Long-term outcome of childhood acute myeloid leukemia in a developing country: experience from a children's hospital in China

A scoring system based on fusion genes to predict treatment outcomes of the non-acute promyelocytic leukemia pediatric acute myeloid leukemia

Background

Fusion genes are considered to be one of the major drivers behind cancer initiation and progression. Meanwhile, non-acute promyelocytic leukemia (APL) pediatric patients with acute myeloid leukemia (AML) in children had limited treatment efficacy. Hence, we developed and validated a simple clinical scoring system for predicting outcomes in non-APL pediatric patients with AML.

Method

A total of 184 non-APL pediatric patients with AML who were admitted to our hospital and an independent dataset (318 patients) from the TARGET database were included. Least absolute shrinkage and selection operation (LASSO) and Cox regression analysis were used to identify prognostic factors. Then, a nomogram score was developed to predict the 1, 3, and 5 years overall survival (OS) based on their clinical characteristics and fusion genes. The accuracy of the nomogram score was determined by calibration curves and receiver operating characteristic (ROC) curves. Additionally, an internal verification cohort was used to assess its applicability.

Results

Based on Cox and LASSO regression analyses, a nomogram score was constructed using clinical characteristics and OS-related fusion genes (CBFβ::MYH11, RUNX1::RUNX1T1, KMT2A::ELL, and KMT2A::MLLT10), yielded good calibration and concordance for predicting OS of non-APL pediatric patients with AML. Furthermore, patients with higher scores exhibited worse outcomes. The nomogram score also demonstrated good discrimination and calibration in the whole cohort and internal validation. Furthermore, artificial neural networks demonstrated that this nomogram score exhibits good predictive performance.

Conclusion

Our model based on the fusion gene is a prognostic biomarker for non-APL pediatric patients with AML. The nomogram score can provide personalized prognosis prediction, thereby benefiting clinical decision-making.

Ethnic differences in acute promyelocytic leukaemia between New Zealand Polynesian and European patients

Ethnic differences in haematologic malignancies remain poorly elucidated, hence research in this area is important. This was a retrospective study into potential ethnic disparity in the presentation and outcomes of acute promyelocytic leukaemia (APL) between New Zealand (NZ) Polynesian and European patients. Data were analysed for patients treated at Auckland City Hospital (ACH; n = 55) and recorded in the New Zealand Cancer Registry (NZCR; n = 173), both for the period 2000-2017. We found that Polynesian patients treated at ACH presented at a younger age than European (P = 0.005), showed higher blast counts (P = 0.033), and a marginally higher prothrombin ratio (P = 0.02). Treatment with all-trans retinoic acid (ATRA) was started faster in Polynesian patients than European (P = 0.021), suggesting Polynesians were sicker at presentation but were managed accordingly. There were no differences in bleeding events, transfusion requirements and early deaths during the first month of treatment. Long-term survival was also similar. Data extracted from the NZCR confirmed NZ Polynesian patients with APL were younger than European (P < 0.001), but long-term survival was similar (P = 0.920). In summary, this study indicates a discrepancy in the presentation and severity of APL between NZ Polynesian and European patients but treatment initiation was rapid with no difference in outcomes. The distinctive features of APL in NZ Polynesians raise the possibility of a predisposing genetic factor or a different risk factor profile, elucidation of which is important for all patients with APL.

Outcomes of pediatric acute myeloid leukemia treatment in Western Kenya

Background

Pediatric acute myeloid leukemia (AML) is a challenging disease to treat in low‐ and middle‐income countries (LMICs). Literature suggests that survival in LMICs is poorer compared with survival in high‐income countries (HICs).

Aims

This study evaluates the outcomes of Kenyan children with AML and the impact of sociodemographic and clinical characteristics on outcome.

