Adverse outcome of AML with aberrant CD16 and CD56 NK cell marker expression

Genetic mutations and immune microenvironment: unveiling the connection to AML prognosis

BACKGROUND

This study aims to investigate the correlation between NK and NKT cell proportion disparities and prognosis in patients with acute myeloid leukemia (AML).

METHODS

Forty-four cases of acute myeloid leukemia patients were selected, and flow cytometry was utilized to evaluate the expression of bone marrow NK and NKT cells. Next-generation sequencing technology was employed to detect genetic mutations in these 44 AML patients, and the rates of first induction remission and overall survival were recorded. Comparisons were made to analyze the respective differences in NK and NKT cell proportions among AML patients with various genetic mutations and risk stratifications.

RESULTS

The FLT-3-ITD+ group exhibited a significant increase in the proportion of NK cells compared to the normal control group and FLT3-ITD+/NPM1+ group, whereas the proportion of NKT cells was significantly decreased. Additionally, the CEBPA+ group showed an increased proportion of NKT cells compared to the TP53+ group and ASXL1+ group. The high-risk group had a higher proportion of NK cells than the intermediate-risk group, while the proportion of NKT cells was lower in the high-risk group compared to the intermediate-risk group.Patients achieving first induction remission displayed a higher proportion of NKT cells at initial diagnosis compared to those who did not achieve remission. The distribution of NK cells show significant differences among AML patients in different survival periods.

CONCLUSION

This results implies that distinct genetic mutations may play a role not only in tumor initiation but also in shaping the tumor microenvironment, consequently impacting prognosis.

DNAM-1/CD226 is functionally expressed on acute myeloid leukemia (AML) cells and is associated with favorable prognosis

DNAM-1 is reportedly expressed on cytotoxic T and NK cells and, upon interaction with its ligands CD112 and CD155, plays an important role in tumor immunosurveillance. It has also been reported to be functionally expressed by myeloid cells, but expression and function on malignant cells of the myeloid lineage have not been studied so far. Here we analyzed expression of DNAM-1 in leukemic cells of acute myeloid leukemia (AML) patients. We found substantial levels of DNAM-1 to be expressed on leukemic blasts in 48 of 62 (> 75%) patients. Interaction of DNAM-1 with its ligands CD112 and CD155 induced release of the immunomodulatory cytokines IL-6, IL-8 IL-10 and TNF-α by AML cells and DNAM-1 expression correlated with a more differentiated phenotype. Multivariate analysis did not show any association of DNAM-1 positivity with established risk factors, but expression was significantly associated with clinical disease course: patients with high DNAM-1 surface levels had significantly longer progression-free and overall survival compared to DNAM-1^low patients, independently whether patients had undergone allogenic stem cell transplantation or not. Together, our findings unravel a functional role of DNAM-1 in AML pathophysiology and identify DNAM-1 as a potential novel prognostic maker in AML.

Clinical, immunophenotypic and genomic findings of NK lymphoblastic leukemia: a study from the Bone Marrow Pathology Group

