Clinical and biological characteristics of acute promyelocytic leukemia in Taiwan: a high relapse rate in patients with high initial and peak white blood cell counts during all-trans retinoic acid treatment

Prognostic significance of isochromosome 17q in hematologic malignancies

Isochromosome 17q [i(17q)] with its two identical long arms is formed by duplication of the q arm and loss of the short p arm. The breakpoint in chromosome 17 that allows the formation of this isochromosome is located at 17p11.2, and the ~240 kb region with its large, palindromic, low-copy repeat sequences are present here. The region is highly unstable and susceptible to a variety of genomic alterations which may be induced by or without toxic agents. One molecular consequence of i(17q) development is the obligatory loss of a single TP53 allele of the tumor suppressor P53 protein located at 17p13.1. Isochromosome 17q is involved in cancer development and progression. It occurs in combination with other chromosomal defects (complex cytogenetics), and rarely as a single mutation. The i(17q) rearrangement has been described as the most common chromosomal aberration in primitive neuroectodermal tumors and medulloblastomas. This isochromosome is also detected in different hematological disorders. In this article, we analyze literature data on the presence of i(17q) in proliferative disorders of the hematopoietic system in the context of its role as a prognostic factor of disease progression. The case reports are added to support the presented data. Currently, there are no indications for the use of specific treatment regimens in the subjects with a presence of the isochromosome 17q. Thus, it is of importance to continue studies on the prognostic role of this abnormality and even single cases should be reported as they may be used for further statistical analyses or meta-analyses.

Incidence of Differentiation Syndrome Associated with Treatment Regimens in Acute Myeloid Leukemia: A Systematic Review of the Literature

Differentiation syndrome (DS) is a potentially fatal adverse drug reaction caused by the so-called differentiating agents such as all-trans retinoic acid (ATRA) and arsenic trioxide (ATO), used for remission induction in the treatment of the M3 subtype of acute myeloid leukemia (AML), acute promyelocytic leukemia (APL). However, recent DS reports in trials of isocitrate dehydrogenase (IDH)-inhibitor drugs in patients with IDH-mutated AML have raised concerns. Given the limited knowledge of the incidence of DS with differentiating agents, we conducted a systematic literature review of clinical trials with reports of DS to provide a comprehensive overview of the medications associated with DS. In particular, we focused on the incidence of DS reported among the IDH-inhibitors, compared to existing ATRA and ATO therapies. We identified 44 published articles, encompassing 39 clinical trials, including 6949 patients. Overall, the cumulative incidence of DS across all treatment regimens was 17.7%. Incidence of DS was notably lower in trials with IDH-inhibitors (10.4%) compared to other regimens, including ATRA and/or ATO (15.4-20.6%). Compared to other therapies, the median time to onset was four times longer with IDH-inhibitors (48 vs. 11 days). Treating oncologists should be mindful of this potentially fatal adverse drug reaction, as we expect the current trials represent an underestimation of the actual incidence.

Integrating microRNA and mRNA expression profiles of acute promyelocytic leukemia cells to explore the occurrence mechanisms of differentiation syndrome

The pathogenesis of therapy-induced differentiation syndrome (DS) in patients with acute promyelocytic leukemia (APL) remains unclear. In this study, mRNA and microRNA (miRNA) expression profiling of peripheral blood APL cells from patients complicated with vs. without DS were integratively analyzed to explore the mechanisms underlying arsenic trioxide treatment-associated DS. By integrating the differentially expressed data with the data of differentially expressed microRNAs and their computationally predicted target genes, as well as the data of transcription factors and differentially expressed target microRNAs obtained from a literature search, a DS-related genetic regulatory network was constructed. Then using an EAGLE algorithm in clusterViz, the network was subdivided into 10 modules. Using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database the modules were annotated functionally, and three functionally active modules were recognized. The further in-depth analyses on the annotated functions of the three modules and the expression and roles of the related genes revealed that proliferation, differentiation, apoptosis and infiltration capability of APL cells might play important roles in the DS pathogenesis. The results could improve our understanding of DS pathogenesis from a more overall perspective, and could provide new clues for future research.

