High relative proportion of acute promyelocytic leukemia in children: experience of a multicenter study in Cuba

Assessment of Molecular Markers in AML Patients: A Hospital-Based Study in Lebanon

BACKGROUND

In the past, research has been focused on elucidating the molecular genetics and epigenetic basis of acute myelogenous leukemia (AML). This has led to the change in the classification and management of AML patients. Because no molecular studies regarding AML characterization in Lebanese patients had yet been reported, we decided to determine in our institution the prevalence of the recurrent genetic rearrangements t(8;21), inv(16), t(15;17) and Fms-like (Suzanne McDonough feline sarcoma) tyrosine kinase 3 (FLT3) and nucleophosmin (NPM1) mutations.

MATERIALS AND METHODS

Fusion gene transcripts from chromosome aberrations were analyzed according to standardized reverse transcription polymerase chain reactions after the report of BIOMED-1 concerted action: investigation of minimal residual disease in acute leukemia. FLT3 and NPM1 mutations were screened using home-brew methodologies.

RESULTS

We reviewed 144 bone marrow samples from AML patients referred to Saint George Hospital for molecular and cytogenetic studies from September 2006 to July 2014. The male to female patient ratio was 1.34 to 1. We detected the inv(16) in 6 patients [4.2%] (type A, 5 [83%]; type D, 1 [17%]), t(8;21) in 7 patients [4.9%] (e5e2), and t(15;17) in 36 patients [25.0%] (24 [67%] breakpoint cluster region 1 (bcr1), 12 [33%] bcr3). Other chromosomal abnormalities (trisomy 8, complex karyotype, t(6;9),…) were found in 44 patients [31.4%] and 51 [35.5%] cases showed normal karyotype. Among the normal karyotypes, 6 patients [11.8%] were FLT3-positive (4 [67%] internal tandem duplication [ITD], 2 [33%] D835V), 8 [15.7%] had type A NPM1 mutation and 8 [15.7%] type A NPM1 and FLT3/ITD concomitantly.

CONCLUSION

Our results, except for the prevalence of acute promyelocytic leukemia, are concordant with those reported in the literature with approximately 35% of the patients cytogenetically normal. Testing patients with normal karyotype for other molecular markers such as CCAAT/enhancer-binding protein alpha mutations, isocitrate dehydrogenase 1/2 mutations, and mixed lineage leukemia rearrangements could therefore provide additional prognostic, predictive, and therapeutic values for AML patients.

Global characteristics of childhood acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) comprises approximately 5-10% of childhood acute myeloid leukemia (AML) cases in the US. While variation in this percentage among other populations was noted previously, global patterns of childhood APL have not been thoroughly characterized. In this comprehensive review of childhood APL, we examined its geographic pattern and the potential contribution of environmental factors to observed variation. In 142 studies (spanning >60 countries) identified, variation was apparent-de novo APL represented from 2% (Switzerland) to >50% (Nicaragua) of childhood AML in different geographic regions. Because a limited number of previous studies addressed specific environmental exposures that potentially underlie childhood APL development, we gathered 28 childhood cases of therapy-related APL, which exemplified associations between prior exposures to chemotherapeutic drugs/radiation and APL diagnosis. Future population-based studies examining childhood APL patterns and the potential association with specific environmental exposures and other risk factors are needed.

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

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

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.

Incidence rates of acute promyelocytic leukemia among Hispanics, blacks, Asians, and non-Hispanic whites in the United States

Despite significant improvements in the prognosis of acute promyelocytic leukemia brought about by therapeutic advances, understanding of the epidemiology of acute promyelocytic leukemia remains limited. Earlier reports have suggested that Hispanics may have an increased incidence of acute promyelocytic leukemia, but no systematic analysis of national data has yet been reported. We performed a retrospective cohort study, using data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute from 1992-2001 in order to compare leukemia incidence rates as a function of race and ethnicity. We identified 709 cases of acute promyelocytic leukemia and analyzed incidence rates by race and sex. Hispanics were not found to have greater lifetime incidence rates than whites, with an incidence relative rate (IRR) of 0.86 that of whites (P=0.17). The age distribution among Hispanics was significantly different from non-Hispanic whites, with greater incidence rates for children ages 1-19 years (IRR=1.9, P=0.02) and adult ages 20-44 years (IRR=1.6, P=0.004). Blacks had lower lifetime incidence rates than non-Hispanic whites (IRR=0.75, P=0.04), Hispanics (IRR=0.64, P=0.007), and Asians (IRR=0.67, P=0.03). Asians did not differ from non-Hispanic whites in lifetime or age-specific incidence rates. These results indicate that while US Hispanics do not have greater lifetime incidence rates of acute promyelocytic leukemia, blacks have lower incidence rates of acute promyelocytic leukemia than Hispanics, non-Hispanic whites, and Asians.

Management of APL in Developing Countries: Epidemiology, Challenges and Opportunities for International Collaboration

Acute promyelocytic leukemia (APL), a relatively rare hematologic malignancy, is highly curable with current treatment strategies. However, these strategies may be unavailable in countries with limited resources. A review of records in several Latin American countries revealed that approximately 30% of deaths among children and adults with APL were caused by early complications associated with the disease or its treatment. Further, APL accounts for 20% to 25% of cases of AML in these countries, consistent with the previous observation of increased incidence of APL in Latin Americans. The lack of population-based registries in developing countries has made it difficult to determine the real incidence of APL. Moreover, APL appears to have other unique epidemiologic characteristics, including association of primary APL with an increased body mass index at diagnosis and association of secondary APL with breast cancer. To facilitate the development of local capacity and implement effective treatment of APL in developing countries, the International Committee of the American Society of Hematology has assembled a working group to formulate treatment guidelines based on evidence from clinical trials results in the developed world but adapted to local resources. It is hoped that uniform treatment, careful documentation of specific outcome data, and ongoing monitoring of treatment efficacy and toxicity will improve the cure rate and provide biologic and epidemiologic information about APL in developing countries. This initial demonstration project may be joined by other countries, providing a framework for additional clinical investigation in this highly curable form of leukemia.