Natural killer (NK) cells are lymphocytes of the native immune system that play a pivotal role in host defense and immune surveillance. While the conceptual view of NK-neoplasms is evolving, little is known about the rare NK lymphoblastic leukemia (NK-LL), which remains as a provisional entity in the 2016 WHO Classification. The goal of this study is to characterize NK-LL cases and compare with other CD56 co-expressing acute leukemias. We identified 105 cases, diagnosed as NK-LL (6), CD56+ acute undifferentiated leukemia (AUL) (6), CD56+ T-lymphoblastic leukemia (T-LL) (51), and CD56+ acute myeloid leukemia (AML) (42). Compared to AUL patients, NK-LL patients were significantly younger (p = 0.021) and presented with higher white blood cell (WBC) (p = 0.037) and platelet counts (p = 0.041). Flow cytometry showed more frequent expression of cytoplasmic CD3 (cCD3, p = 0.064) and CD33, (p = 0.065), while HLA-DR was significantly absent from NK-LL (p = 0.035) compared to AUL. Compared to T-ALL, NK-LL cases showed less frequent cCD3 (p = 0.002), CD4 (p = 0.051), and CD10 expression (p = 0.06). The frequency of abnormal karyotypes was similar between NK-LL, AUL, and T-ALL. The mutational profile differed in four leukemia groups, with a significance enrichment of NOTCH1 (p = 0.002), ETV6 (p = 0.002) and JAK3 (p = 0.02) mutations in NK-LL as compared to AML. As compared to T-ALL, NK-LL cases showed a higher number of total mutations (p = 0.04) and significantly more frequent ETV6 mutations (p = 0.004). Clinical outcome data showed differences in overall survival between all four groups (p = 0.0175), but no difference in event free survival (p = 0.246). In this largest study to date, we find that that NK-LL shows clinical presentation, immunophenotypic and molecular characteristics distinct from AUL, T-ALL, and AML. Our findings suggest NK-LL is a distinct acute leukemia entity and should be considered in the clinical diagnosis of acute leukemias of ambiguous lineage.

miR-29c&b2 encourage extramedullary infiltration resulting in the poor prognosis of acute myeloid leukemia

Extramedullary infiltration (EMI), as a concomitant symptom of acute myeloid leukemia (AML), is associated with low complete remission and poor prognosis in AML. However, the mechanism of EMI remains indistinct. Clinical trials showed that increased miR-29s were associated with a poor overall survival in AML [14]. Nevertheless, they were proved to work as tumor suppressor genes by encouraging apoptosis and inhibiting proliferation in vitro. These contradictory results led us to the hypothesis that miR-29s may play a notable role in the prognosis of AML rather than leukemogenesis. Thus, we explored the specimens of AML patients and addressed this issue into miR-29c&b2 knockout mice. As a result, a poor overall survival and invasive blast cells were observed in high miR-29c&b2-expression patients, and the wildtype mice presented a shorter survival with heavier leukemia infiltration in extramedullary organs. Subsequently, we found that the miR-29c&b2 inside leukemia cells promoted EMI, but not the one in the microenvironment. The analysis of signal pathway revealed that miR-29c&b2 could target HMG-box transcription factor 1 (Hbp1) directly, then reduced Hbp1 bound to the promoter of non-muscle myosin IIB (Myh10) as a transcript inhibitor. Thus, increased Myh10 encouraged the migration of leukemia cells. Accordingly, AML patients with EMI were confirmed to have high miR-29c&b2 and MYH10 with low HBP1. Therefore, we identify that miR-29c&b2 contribute to the poor prognosis of AML patients by promoting EMI, and related genes analyses are prospectively feasible in assessment of AML outcome.

Blast counts are lower in the aspirate as compared to trephine biopsy in acute myeloid leukemia and myelodysplastic syndrome expressing CD56

INTRODUCTION

CD56 is aberrantly expressed in myeloid neoplasms including myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Considering the adhesion effects of CD56, blast quantification in bone marrow might depend on the technique used to obtain respective diagnostic specimens. Therefore, the objective of our study was to investigate the impact of CD56-expression on blast counts in myeloid neoplasms comparing bone marrow aspirates to biopsies.

METHODS

We retrospectively analyzed 75 patients diagnosed with MDS and AML. We compared patients with (n = 36) and without (n = 39) CD56-expression by flow cytometry with respect to their blast quantities assessed on bone marrow aspirates versus biopsies.

RESULTS

The frequency of CD56-expression on blasts correlated with higher blast counts on biopsies vs. aspirate smears (r_s  = 0.52; P = .001). This difference in blast counts was only significant in the CD56 high expressing subgroup (median 68%, 5.5%-95% in biopsy compared to median 32.5%, 1.5%-90% in aspirate; P < .01). The percentage of CD56-positive blasts among the total blast population was lower in the peripheral blood compared to bone marrow (median 31%, 6%-88% vs. 55%, 14%-98%; P = .016). The discrepancy in the blast count between the aspirate and trephine biopsy would have led to misclassification of four cases as MDS instead of AML, if diagnosis had based on the bone marrow aspirate blast count alone.

