Clinical networking results in continuous improvement of the outcome of patients with acute promyelocytic leukemia.

The introduction of all-trans retinoic acid (ATRA) combined with anthracyclines has significantly improved the outcomes for patients with acute promyelocytic leukemia (APL), and this strategy remains the standard of care in countries where arsenic trioxide is not affordable. However, data from national registries and real-world databases indicate that low- and middle-income countries (LMIC) still face disappointing results, mainly due to high induction mortality and suboptimal management of complications. The American Society of Hematology established the International Consortium on Acute Leukemias (ICAL) to address this challenge through international clinical networking. Here, we present the findings from the ICAPL study involving 806 patients with APL recruited in Brazil, Chile, Paraguay, Peru, and Uruguay. The induction mortality rate has decreased to 14.6% compared to the pre-ICAL rate of 32%. Multivariable logistic regression analysis revealed as factors associated with induction death: age ≥ 40 years, ECOG = 3, high-risk status based on the PETHEMA/GIMEMA classification, albumin level ≤ 3.5 g/dL, bcr3 PML/RARA isoform, the interval between presenting symptoms to diagnosis exceeding 48 hours, and the occurrence of central nervous system and pulmonary bleeding. With a median follow-up of 53 months, the estimated 4-year overall survival (OS) rate is 81%, the 4-year disease-free survival (DFS) rate is 80%, and the 4-year cumulative incidence of relapse (CIR) rate is 15%. These results parallel those observed in studies conducted in high-income countries, highlighting the long-term effectiveness of developing clinical networks to improve clinical care and infrastructure in LMIC.

Clinical significance of mitochondrial DNA content in acute promyelocytic leukaemia.

Although a growing body of evidence demonstrates that altered mtDNA content (mtDNAc) has clinical implications in several types of solid tumours, its prognostic relevance in acute promyelocytic leukaemia (APL) patients remains largely unknown. Here, we show that patients with higher-than-normal mtDNAc had better outcomes regardless of tumour burden. These results were more evident in patients with low-risk of relapse. The multivariate Cox proportional hazard model demonstrated that high mtDNAc was independently associated with a decreased cumulative incidence of relapse. Altogether, our data highlights the possible role of mitochondrial metabolism in APL patients treated with ATRA.

STMN1 is highly expressed and contributes to clonogenicity in acute promyelocytic leukemia cells.

Stathmin 1 (STMN1) is a microtubule-destabilizing protein highly expressed in hematological malignancies and involved in proliferation and differentiation. Although a previous study found that the PML-RARα fusion protein, which contributes to the pathophysiology of acute promyelocytic leukemia (APL), positively regulates STMN1 at the transcription and protein activity levels, little is known about the role of STMN1 in APL. In this study, we aimed to investigate the STMN1 expression levels and their associations with laboratory, clinical, and genomic data in APL patients. We also assessed the dynamics of STMN1 expression during myeloid cell differentiation and cell cycle progression, and the cellular effects of STMN1 silencing and pharmacological effects of microtubule-stabilizing drugs on APL cells. We found that STMN1 transcripts were significantly increased in samples from APL patients compared with those of healthy donors (all p < 0.05). However, this had no effect on clinical outcomes. STMN1 expression was associated with proliferation- and metabolism-related gene signatures in APL. Our data confirmed that STMN1 was highly expressed in early hematopoietic progenitors and reduced during cell differentiation, including the ATRA-induced granulocytic differentiation model. STMN1 phosphorylation was predominant in a pool of mitosis-enriched APL cells. In NB4 and NB4-R2 cells, STMN1 knockdown decreased autonomous cell growth (all p < 0.05) but did not impact ATRA-induced apoptosis and differentiation. Finally, treatment with paclitaxel (as a single agent or combined with ATRA) induced microtubule stabilization, resulting in mitotic catastrophe with repercussions for cell viability, even in ATRA-resistant APL cells. This study provides new insights into the STMN1 functions and microtubule dynamics in APL.

