Presenting White Blood Cell Count and Kinetics of Molecular Remission Predict Prognosis in Acute Promyelocytic Leukemia Treated With All-Trans Retinoic Acid: Result of the Randomized MRC Trial

Incidence of secondary neoplasms in patients with acute promyelocytic leukemia treated with all-trans retinoic acid plus chemotherapy or with all-trans retinoic acid plus arsenic trioxide

The incidence and pattern of secondary neoplasms in patients with acute promyelocytic leukemia (APL) treated with all-trans retinoic acid (ATRA)-containing regimens is not well described. We compared 160 patients with APL treated with ATRA plus idarubicin (n = 54) or ATRA plus arsenic trioxide (ATO) (n = 106) for the incidence of secondary cancers per unit time of follow-up. Median follow-up times for the two cohorts were 136 and 29 months, respectively. Nine patients developed secondary cancers in the chemotherapy group. These included two breast cancers, three myelodysplastic syndromes/acute myeloid leukemia, one vulvar cancer, one prostate cancer, one colon cancer and one soft tissue sarcoma. A melanoma and one pancreatic cancer developed in the ATO group. We conclude that treatment of patients with APL using the non-chemotherapy regimen of ATRA plus ATO is not associated with a higher incidence of secondary cancers (p = 0.29) adjusted for unit time of exposure.

Clinical characteristics and outcomes in patients with acute promyelocytic leukaemia and hyperleucocytosis

The clinical characteristics, treatment options and outcomes in patients with acute promyelocytic leukaemia (APL) and hyperleucocytosis remain poorly defined. This study reviewed 242 consecutive patients with APL; 29 patients (12%) had a white blood cell count (WBC) ≥ 50 × 10(9) /l at presentation (median WBC 85·5 × 10(9) /l). Patients with hyperleucocytosis had inferior complete remission (CR) rates (69% vs. 88%; P = 0·004) and higher 4-week mortality (24% vs. 9%; P = 0·018) compared to patients without hyperleucocytosis. We noted a trend towards inferior 3-year disease-free survival (DFS) (69% vs. 80%; P = 0·057) and inferior 3-year overall survival (OS) (74% vs. 92%; P = 0·2) for patients with hyperleucocytosis. Leukapheresis was performed in 11 (38%) of the 29 patients with hyperleucocytosis. CR rate and 3-year OS were not significantly improved in patients who received leukapheresis. CR rate and 3-year OS for the 15 patients with hyperleucocytosis treated with all-trans retinoic acid (ATRA) plus arsenic trioxide (ATO) plus cytotoxic therapy (idarubicin or gemtuzumab ozogamicin) combinations were 100% and 100% vs. 57% and 35% for the 14 patients treated with non-ATRA/ATO combinations (P = 0·004 and P = 0·002). Leukapheresis does not improve the outcomes in patients with APL presenting with hyperleucocytosis. ATRA/ATO-based combinations are superior to other regimens in these patients.

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.

Conventional induction and post-remission therapy in APL: have we arrived?

Since the introduction of all-trans-retinoic acid, the use of this molecularly targeted treatment in combination with anthracycline-based chemotherapy has completely changed the prognosis of acute promyelocytic leukemia (APL) turning it into the most curable acute myeloid leukemia. Also, the use of risk-adapted protocols has optimized the drug combination and the most appropriate dose intensity for each subset of patients classified according to both risk of relapse and vulnerability to drug toxicity. Recent developments have included the investigation of the role of arsenic trioxide (ATO) as front-line treatment after its success in relapsed APL, both to minimize or even omit the use of cytotoxic agents and to reinforce the conventional chemotherapy-based approach. In the present chapter we will address the achievements of conventional treatment with ATRA and chemotherapy, as well as the opportunity to cure more patients with modifications of this therapeutic backbone with the addition of ATO in any phase of treatment.

RARA fusion genes in acute promyelocytic leukemia: a review

The t(15;17)(q24;q21), generating a PML-RARA fusion gene, is the hallmark of acute promyelocytic leukemia (APL). At present, eight other genes fusing with RARA have been identified. The resulting fusion proteins retain domains of the RARA protein allowing binding to retinoic acid response elements (RARE) and dimerization with the retinoid X receptor protein (RXRA). They participate in protein-protein interactions, associating with RXRA to form hetero-oligomeric complexes that can bind to RARE. They have a dominant-negative effect on wild-type RARA/RXRA transcriptional activity. Moreover, RARA fusion proteins can homodimerize, conferring the ability to regulate an expanded repertoire of genes normally not affected by RARA. RARA fusion proteins behave as potent transcriptional repressors of retinoic acid signalling, inducing a differentiation blockage at the promyelocyte stage which can be overcome with therapeutic doses of ATRA or arsenic trioxide. However, resistance to these two drugs is a major problem, which necessitates development of new therapies.

Acute promyelocytic leukemia: do we have a new front-line standard of treatment?

Since the introduction of all-trans retinoic acid, the use of this molecularly targeted treatment in combination with anthracycline-based chemotherapy has completely changed the prognosis of acute promyelocytic leukemia, turning it into the most curable myeloid leukemia. Also, the use of risk-adapted protocols has contributed to optimizing the drug combination and the most appropriate dose intensity for each subset of patients classified according to both the risk of relapse and vulnerability to drug toxicity. Recent developments have included the investigation of the role of arsenic trioxide as front-line treatment after its success in treating relapsed APL, both to minimize or even omit the use of cytotoxic agents and to improve the outcome of the conventional chemotherapy-based approach. In this review, we discuss the current treatment approach for acute promyelocytic leukemia in newly diagnosed patients, particularly taking into account the latest developments with the use of the arsenic trioxide based regimen as targeted first-line treatment without chemotherapy.

