Clinical, Cytogenetic Characteristics and Survival of Acute Leukemia in a National Research Center Database, 10-Year Real-World Data Review

Introduction

Major resources of our current knowledge on acute leukemia epidemiology and prognosis are based on data from clinical trials. Due to the selective bias of clinical trials, data might differ from the general leukemia population in real-life setting. National Clinical Research Center for Blood Disease established a comprehensive database through the electronic health records (EHR) to facilitate research of the hematologic cancers i.e. acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), and acute promyelocytic leukemia (APL). The aim of the database is to gain insight into the epidemiology of these cancers, to evaluate treatment responses, to compare results between geographical regions of China. Furthermore, with the privilege of national research center, the database expects to identify prognostic and predictive factors for outcome to improve the quality of treatment and patients care.

Methods

The database development was initiated in 2001. Standard data elements were established to capture the key clinical variables. For individual patients, data from EHRs were extracted, integrated and quality checked. The implement of database facilitated the clinical professions to identify eligible patients, establish research projects, conduct retrospective analysis and follow-up patient outcomes. Continued efforts were made for improving the construction and quality of the database over two decades.

We performed a 10-year real-world data review in the database to evaluate the quality of the recorded data and, moreover to describe the clinical, cytogenetic characteristics and survival of acute leukemia patients. The completeness for collected variables was acceptable for statistical analysis. In total, 3,404 patients (1,895 males and 1,509 females) who were diagnosed and treated between Jan. 1, 2010 and Dec. 31, 2020 were enrolled. A substantial proportion (>60%) of patients were residents of the northern and northeast region of China. Demographic and baseline characteristics also included age, age class, baseline blood test, transplantation and research participation. Molecular mutations such as nucleophosmin-1 (NPM1), FMS-related tyrosine kinase 3 (FLT3), and CCAAT/enhancer-binding protein alpha (CEBPA) et al were included in the screening panels. We explored the treatment remission rate and prognosis of different chromosomal karyotype groups among AML patients.

Results

The patient numbers of the AML, ALL and APL subgroups were 2,345, 769 and 290 respectively. Blood routine results well demonstrated the clinical characteristics of each subgroup (Tbl. 1). In AML group, the frequencies of NPM1, FLT3-ITD, KIT and CEBPA double mutations were 17.9%, 13.2%, 8.7% and 10.1%, respectively (Tbl. 2). In term of ALL, 640 cases (83.2%) were B-ALL and 129 (16.8%) were T-ALL. Among B-ALL, 256 cases (33.3%) were Ph positive. 10-year analysis for overall survival shown that AML patients had better outcomes as compared with ALL group (Fig. 1). In this database, 1,780 AML cases (excluding APL) were enrolled in cytogenetic analysis. The survival rates of different cytogenetic risk groups from our real-world data were separated by the ELN2017 and MRC risk stratification respectively (Fig. 2A-B). Remarkably, we found two rare but recurrent abnormalities, 16 cases with t(7;11) (p15;p15) and 12 cases with t(16;21)(p11;q22/q24;q22). Cases showed high relapse and mortality rate. Compared with the normal karyotype group, the survival of both subentities was worse and transplantation might be recommended in CR1 phase (Fig. 2C), therefore, we recommend that these two subtypes might be regarded as the worse risk group, although neither is mentioned in the current guidelines. The incidence of t(8;21) in our database was 17.9% (Fig. 3). To explore the impact of additional chromosomal abnormalities on the prognosis of t(8;21), we found that the overall survival of patients with additional trisomy 4 was worse than those without trisomy 4 (Fig. 2D), which was rarely mentioned in previous reports.

Conclusion

The real-world database is of great importance for defining the comprehensive features of AML, APL and ALL in clinical setting. The results offered a remarkable contribution to our knowledge on acute leukemia and identified the prognosis of rare chromosomal karyotype in AML.

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