Combining gene mutation with gene expression analysis improves outcome prediction in acute promyelocytic leukemia.

By combining the analysis of mutations with aberrant expression of genes previously related to poorer prognosis in both acute promyelocytic leukemia (APL) and acute myeloid leukemia, we arrived at an integrative score in APL (ISAPL) and demonstrated its relationship with clinical outcomes of patients treated with all-trans retinoic acid (ATRA) in combination with anthracycline-based chemotherapy. Based on fms-like tyrosine kinase-3-internal tandem duplication mutational status; the ΔNp73/TAp73 expression ratio; and ID1, BAALC, ERG, and KMT2E gene expression levels, we modeled ISAPL in 159 patients (median ISAPL score, 3; range, 0-10). ISAPL modeling identified 2 distinct groups of patients, with significant differences in early mortality (P < .001), remission (P = .004), overall survival (P < .001), cumulative incidence of relapse (P = .028), disease-free survival (P = .03), and event-free survival (P < .001). These data were internally validated by using a bootstrap resampling procedure. At least for patients treated with ATRA and anthracycline-based chemotherapy, ISAPL modeling may identify those who need to be treated differently to maximize their chances for a cure.

Improving acute promyelocytic leukemia (APL) outcome in developing countries through networking, results of the International Consortium on APL.

Thanks to modern treatment with all-trans retinoic acid and chemotherapy, acute promyelocytic leukemia (APL) is now the most curable type of leukemia. However, this progress has not yielded equivalent benefit in developing countries. The International Consortium on Acute Promyelocytic Leukemia (IC-APL) was established to create a network of institutions in developing countries that would exchange experience and data and receive support from well-established US and European cooperative groups. The IC-APL formulated expeditious diagnostic, treatment, and supportive guidelines that were adapted to local circumstances. APL was chosen as a model disease because of the potential impact on improved diagnosis and treatment. The project included 4 national coordinators and reference laboratories, common clinical record forms, 5 subcommittees, and laboratory and data management training programs. In addition, participating institutions held regular virtual and face-to-face meetings. Complete hematological remission was achieved in 153/180 (85%) patients and 27 (15%) died during induction. After a median follow-up of 28 months, the 2-year cumulative incidence of relapse, overall survival (OS), and disease-free survival (DFS) were 4.5%, 80%, and 91%, respectively. The establishment of the IC-APL network resulted in a decrease of almost 50% in early mortality and an improvement in OS of almost 30% compared with historical controls, resulting in OS and DFS similar to those reported in developed countries.

All-trans retinoic acid with daunorubicin or idarubicin for risk-adapted treatment of acute promyelocytic leukaemia: a matched-pair analysis of the PETHEMA LPA-2005 and IC-APL studies.

Front-line treatment of acute promyelocytic leukaemia (APL) consists of all-trans retinoic acid (ATRA) and anthracycline-based chemotherapy. In this setting, a comparison of idarubicin and daunorubicin has never been carried out. Two similar clinical trials using ATRA and chemotherapy for newly diagnosed APL were compared using matched-pair analysis. One was conducted by the PETHEMA/HOVON group with idarubicin and the other by the International Consortium on APL (IC-APL) using daunorubicin. Three hundred and fifty patients from the PETHEMA/HOVON cohort were matched with 175 patients in the IC-APL cohort, adjusting for the significantly unbalanced presenting features of the two entire cohorts. Complete remission (CR) rate was significantly higher in the PETHEMA/HOVON (94 %) than in the IC-APL cohort (85 %) (P = 0.002). The distribution of causes of induction failure and the time to achieve CR were similar in both cohorts. Patients who achieved CR had comparable cumulative incidence of relapse and disease-free survival rates, but lower overall and event-free survivals were observed in the IC-APL cohort, which was mainly due to a higher death rate during induction therapy. A higher death rate during consolidation therapy was also observed in the IC-APL. These results show that daunorubicin and idarubicin have similar antileukaemic efficacy in terms of primary resistance, molecular persistence, as well as molecular and haematological relapse rates when combined with ATRA in treatment of APL. However, a higher toxic death rate during induction and consolidation therapy was observed in the IC-APL cohort. This trial was registered at www.clinicaltrials.gov as #NCT00408278 [ClinicalTrials.gov].