How I treat children and adolescents with acute promyelocytic leukaemia

Acute promyelocytic leukaemia (APL) is a rare subtype of acute myeloid leukaemia. The outcome of paediatric APL has improved substantially over the past 20 years; cure rates above 80% are expected when all-trans retinoic acid (ATRA) is given with anthracycline-based regimens. The presenting features of paediatric APL may include severe bleeding and thrombotic complications, which contribute to the high early death rate. The incidence of leucocytosis and the microgranular subtype is greater in paediatric than adult APL, and children experience greater ATRA-related toxicity. It is crucial to begin ATRA therapy and intensive platelet and fibrinogen replacement on first suspicion of APL. Recent risk-adapted therapeutic trials have shown that patients at greater risk of relapse benefit from the introduction of high-dose cytarabine during consolidation. Combination therapy with ATRA and arsenic trioxide provides very effective frontline treatment and may reduce the need for subsequent anthracycline therapy.

Old and new prognostic factors in acute myeloid leukemia with deranged core-binding factor beta

Acute myeloid leukemia (AML) with deranged core-binding factor beta (CBFβ) is usually associated with a favorable prognosis with 50-70% of patients cured using contemporary treatments. We analyzed the prognostic significance of clinical features on 58 patients with CBFβ-AML aged ≤60 years. Increasing age was the only predictor for survival (P <0.001), with an optimal cut-point at 43 years. White blood cells (WBCs) at diagnosis emerged as an independent risk factor for relapse incidence (P = 0.017), with 1.1% increase of hazard for each 1.0 × 10(9) /L WBC increment. KIT mutations lacked prognostic value for survival and showed only a trend for relapse incidence (P = 0.069).

Outcomes in patients with relapsed or refractory acute promyelocytic leukemia treated with or without autologous or allogeneic hematopoietic stem cell transplantation

BACKGROUND

Outcomes in patients with acute promyelocytic leukemia (APL) have improved; however, a significant number of patients still relapse despite receiving all-trans-retinoic acid (ATRA) and arsenic-based therapies.

PATIENTS AND METHODS

Outcomes of patients with relapsed APL who were treated at our institution (1980-2010) and who received HCT were compared with those who received chemotherapy (CT) only.

RESULTS

Among 40 patients, 24 received HCT (autologous [auto] HCT, 7; allogeneic [allo] HCT, 14; both, 3); 16 received CT only. The median age at diagnosis was 36 years (range, 13-50 years), 31 years (range, 16-58 years), and 44 years (range, 24-79 years) for the auto-HCT, allo-HCT, and CT groups, respectively. Ten (100%) patients who received auto-HCT and 12 (71%) who received allo-HCT were in complete remission at the time of the HCT. The median follow-ups in the auto-HCT, allo-HCT, and CT groups were 74 months (range, 26-135 months), 118 months (range, 28-284 months), and 122 months (range, 32-216 months), respectively. Transplantation-related mortality (1 year) after auto-HCT and allo-HCT were 10% and 29%, respectively. The 7-year event-free survival after auto-HCT and allo-HCT was 68.6% and 40.6%, respectively (P = .45). The 7-year overall survival was 85.7%, 49.4%, and 40% in the auto-HCT, allo-HCT, and CT groups, respectively (P = .48).

CONCLUSION

Both auto-HCT and allo-HCT are associated with durable remission and prolonged survival. All 3 strategies (auto-HCT, allo-HCT, CT) were found to be feasible in the relapsed APL setting and result in long-term disease control in selected patients. In this retrospective analysis, overall survival for patients who received HCT was not significantly better than patients who received CT only, but a trend toward better outcomes was seen in patients who underwent auto-HCT, although not statistically significant.

Management of elderly patients with acute promyelocytic leukemia: progress and problems

Despite substantial progress in the management and outcome of acute promyelocytic leukemia (APL) during the last decades, older age remains a prominent negative prognostic factor. The improvement of long-term stabilization and cure of older APL patients is therefore a particular challenge. Data of unselected population-based studies suggest a high rate of exclusion from clinical trials in older age. The comparison of registry and study data indicates that study patients represent a positive selection. Older APL patients seem as sensitive to therapy as younger patients. With conventional therapy, based on all-trans retinoic acid (ATRA) and chemotherapy, over 50 % of older APL patients can probably be cured. Special problems of advanced age are the high rate of early death before or during induction therapy and the high frequency of death in remission with negative influence on the outcome. Both may be related in part to a higher vulnerability against the common treatment with ATRA and chemotherapy. Alternative less toxic approaches including arsenic trioxide (ATO) with or without ATRA and combinations with gemtuzumab ozogamicin or with reduced chemotherapy can induce long-lasting remission in all stages of APL. Considering the high curative potential and the excellent tolerance of ATO in newly diagnosed and relapsed APL, older patients are probably a particular target group for a chemotherapy-free approach with ATO.