A Pediatric Acute Promyelocytic Leukemia With a Rare Karyotype of ider(17)(q10)t(15;17) and Favorable Outcome: A Case Report

Acute promyelocytic leukemia (APL) is a specific malignant hematological disorder with a diagnostic hallmark of chromosome translocation t(15;17)(q22;q21). As a very rare secondary cytogenetic aberration in pediatric APL, ider(17q) (q10)t(15;17) was suggested to be a poor prognostic factor based on previous case reports.Here, we report a pediatric APL case with a rare karyotype of ider(17)(q10)t(15;17). Bone marrow aspiration, immunophenotyping, molecular biology, cytogenetic, and fluorescence in situ hybridization (FISH) analyses were performed at initial diagnosis and during the treatment.A 6-year-old boy was brought to our hospital with the chief complaint of bleeding gums twice and intermittent fever for 3 days in January 2013. He was diagnosed as low-risk APL according to the 2012 NCCN guideline on APL, with the expression of PML-RARA (bcr3 subtype) and the karyotype of 46,XY, der(15)t(15;17)(q22;q21),ider(17)(q10)t(15;17), which was further verified by FISH. The patient was treated through combination all-trans retinoic acid (ATRA) and arsenic with daunorubicin according to the 2012 NCCN guideline for APL. Continuous hematological completed remission (HCR) and major molecular remission (MMR) were achieved with normal karyotype for >28 months after induction chemotherapy.Different from previously reported cases, this pediatric APL patient with ider(17)(q10)t(15;17) displays favorable clinical outcomes, which might be related to the low-risk classification and arsenic treatment during the treatment. It suggests that ider(17)(q10)t(15;17) may not be the sole determinant for worse outcomes in pediatric APL and implies that more contributed factors should be considered for pediatric APL prognosis.

Acute promyelocytic leukemia, study of predictive factors for Differentiation Syndrome, single center experience

Reports about patients with acute promyelocytic leukemia from the Middle East are few; in this study we are reporting our single center experience of treating 29 patients over 6years. Acute promyelocytic leukemia treatment response is markedly improved after the introduction of ATRA. Treatment related complication is still an important issue particularly Differentiation Syndrome. Prediction to its occurrence has been tried by other groups. We aimed to study all the possible predictive factors of acute promyelocytic leukemia. Our chemotherapy induction protocol is AIDA protocol which includes ATRA 45mg/m(2)/d in divided doses every12h, and Idarubicin 12mg/m(2)/d IV on days 3, 5, 7, and 9. Differentiation Syndrome occurred in 48.3% of patients and was mainly presented by pulmonary symptoms in 55.2%, 6 cases died during induction. None of the predictive factors studied showed a statistically significant difference between patients who developed Differentiation Syndrome and those who did not. Differentiation Syndrome did not affect overall survival. Cox regression showed an inverse yet a non significant association between PETHEMA and overall survival probability (P=0.168). In conclusion, Differentiation Syndrome has no clear predictive factor to date. The best approach is to hold ATRA and give dexamethasone which is quite effective as reported in the literature. PETHEMA risk model has a moderately significant prognostic value.

A rare case of microgranular acute promyelocytic leukemia associated with ider(17)(q10)t(15;17) in an old-age patient

We present a rare case of microgranular variant acute promyelocytic leukemia (APL) associated with ider(17)(q10)t(15;17)(q22;q12) of an old-age patient. The initial chromosome study showed a 46,XX,del(6)(?q21q25),der(15)t(15;17)(q22;q12),ider(17)(q10)t(15;17)[10]/47,sl,+ider(17)(q10)t(15;17)[3]/46,XX[16]. FISH signals from a dual color dual fusion translocation PML-RARA probe were consistent with the results of conventional cytogenetics. Because of the rarity of ider(17)(q10)t(15;17) in microgranular APL, further studies on both gene dosage effect of this chromosomal abnormality and the influence of ider(17)(q10)t(15;17) on clinical features such as prognosis, survival, and treatment response of APL cases are recommended.

ider(17)(q10)t(15;17) associated with relapse and poor prognosis in a pediatric patient with acute promyelocytic leukemia