Prognostic impact of KMT2E transcript levels on outcome of patients with acute promyelocytic leukaemia treated with all-trans retinoic acid and anthracycline-based chemotherapy: an International Consortium on Acute Promyelocytic Leukaemia study.

The KMT2E (MLL5) gene encodes a histone methyltransferase implicated in the positive control of genes related to haematopoiesis. Its close relationship with retinoic acid-induced granulopoiesis suggests that the deregulated expression of KMT2E might lead acute promyelocytic leukaemia (APL) blasts to become less susceptible to the conventional treatment protocols. Here, we assessed the impact of KMT2E expression on the prognosis of 121 APL patients treated with ATRA and anthracycline-based chemotherapy. Univariate analysis showed that complete remission (P = 0·006), 2-year overall survival (OS) (P = 0·005) and 2-year disease-free survival (DFS) rates (P = 0·037) were significantly lower in patients with low KMT2E expression; additionally, the 2-year cumulative incidence of relapse was higher in patients with low KMT2E expression (P = 0·04). Multivariate analysis revealed that low KMT2E expression was independently associated with lower remission rate (odds ratio [OR]: 7·18, 95% confidence interval [CI]: 1·71-30·1; P = 0·007) and shorter OS (hazard ratio [HR]: 0·27, 95% CI: 0·08-0·87; P = 0·029). Evaluated as a continuous variable, KMT2E expression retained association with poor remission rate (OR: 10·3, 95% CI: 2·49-43·2; P = 0·001) and shorter survival (HR: 0·17, 95% IC: 0·05-0·53; P = 0·002), while the association with DFS was of marginal significance (HR: 1·01; 95% CI: 0·99-1·02; P = 0·06). In summary, low KMT2E expression may predict poor outcome in APL patients.

Internal tandem duplication of the FLT3 gene confers poor overall survival in patients with acute promyelocytic leukemia treated with all-trans retinoic acid and anthracycline-based chemotherapy: an International Consortium on Acute Promyelocytic Leukemia study.

Activating internal tandem duplication (ITD) mutations in the fms-like tyrosine kinase 3 (FLT3) gene (FLT3-ITD) are associated with poor outcome in acute myeloid leukemia, but their prognostic impact in acute promyelocytic leukemia (APL) remains controversial. Here, we screened for FLT3-ITD mutations in 171 APL patients, treated with all-trans retinoic acid (ATRA) and anthracycline-based chemotherapy. We identified FLT3-ITD mutations in 35 patients (20 %). FLT3-ITD mutations were associated with higher white blood cell counts (P < 0.0001), relapse-risk score (P = 0.0007), higher hemoglobin levels (P = 0.0004), higher frequency of the microgranular morphology (M3v) subtype (P = 0.03), and the short PML/RARA (BCR3) isoform (P < 0.0001). After a median follow-up of 38 months, FLT3-ITD(positive) patients had a lower 3-year overall survival rate (62 %) compared with FLT3-ITD(negative) patients (82 %) (P = 0.006). The prognostic impact of FLT3-ITD on survival was retained in multivariable analysis (hazard ratio: 2.39, 95 % confidence interval [CI] 1.17-4.89; P = 0.017). Nevertheless, complete remission (P = 0.07), disease-free survival (P = 0.24), and the cumulative incidence of relapse (P = 0.94) rates were not significantly different between groups. We can conclude that FLT3-ITD mutations are associated with several hematologic features in APL, in particular with high white blood cell counts. In addition, FLT3-ITD may independently predict a shorter survival in patients with APL treated with ATRA and anthracycline-based chemotherapy.

