模型的Transwell小室上层与BMVEC共培养，倒置相差显微镜观察BMVEC的形态变化，激光共聚焦显微镜观察紧密连接蛋白ZO-1、claudin-5和occludin的表达，计算白血病细胞的穿膜率。

结果

①SHI-1细胞表达较高转录水平的MMP-2和MMP-9及酶活性，且侵袭能力强于HL-60、U937细胞（P< 0.01）。②与HL-60、SHI-1和U937细胞共培养后，融合致密的BMVEC之间出现间隙、细胞呈单个生长，紧密连接蛋白ZO-1、claudin-5和occludin的表达明显下调，各白血病细胞均不同程度地穿过体外BBB进入Transwell小室下层。其中SHI-1细胞对BMVEC的形态改变及3种紧密连接蛋白的下调最为明显，穿膜率最高。GM6001明显抑制白血病细胞分泌MMP-2和MMP-9，使BMVEC的形态有所恢复，同时上调ZO-1、claudin-5和occludin的表达，降低了BBB的通透性。③用siRNA分别沉默MMP-2和MMP-9基因后，SHI-1细胞分泌MMP-2和MMP-9被抑制，SHI-1细胞穿膜率较沉默前分别下降43.64％和57.30%（P<0.01），ZO-1、claudin-5和occludin表达上调。

结论

白血病细胞株分泌的MMP-2和MMP-9能通过降解BMVEC紧密连接蛋白ZO-1、claudin-5和occludin而破坏BBB。

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.

Expression of CD56 is a risk factor for acute lymphocytic leukemia with central nervous system involvement in adults

OBJECTIVE

To gain further insights into the predisposing risk factors for central nervous system (CNS) involvement in patients with acute lymphocytic leukemia (ALL), the impact of CD56 expression in these patients was investigated.

METHODS

We reviewed the clinical features of CD56 expression in 588 consecutive ALL patients treated with systemic chemotherapy regimens between 2000 and 2014. The categorical data from CD56⁺ ALL patients were compared with those from CD56^- ALL patients.

RESULTS

Among the 588 patients studied, 18.9% showed CD56 expression. The expression was significantly associated with CD33⁺, CD10^-, CD15⁺, TdT^-, and CD5⁺ immunophenotypes. After systemic chemotherapy, 8.8% patients showed CNS involvement, of which 3.2% exhibited combined recurrences and 5.6% exhibited isolated CNS involvement. The 5-year event-free survival was significantly lower for patients with CD56⁺ immunophenotype compared with patients with CD56^- immunophenotype (22.5% vs. 32.7%, P = 0.04). Cumulative incidences of CNS involvement were significantly greater in the CD56⁺ cohort compared with the CD56^- cohort (14.4% vs. 7.5%, P = 0.02). Multivariate analysis revealed CD56 expression to be statistically significant risk factors for CNS involvement.

CONCLUSION

CD56 expression should be regarded as an independent risk factor for ALL with CNS involvement in adults.

Evolution of a FLT3-TKD mutated subclone at meningeal relapse in acute promyelocytic leukemia

Here, we report the case of an acute promyelocytic leukemia (APL) patient who—although negative for FLT3 mutations at diagnosis—developed isolated FLT3 tyrosine kinase II domain (FLT3-TKD)-positive meningeal relapse, which, in retrospect, could be traced back to a minute bone marrow subclone present at first diagnosis. Initially, the 48-yr-old female diagnosed with high-risk APL had achieved complete molecular remission after standard treatment with all-trans retinoic acid (ATRA) and chemotherapy according to the AIDA (ATRA plus idarubicin) protocol. Thirteen months after the start of ATRA maintenance, the patient suffered clinically overt meningeal relapse along with minute molecular traces of PML/RARA (promyelocytic leukemia/retinoic acid receptor alpha) in the bone marrow. Following treatment with arsenic trioxide and ATRA in combination with intrathecal cytarabine and methotrexate, the patient achieved a complete molecular remission in both cerebrospinal fluid (CSF) and bone marrow, which currently lasts for 2 yr after completion of therapy. Whole-exome sequencing and subsequent ultradeep targeted resequencing revealed a heterozygous FLT3-TKD mutation in CSF leukemic cells (p.D835Y, c.2503G>T, 1000/1961 reads [51%]), which was undetectable in the concurrent bone marrow sample. Interestingly, the FLT3-TKD mutated meningeal clone originated from a small bone marrow subclone present in a variant allele frequency of 0.4% (6/1553 reads) at initial diagnosis. This case highlights the concept of clonal evolution with a subclone harboring an additional mutation being selected as the “fittest” and leading to meningeal relapse. It also further supports earlier suggestions that FLT3 mutations may play a role for migration and clonal expansion in the CSF sanctuary site.

