An analysis of 97 previously diagnosed de novo adult acute erythroid leukemia patients following the 2016 revision to World Health Organization classification

All patients were diagnosed de novo acute erythroid/myeloid leukemia, while pure erythroid leukemia, AML with MDS-related changes and recurrent genetic abnormalities were precluded. All study regimens were in accordance with the Declaration of Helsinki and approved by the institutional review boards of the hospital. All patients were investigated by morphology, bone marrow aspiration and cytogenetic analysis. They all provided written informed consent for sample analyses. All the patients received DA (daunorubicin 40-45 mg/m² on day1–3 and cytarabine 100-150 mg/m² on day 1–7) or HAA (Homoharringtonine 2 mg/m² on day 1–7,cytarabine 100-150 mg/m² on day 1–7 and aclarubincin 20 mg/d on day 1–7) or HAD (Homoharringtonine 2 mg/m² on day 1–7,cytarabine 100-150 mg/m² on day 1–7 and daunorubicin 40 mg/m² on day 1–3) as induction regimens. Once CR had been achieved, all the patients were suggested to receive allogeneic hematopoietic stem cell transplantation. If the patients cannot afford transplantation or cannot find suitable donor, they would receive HD-Ara-C (cytarabine 3 g/m² per 12 h on day1–3) or MA (mitoxantrone 8 mg/m² on day 1–3 and cytarabine 1.5 g/m² per 12 h on day1–3) or DA (daunorubicin 40 mg/m² on day 1–3 and cytarabine 1.5 g/m² per 12 h on day1–3) as consolidation regimens. Clinical follow-up information, including overall survival (OS) and disease free survival (DFS) were retrieved from the electronic medical record and telephone communication. The median follow up was 21.9 month, the last follow-up time was 31/8/2016.

At least twenty metaphases were analyzed in chromosomal analysis. The results were recorded adopting the International system for Human Cytogenetic Nomenclature.

Gene mutation analysis was performed for FLT3-ITD (n = 69), NPM1 (n = 47), CEBPA-BZIP (n = 47), CEBPA-TAD (n = 47), C-kit exon8 (n = 47), C-kit exon17 (n = 47), DNMT3A (n = 33), IDH1 (n = 16), IDH2 (n = 16).

The Fisher exact test and χ²test were applied to variables. OS was defined as the time from diagnosis to death or last follow-up time. DFS was defined as the time from complete remission (CR) to relapse or death or last follow-up time. OS and DFS were estimated by Kaplan-Meier method. Survival curves were compared by the log-rank test. Multivariate analysis was performed by Cox proportional regression model. All tests were two-sided, accepting p value of 0.05 or below as indicating a statistically significant difference. Statistical analyses were performed by SPSS software version 18.0.

Total 97 patients were previously diagnosed as de novo AEL following WHO2008 criteria from 2004 to 2016. According to the new criteria, of them 65 patients were modified as MDS, 32 patients were diagnosed as AML, NOS. Therefore, majority of previous AEL were diagnosed as MDS according to the new classification criterion. The clinical features of total cases were summarized in Table 1. As shown, incidence was higher in male in totally, particular MDS cases. The median age of total cases was 37 years old. And the age of MDS cases was older than that of AML cases (39 vs 33, p = 0.044). However, the median hemoglobin, white blood cell count, platelet count was nearly the same in both cases.

Further, the chromosome karyotype were investigated. The results were available for 90 patients, including 59 MDS cases and 31 AML cases. Totally, the proportion of aberrant karyotype accounted for 20%, there were no difference in the proportion of normal karyotype, complex karyotype and monosomy karyotype between two subtypes. The proportions of each cytogenetic risk category using the IPSS and UKMRC schemes were also similar in both cases. Following MRC category, the majority of patients belonged to intermediate risk (87.8%), only 12.2% patients belonged to unfavorable risk.