Association of Human Development Index with rates and outcomes of hematopoietic stem cell transplantation for patients with acute leukemia.

Human Development Index (HDI) is used by the United Nations Organization to measure socioeconomic achievements of countries. We evaluated the association of HDI with rates and outcomes of hematopoietic stem cell transplantation (HSCT) for patients with acute leukemia. For the analysis of HSCT rates, all adults with acute leukemia (n = 16 403) treated in 30 European countries, between 2001 and 2005, were included. Association of HDI with the outcome was analyzed for 2015 patients with acute myeloid leukemia treated with myeloablative allotransplantation. Countries were classified according to HDI quintiles. Highly significant correlation was found for HDI and the total number of HSCT per population (R = 0.78; P < .001), as well as separately for sibling HSCT (R = 0.84; P < .001), unrelated HSCT (R = 0.66; P < .001), and autologous HSCT (R = 0.43; P = .02). The probabilities of leukemia-free survival for 5 consecutive groups of countries with increasing HDI were: 56%, 59%, 63%, 58%, and 68% (P = .01). In a multivariate analysis, transplantations performed in countries belonging to the upper HDI category were associated with higher leukemia-free survival compared with the remaining ones (HR = 1.36, P = .008), which resulted mainly from reduced risk of relapse (HR = 0.72, P = .04). We conclude that, in Europe, the HDI is associated with both rates and results of HSCT for acute leukemia.

Reduced SLIT2 is Associated with Increased Cell Proliferation and Arsenic Trioxide Resistance in Acute Promyelocytic Leukemia.

The SLIT-ROBO axis plays an important role in normal stem-cell biology, with possible repercussions on cancer stem cell emergence. Although the Promyelocytic Leukemia (PML) protein can regulate SLIT2 expression in the central nervous system, little is known about SLIT2 in acute promyelocytic leukemia. Hence, we aimed to investigate the levels of SLIT2 in acute promyelocytic leukemia (APL) and assess its biological activity in vitro and in vivo. Our analysis indicated that blasts with SLIT2high transcript levels were associated with cell cycle arrest, while SLIT2low APL blasts displayed a more stem-cell like phenotype. In a retrospective analysis using a cohort of patients treated with all-trans retinoic acid (ATRA) and anthracyclines, high SLIT2 expression was correlated with reduced leukocyte count (p = 0.024), and independently associated with improved overall survival (hazard ratio: 0.94; 95% confidence interval: 0.92-0.97; p < 0.001). Functionally, SLIT2-knockdown in primary APL blasts and cell lines led to increased cell proliferation and resistance to arsenic trioxide induced apoptosis. Finally, in vivo transplant of Slit2-silenced primary APL blasts promoted increased leukocyte count (p = 0.001) and decreased overall survival (p = 0.002) compared with the control. In summary, our data highlight the tumor suppressive function of SLIT2 in APL and its deteriorating effects on disease progression when downregulated.

NTAL is associated with treatment outcome, cell proliferation and differentiation in acute promyelocytic leukemia.

Non-T cell activation linker (NTAL) is a lipid raft-membrane protein expressed by normal and leukemic cells and involved in cell signaling. In acute promyelocytic leukemia (APL), NTAL depletion from lipid rafts decreases cell viability through regulation of the Akt/PI3K pathway. The role of NTAL in APL cell processes, and its association with clinical outcome, has not, however, been established. Here, we show that reduced levels of NTAL were associated with increased all-trans retinoic acid (ATRA)-induced differentiation, generation of reactive oxygen species, and mitochondrial dysfunction. Additionally, NTAL-knockdown (NTAL-KD) in APL cell lines led to activation of Ras, inhibition of Akt/mTOR pathways, and increased expression of autophagy markers, leading to an increased apoptosis rate following arsenic trioxide treatment. Furthermore, NTAL-KD in NB4 cells decreased the tumor burden in (NOD scid gamma) NSG mice, suggesting its implication in tumor growth. A retrospective analysis of NTAL expression in a cohort of patients treated with ATRA and anthracyclines, revealed that NTAL overexpression was associated with a high leukocyte count (P = 0.007) and was independently associated with shorter overall survival (Hazard Ratio: 3.6; 95% Confidence Interval: 1.17-11.28; P = 0.026). Taken together, our data highlights the importance of NTAL in APL cell survival and response to treatment.