Central nervous system prophylaxis in diffuse large B-cell lymphoma

Central nervous system (CNS) involvement with diffuse large B-cell lymphoma (DLBCL) is a relatively uncommon manifestation; with most cases of CNS involvement occuring during relapse after primary therapy. CNS dissemination typically occurs early in the disease course and is most likely present subclinically at the time of diagnosis in many patients who later relapse in the CNS. CNS relapse in these patients is associated with poor outcomes. Based on a CNS relapse rate of 5% in DLBCL and weighing the benefits against the toxicities, universal application of CNS prophylaxis is not justified. The introduction of rituximab has significantly reduced the incidence of CNS relapse in DLBCL. Different studies have employed other agents for CNS prophylaxis, such as intrathecal chemotherapy and high-dose systemic agents with sufficient CNS penetration. If CNS prophylaxis is to be given, it should be preferably administered during primary chemotherapy. However, there is no strong evidence that supports any single approach for CNS prophylaxis. In this review, we outline different strategies of administering CNS prophylaxis in DLBCL patients reported in literature and discuss their advantages and drawbacks.

Autologous transplant remains the preferred therapy for relapsed APL in CR2

Despite their favorable prognosis, 10-20% of acute promyelocytic leukemia (APL) patients relapse. Reinduction therapy is often followed by autologous hematopoietic cell transplantation (auto-HCT). Arsenic trioxide (ATO) has become part of standard reinduction and is often followed by auto-HCT. Data on patients in CR2 were collected from two large transplant registries (Center for International Blood and Marrow Transplant Research (CIBMTR) and European Group for Blood and Marrow Transplant (EBMT)) and two specialty referral centers. The outcome of patients in CR2 who received only ATO-based therapy as reinduction was retrospectively compared with those who got an auto-HCT, with or without ATO. Prognostic factors included age, disease risk, extramedullary disease and duration of CR1. Of 207 evaluable patients, the median age was 31.5 years, 15.3% had extramedullary disease and median WBC at diagnosis was 4.8 × 10(9)/L. Sixty-seven patients received ATO alone and 140 underwent auto-HCT. The groups were comparable for age, gender, extramedullary disease, risk group and duration of CR1. At 5 years, overall survival (OS) was 42% and 78% for the ATO-only and auto-HCT groups, respectively (P<0.001). In addition, OS was associated with longer duration of CR1 (P=0.002), but not with disease risk at diagnosis. These data suggest that auto-HCT for APL patients in CR2 results in better OS than ATO-based therapy alone.

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.

[Relapse of acute promyelocytic leukemia in the central nervous system revealed by isolated dementia]

INTRODUCTION

Approximately 1.5% of dementia is due to curable aetiology. We report an isolated dementia syndrome due to a meningeal relapse of acute promyelocytic leukaemia with favourable outcome after appropriate treatment.

CASE REPORT

A 72-year-old woman, in remission of an acute promyelocytic leukaemia, presented a loss of autonomy for several months due to corticosubcortical dementia. Lumbar puncture showed blast cells indicating meningeal relapse of leukaemia. Intrathecal chemotherapy and arsenic trioxide obtained biological and molecular remission as well as restoration of normal cognitive functions.

CONCLUSION

In patients with hematologic past history such as acute promyelocytic leukaemia, an isolated cognitive impairment should alert physicians to search for an isolated neuromeningeal relapse.

Current standard treatment of adult acute promyelocytic leukaemia

The outcome of patients with acute promyelocytic leukaemia (APL) has dramatically improved over the last two decades, due to the introduction of combined all-trans retinoic acid (ATRA) and chemotherapy regimens and, more recently, to the advent of arsenic trioxide (ATO). ATRA and anthracycline-based chemotherapy remains a widely used strategy, providing cure rates above 80%, but it is associated with risk of severe infections and occurrence of secondary leukaemias. ATO is the most effective single agent in APL and, used alone or in combination with ATRA or ATRA and reduced-intensity chemotherapy, results in greater efficacy with considerably less haematological toxicity. The toxic profile of ATO includes frequent, but manageable, QTc prolongation and increase of liver enzymes. Two large randomized studies have shown that ATRA + ATO is superior to ATRA + chemotherapy for newly diagnosed low-risk APL resulting in 2-4 year event-free survival rates above 90% and very few relapses. According to real world data, the spectacular progress in APL outcomes reported in clinical trials has not been paralleled by a significant improvement in early death rates, this remains the most challenging issue for the final cure of the disease.