Aquaporin 9, a promising predictor for the cytocidal effects of arsenic trioxide in acute promyelocytic leukemia cell lines and primary blasts

A close correlation between the cytocidal effects of arsenic trioxide (ATO) and aquaporin-9 (AQP9) expression levels has been proposed, yet detailed studies are still needed to confirm this association. Thus, in the present study, the correlation between the expression levels of AQP9 and sensitivity to ATO was investigated using two acute promyelocytic leukemia (APL) cell lines, NB4 and HT93A, as well as primary APL cells from newly diagnosed and relapsed APL patients. A substantially higher sensitivity to ATO-mediated induction of apoptosis was observed in the NB4 cells when compared to that in the HT93A cells. In addition, markedly higher expression levels of AQP9, as assessed using flow cytometry, along with more intracellular arsenic accumulation, were observed in the NB4 cells. More importantly, similar to APL cell lines, the trend of expression levels of AQP9 correlated closely with the differential sensitivity to ATO-mediated induction of apoptosis in primary APL cells. In contrast, no correlation was observed between ATO sensitivity associated with AQP9 expression levels and the expression profiles of cell surface markers as well as chromosomal alterations. These results provide direct evidence that the expression levels of AQP9, rather than other biomarkers such as cell surface markers and chromosomal alterations, correlate closely with the sensitivity to ATO in both APL cell lines and primary blasts. These findings suggest that the AQP9 expression status of APL patients is a predictive marker for the successful outcome of ATO treatment, since AQP9 plays a pivotal role in various arsenite-mediated biological effects on normal and cancer cells. Moreover, flow cytometry may be a new convenient and valuable tool for analyzing the AQP9 status of APL patients compared to current methods such as western blotting.

The role of maintenance therapy in acute promyelocytic leukemia in the first complete remission

BACKGROUND

Acute promyelocytic leukemia (APL) is the most curable type of leukemia. A consensus exists regarding the need for administration of both induction and consolidation treatments, albeit using different approaches. However, there is conflicting evidence for the role of maintenance treatment in APL patients.

OBJECTIVES

To examine the efficacy and safety of maintenance therapy in APL patients and to establish the optimal regimen for maintenance.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 6), MEDLINE (January 1966 to July 2012), LILACS (1982 to July 2012), relevant conference proceedings (2000 to 2012) and databases of ongoing and unpublished trials.

SELECTION CRITERIA

Randomized controlled trials assessing maintenance treatment in patients with newly diagnosed APL in first complete remission (CR) following induction or induction and consolidation therapy.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the quality of trials and extracted data. We estimated and pooled hazard ratios (HR) and risk ratios (RR) with 95% confidence intervals (CI) using the fixed-effect model. If significant heterogeneity was present we explored potential causes for such heterogeneity and if not found we used also the random-effects model.

MAIN RESULTS

We included 10 randomized controlled trials enrolling 2072 patients in the systematic review, and conducted meta-analysis on nine of them. There was no statistically significant effect on overall survival (OS) in the three main comparisons (HR for any maintenance treatment versus observation 0.79, 95% CI 0.49 to 1.27; HR for all-trans retinoic acid (ATRA)-based maintenance versus non-ATRA based maintenance 1.21, 95% CI 0.73 to 1.98; HR for ATRA alone maintenance versus ATRA and chemotherapy 0.99, 95% CI 0.69 to 1.43). However, disease free survival (DFS) was improved with any maintenance therapy compared to observation (HR 0.59, 95% CI 0.48 to 0.74; 5 trials, 1209 patients) and with ATRA and chemotherapy compared to ATRA alone maintenance (HR for ATRA alone compared to ATRA and chemotherapy 1.38, 95% CI 1.09 to 1.76; 4 trials, 1028 patients). DFS was not improved with ATRA-based regimens compared to non-ATRA based regimens (HR 0.72, 95% CI 0.51 to 1.01; 4 trials, 670 patients). Analysis of clinically relevant adverse events could not be conducted due to paucity of data. Yet, increased reports of grade 3/4 adverse events were noted for any maintenance versus observation and for combined ATRA and chemotherapy versus ATRA alone treatment. The major limitation of this review lies in the variability between the included trials in both maintenance and pre-maintenance parameters. We tried to address this variability and to reduce its potential biases by conducting three separate main comparisons, as outlined above, leaving less statistical power to the presented results.

AUTHORS' CONCLUSIONS

Maintenance therapy compared to observation in APL patients improved DFS but not OS. Similarly, ATRA and chemotherapy compared to ATRA improved DFS but not OS. In contrast, ATRA based regimens compared to non-ATRA based regimens did not demonstrate a survival benefit. The significance of these findings is limited due to clinical heterogeneity between studies.

All-trans retinoic acid and late relapses in acute promyelocytic leukemia: very long-term follow-up of the North American Intergroup Study I0129

We report a long-term follow-up (median 11.8 years) of the First North American Intergroup Study. 379 patients were randomized to induction with ATRA or to chemotherapy. All complete responders (CR) received consolidation chemotherapy, then randomized to 1 year ATRA or observation. 245 patients received ATRA sometime during the study: 195 (80%) achieved a CR. Nine (4.6%) relapsed late (>3 years from CR), the last occurred after 4.6 years; 7 of them were still alive after 5.5-15 years. In APL patients, late relapses are uncommon, and those who sustain CR >5 years can be considered cured.

All-trans retinoic acid in the treatment of pediatric acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a rare form of acute myeloid leukemia with specific epidemiological, pathogenetic and clinical features. Its frequency varies widely among nations, with a decreased incidence among 'Nordic' origin populations. The molecular hallmark of the disease is the presence of a balanced reciprocal translocation resulting in the PML/RAR-α gene fusion, which represents the target of the all-trans retinoic acid (ATRA) therapy. The introduction of ATRA in conjunction with anthracyclines marked a turning point in the treatment of APL, previously associated with a significant morbidity and mortality. Nowadays the standard front-line therapy for pediatric APL includes ATRA in every phase of the treatment, resulting in a complete remission rate of 90-95%. Here we provide an overview of the role of ATRA in the treatment of pediatric APL, summarizing the most relevant clinical results of recent decades and investigating future therapeutic perspectives for children with APL.