Clinical features and outcomes of 134 Brazilians with acute promyelocytic leukemia who received ATRA and anthracyclines.

We report an increased incidence of high relapse risk features in 157 APL Brazilian patients. Out of 134 patients treated with ATRA and anthracyclines, only 91 (67.9%) achieved remission because 43 (32%) died during induction. The death rate during consolidation was 10.5%. Bleeding complications were the most frequent cause of failure (21.6%).

Evaluation of the European LeukemiaNet recommendations for predicting outcomes of patients with acute myeloid leukemia treated in low- and middle-income countries (LMIC): A Brazilian experience.

BACKGROUND: Current results regarding treatment outcomes in acute myeloid leukemia (AML) point to significant differences between low- and middle-income countries (LMIC) and high-income countries (HIC). Excluding well-known socioeconomic issues, genetic markers important for prognosis have not been properly incorporated into the clinical practice so far and their usefulness outside of well-controlled clinical trials remain unknown. METHODS: Here, we assessed the clinical significance of the European LeukemiaNet (ELN) recommendations in 196 consecutive patients with AML in a real-life setting. All patients were younger than 60 years of age (49% male) and treated with conventional chemotherapy for induction and consolidation in three Brazilian Institutions that well represent Brazilian geographic and socioeconomic diversity. FINDINGS: Multivariable analysis showed that ELN recommendations had a slight association with complete remission achievement (odds ratio: 0.74, 95% confidence interval, CI: 0.53-1.01; P=0.06), but were independently associated with poor overall survival (OS) (hazard ratio, HR: 1.3, 95% CI: 1.1-1.54; P=0.002), disease-free survival (DFS) (HR: 1.42, 95% CI: 1.03-1.95; P=0.028) and event-free survival (EFS) (HR: 1.24, 95% CI: 1.06-1.47; P=0.007), considering initial leukocyte counts and age as confounders. ELN recommendations had no impact on cumulative incidence of relapse (P=0.09). INTERPRETATION: Our results suggest that within the context of LMIC, the prognostic markers recommended by ELN may be useful to predict patient's clinical outcomes; however, the OS, DFS and EFS were shorter than the reported in Europe and US for the respective risk groups.

Clinical impact of BAALC expression in high-risk acute promyelocytic leukemia.

Although overexpression of the brain and acute leukemia, cytoplasmic (BAALC) gene is associated with primary resistant disease and shorter relapse-free, disease-free, and overall survival in different subsets of acute myeloid leukemia (AML), little is known about its clinical impact in acute promyelocytic leukemia (APL). Using real-time reverse transcriptase polymerase chain reaction, we showed that BAALC expression is significantly lower in APL compared with other subsets of AML (P < .001). We also demonstrated that BAALC overexpression was associated with shorter disease-free survival (DFS) (hazard ratio [HR], 4.43; 95% confidence interval [CI], 1.29-15.2; P = .018) in 221 consecutive patients (median age, 35 years; range, 18-82 years) with newly diagnosed APL homogeneously treated with all-trans retinoic acid and anthracycline-based chemotherapy. Cox proportional hazard modeling showed that BAALC overexpression was independently associated with shorter DFS in the total cohort (HR, 5.26; 95% CI, 1.52-18.2; P = .009) and in patients with high-risk disease (ie, those with initial leukocyte counts >10 × 109/L) (HR, 5.3; 95% CI, 1.14-24.5; P = .033). We conclude that BAALC expression could be useful for refining risk stratification in APL, although this needs to be confirmed in independent cohorts.