Methods and Results

A retrospective medical records study was performed at Moi Teaching and Referral Hospital (MTRH) in Eldoret, Kenya, between January 2010 and December 2018. Sociodemographic and clinical characteristics, and treatment outcomes were evaluated. Chemotherapy included two “3 + 7” induction courses with doxorubicin and cytarabine and two “3 + 5” consolidation courses with etoposide and cytarabine. Supportive care included antimicrobial prophylaxis with cotrimoxazole and fluconazole, and blood products, if available. Seventy‐three children with AML were included. The median duration of symptoms before admission at MTRH was 1 month. The median time from admission at MTRH to diagnosis was 6 days and to the start of AML treatment 16 days. Out of the 55 children who were started on chemotherapy, 18 (33%) achieved complete remission, of whom 10 (56%) relapsed. The abandonment rate was 22% and the early death rate was 46%. The 2‐year probabilities of event‐free survival and overall survival were 4% and 7%, respectively. None of the sociodemographic and clinical characteristics were significantly associated with outcome.

Conclusion

Survival of Kenyan children with AML is dismal and considerably lower compared with survival in HICs. Strategies to improve survival should be put in place including better supportive care, optimization of the treatment protocol, and reduction of the abandonment rate and time lag to diagnosis with sooner start of treatment.

Outcome of pediatric acute myeloid leukemia (AML) in low- and middle-income countries: a systematic review of the literature

Introduction: Survival rates of pediatric acute myeloid leukemia (AML) in low- and middle-income countries (LMICs) seem extremely poor, and the available literature on the matter is scarce. Accordingly, there is a limited understanding of poor treatment outcomes seen in this population.Areas covered: We provide an overview of the available literature with respect to treatment outcomes of pediatric AML in LMICs yielding poor outcomes compared to high-income countries. Moreover, treatment outcomes vary markedly between LMICs. In addition, there is a wide variation among studies in how treatment outcomes are reported and analyzed.Expert opinion: The substantially inferior treatment outcomes of pediatric AML in LMICs emphasize the unprecedented importance of global initiatives and international collaborations to improve the survival of these patients. A coordinated approach is necessary to carry out country-specific situational analyses. These analyses will result in operational plans on how to structurally implement childhood cancer registries, align healthcare infrastructure, build on capacities, and provide universal health coverage in LMICs. In addition, we strongly recommend that, in the future, LMICs document, analyze, and publish pediatric AML treatment outcomes in a more structured and uniform manner.

Disseminated intravascular coagulation in children with cancer: A systematic review

Disseminated intravascular coagulation (DIC) may complicate malignant disease. Numerous studies have investigated this association in adults, however only sparse knowledge exists on DIC in pediatric cancer patients. The objective of this article was to systematically review the literature regarding DIC in pediatric malignancies. PubMed and Embase were searched for relevant articles on January 31, 2020. In total, 6,070 articles were identified out of which 24 articles met inclusion and exclusion criteria. These were included in the qualitative synthesis. The National Institutes of Health's Quality Assessment Tools was used to assess bias in the included articles. The studies were of only moderate quality mainly based on medical charts and demonstrated high heterogeneity, especially as regards to diagnostic criteria. DIC was reported most frequently in patients with acute leukemia, particularly the subtype acute promyelocytic leukemia (APL). Standard coagulation parameters were used as diagnostic laboratory tests supporting the diagnosis of DIC. Hemorrhage was the predominant clinical manifestation, whereas thromboembolic events and organ failure were reported less frequently. Unfractionated heparin, platelet concentrate and fresh frozen plasma were the most frequently used supportive treatment agents. Hemorrhage accounted for the majority of deaths in children with acute leukemia and solid tumors. In conclusion, only a limited number of studies, being heterogenous and of moderate quality, have investigated DIC in pediatric malignancy. Notably, this entity seems to be complicated mainly by hemorrhage. High quality studies are needed to evaluate diagnosis, clinical manifestations and optimal treatment of DIC in childhood cancers.