Inclusion of hemoglobin level in prognostic score provides better prognostic stratification in patients with acute promyelocytic leukemia (APL)

The clinical outcomes of acute promyelocytic leukemia (APL) have improved greatly, but treatment failure still occurs. Identification of patients with poor prognosis is fundamental, and we propose a new clinical prognostic system (CBC-score) consisting of WBC, platelet count, and hemoglobin level. Between 1995 and 2009, 156 patients with APL from seven institutes in Korea were retrospectively reviewed. In the new CBC-score system, each of the following (WBC ≥ 10 × 109/L, platelet <40 × 109/L, hemoglobin <8.0 g/dL) was considered as a risk factor; the sum of each was designated as the CBC-score. With a median follow-up of 8.4 years, the complete remission (CR) rate was 81.4 % (127/156), while 24 (15.4 %) were considered as treatment failures due to early death (ED). The 5-year overall survival (OS), leukemia-free survival, and cumulative incidence of relapse were 73.8, 82.8, and 13.5 %, respectively. Compared to the individual CBC parameters, combined prognostic systems such as PETHEMA or CBC-score provided better prognostic stratification. Compared to PETHEMA stratification, the proposed prognostic CBC-score system showed better stratification of APL patients in terms of CR rates (p = 0.004), OS (p = 0.004), and ED (p = 0.008). This retrospective study suggests that the proposed CBC-score may provide better prognostic stratification of APL patients.

In acute promyelocytic leukemia (APL) low BAALC gene expression identifies a patient group with favorable overall survival and improved relapse free survival

We evaluated the prognostic value of BAALC expression in 86 patients with acute promyelocytic leukemia (APL). At 10 years, the overall survival (OS) was 66% in all patients and 75% in patients who achieved a complete remission (CR). Patients in the BAALC(low) group showed an OS of 87% as compared to 60% in the BAALC(high) group (p=0.019). This difference was more pronounced in treatment responders (92% vs. 70%; p=0.035). In multivariate analyses low BAALC expression retained its prognostic relevance. In conclusion, BAALC expression analysis might be useful in further risk stratification in APL patients.

Outcome of elderly patients with acute promyelocytic leukemia: results of the German Acute Myeloid Leukemia Cooperative Group

Despite improvement of prognosis, older age remains a negative prognostic factor in acute promyelocytic leukemia (APL). Reports on disease characteristics and outcome of older patients are conflicting. We therefore analyzed 91 newly diagnosed APL patients aged 60 years or older (30 % of 305 adults with APL) registered by the German AML Cooperative Group (AMLCG) since 1994; 68 patients (75 %) were treated in studies, 23 (25 %) were non-eligible, and 31 % had high-risk APL. Fifty-six patients received induction therapy with all-trans retinoic acid and TAD (6-thioguanine, cytarabine, daunorubicin), and consolidation and maintenance therapy. Treatment intensification with a second induction cycle (high dose cytarabine, mitoxantrone; HAM) was optional (n = 14). Twelve patients were randomized to another therapy not considered in this report. The early death rate was 48 % in non-eligible and 19 % in study patients. With the AMLCG regimen, 7-year overall, event-free and relapse-free survival (RFS) and cumulative incidence of relapse were 45 %, 40 %, 48 %, and 24 %, respectively. In patients treated with TAD–HAM induction, 7-year RFS was superior (83 %; p = 0.006) compared to TAD only, and no relapse was observed. In our registered elderly patients, we see a high rate of non-eligibility for treatment in studies and of high-risk APL. In patients who can undergo a curative approach, intensified chemotherapy is highly effective, but is restricted to a selection of patients. Therefore, new less toxic treatment approaches with broader applicability are needed. Elderly patients might be a particular target group for concepts with arsenic trioxide.

FLT3 mutation status is a predictor of early death in pediatric acute promyelocytic leukemia: a report from the Children's Oncology Group

BACKGROUND

FLT3 mutations (FLT3/Mut) are prevalent in de novo AML and are associated with early relapse. The prevalence and prognostic significance of FLT3/Mut have not been well defined in childhood acute promyelocytic leukemia (APL).

PROCEDURE

Diagnostic specimens from 104 pediatric APL patients were screened for FLT3/Mut (FLT3/ITD or FLT3/ALM). FLT3/Mut status was correlated with disease characteristics and clinical outcome for patients treated on CALGB C9710 (n = 50).

RESULTS

Forty-two of the 104 patients (40%) had either FLT3/ITD (n = 28, 27%) or FLT3/ALM (n = 15, 14%). Median diagnostic WBC count was 23,400 cells/µl vs. 3,600 cells/µl for those with and without FLT3/Mut (P < 0.001), and similar results for the cohort of 50 patients treated on C9710 (P < 0.001). In patients treated on C9710, presence of a FLT3 mutation was highly correlated with diagnostic WBC count >10,000 (P = 0.004), microgranular variant histology (P = 0.035), and a lower remission rate (P = 0.009). In patients who received ATRA (C9710 or CCG-2911, n = 8), those with FLT3/Mut had an induction death rate of 30% (7/23) compared to 3% (1/35) in FLT3/WT patients (P = 0.005). In patients with high WBC counts (>10,000), those with FLT3/Mut had a significantly higher risk of induction death versus FLT3/WT patients (47% vs. 0%, P = 0.05). FLT3/Mut was not associated with adverse outcome in those who survived induction therapy.

CONCLUSIONS

FLT3/Mut are prevalent in pediatric APL and are associated with high WBC count and increased induction death. This study provides further evidence for testing APL patients for FLT3/Mut and the potential role for FLT3 inhibitors in this disease.

Diagnostic and prognostic value of cytogenetics in acute myeloid leukemia

The last 4 decades have seen major advances in understanding the genetic basis of acute myeloid leukemia (AML), and substantial improvements in survival of children and young adults with the disease. A key step forward was the discovery that AML cells harbor recurring cytogenetic abnormalities. The identification of the genes involved in chromosomal rearrangements has provided insights into the regulation of normal hematopoiesis and how disruption of key transcription factors and epigenetic modulators promote leukemic transformation. Cytogenetics has been widely adopted to provide the framework for development of risk-stratified treatment approaches to patient management.