Although acute promyelocytic leukemia (APL) has been regarded as a serious medical emergency associated with disseminated intravascular coagulopathy or subsequent mortality, it is now considered a curable leukemia that is particularly sensitive to treatment with all-trans retinoic acid combined with chemotherapy. However, it is not clear whether additional chromosomal abnormalities in APL patients directly influence the prognosis or treatment response. ider(17)(q10)t(15;17)(q22;q21) has mostly been reported in adult APL patients, and only three cases of pediatric APL associated with ider(17)(q10)t(15;17) showing poor prognosis have been described in the literature. Here, we report the close follow-up (clinical and laboratory) data of a pediatric APL case associated with ider(17)(q10)t(15;17). This patient had APL relapse from the same clone 15 months after morphological remission. Furthermore, despite subsequent chemotherapy, the patient died 16 months after the initial APL diagnosis. Although based on a limited amount of data (four pediatric APL cases), such results in pediatric APL patients may provide important insight into the relationship between ider(17)(q10)t(15;17) and poor prognosis. However, further well-designed case-control studies are necessary to determine the treatment response and prognosis in pediatric or adult APL patients with ider(17)(q10)t(15;17).

Clinical and Biological Significance of CD56 Antigen Expression in Acute Promyelocytic Leukemia

The biological significance of CD56 antigen expression in patients with acute promyelocytic leukemia (APL) has been under investigation. We investigated the clinical and biologic features of CD56+APL. In our series, CD56 antigen was positive in 4 of 28 (14%) APL patients. No differences were found regarding age, gender, performance status (PS), initial leukocyte and platelet counts, lactate dehydrogenase (LDH) and fibrinogen (Fbg) levels according to CD56 expression. CD34 antigen was co-expressed in 3 of the 4 patients with CD56+ APL, in contrast to 2 of the 24 patients with CD56- APL (P = .01). Extramedullary relapse occurred in 3 of the 4 patients with CD56+ APL, in contrast to none of the 24 patients with CD56- APL (P = .001). Median remission duration was 4 months in CD56+ APL and was not reached in CD56- APL. The CD56+ population had a shorter remission duration (P < .0001) and disease-free survival (P < .0001). In contrast, no difference was found in overall survival. These results suggested that CD56 expression was associated with the leukemogenetic mutation at the primitive hematopoietic progenitor cell level and extramedullary relapse in APL patients treated with ATRA and chemotherapy.

Expression of angiopoietins and vascular endothelial growth factors and their clinical significance in acute myeloid leukemia

Angiogenic factors play an essential role in normal and pathologic angiogenesis, but their clinical role in acute myeloid leukemia (AML) remains unclear. We investigated the expression of Ang-1, Ang-2, Tie2, VEGF-A, and VEGF-C genes in bone marrow (BM) mononuclear cells by real-time quantitative PCR (RQ-PCR) in a cohort of 126 patients with newly diagnosed de novo AML and normal marrow donors. Here we show that high pre-treatment levels of Ang-2 in the BM indicate an unfavorable prognosis in AML. Only karyotype (hazard ratio 2.19, 95% CI 1.25-3.42, P=0.005) and expression of Ang-2 (hazard ratio 2.05, 95% CI 1.20-3.52, P=0.009), but not other angiogenic factors, were independent prognostic factors for overall survival by multivariate analysis. The prognostic significance of Ang-2 expression was more obvious in the subgroup of patients with intermediate-risk cytogenetics. Subgroup analysis showed that Ang-2 expression had prognostic impact on patients with low (but not high) Ang-1 or Tie2 levels, and on patients with high (but not low) VEGF-A or VEGF-C levels.

Role of interleukin-8 and growth-regulated oncogene-α in the chemotactic migration of all-trans retinoic acid-treated promyelocytic leukemic cells toward alveolar epithelial cells*

OBJECTIVE

Although all-trans retinoic acid (ATRA) can treat acute promyelocytic leukemia (APL), it also causes retinoic acid syndrome with presentations similar to acute respiratory distress syndrome. We investigated the role of interleukin (IL)-8 and growth-regulated oncogene (GRO)-alpha in the chemotactic transmigration of ATRA-treated NB4 (ATRA-NB4) APL cells toward A549 alveolar epithelial cells.

DESIGN

An in vitro human cell culture study.

SETTING

University hospital research laboratories.

SUBJECTS

NB4 and A549 cells.

INTERVENTIONS

NB4 and A549 cells were separately cultured with ATRA and/or dexamethasone for 1-3 days. NB4 or ATRA-NB4 cells were then placed in an upper insert and co-incubated with A549 cells or their conditioned medium located in a lower plate.