Extramedullary relapse in lumbar spine of patient with acute promyelocytic leukemia after remission for 16 years: a case report and literature review

Acute promyelocytic leukemia (APL) is a common myeloid leukemia. At the newly diagnosed stage, it can be fatal because of the serious complication-disseminated intravascular coagulation. With the advent and early application of all-trans retinoic acid, most APL patients can achieve a long-term survival, and only a minority of patients will develop extramedullary relapse after remission. The most common site of extramedullary relapse is central nervous system, while other sites are relatively rare. Here, we report a particularly rare APL patient who experienced extramedullary relapse with lumbar spine as the isolated site after a rather long time of remission for 16 years. At the time of relapse, the main clinical manifestations of the patient are obvious low back pain, weakness in lower limbs and limitation of activity. After treatment of local radiotherapy combined with ATRA and arsenic trioxide, the patient achieved and maintained a second complete remission by now.

Use of arsenic trioxide in remission induction and consolidation therapy for acute promyelocytic leukaemia in the Australasian Leukaemia and Lymphoma Group (ALLG) APML4 study: a non-randomised phase 2 trial

BACKGROUND

Initial treatment of acute promyelocytic leukaemia traditionally involves tretinoin (all-trans retinoic acid) combined with anthracycline-based risk-adapted chemotherapy, with arsenic trioxide being the treatment of choice at relapse. To try to reduce the relapse rate, we combined arsenic trioxide with tretinoin and idarubicin in induction therapy, and used arsenic trioxide with tretinoin as consolidation therapy.

METHODS

Patients with previously untreated genetically confirmed acute promyelocytic leukaemia were eligible for this study. Eligibilty also required Eastern Cooperative Oncology Group performance status 0-3, age older than 1 year, normal left ventricular ejection fraction, Q-Tc interval less than 500 ms, absence of serious comorbidity, and written informed consent. Patients with genetic variants of acute promyelocytic leukaemia (fusion of genes other than PML with RARA) were ineligible. Induction comprised 45 mg/m(2) oral tretinoin in four divided doses daily on days 1-36, 6-12 mg/m(2) intravenous idarubicin on days 2, 4, 6, and 8, adjusted for age, and 0·15 mg/kg intravenous arsenic trioxide once daily on days 9-36. Supportive therapy included blood products for protocol-specified haemostatic targets, and 1 mg/kg prednisone daily as prophylaxis against differentiation syndrome. Two consolidation cycles with tretinoin and arsenic trioxide were followed by maintenance therapy with oral tretinoin, 6-mercaptopurine, and methotrexate for 2 years. The primary endpoints of the study were freedom from relapse and early death (within 36 days of treatment start) and we assessed improvement compared with the 2 year interim results. To assess durability of remission we compared the primary endpoints and disease-free and overall survival at 5 years in APML4 with the 2 year interim APML4 data and the APML3 treatment protocol that excluded arsenic trioxide. This study is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12605000070639.

FINDINGS

124 patients were enrolled between Nov 10, 2004, and Sept 23, 2009, with data cutoff of March 15, 2012. Four (3%) patients died early. After a median follow-up of 4·2 years (IQR, 3·2-5·2), the 5 year freedom from relapse was 95% (95% CI 89-98), disease-free survival was 95% (89-98), event-free survival was 90% (83-94), and overall survival was 94% (89-97). The comparison with APML3 data showed that hazard ratios were 0·23 (95% CI 0·08-0·64, p=0·002) for freedom from relapse, 0·21 (0·07-0·59, p=0·001) for disease-free survival, 0·34 (0·16-0·69, p=0·002) for event-free survival, and 0·35 (0·14-0·91, p=0·02) for overall survival.

INTERPRETATION

Incorporation of arsenic trioxide in initial therapy induction and consolidation for acute promyelocytic leukaemia reduced the risk of relapse when compared with historical controls. This improvement, together with a non-significant reduction in early deaths and absence of deaths in remission, translated into better event-free and overall survival.

FUNDING

Phebra.

Acute promyelocytic leukemia harbouring rare FLT3-TKD and WT1 mutations: A case report

The involvement of the central nervous system (CNS) is rare in acute promyelocytic leukemia (APL). The present study reported the case of a 34-year-old male patient with APL that possessed a rare point mutation (p.Asn841Gly, c.2523C>A) in the tyrosine kinase domain of the FMS-like tyrosine kinase 3 (FLT3) gene and a novel Wilm tumor gene mutation (c.1209_1210insT/p.K404X). The patient suffered central nervous system and systemic relapses twice during systemic and intrathecal chemotherapy. At present, the patient is undergoing alternative induction and consolidation therapies, including the administration of FLT3 inhibitor, tetraarsenic tetrasulfide and novel cytotherapy, and is prepared for salvage allogeneic hematopoietic stem cell transplantion (allo-HSCT). The present study indicated that patients with APL that are at a high risk of relapse and unfavorable gene mutations should receive immediate allo-HSCT, whenever possible.