A functional variant in the core promoter of the CD95 cell death receptor gene predicts prognosis in acute promyelocytic leukemia

Up to 15% of acute promyelocytic leukemia (APL) patients fail to achieve or maintain remission. We investigated a common G > A polymorphism at position -1377 (rs2234767) in the core promoter of the CD95 cell death receptor gene in 708 subjects with acute myeloid leukemia, including 231 patients with APL. Compared with the GG genotype, carrier status for the -1377A variant was associated with a significantly worse prognosis in APL patients. Carriers were more likely to fail remission induction (odds ratio = 4.22; 95% confidence interval, 1.41-12.6, P = .01), were more likely to die during the first 8 weeks of remission induction therapy (hazard ratio = 7.26; 95% confidence interval, 2.39-22.9, P = .0005), and had a significantly worse 5-year overall survival (odds ratio = 2.14; 95% confidence interval, 1.10-4.15, P = .03). The -1377A variant destroys a binding site for the SP1 transcriptional regulator and is associated with lower transcriptional activity of the CD95 promoter. Identifying patients at high risk of life-threatening events, such as remission induction failure, is a high priority in APL, especially because such events represent a major cause of death despite the introduction of differentiation therapy.

Increased BMI correlates with higher risk of disease relapse and differentiation syndrome in patients with acute promyelocytic leukemia treated with the AIDA protocols

We investigated whether body mass index (BMI) correlates with distinct outcomes in newly diagnosed acute promyelocytic leukemia (APL). The study population included 144 patients with newly diagnosed and genetically confirmed APL consecutively treated at a single institution. All patients received All-trans retinoic acid and idarubicin according to the GIMEMA protocols AIDA-0493 and AIDA-2000. Outcome estimates according to the BMI were carried out together with multivariable analysis for the risk of relapse and differentiation syndrome. Fifty-four (37.5%) were under/normal weight (BMI < 25), whereas 90 (62.5%) patients were overweight/obese (BMI ≥ 25). An increased BMI was associated with older age (P < .0001) and male sex (P = .02). BMI was the most powerful predictor of differentiation syndrome in multivariable analysis (odds ratio = 7.24; 95% CI, 1.50-34; P = .014). After a median follow-up of 6 years, the estimated cumulative incidence of relapse at 5 years was 31.6% (95% CI, 22.7%-43.8%) in overweight/obese and 11.2% (95% CI, 5.3%-23.8%) in underweight/normal weight patients (P = .029). Multivariable analysis showed that BMI was an independent predictor of relapse (hazard ratio = 2.45, 95% CI, 1.00-5.99, in overweight/obese vs under/normal weight patients, P = .049). An increased BMI at diagnosis is associated with a higher risk of developing differentiation syndrome and disease relapse in APL patients treated with AIDA protocols.

Advances in therapies for acute promyelocytic leukemia

Acute promyelocytic leukemia (APL), a distinct subtype of acute myelogenous leukemia (AML), results from the arrest of the maturation of hematopoietic progenitors at the promyelocyte stage. It has been shown that APL is associated with a reciprocal chromosomal translocation, involving chromosomes 15 and 17, which fuses the gene encoding the retinoic acid receptor α (RARα) and the promyelocytic leukemia (PML) gene. The resultant PML-RARα fusion protein plays a critical role in the pathogenesis of APL. Although there are many subtypes of AML, all are typically managed using a standard chemotherapy regimen of an anthracycline plus cytarabine arabinoside (CA). Despite high rates of complete remission following standard chemotherapy, most patients relapse and long-term disease-free survival is only 30-40%. The introduction of drugs such as all-trans retinoic acid (ATRA) that promote progenitor differentiation by directly inhibiting the PML-RARα fusion protein has changed the treatment paradigm for APL and markedly improved patient survival. The purposes of the present review are to provide the latest results and future directions of clinical research into APL and to illustrate how new therapies, such as ATRA plus anthracycline-based induction and consolidation therapy, risk-adapted therapy, salvage therapy containing arsenic trioxide-based regimens, and hematopoietic stem cell transplantation, have improved the treatment outcomes for APL patients.

AIDA 0493 protocol for newly diagnosed acute promyelocytic leukemia: very long-term results and role of maintenance

All-trans-retinoic acid (ATRA) has greatly modified the prognosis of acute promyelocytic leukemia; however, the role of maintenance in patients in molecular complete remission after consolidation treatment is still debated. From July 1993 to May 2000, 807 genetically proven newly diagnosed acute promyelocytic leukemia patients received ATRA plus idarubicin as induction, followed by 3 intensive consolidation courses. Thereafter, patients reverse-transcribed polymerase chain reaction–negative for the PML-RARA fusion gene were randomized into 4 arms: oral 6-mercaptopurine and intramuscular methotrexate (arm 1); ATRA alone (arm 2); 3 months of arm1 alternating to 15 days of arm 2 (arm 3); and no further therapy (arm 4). Starting from February 1997, randomization was limited to ATRA-containing arms only (arms 2 and 3). Complete remission was achieved in 761 of 807 (94.3%) patients, and 681 completed the consolidation program. Of these, 664 (97.5%) were evaluated for the PML-RARA fusion gene, and 586 of 646 (90.7%) who tested reverse-transcribed polymerase chain reaction–negative were randomized to maintenance. The event-free survival estimate at 12 years was 68.9% (95% confidence interval, 66.4%-71.4%), and no differences in disease-free survival at 12 years were observed among the maintenance arms.