Long-term outcome of childhood acute myeloid leukemia: A 10-year retrospective cohort study

Acute Myeloid Leukemia (AML) in children is a serious disease. With a proper treatment, a long-term survival rate above 50% is typical. Before 2010, all the AML patients died in our hospital, and abandonment rate was more than 50%. The aims of this study are to explore the long-term outcome of newly childhood acute myeloid patients treated at Hue Central Hospital from 2010 to 2019.A retrospective study was conducted on 98 children with AML who admitted Hue Central Hospital from January 2010 to December 2019. The diagnosis was confirmed by morphological FAB criteria, cytochemistry and immunophenotype. Patients were treated with using modified AML 7-3 Regimen. Social supports were provided to patients/families. A total of 98 children with AML were analyzed with mean age of 5.6 years ranging from 3 months to 15 years. The male to female ratio was 1.8:1. The overall complete remission rate after induction were 82.6%). Patients accounted for 46 (46.9%) had relapses which occurred in during chemotherapy n=27 (27,6%), after finishing chemotherapy n=19(19,4%). Overall survival at 3 years were 23.2%. The event-free survival at 3 years were 20.2%o. Abandonment cases were 4 (4.1%). During the period study, abandonment has been reduced successfully with holistic strategies such as financial support, managing family group, providing education, early follow-up of patients who missed appointments and free accommodation near hospital for patients/families. However, with a high rate patient achieved complete remission after induction phase (82.6%), but the overal survival and event-free survival at 3 years were still low in my hospital (23.2 % and 20.2% respectively). It reflected that it was very difficult to treat successfully AML in lowand middle-income countries. We are considering the way how to improve the quality treatment for childhood acute myeloid leukemia in my hospital.

Ecological principle meets cancer treatment: treating children with acute myeloid leukemia with low-dose chemotherapy

Standard chemotherapy regimens for remission induction of pediatric acute myeloid leukemia (AML) are associated with significant morbidity and mortality. We performed a cohort study to determine the impact of reducing the intensity of remission induction chemotherapy on the outcomes of selected children with AML treated with a low-dose induction regimen plus granulocyte colony stimulating factor (G-CSF) (low-dose chemotherapy (LDC)/G-CSF). Complete response (CR) after two induction courses was attained in 87.0% (40/46) of patients receiving LDC/G-CSF. Post-remission therapy was offered to all patients, and included standard consolidation and/or stem cell transplantation. During the study period, an additional 94 consecutive children with AML treated with standard chemotherapy (SDC) for induction (80/94 (85.1%) of the patients attained CR after induction II, P = 0.953) and post-remission. In this non-randomized study, there were no significant differences in 4-year event-free (67.4 vs. 70.7%; P = 0.99) and overall (70.3 vs. 74.6%, P = 0.69) survival in the LDC/G-CSF and SDC cohorts, respectively. After the first course of induction, recovery of white blood cell (WBC) and platelet counts were significantly faster in patients receiving LDC/G-CSF than in those receiving SDC (11.5 vs. 18.5 d for WBCs (P < 0.001); 15.5 vs. 22.0 d for platelets (P < 0.001)). To examine the quality of molecular response, targeted deep sequencing was performed. Of 137 mutations detected at diagnosis in 20 children who attained hematological CR after two courses of LDC/G-CSF (n = 9) or SDC (n = 11), all of the mutations were below the reference value (variant allelic frequency <2.5%) after two courses, irrespective of the treatment group. In conclusion, children with AML receiving LDC/G-CSF appear to have similar outcomes and mutation clearance levels, but significantly lower toxicity than those receiving SDC. Thus, LDC/G-CSF should be further evaluated as an effective alternative to remission induction in pediatric AML.