MEASUREMENTS AND MAIN RESULTS

ATRA stimulated NB4 cells to transmigrate toward the A549 cells in a time- and dose-dependent manner. Replacement of A459 condition medium by its original medium abrogated this transmigration. Only A549 cells constitutively secreted GRO-alpha, and both A549 and NB4 cells constitutively secreted IL-8, which was enhanced by ATRA. Exogenous administration of IL-8 or GRO-alpha also promoted the ATRA-NB4 transmigration. The binding assay demonstrated that ATRA-NB4 cells bound IL-8, but not GRO-alpha, more avidly. Pretreatment with antibodies directed against IL-8 and GRO-alpha receptors reduced ATRA-NB4 transmigration by about 60%. Dexamethasone did not suppress their IL-8 secretion and transmigration in ATRA-NB4 cells, but when applied to A549 cells, IL-8 secretion was suppressed but not GRO-alpha secretion, and there was attenuation of ATRA-NB4 transmigration.

CONCLUSIONS

IL-8 and GRO-alpha secreted from alveolar epithelial cells play an important role in the cell-cell interaction involved in the chemotactic transmigration of ATRA-treated APL cells toward alveolar epithelial cells.

A survival study and prognostic factors analysis on acute promyelocytic leukemia at a single center

This study was aimed to investigate the factors influencing long-term survival on patients with acute promyelocytic leukemia. Here, we present a single center retrospective study with long-term follow-up to explore the prognostic factors and a rationale of the using of ATRA, chemotherapy and As(2)O(3) in the treatment of newly diagnosed APL patients. In total, 222 patients, 184 achieved complete remission (CR) with the CR rate of 82.88% and 22 patients died during early induction therapy with the early-death-rate of 10%. Total 171 newly diagnosed APL patients entering CR were retrospectively analyzed from November 1989 to December 2004,with a median follow-up of 36 months (6-185 months). Univariate and multivariate analysis of eight factors potentially influencing survival and prognosis were carried out with Log-Rank and Cox regression method, including sex, age, initial WBC count, the level of lactic dehydrogenase (LDH), first induction regimen, days from induction therapy to CR, post-remission therapy and the status of PML-RAR alpha fusion gene by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the estimated 5-year overall survival (OS) and relapse-free survival (RFS) were 80.9+/-4.0 and 71.0+/-4.0%, respectively. Univariate analyses showed that initial WBC count, first induction regimen, days from induction therapy to CR, post-remission therapy regimen and the status of PML-RAR alpha in remission were important prognostic factors for long-term survival. Multivariate study showed that only post-remission therapy regimen was associated with RFS and OS. It is concluded that the post-remission treatment combining ATRA, As(2)O(3) and chemotherapy would significantly improve the long-term survival of APL patients achieving CR(1).

Arsenic trioxide (trisenox) therapy for acute promyelocytic leukemia in the setting of hematopoietic stem cell transplantation

The relapse-free survival of patients with acute promyelocytic leukemia (APL) has significantly increased during the last decade. The introduction of all-trans retinoic acid (ATRA) doubled the survival of patients with this disease. However, despite ATRA and anthracycline-based chemotherapy, 12%-30% of patients will still relapse. Arsenic trioxide (ATO) has demonstrated efficacy and safety in patients with first and subsequent relapsed or refractory APL, regardless of the disease-free interval. Treatment of relapsed and refractory patients with this novel therapy produces complete remission in 87% of patients and molecular remission in 83%. Studies have documented the efficacy of autologous and allogeneic transplantation as salvage therapy in relapsed and refractory APL. The introduction of ATO into the treatment regimen for APL has stimulated discussion on its role in the transplantation setting. Investigators recently met to discuss the issue and make recommendations regarding ATO therapy in patients who are in their second or subsequent complete remission and are candidates for transplantation. This article describes the pivotal studies of this novel agent, discusses risk factor stratification for relapse in patients with APL, and proposes protocols for treatment incorporating ATO therapy. In addition, it describes scientific issues in ongoing and proposed clinical trials of ATO therapy for this disease.