Treatment outcome of all-trans retinoic acid/anthracycline combination chemotherapy and the prognostic impact of FLT3/ITD mutation in acute promyelocytic leukemia patients

Background

All-trans retinoic acid (ATRA)/anthracycline chemotherapy is beneficial in newly diagnosed acute promyelocytic leukemia (APL); however, it is important to identify patients with high-risk disease to increase the cure rate. We investigated the outcome of ATRA/anthracycline chemotherapy and clinicobiological correlations of FLT3/ITD and NPM1 mutations in APL patients.

Methods

Induction therapy included oral ATRA (45 mg/m²/day) and idarubicin (12 mg/m²/day, intravenous, on days 2, 4, and 6). Patients achieving complete remission (CR) received 3 courses of ATRA combined with reinforced consolidation therapy. Mutations were analyzed using GeneScan and polymerasae chain reaction assays of bone marrow samples obtained from patients at diagnosis.

Results

Forty-five (84.9%) of 53 eligible patients achieved CR. The overall relapse rate was 8.9%, and the 3-year overall survival (OS) and leukemia-free survival (LFS) were 84.9±4.9% and 77.5±6.0%, respectively. The NPM1 mutation was not found in any patient, while the FLT3/ITD mutation was found in 10 (20.0%) patients. Of the FLT3/ITD+ patients, 80% belonged to the high-risk group, defined according to the presenting WBC and platelet counts. Among the patients who achieved CR, those who were FLT3/ITD+ had a higher relapse rate than those FLT3/ITD-. FLT3/ITD+ patients also had a significantly lower 3-year LFS than FLT3/ITD- patients. Multivariate analysis of the LFS showed that the FLT3/ITD mutation was independently associated with a shorter overall LFS, after adjusting for pretreatment risk stratification.

Conclusion

This study investigated the clinical outcome of newly diagnosed APL patients treated with ATRA/anthracycline chemotherapy. Patients carrying the FLT3/ITD mutation had more aggressive clinical features and a poorer clinical outcome.

The biological characteristics of adult CD34+ acute promyelocytic leukemia

We aimed to explore the expression of CD34 and its impact on the disease outcome in patients with APL. The study comprised 40 de novo APL patients. Diagnostic tools included peripheral blood and bone marrow morphology and cytochemistry, immunophenotyping, cytogenetic studies, and PML/RARα fusion gene detection using RT-PCR. CD34 was expressed in 13 (32.5%) of cases with higher expression in M3v compared to M3 subtype. All M3v cases were CD34+, while only 7.4% of M3 cases were CD34+. CD34+ cases were associated with significant higher white blood cell count and peripheral blood promyelocytes. No significant association was found between PML/RAR-α isoform and molecular remission. CD34+ expression was significantly associated with decreased incidence of molecular remission and increased incidence of early death. The overall survival of patients with WBC count >11 × 103/μl was inferior to patients with WBC count <11 × 103/μl, but no significant differences were observed in overall survival between CD34- and CD34+ or between bcr1 and bcr3 groups. Immunophenotypic analysis for CD34 could distinguish an APL subset with different biological characteristics and adverse prognostic outcome.

Modern Approaches to Treating Acute Promyelocytic Leukemia

The advent of all-trans-retinoic acid (ATRA) and its combination with anthracycline-containing chemotherapy have contributed in the past 2 decades to optimize the antileukemic efficacy in acute promyelocytic leukemia (APL), leading to complete remission rates greater than 90%, virtual absence of resistance, and cure rates of nearly 80%. Recently reported studies from large cooperative trials have also shown that more rational delivery of treatment and improved outcomes may derive from the use of risk-adapted protocols. In particular, patients at higher risk of relapse (ie, those presenting with WBC > 10 × 109/L) seem to benefit from treatments that include cytarabine in the ATRA-plus-chemotherapy scheme, whereas patients with standard-risk disease can be successfully managed with less-intensive regimens that contain ATRA and anthracycline-based chemotherapy. After the outstanding results with arsenic trioxide (ATO) in the treatment of APL relapse, several experimental trials have been designed to explore the role of ATO in front-line therapy with the aim not only of minimizing the use of chemotherapy but also to reinforce standard ATRA-plus-chemotherapy regimens and additionally improve therapeutic efficacy. In this review article, we discuss most recent advances in the treatment of patients with newly diagnosed and relapsed APL.

Treatment of acute promyelocytic leukemia with PETHEMA LPA 99 protocol: a Tunisian single center experience

Acute promyelocytic leukemia (APL) has now become the most curable of all subtypes of acute myeloid leukemia. A cure rate of 75-80% can be anticipated with a combination of all-trans retinoic acid (ATRA) and anthracyclines. In Tunisia, the ATRA era began in 1998 with the use, consecutively, of two regimens of a combination of ATRA with anthracycline and cytarabine (APL93), and without cytarabine (LPA99). From 2004, 39 patients with confirmed APL either by t(15;17) or PML/RARA were treated by the PETHEMA LPA 99 trial. The rationale of this protocol by avoiding cytarabine is to reduce death in complete remission (CR) without increasing the incidence of relapse. Thirty-three patients achieved CR (84.6%). The remaining six patients were considered as failure due to early death: three caused by differentiation syndrome (DS) and three died from central nervous system hemorrhage. Baseline blood cell count (WBC) >10 x 10(9)/l (P=0.26) and creatinine >1.4 mg/dl (P=0.42) were not predictive of mortality. DS was observed in 11 patients (30.5%) with a median onset time of 12 days (range: 3-23 days) and median WBC of 29 x 10(9)/L (range: 1.2 x 10(9)-82.7 x 10(9)/l). DS was severe in seven cases, moderate in four, and fatal in three cases. Body mass index > or =30 (P=0.044) and baseline WBC > or =20 x 10(9)/l (P=0.025) are independent predictors of DS. The median follow-up of this study is 36 months. Thirty patients are alive in continuous complete remission; two patients died in CR from septic shock and secondary myelodysplastic syndrome respectively; one patient died 47 months after achieving two relapses. Event free survival from diagnosis was 80% and overall survival was 82%. Our results are quite acceptable and can be improved by reducing mortality rate.