Finally, some specific molecular mutations were further investigated. Only 69 cases were assessed for FLT3-ITD mutation, 47 cases were assessed for NPM1 mutation, CEBPA mutation (B-ZIP domain and TAD domain), C-kit mutation, 33 cases were assessed for DNMT3A mutation. The incidence of the above mutations was 19.1% (NPM1), 4.3% (FLT3-ITD), 6.4% (CEBPA single), 6.4% (CEBPA double) and 9.1% (DNMT3A)separately. However, there were no difference in the incidence of these mutations in both cases. In addition, C-kit mutations were not found in these patients.

Survival of the total AEL patients was firstly investigated by MDS vs AML subtype, as presented in Fig. 1 and Table 2, the 3-year OS was 56% (MDS subtype) and 64.4% (AML subtype) respectively. The median OS of MDS subtype was 44.6 months. And median OS of AML subtype had not been reached. The 3-year DFS was 75.1% (MDS subtype) and 60.7% (AML subtype) respectively. There were no difference between these two subtype in OS and DFS (p > 0.05).

Further, the survival was explored according to cytogenetic category in all 97 patients. The MRC criteria and IPSS category were both investigated, as Table 2 showed, MRC category might be more suitable for distinguishing clinical outcome than IPSS category. As shown in the Fig. 2a, unfavorable karyotype was associated with an observable inferior 3-year OS compared to intermediate karyotype (12% vs 62.5%, p = 0.000), the results occurred both in MDS subtype and AML subtype (Fig. 2b and c). However, the survival of same category in MDS subtype or AML subtype did not show any difference (Fig. 3). The 3-year OS of intermediate category in MDS and AML subtype was similar (59.7% vs 69.1%, p = 0.706), so were the median OS of unfavorable category (MDS 5.03 month vs AML 1.5 month, p > 0.05).

When we analyzed various clinical characteristics, including MDS vs AML subtype, cytogenetic and molecular mutations with regards to their ability to predict overall survival of all 97 patients (Table 3), only cytogenetic risk and age were related. As shown in Additional file 1: Fig. S1, with the age increased, the survival decreased significantly. The 3-year OS of age < 40, 40–60, >60 was 65%, 52.3% and 33.3% respectively (p = 0.013). As shown in Additional file 2: Table S1, with the age increased, the proportion of unfavorable cytogenetic category increased sharply, the ratio was only 7.8% in age < 40 group, but when age was older than 60, the ratio was 25%. However, MDS vs AML subtype, gender, WBC, NPM1 mutation, FLT3-ITD mutation have little impact on the survival. Further, adopting multivariate analysis, the cytogenetic classification (p = 0.000, RR = 5.614) became the only independent parameter that implied outcome as shown in Table 3, the results confirmed that cytogenetic, rather than arbitrary myeloblast percentage of total marrow cells, can better represent the outcome of patients.

The influence of the treatment modalities was also investigated. Of total 97 patients, 70 patients received chemotherapy or best supportive treatment as their treatment choice. 27 patients received transplantation eventually after chemotherapy, of them 25 patients attained complete remission (CR) before transplantation. The distribution of treatment choice in clinical characteristics such as cytogenetic category, age group and MDS vs AML subtype were listed in Table 4. In the intermediate cytogenetic risk, 31.6% of patients received transplantation. The proportion of transplantation patients in the age < 40 and 40–60 group was 40.7% and 14.7%. The proportion of transplantation cases in AML or MDS subtype patients was similar, 25% (AML) vs 29.2% (MDS).

The survival of transplantation cases and chemotherapy/supportive treatment cases were shown in Fig. 4. Totally, the 3-year OS of the two groups were 67.1% and 54.6%, there was no significant difference (p = 0.114) (Fig. 4a). The survival of transplantation was further explored in MDS and AML subtype. In MDS subtype, the 3-year OS of two groups was 68.9% and 49.7% respectively (p = 0.068) (Fig. 4b). However, in AML subtype, the difference of 3-year OS was similar (62.5% vs 62.6%, p > 0.05) (Fig. 4c). Further analysis showed that when the cytogenetic risk of patients belonged to MRC intermediate risk and age were below 40 years-old, the patients who received chemotherapy without transplantation had a similar survival compared with the patients who underwent transplantation (3-year OS: 67.2% vs 68.5%) as Fig. 4d shown.