Choice of chemotherapy in induction, consolidation and maintenance in acute promyelocytic leukaemia

Cure of acute promyelocytic leukaemia (APL) is now a reality for most patients through the use of combined all-trans retinoic acid (ATRA) and chemotherapy. The simultaneous administration of ATRA and anthracycline-based chemotherapy is currently considered the most appropriate induction therapy. However, no consensus has been reached on the consolidation strategy. Therapeutic efficacy apparently did not differ according to the number of cycles and types of drug combined with anthracyclines. Encouraging results have been reported recently using less-intensive chemotherapy with anthracyclines alone, leading to a significant reduction in treatment-related toxicity during the consolidation phase and a high degree of compliance. Some ongoing risk-adapted protocols are now exploring the potential synergistic effect of ATRA and chemotherapy given simultaneously in consolidation. Preliminary data suggest that higher molecular remission rates post-consolidation and improved outcome may be obtained through this strategy. Persistence or recurrence of molecular disease at the end of consolidation is strongly associated with impending relapse and poor prognosis, indicating the need for further aggressive therapy. As for maintenance therapy, once demonstrated, the advantage of using ATRA with or without low-dose methotrexate and 6-mercaptopurine has encouraged most groups to incorporate such treatment into their protocols for APL.

Acute promyelocytic leukaemia:a review

Acute promyelocytic leukaemia (APL) is characterised by the fusion gene transcript PML-RAR-alpha and is now the most frequently curable acute leukaemia in adults if promptly diagnosed and adequately treated. The clinical presentation is associated with a haemorrhagic diathesis and the blasts almost always have Auer rods. Poor prognostic factors include older age, elevated white blood cell count, low platelet count, and CD56 expression. The introduction of all-trans retinoic acid (ATRA), which leads to the differentiation of leukaemic blasts into mature granulocytes has been the major breakthrough in the treatment of APL. Induction treatment with concurrent ATRA and chemotherapy leads to a rapid resolution of the characteristic life-threatening coagulopathy, high complete remission rates and excellent survival rates, compared to chemotherapy alone. However, treatment with ATRA is associated with the retinoic acid syndrome (RAS), which is a major toxicity and may lead to mortality. The role of cytarabine as a part of initial induction regimen remains unclear. After achievement of complete remission (CR), there is a definitive role of maintenance therapy with ATRA with or without low-dose chemotherapy. In relapsed patients, arsenic trioxide is considered the treatment of choice. However, the best postremission treatment for patients with second CR remains unknown. With the continued improvement in the field of stem cell transplantation, it may play an important role in the few patients with relapsed/refractory disease or those in second CR.

CD34 expression is associated with poor clinical outcome in patients with acute promyelocytic leukemia

This study investigated the clinical characteristics and prognostic relevance of CD34 expression in 47 patients with acute promyelocytic leukemia (APL), showing t(15;17) or PML/RARalpha. Ten (21.3%) of the APL patients were CD34(+). CD34 expression was associated with hypogranular morphology (P = 0.002) and hyperleukocytosis (P = 0.015). However, there were no statistically significant differences in age, sex, hemoglobin level, platelet count, or percentage of blasts between the CD34(+) and CD34(-) APL groups. Multiplex RT-PCR analysis showed that the L-form (BCR1) and S-form (BCR3) were correlated with CD34(-) APL and CD34(+) APL, respectively. Despite the lack of a difference in the complete remission rate, overall survival (OS) and disease-free survival (DFS) were significantly lower in the CD34(+) group than in the CD34(-) group (P = 0.012 and P = 0.0051, respectively). By multivariate analysis, the CD34(+) group showed a significant independent variable in DFS compared with the CD34(-) group, but this was not demonstrated for OS. In conclusion, CD34 expression in APL is a unique clinical feature associated with leukocytosis and atypical morphology with hypogranular pattern and is associated with a poor clinical outcome.

Acute promyelocytic leukemia: a case-based review

Retinoid therapy for acute promyelocytic leukemia (APL) is one of the major achievements of leukemia research in the last 15 years. Use of all trans retinoic acid (ATRA) has changed the prognosis of APL from a fatal leukemia to a highly curable disease. This case-based review examines the available clinical and scientific data to form evidence-based decisions in the management of APL. The main aim of this review is to highlight recent progress made in the management of APL and address the role of maintenance therapy, prognostic factors for relapse and treatment of relapsed disease.