Survival and risk factors for mortality in pediatric patients with acute myeloid leukemia in a single reference center in low-middle-income country

Despite advances in therapy and care for children with acute myeloid leukemia (AML), survival rates for children in low- and middle-income countries (LMICs) remain poor. We studied risk factors for mortality and survival in children with AML in a LMIC to develop strategies to improve survival for AML children in these countries. This retrospective cohort (2000-2014) analyzed newly diagnosed AML patients (age < 19 years) at a reference center in Brazil. Demographic and clinical variables were reviewed by AML subtype: acute promyelocytic leukemia (APL), AML with Down syndrome (AML-DS), and other AML subtypes. Cumulative hazard risk for early death (ED) until 6 weeks of treatment and risk factors for mortality were determined by the multivariate Cox hazard models. Survival was assessed for each AML subtypes. A total of 220 patients were diagnosed: APL 50 (22.7%), AML-DS 16 (7.3%), and other AML subtypes 154 (70.0%). The cumulative hazard function values for ED for all patients with AML were 12.5% (95% CI 8.5-18.4%); for each AML patients subtypes: APL, 21.7% (95% CI 11.7-40.5%); AML-DS, 6.2% (95% CI 0.9-44.4%); and other AML subtypes, 10.2% (95% CI 6.2-17.0%). White blood cell count (cutoff 10 × 10⁹/L for APL and 100 × 10⁹/L for other AML subtypes) and Afro-descendance were significant risk factors for mortality in APL and other AML subtypes, respectively. Overall survival for patients with APL, AML-DS, and other AML subtypes was 66.8%, 62.5%, and 38.0%, respectively. APL patients had the highest incidence of ED and those with other subtypes had increased relapse risk. We also observed high rates of death in complete remission mainly due to infection. Better risk classification and identification of risk factors for infection may improve the survival of these patients.

Factors associated with abandonment of therapy by children diagnosed with solid tumors in Peru

BACKGROUND

Abandonment of treatment is a major cause of treatment failure and poor survival in children with cancer in low- and middle-income countries. The incidence of treatment abandonment in Peru has not been reported. The aim of this study was to examine the prevalence of and factors associated with treatment abandonment by pediatric patients with solid tumors in Peru.

METHODS

We retrospectively reviewed the sociodemographic and clinical data of children referred between January 2012 and December 2014 to the two main tertiary centers for childhood cancer in Peru. The definition of treatment abandonment followed the International Society of Paediatric Oncology, Paediatric Oncology in Developing Countries, Abandonment of Treatment recommendation.

RESULTS

Data from 1135 children diagnosed with malignant solid tumors were analyzed, of which 209 (18.4%) abandoned treatment. Bivariate logistic regression analysis showed significantly higher abandonment rates in children living outside the capital city, Lima (forest; odds ratio [OR] 3.25; P < 0.001), those living in a rural setting (OR 3.44; P < 0.001), and those whose parent(s) lacked formal employment (OR 4.39; P = 0.001). According to cancer diagnosis, children with retinoblastoma were more likely to abandon treatment compared to children with other solid tumors (OR 1.79; P = 0.02). In multivariate regression analyses, rural origin (OR 2.02; P = 0.001) and lack of formal parental employment (OR 2.88; P = 0.001) were independently predictive of abandonment.

CONCLUSION

Treatment abandonment prevalence of solid tumors in Peru is high and closely related to sociodemographical factors. Treatment outcomes could be substantially improved by strategies that help prevent abandonment of therapy based on these results.

Foundation of pediatric cancer treatment in Lao People's Democratic Republic at the Lao-Korea National Children's Hospital

AIM

The Lao-Korea National Children's Hospital initiated and developed a pediatric cancer treatment program for the first time in September 2012, through education by the Lee Jong-Wook project, establishment of infrastructure by the Korea International Cooperation Agency, and cooperation of medical staff.

MATERIAL AND METHODS

we describe the experience of initiating and building this program by retrospectively reviewing the data from pediatric patients with cancer diagnosed at the Lao-Korea National Children's Hospital between September 2012 and December 2016.