Utilization of molecular phenotypes to detect relapse and optimize the management of acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is characterized by a unique genetic aberration, the t(15;17) chromosome translocation. Translocation breakpoints are located within the promyelocytic leukemia (PML) locus on chromosome 15 and the retinoic acid receptor alpha (RARA) locus on chromosome 17. In the past 2 decades, critical advances have been made in understanding the molecular pathogenesis of APL. APL represents a paradigm for molecularly targeted therapy in cancer and an extraordinary model for translational research in medicine. In fact, the release of differentiation block upon treatment of APL with all-trans-retinoic acid (ATRA) has represented the first example of targeted therapy in human cancer. More recently, the advent of arsenic trioxide (ATO) has allowed further progress in the management of this disease through improved outcomes in patients receiving this agent in combination with ATRA. Finally, optimization of therapy and minimization of toxicity is feasible in this disease through careful monitoring of residual disease using polymerase chain reaction-based approaches targeting the PML-RARA fusion gene.

Treatment of patients with acute promyelocytic leukemia: a consensus statement on risk-adapted approaches to therapy

The integration of all-trans-retinoic acid (ATRA) with anthracycline chemotherapy into up-front regimens for acute promyelocytic leukemia (APL) has produced striking improvements in clinical outcomes, making APL one of the most curable forms of hematologic malignancies in adults. In addition, arsenic trioxide has proven efficacy in relapse and when combined with ATRA in frontline regimens has demonstrated high efficacy in a number of trials and the potential to replace chemotherapy, which would thereby reduce chemotherapy-related adverse events. Cure in APL is also largely dependent on timely and effective supportive care measures that counteract such life-threatening emergencies as coagulopathy and APL differentiation syndrome. The risk of mortality during induction and the risk of relapse following frontline therapy are related to the individual's initial clinical presentation and relapse-risk score at diagnosis; however, these risks are now quite low even in high-risk patients as long as appropriate therapy is initiated expeditiously. Multiple European and North American trials have investigated risk-adapted approaches to the treatment of APL and have reported high success rates. Further refinement of risk-adapted strategies is ongoing and will likely contribute to better patient care. A roundtable conference was conducted to discuss risk-adapted therapy for APL and to develop a consensus statement and approach for clinical oncologists. Expert opinions and evidence-based strategies presented during the roundtable are summarized herein.

ATRA and anthracycline-based chemotherapy in the treatment of childhood acute promyelocytic leukemia (APL): A 10-year experience in Tunisia

Reports on childhood APL from developing countries are scarce. We treated 65 APL with two consecutive trials combining ATRA and chemotherapy. Twenty (30.7%) were aged less than 20 years including 11 girls and 9 boys, with a median age of 12 years. Fever at presentation (P=0.002) and variant APL (P=0.044) were more frequent in children, while there were no significant difference between children and adults for WBC count, Sanz's score distribution and additional cytogenetic abnormalities. The CR rate was 95% (19/20) in children and 80% (36/45) in adults (P=0.13). Differentiation syndrome (DS) was less often observed in children (1/20) than in adults (13/45) (P=0.031). Two children relapsed and died during salvage therapy, and 2 died in CR from infection and from cardiac failure attributed to anthracyclines, while other children remained alive in CR. With a median follow-up of 4 years, 4-year EFS was 75% in children and 71.1% in adults (P=0.57), while 4-year OS was 75% in children vs. 73.3% in adults (P=0.72). Our results suggest that, even in the absence of optimal socio-economic condition, ATRA combined with anthracycline-based chemotherapy gives adequate results in childhood APL, as in adults.

[Special issues related to the treatment of acute leukemias in women]

The treatment of acute leukemia is usually similar in women and men. The outcome is also generally the same. However, diagnosis in women poses additional challenges in clinical practice such as leukemia following breast or ovarian cancers, prevention of abnormal uterine bleeding in premenopausal females, treatment during pregnancy related-problems in long-term survivors. All these special issues are addressed in this review of the literature.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: report from the Committee on the Epidemiology and Natural History of Relapse following Allogeneic Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is increasingly being used for treatment of hematologic malignancies, and the immunologic graft-versus-tumor effect (GVT) provides its therapeutic effectiveness. Disease relapse remains a cause of treatment failure in a significant proportion of patients undergoing alloHSCT without improvements over the last 2-3 decades. We summarize here current data and outline future research regarding the epidemiology, risk factors, and outcomes of relapse after alloHSCT. Although some factors (eg, disease status at alloHSCT or graft-versus-host disease [GVHD] effects) are common, other disease-specific factors may be unique. The impact of reduced-intensity regimens on relapse and survival still need to be assessed using contemporary supportive care and comparable patient populations. The outcome of patients relapsing after an alloHSCT generally remains poor even though interventions including donor leukocyte infusions can benefit some patients. Trials examining targeted therapies along with improved safety of alloHSCT may result in improved outcomes, yet selection bias necessitates prospective assessment to gauge the real contribution of any new therapies. Ongoing chronic GVHD (cGVHD) or other residual post-alloHSCT morbidities may limit the applicability of new therapies. Developing strategies to promptly identify patients as alloHSCT candidates, while malignancy is in a more treatable stage, could decrease relapses rates after alloHSCT. Better understanding and monitoring of minimal residual disease posttransplant could lead to novel preemptive treatments of relapse. Analyses of larger cohorts through multicenter collaborations or registries remain essential to probe questions not amenable to single center or prospective studies. Studies need to provide data with detail on disease status, prior treatments, biologic markers, and posttransplant events. Stringent statistical methods to study relapse remain an important area of research. The opportunities for improvement in prevention and management of post-alloHSCT relapse are apparent, but clinical discipline in their careful study remains important.