Additional chromosomal abnormalities and variability of BCR breakpoints in Philadelphia chromosome/BCR-ABL-positive acute lymphoblastic leukemia in Taiwan

From 1986 to 1998, 26 (23%) of 114 adult acute lymphoblastic leukemia (ALL) patients and 11 (4%) of 328 pediatric patients were found to have Philadelphia (Ph) chromosome. In the 30 patients with available data at diagnosis, 18 (60%) had extra-chromosomal abnormalities. They included 1q duplication (5/18, 28%), supernumerary Ph chromosome (4/18, 22%), 9p abnormalities (3/18, 17%), 7q deletion/monosomy 7 (3/18, 17%), trisomy 19 (1/18, 6%), and trisomy 8 (1/18, 6%). Excluding those with specific cytogenetic changes, only one patient had hyperdiploid karyotype with more than 50 chromosomes. The incidence of 1q duplication was higher and that of hyperdiploidy was lower in this study than has been previously reported. There was no prognostic implication of these additional cytogenetic abnormalities. With fluorescence in situ hybridization (FISH) and reverse transcription-polymerase chain reaction (RT-PCR), 14 (27%) of 53 unselected adult ALL patients and 2 (5%) of 38 unselected pediatric patients were BCR-ABL-positive, including one adult and two children without Ph chromosome. The BCR-ABL fusion genes/transcripts were also present in all other 16 selected Ph-positive ALL patients. The BCR-ABL fusion subtypes were determined in all these 32 patients: 91% (11/12) childhood cases showed m-type fusion gene while 45% (9/20) adult ones did so (P = 0.0083). The clinical outcome was similar between the two groups of patients with m-type and M-type BCR-ABL. In conclusion, both cytogenetic and molecular studies are very helpful for identifying the subgroup of ALL patients with Ph/BCR-ABL. The additional cytogenetic abnormalities and subtypes of BCR-ABL fusion genes/transcripts had no significant implications in this group of patients.

Molecular cytogenetics of the acute promyelocytic leukemia-derived cell line NB4 and of four all-trans retinoic acid-resistant subclones

The retinoic acid (RA)-sensitive NB4 cell line was the first established acute promyelocytic leukemia (APL) permanent cell line. It harbors the (15;17) translocation, which fuses the PML and RARA genes. Given the low frequency of APLs, their generally low white blood cell count, and the difficulty to work on APL patient cells, this cell line represents a remarkable tool for biomolecular studies. To investigate possible mechanisms of retinoid resistance, subclones of NB4 resistant to all-trans retinoic acid (ATRA) were established. To characterize better the parental NB4 cell line and four ATRA-resistant subclones (NB4-R4, NB4-A1, NB4-B1, and NB4-007/6), we have performed both conventional and 24-color FISH karyotyping. Thus, we could identify all chromosomal abnormalities including marker chromosomes that were unclassified with R banding. Moreover, we have performed dual-color FISH by use of specific PML and RARA probes, to evaluate the number of copies for each gene and fusion gene. Interestingly, the number of copies of PML, RARA, and fusion genes was different for each cell line. Finally, we assessed the presence of the PML, RARA, PML/RARA, and RARA/PML transcripts by RT-PCR and of the PML/RARA and RARA proteins by Western blotting in all the cell lines. These data could focus further research for a better understanding of the molecular mechanisms underlying response or resistance to differentiating and/or apoptotic reagents.

Management of acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) has become the most potentially curable subtype of acute myeloid leukemia (AML) in adults. With current treatment strategies that incorporate all-trans retinoic acid (ATRA), long-term disease-free survival and potential cure rates of 70% to 80% can be expected. Such progress reflects what can be accomplished with insights into the molecular pathogenesis of leukemia, identification of a molecular target, and rapid accrual to a series of clinical trials. The leukemic promyelocytes from patients with APL are uniquely susceptible to a variety of novel agents in addition to ATRA, including arsenic trioxide, and in preliminary studies, gemtuzumab ozogamicin, the immunoconjugate comprised of an anti-CD33 monoclonal antibody linked to the potent cytotoxic agent calicheamicin. Incorporation of such agents into the treatment of patients with high-risk disease may be an important future direction to pursue.