RESULTS

A total of 78 patients diagnosed with acute lymphoblastic leukemia (ALL) (n = 44), acute myeloid leukemia (AML) (n = 12), chronic myeloid leukemia (n = 7), lymphoma (n = 6), retinoblastoma (n = 5), Wilms tumor (n = 3), and germ cell tumor (n = 1) were included. Of the 44 patients with ALL, 40 received induction chemotherapy, and 4 refused chemotherapy. Of these 40 patients, 29 (73.6%) achieved complete remission (CR) and 9 (22.5%) died during chemotherapy. Of the 29 patients with CR, 4 completed the chemotherapy, 19 were still on chemotherapy, 4 relapsed, and 2 were deceased. Treatment was unsuccessful for all 12 patients with AML.

CONCLUSION

We successfully initiated the pediatric cancer care program but faced challenges associated with high mortality because of insufficient resources. We should continue our efforts to find more abandoned patients, detect cancer earlier, and reduce the overall associated mortality.

Improvement of treatment outcome over 2 decades in children with acute myeloid leukemia

Background

The prognosis of pediatric acute myeloid leukemia (AML) has recently improved. This study aimed to describe the epidemiology, changes in treatment strategies, and improvement of outcomes in Gwangju-Chonnam children with AML over 2 decades.

Methods

Medical records of 116 children with newly diagnosed AML were retrospectively reviewed for demographic characteristics, prognostic groups including cytogenetic risks, treatment protocols, and survival rates over the periods between 1996 and 2005 (Period I, N=53), and 2006 and 2015 (Period II, N=38).

Results

The annual incidence of AML has decreased with reduced pediatric population. The 5-year Kaplan-Meier (K-M) estimated overall survival (OS) and event-free survival (EFS) rates in 110 AML patients were 53.2±5.1% and 43.8±5.1%, respectively. The 5-year OS rate significantly improved during period II (70.3±7.0%) as compared to that during period I (40.0±6.8%) (P =0.001). The 5-year OS was not significantly different among cytogenetic risk groups (P =0.11). Fifty-eight patients underwent hematopoietic stem cell transplantation (HSCT). The K-M 5-year estimated survival for transplanted patients was 53.7±7.0%, while that for chemotherapy-only patients was 30.1±9.1% (P =0.014). Among the prognostic factors, treatment modality was the only independent factor. The chemotherapy-only group had a relative risk of 2.06 for death compared with the transplantation group (P=0.015).

Conclusion

The survival of Korean children with AML has improved to a level comparable with that of developed countries over 2 decades, owing to a change in induction strategy, better supportive care with economic growth, refinement of HSCT techniques including a better selection of patients based on prognostic groups, and stem cell donor selection.

A 10-Year Follow-up Survey of Treatment Abandonment of Children With Acute Myeloid Leukemia in Suzhou, China

A survey of the clinical data on acute myeloid leukemia (AML) over the past 10 years in the treatment center of Children's Hospital was presented. The aim of the study was to identify the factors influencing the treatment abandonment rate (AR) of AML. Of the 474 AML cases examined, 264 were abandoned (55.7%). The most important factor affecting AR appeared to be the AML subtype-that is, the M3 versus non-M3 (42% vs. 60%). Patient age was observed to be closely related to AR-the older the patients, the lower the AR-and infants had the highest prevalence of abandonment (84.2%). The patient's residential location was markedly correlated to AR, which was almost inversely proportional to the size of the township where the patient came from. From large cities, intermediate and small towns to countryside villages, the AR increased linearly. So was the correlation with health insurance coverage, which decreased in the same way. Sex and karyotypes did not affect AR. In conclusion, the patients' financial burden and the perceived incurability of AML were the 2 leading factors dominating the decision for abandonment in parents and caregivers.

Acute Myeloid Leukemia: analysis of epidemiological profile and survival rate

OBJECTIVE

To describe the epidemiological profile and the survival rate of patients with acute myeloid leukemia (AML) in a state reference pediatric hospital.

METHOD

Clinical-epidemiological, observational, retrospective, descriptive study. The study included new cases of patients with AML, diagnosed between 2004 and 2012, younger than 15 years.