Arsenic trioxide-based therapy of relapsed acute promyelocytic leukemia: registry results from the European LeukemiaNet

In 2008, a European registry of relapsed acute promyelocytic leukemia was established by the European LeukemiaNet. Outcome data were available for 155 patients treated with arsenic trioxide in first relapse. In hematological relapse (n=104), 91% of the patients entered complete hematological remission (CR), 7% had induction death and 2% resistance, 27% developed differentiation syndrome and 39% leukocytosis, whereas no death or side effects occurred in patients treated in molecular relapse (n=40). The rate of molecular (m)CR was 74% in hematological and 62% in molecular relapse (P=0.3). All patients with extramedullary relapse (n=11) entered clinical and mCR. After 3.2 years median follow-up, the 3-year overall survival (OS) and cumulative incidence of second relapse were 68% and 41% in hematological relapse, 66% and 48% in molecular relapse and 90 and 11% in extramedullary relapse, respectively. After allogeneic or autologous transplantation in second CR (n=93), the 3-year OS was 80% compared with 59% without transplantation (n=55) (P=0.03). Multivariable analysis demonstrated the favorable prognostic impact of first remission duration ⩾1.5 years, achievement of mCR and allogeneic or autologous transplantation on OS of patients alive after induction (P=0.03, P=0.01, P=0.01) and on leukemia-free survival (P=0.006, P<0.0001, P=0.003), respectively.

Treatment of paediatric APL: how does the therapeutic approach differ from adults?

Acute promyelocytic leukaemia (APL) in children and adolescents shares many features with APL in adults. There are important distinctions, however, between these age groups in the presentation, complications and treatment outcomes. Paediatric patients are more likely to present with high risk features including elevated WBC count or microgranular variant (M3v). Yet the early death rate is lower in paediatric patients compared to adult patients. Overall outcomes such as CR, OS and EFS appear similar in paediatric and adult patients treated on similar regimens except that very young children may have a higher risk of relapse. While contemporary studies have clearly demonstrated improved survival in adults receiving ATO therapy, currently there is more limited data on the role of ATO in paediatric patients. Here we highlight the similarities and important distinctions between paediatric and adult APL while reviewing available data on treatment of paediatric APL.

Acute Promyelocytic Leukemia (APL): Comparison Between Children and Adults

The outcome of adults and children with Acute Promyelocytic Leukemia (APL) has dramatically changed since the introduction of all trans retinoic acid (ATRA) therapy. Based on the results of several multicenter trials, the current recommendations for the treatment of patients with APL include ATRA and anthracycline-based chemotherapy for the remission induction and consolidation, and ATRA combined with low-dose chemotherapy for maintenance. This has improved the prognosis of APL by increasing the complete remission (CR) rate, actually > 90%, decreasing the induction deaths and by reducing the relapse rate, leading to cure rates nowadays exceeding 80% considering both adults and children.1-9 More recently the combination of ATRA and arsenic trioxide (ATO) as induction and consolidation therapy has been shown to be at least not inferior and possibly superior to ATRA plus chemotherapy in adult patients with APL conventionally defined as non-high risk (Sanz score).10 Childhood APL has customarily been treated on adult protocols. Data from several trials have shown that the overall outcome in pediatric APL appears similar to that reported for the adult population; however, some clinical and therapeutic aspects differ in the two cohorts which require some important considerations and treatment adjustments.

Leptomeningeal Relapse of Acute Promyelocytic Leukemia

Extramedullary relapse (EMR) of acute promyelocytic leukemia (APL) is a rare entity, with predilection to involve the central nervous system (CNS). Risk factors include leukocytosis of > 10 × 10⁹/L, bcr3 isoform, microgranular variant, age > 45 years and development of subarachnoid hemorrhage (SAH) during induction therapy. We report a case of APL who completed induction and consolidation therapy but subsequently relapsed with leptomeningeal involvement. Retrospectively, we identified several risk factors for EMR in our patient. Interestingly, the use of all-trans retinoic acid has recently been associated with higher risk of EMR possibly due to up-regulation of adhesion molecules on the surface of the leukemic cell, resulting in their passage through the endothelium to extramedullary tissues. However, data remain conflicting in that regard. Although universal CNS prophylaxis has been suggested, the low incidence of EMR among APL patients renders this strategy less attractive. Nonetheless, active surveillance and CNS prophylaxis may be considered in patients at high risk for EMR, particularly in those of SAH during induction therapy. Further research is needed to evaluate the effectiveness and safety of this strategy.