Acute promyelocytic leukemia: evolving therapeutic strategies

Acute promyelocytic leukemia (APL) is now the most curable subtype of acute myeloid leukemia in adults. All-trans retinoic acid (ATRA), which induces differentiation of the leukemic cells into mature granulocytes, represents the important advance. The incorporation of ATRA in induction results in a high complete remission rate, leads to rapid resolution of the characteristic life-threatening coagulopathy, and, most importantly, decreases the relapse rate compared with treatment with chemotherapy alone. However, ATRA is associated with unique toxicities not observed with conventional cytotoxic chemotherapy. A number of clinical trials have been performed to define the optimal role of ATRA in the treatment of patients. The therapeutic strategies have rapidly evolved as a result of both single institution and large cooperative group trials. Arsenic trioxide and stem cell transplantation are effective treatments for patients with APL who relapse after or are refractory to ATRA-based therapy. As experience with ATRA and arsenic trioxide in patients with APL accumulates, a number of important questions arise that need to be addressed.

CD34-positive acute promyelocytic leukemia is associated with leukocytosis, microgranular/hypogranular morphology, expression of CD2 and bcr3 isoform

Acute promyelocytic leukemia (APL) has a favorable prognosis. Current therapy includes chemotherapy used in combination with all-trans-retinoic acid (ATRA). Although the differentiating effects of ATRA on promyelocytes have been well established, in vitro studies have shown that less-differentiated APL blasts (CD34(+)) demonstrate a variable responsiveness to ATRA. To assess the clinical relevance of this finding, we analyzed a cohort of 38 patients with t(15;17) and/or PML-RARalpha APL to determine the incidence and laboratory features of CD34(+) APL. Thirty-two percent (12/38) of cases were CD34(+). There was a difference in WBC at presentation between CD34(+) and CD34(-) cases (34.6 +/- 9.2, mean +/- standard error vs. 5.4 +/- 2.0, P = 0.009). Patients with CD34(+) APL demonstrated a micro/hypogranular phenotype (75%) (P = 0.001), co-expression of CD2(+) (83%) (P = 0.001), and the bcr3 isoform (100%) (P = 0.017). In contrast, CD34(-) cases demonstrated hypergranular morphology (65%), CD2(+) (15%), and the bcr1 isoform (50%). A high presenting WBC count (\G10 x 10(9)/L) was associated with an inferior overall survival (Log rank = 0.0047). Patients with CD34(+) APL demonstrated an incidence of early mortality of 50%. Despite a marked correlation between CD34 positivity and increased WBC count, overall survival of CD34(+) and CD34(-) cases did not differ significantly in our small cohort. Immunophenotypic analysis for CD34 expression should be included in future large APL trials to determine if detection of CD34(+) blasts represents an independent adverse prognostic factor.

Clinico-biological features of 30 patients with acute promyelocytic leukemia and response to combination induction chemotherapy with all-trans retinoic acid and anthracycline

30 adult patients with acute promyelocytic leukemia (APL) were seen at our institution overthe past 7 years. Their white cell count at presentation ranged from 400/microl to 54,900/microl. Cytogenetic studies were successful in 28 patients, of which 26(93%) were positive for t(15;17). Molecular analysis by reverse-transcription polymerase chain reaction demonstrated the PML-RARalpha fusion transcript in all 30 patients. The majority of patients had breakpoints at the 3' end with bcr1 products predominating. Complete remission rate of 92% was achieved using all-trans retinoic acid and anthracycline as induction chemotherapy in 26 patients. Of these, retinoic acid syndrome was observed in 4 cases, with 1 fatality. In conclusion, APL is a distinct entity with a highly specific molecular marker - t(15;17) translocation - that can be successfully induced into remission with all-trans retinoic acid and anthracycline in most patients.

Double induction strategy including high dose cytarabine in combination with all-trans retinoic acid: effects in patients with newly diagnosed acute promyelocytic leukemia. German AML Cooperative Group