Refinement of cytogenetic classification in acute myeloid leukemia: determination of prognostic significance of rare recurring chromosomal abnormalities among 5876 younger adult patients treated in the United Kingdom Medical Research Council trials

Diagnostic karyotype provides the framework for risk-stratification schemes in acute myeloid leukemia (AML); however, the prognostic significance of many rare recurring cytogenetic abnormalities remains uncertain. We studied the outcomes of 5876 patients (16-59 years of age) who were classified into 54 cytogenetic subgroups and treated in the Medical Research Council trials. In multivariable analysis, t(15;17)(q22;q21), t(8;21)(q22;q22), and inv(16)(p13q22)/t(16;16)(p13;q22) were the only abnormalities found to predict a relatively favorable prognosis (P < .001). In patients with t(15;17) treated with extended all-trans retinoic acid and anthracycline-based chemotherapy, additional cytogenetic changes did not have an impact on prognosis. Similarly, additional abnormalities did not have a significant adverse effect in t(8;21) AML; whereas in patients with inv(16), the presence of additional changes, particularly +22, predicted a better outcome (P = .004). In multivariable analyses, various abnormalities predicted a significantly poorer outcome, namely abn(3q) (excluding t(3;5)(q25;q34)), inv(3)(q21q26)/t(3;3)(q21;q26), add(5q)/del(5q), -5, -7, add(7q)/del(7q), t(6;11)(q27;q23), t(10;11)(p11 approximately 13;q23), other t(11q23) (excluding t(9;11)(p21 approximately 22;q23) and t(11;19)(q23;p13)), t(9;22)(q34;q11), -17, and abn(17p). Patients lacking the aforementioned favorable or adverse aberrations but with 4 or more unrelated abnormalities also exhibited a significantly poorer prognosis (designated "complex" karyotype group). These data allow more reliable prediction of outcome for patients with rarer abnormalities and may facilitate the development of consensus in reporting of karyotypic information in clinical trials involving younger adults with AML. This study is registered at http://www.isrctn.org as ISRCTN55678797 and ISRCTN17161961.

The impact on outcome of the addition of all-trans retinoic acid to intensive chemotherapy in younger patients with nonacute promyelocytic acute myeloid leukemia: overall results and results in genotypic subgroups defined by mutations in NPM1, FLT3, and CEBPA

We investigated the benefit of adding all-trans retinoic acid (ATRA) to chemotherapy for younger patients with nonacute promyelocytic acute myeloid leukemia and high-risk myelodysplastic syndrome, and considered interactions between treatment and molecular markers. Overall, 1075 patients less than 60 years of age were randomized to receive or not receive ATRA in addition to daunorubicin/Ara-C/thioguanine chemotherapy with Ara-C at standard or double standard dose. There were data on FLT3 internal tandem duplications and NPM1 mutations (n = 592), CEBPA mutations (n = 423), and MN1 expression (n = 195). The complete remission rate was 68% with complete remission with incomplete count recovery in an additional 16%; 8-year overall survival was 32%. There was no significant treatment effect for any outcome, with no significant interactions between treatment and demographics, or cytarabine randomization. Importantly, there were no interactions by FLT3/internal tandem duplications, NPM1, or CEBPA mutation. There was a suggestion that ATRA reduced relapse in patients with lower MN1 levels, but no significant effect on overall survival. Results were consistent when restricted to patients with normal karyotype. ATRA has no overall effect on treatment outcomes in this group of patients. The study did not identify any subgroup of patients likely to derive a significant survival benefit from the addition of ATRA to chemotherapy. This study is registered at http://www.controlled-trials.com under ISRCTN17833622.

Attempts to Optimize Induction and Consolidation Treatment in Acute Myeloid Leukemia: Results of the MRC AML12 Trial

Purpose

To optimize treatment for younger patients with acute myeloid leukemia and high-risk myelodysplastic syndrome by comparing induction options and the number of consolidation courses and whether consolidation should include transplantation.

Patients and Methods

We randomly assigned 1,658 patients younger than age 60 years to receive mitoxantrone/cytarabine/etoposide versus cytarabine/daunorubicin/etoposide and subsequently 1,193 patients to daunorubicin/cytarabine/thioguanine (DAT) where the cytarabine dose was standard (S-DAT) versus double the standard dose (H-DAT). Patients in this randomization were randomly assigned to all-trans-retinoic acid or not. In consolidation, 992 patients were randomly assigned between a total of four courses versus five courses, and 324 patients who were not good risk were randomly assigned to transplantation or chemotherapy as the final course.

Results

Complete remission (CR) was achieved in 74% of patients and CR without recovery was achieved in an additional 11%; overall survival (OS) at 8 years was 38%. No differences in CR, relapse-free survival, relapse, or OS were seen between any of the induction randomizations except for a reduction in relapse risk (RR) on the mitoxantrone arm, which was offset by increased myelosuppression and deaths in CR. The addition of a fifth course did not improve OS and may be detrimental in older patients. Although transplantation reduced RR, it did not improve OS for the intermediate-risk group but was probably of benefit in high-risk patients.

Conclusion

Several chemotherapy schedules achieved similar remission rates and OS. Four courses of chemotherapy are adequate, but the addition of transplantation as a final course does not improve OS. New agents are required to enhance conventional chemotherapy.