De novo acute myeloid leukemia in adults younger than 60 years of age: socioeconomic aspects and treatment results in a Brazilian university center.

We retrospectively studied the outcomes of adults with de novo acute myeloid leukemia treated in a reference center in Brazil and analyzed the association with the human development index (HDI) of the United Nations used as a socioeconomic factor. Among 123 patients, 46 (37%) died during induction, 65 (53%) reached complete remission and 45 (37%) received high-dose cytarabine (Hidac) consolidation. The 5-year overall survival and leukemia-free survival (LFS) were 17 and 26%, respectively, for all patients and 36 and 30%, respectively, for those receiving Hidac. In multivariate analysis, an HDI <0.660 was associated with a lower probability to receive Hidac (P = 0.001), a trend for higher mortality in remission induction (P = 0.062) and a decreased LFS (P < 0.0001). However, it was not associated with outcomes for patients receiving Hidac. In conclusion, survival for patients who received Hidac consolidation is satisfactory; however, socioeconomic factors may have selected patients to receive intensive Hidac consolidation.

Granulocytic sarcoma of the small intestine with CBFbeta/MYH11 fusion gene: report of an aleukaemic case and review of the literature.

Granulocytic sarcomas (GS) are rare extramedullary tumours composed of immature myeloid cells. Inversion of chromosome 16 [inv(16)] is a cytogenetic marker for M4Eo subtype of acute myeloid leukaemia (AML). The possibility of an association between the development of granulocytic sarcoma of the small intestine (GSSI) and the M4Eo subtype of AML was suggested in nine previous case reports. Here we report an aleukaemic case of GSSI with inv(16) and its molecular equivalent, the CBFbeta/MYH11 fusion gene, detected by reverse transcriptase-polymerase chain reaction (RT-PCR), that after treatment with conventional AML chemotherapy followed by autologous bone marrow transplantation, achieved complete haematological and molecular remission on bone marrow examination. After chemotherapy, a thickened ileum wall positive for CBFbeta/MYH11 on tumour mass samples was still observed on computed tomography (CT) studies, raising the question of residual GS representing a reservoir of malignant cells. This case demonstrates the critical need of multidisciplinary diagnosis and follow-up of this entity combining immunopathologic, cytogenetic and molecular studies, reinforcing the potentiality of risk-adapted therapy strategies, as it is increasingly claimed for patients with overt AML.

The impact of medical education and networking on the outcome of leukemia treatment in developing countries. The experience of International Consortium on Acute Promyelocytic Leukemia (IC-APL).

OBJECTIVES: Several clinical trials conducted in Europe and US reported favorable outcomes of patients with APL treated with the combination of all trans retinoic acid (ATRA) and anthracyclines. Nevertheless, the results observed in developing countries with the same regimen was poorer, mainly due to high early mortality mainly due bleeding. The International Consortium on Acute Promyelocytic Leukemia (IC-APL) is an initiative of the International Members Committee of the ASH and the project aims to reduce this gap through the establishment of international network, which was launched in Brazil, Mexico and Uruguay. METHODS: The IC-APL treatment protocol is similar to the PETHEMA 2005, but changing idarubicin to daunorubicin. All patients with a suspected diagnosis of APL were immediately started on ATRA, while bone marrow samples were shipped to a national central lab where genetic verification of the diagnosis was performed. The immunofluorescence using an anti-PML antibody allowed a rapid confirmation of the diagnosis and, the importance of supportive measures was reinforced. RESULTS: The interim analysis of 97 patients enrolled in the IC-APL protocol showed that complete remission (CR) rate was 83% and the 2-year overall survival and disease-free survival were 80% and 90%, respectively. Of note, the early mortality rate was reduced to 7.5%. DISCUSSION: The results of IC-APL demonstrate the impact of educational programs and networking on the improvement of the leukemia treatment outcome in developing countries.