RESULTS

Of the 51 patients studied, 84% were white; 45% were females and 55%, males. Regarding age, 8% were younger than 1 year, 47% were aged between 1 and 10 years, and 45% were older than 10 years. The main signs/symptoms were fever (41.1%), asthenia/lack of appetite (35.2%), and hemorrhagic manifestations (27.4%). The most affected extra-medullary site was the central nervous system (14%). In 47% of patients, the white blood cell (WBC) count was below 10,000/mm(3) at diagnosis. The minimal residual disease (MRD) was less than 0.1%, on the 15th day of treatment in 16% of the sample. Medullary relapse occurred in 14% of cases. When comparing the bone marrow MRD with the vital status, it was observed that 71.42% of the patients with type M3 AML were alive, as were 54.05% of those with non-M3 AML. The death rate was 43% and the main proximate cause was septic shock (63.6%).

CONCLUSIONS

In this study, the majority of patients were male, white, and older than 1 year. Most patients with WBC count <10,000/mm(3) at diagnosis lived. Overall survival was higher in patients with MRD <0.1%. The prognosis was better in patients with AML-M3.

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.

Prognostic significance of flow cytometric minimal residual disease assessment after the first induction course in Chinese childhood acute myeloid leukemia

Flow cytometry based minimal residual disease (MRD) was evaluated for outcome prediction in childhood acute myeloid leukemia (AML). The median levels of MRD in relapsed and nonrelapsed patients were different after the first induction (0.64% vs. 0.18%, P=0.030). A cutoff level of ≥ 0.25% after the first course of induction was correlated with a high risk of relapse in both univariate analysis (5-year cumulative incidence of relapse: 66.8% vs. 21.2%, P=0.002) and multivariate analyses (hazard ratio: 3.70, 95% CI, 1.23-11.08, P=0.020). Our results showed that MRD level after the first induction therapy provides important information for risk assessment in childhood AML.

WT1 mutations and single nucleotide polymorphism rs16754 analysis of patients with pediatric acute myeloid leukemia in a Chinese population

Acute myeloid leukemia (AML) is relatively rare in children. Somatic mutations including the single nucleotide polymorphism (SNP) rs16754 in Wilms tumor 1 gene (WT1) and their prognostic relevance in pediatric AML have not been studied in Chinese populations. We analyzed WT1 mutations and rs16754 genotypes in a cohort of 86 patients with de novo pediatric AML in a Chinese population. We detected WT1 mutations in approximately 20% of the patients. Most of the mutations identified were deletions and insertions clustered in exons 7 and 9. No differences were observed with respect to overall survival and relapse-free survival between patients with and without WT1 mutations. The analysis of rs16754 in WT1 exon 7 revealed G as the major allele. Patients with the rs16754(GG) genotype had improved overall survival (p =0.020) and relapse-free survival (p =0.025) compared with those with either rs16754(GA) or rs16754(AA). Moreover, better overall survival (p =0.044) and relapse-free survival (p =0.068) were observed among patients with wild-type CEBPA with rs16754(GG) compared with those carrying rs16754(GA/AA).

Epidemiology, diagnosis and treatment of acute promyelocytic leukemia in children: the experience in china

Acute promyelocytic leukemia (APL) is the subtype of acute myeloid leukemia characterized by an accumulation of abnormal promyelocytes in bone marrow, a severe bleeding tendency and the presence of the chromosomal translocation t(15;17) or variants. APL, the most fatal type of leukemia two decades ago, is highly curable with current treatment strategies. There is evidence that the incidence of APL varies across ethnic groups and that genetic factors play a role in the etiology of APL. And there are some difference between children and adults in APL.1-3 The limited data of children available in many developing countries suggest that the rate of early mortality is high and that long-term survival is poor. Death from bleeding and infection during chemotherapy, relapse and treatment abandonment are among the main cause of treatment failure in APL children as well in adults.2 The status of children APL treatment in China has not been described in general.Here we describe the epidemiology and treatment of APL in children in China. In addition, we review the results of a survey of its clinical manifestations and outcome in China.