A prospective multicenter study was performed to investigate the clinical and molecular results of intensified double induction therapy including high-dose cytarabine (ara-C) in combination with ATRA in newly diagnosed acute promyelocytic leukemia (APL), followed by consolidation and 3 years maintenance therapy. Fifty-one patients, diagnosed and monitored from December 1994 to June 1999, were evaluated. The median age was 43 (16-60) years. The morphologic diagnosis was M3 in 40 (78%) and M3v in 11 (22%) patients. In 15 (30%) patients the initial white blood cell counts were > or =5 x 10(9)/l. The cytogenetic or molecular proof of the translocation t(15;17) was a mandatory prerequisite for eligibility. The diagnosis was confirmed by karyotyping in 46 and by RT-PCR of the PML/RARalpha transcript in 45 cases. The rate of complete hematological remission was 92% and the early death rate 8%. Monitoring of minimal residual disease by RT-PCR of PML/RARalpha (sensitivity 10(-4)) showed negativity in 29 of 32 (91%) evaluable cases after induction, in 23 of 25 (92%) after consolidation, and in 27 of 30 (90%) during maintenance, after a median time of 2, 4 and of 18 months after diagnosis, respectively. After a median follow-up of 27 months, the estimated actuarial 2 years overall and event-free survival were both 88% (79, 97), and the 2 years relapse-free survival 96% (90, 100). The high antileukemic efficacy of this treatment strategy is demonstrated by a rapid and extensive reduction of the malignant clone and by a low relapse rate. The results suggest that the intensity of the induction chemotherapy combined with ATRA is one of the factors which may have a critical influence on the outcome of APL. A randomized trial should assess the value of an induction therapy including ATRA and high-dose ara-C in comparison to standard-dose ara-C.

A case for steroids in acute lung injury associated with the retinoic acid syndrome

A 62-year-old woman with acute promyelocytic leukaemia was treated with all-trans retinoic acid. On day 2 she suffered with dyspnoea and general fatigue. Marked hypoxia suggested the occurrence of retinoic acid syndrome. She underwent endotracheal intubation and mechanical ventilation with the administration of dexamethasone. Her symptoms promptly abated. She was subsequently treated with conventional chemotherapy and achieved complete remission.

CD56 expression is an indicator of poor clinical outcome in patients with acute promyelocytic leukemia treated with simultaneous all-trans-retinoic acid and chemotherapy

PURPOSE

Preliminary reports suggest that leukemic cell expression of CD56, a neural cell adhesion molecule, is associated with adverse clinical outcome in either acute myeloid leukemia with t(8;21) or acute promyelocytic leukemia (APL). We investigated the prognostic relevance of CD56 in a series of patients with APL who were treated homogeneously with all-trans-retinoic acid (ATRA) and chemotherapy.

PATIENTS AND METHODS

Clinicobiologic presenting features and therapeutic results were analyzed in a series of 100 patients with genetically proven APL who were treated, according to the example of the Gruppo Italiano Malattie Ematologiche Maligne dell'Adulto multicenter trial, with ATRA plus idarubicin (AIDA) and for whom data on CD56 expression were available at diagnosis.

RESULTS

Fifteen patients (15%) showed expression of CD56 in greater than or equal to 20% blasts at diagnosis and were considered as CD56(+). No differences were found regarding age, sex, WBC and platelet counts, incidence of coagulopathy, hemoglobin and fibrinogen levels, promyelocytic leukemia/retinoic acid receptor (PML/RAR) alpha fusion type, or complete remission (CR) rate in the comparison of the CD56(+) and CD56(-) populations. Conversely, compared with patients who were CD56(-), patients with CD56(+) APL had shorter CR duration (P =.04) and overall survival (P =.002). In the multivariate analysis, CD56 positivity and initial WBC count greater than 10 x 10(9) cells/L retained statistical significance in overall survival (P =.04 and P =.02, respectively).

CONCLUSION

The expression of CD56 is significantly associated with inferior CR duration and survival in patients with APL who were treated with modern frontline treatment that included ATRA and simultaneous chemotherapy. Combined with other well-established prognostic factors such as WBC count, CD56 expression at diagnosis might be used to build prognostic scores for risk-adapted therapy in APL.

Acute and chronic arsenic poisoning associated with treatment of acute promyelocytic leukaemia

Seven relapsed and/or refractory acute promyelocytic leukaemia patients were treated by arsenic trioxide (As2O3). Four patients (4/7, 57%) achieved complete remission after one to three cycles of treatment and the most common acute side-effect was fluid retention (in six patients, 86%), including weight gains and pleuro-pericardial effusions. Evident polyneuropathy compatible with chronic arsenic toxicity was noted in two of the three patients who received As2O3 maintenance therapy and one of them had marked distal muscular atrophy. We suggest that As2O3 may be a useful salvage therapy for relapsed and refractory APL patients, but the acute or chronic arsenic toxicity should be carefully monitored.