Etiology of septicemia in children with acute leukemia: 9-year experience from a children's hospital in China

Bloodstream infection is an important cause of death among leukemia patients, and the etiologic agent surveillance is important for the prophylaxis and treatment. This study aims to identify the common bloodstream isolates in hospitalized leukemia patients with septicemia in our hospital, to choose the ideal combination of antimicrobial agents for infection prophylaxis and to clarify the appropriate time for antibiotic prophylaxis. To know this information, a retrospective analysis was conducted over a 9-year period from July 2001 to July 2010 by reviewing medical records of leukemia children admitted to our hospital. The overall frequencies of isolation were 45% in Gram-positive bacteria, 53.8% in Gram-negative bacteria, and 1.2% in fungi, respectively. Coagulase-negative Staphylococci were the most common organisms isolated, accounting for 32.7% of the total blood culture isolates, followed by Escherichia coli (15.7%) and Klebsiella pneumoniae (7.1%). The incidence of septicemia caused by extended-spectrum β-lactamase-producing E. coli and K. pneumoniae was high (69.2% and 58.8% of total isolates, respectively). The coverage rate of antimicrobial combinations of "vancomycin+cefoperazone-sulbactam" and "vancomycin+piperacillin-tazobactam" to blood culture isolates of leukemia patients in our hospital were 91.88% and 90.27%, respectively. More than 90% of septicemia occurred when the absolute neutrophil count was lower than 1.6×10⁹/L and 83.05% when absolute neutrophil count was lower than 1.0×10⁹/L. These results suggest that ongoing surveillance for antimicrobial susceptibility in leukemia children remains essential. Vancomycin+cefoperazone-sulbactam and vancomycin+piperacillin-tazobactam are the good choice for leukemia children to prevent bacterial infections in our hospital. In an effort to reduce total consumption of antibiotics and to elevate the therapeutic efficacy, antibiotics prophylaxis should be started with the appearance of neutropenia in leukemia children.

3A4, a new potential target for B and myeloid lineage leukemias

Antibody-targeting therapy has drawn great interests to the hematologists and oncologists. Many antibodies have been studied for their potential targeting for hematopoietic malignancies. A few have been proved to be very effective for patients with these diseases. However, more antibodies are needed for clinical use. CD45 and its isoforms may convey clinical potential in terms of targeting therapy. Zhejiang Children's Hospital (ZCH)-6-3A4 (3A4), a novel antibody that can recognize an isoform of CD45 has been found to react with restricted cell components in hematopoietic system, which may have the potential for targeting therapy. Herein, we conducted an in vitro study of our newly prepared antibody 3A4 using various cellular and immunocytological methods. The results showed that the antibody 3A4 (murine IgG1κ) was a new clone of anti-CD45RA. It could block the binding to an epitope of CD45RA recognized by a standard anti-CD45RA antibody (Clone name L48). The reactivity of the 3A4 to both fresh leukemia cells from patients and well-defined leukemia cell lines was largely similar to those of L48, but the former recognized more leukemia cells than the latter. Cytometric analysis after papain treatment showed that the internalization rate of the 3A4 antibody to the target cells was as high as 71.3% after incubation at 37°C for 4 h, which was significantly higher than that of L48 (20.4%). The norcantharidin (NCTD)-conjugated immunotoxin (NCTD-3A4) was generated using an active ester method. The targeting inhibition rate on KG1a was as high as 61.10% after 96 h incubation in a dose-dependent manner, which was significantly higher than that (3.56%, P < 0.01) with 3A4-negative Nalm-6 cells. In conclusion, our new anti-CD45RA antibody 3A4 is probably a new target molecule of leukemia cells and holds a targeting therapeutic potential for hematopoietic malignancies, which warrants further development of this agent.