CONCLUSION

Counting blasts in bone marrow aspirates of CD56-positive AML and MDS may be linked to underestimation, potentially leading to misclassification of these myeloid neoplasms, and should therefore be adjusted considering the results obtained on trephine biopsies for reliable diagnosis.

Fc gamma receptor expression serves as prognostic and diagnostic factor in AML

Risk assessment in acute myeloid leukemia (AML) mainly relies on (cyto-)genetic and morphologic features. Nonetheless, further markers are needed to allow for accurate risk stratification. Type I Fc gamma receptors (FcγRs) such as CD16, CD32, and CD64 play an important role in mediating immunomodulatory functions in different myeloid cell types as well as NK and B cells. We here evaluated expression of the three FcγR on peripheral blood AML blasts. Using flow cytometry, we found heterogeneous expression of the FcγR throughout the patient cohort. Correlation of expression levels with disease outcome revealed significantly shorter OS in patients with CD16⁺ blasts at first diagnosis. CD32 and CD64 expression showed no association with survival but correlated with a mature phenotype and FAB M6. Our data provide clear evidence for the value of immunophenotyping FcγR expression on leukemic cells using peripheral blood, which is rapidly available and improves risk stratification in AML.

Gene coexpression network analysis revealed biomarkers correlated with blast cells and survival in acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematological malignancy with a poorly understood pathogenesis, especially among patients with no known cytogenetic abnormalities. Furthermore, there is a lack of therapeutic gene targets and diagnostic biomarkers for the effective treatment of AML. The present study aimed to identify candidate biomarkers correlated with the clinical prognosis of patients with AML. Leukemic cells from 5 patients with AML exhibiting a normal karyotype, and hematopoietic cells from 5 healthy donors were processed for RNA sequencing (RNA-seq), and the obtained RNA expression profiles were subjected to weighted gene correlation network analysis. A novel group of genes (the red module) were identified to be significantly associated with AML, and this module contained a closely connected network with 147 nodes, which corresponded to 114 mRNAs. Analysis of the correlation between these mRNAs and blast cell percentage, overall survival (OS) and disease-free survival (DFS) using cases from The Cancer Genome Atlas (TCGA) database revealed that CSF3R, ALPL and LMTK2 were negatively associated with the percentage of blast cells, while high expression of these genes was associated with longer OS and DFS in patients with AML. The differential expression of these three genes between patients with AML and healthy control subjects was supported using the Genotype-Tissue Expression and TCGA databases and was further confirmed using reverse transcription-quantitative (RT-qPCR). These genes exhibited significantly lower expression in patients with AML compared with control subjects. The results indicated that CSF3R, ALPL and LMTK2 exhibit the potential to be prognostic biomarkers. However, the biological functions of these three candidate genes need to be assessed in further studies.

CD56 Homodimerization and Participation in Anti-Tumor Immune Effector Cell Functioning: A Role for Interleukin-15

A particularly interesting marker to identify anti-tumor immune cells is the neural cell adhesion molecule (NCAM), also known as cluster of differentiation (CD)56. Namely, hematopoietic expression of CD56 seems to be confined to powerful effector immune cells. Here, we sought to elucidate its role on various killer immune cells. First, we identified the high motility NCAM-120 molecule to be the main isoform expressed by immune cells. Next, through neutralization of surface CD56, we were able to (1) demonstrate the direct involvement of CD56 in tumor cell lysis exerted by CD56-expressing killer cells, such as natural killer cells, gamma delta (γδ) T cells, and interleukin (IL)-15-cultured dendritic cells (DCs), and (2) reveal a putative crosstalk mechanism between IL-15 DCs and CD8 T cells, suggesting CD56 as a co-stimulatory molecule in their cell-to-cell contact. Moreover, by means of a proximity ligation assay, we visualized the CD56 homophilic interaction among cancer cells and between immune cells and cancer cells. Finally, by blocking the mitogen-activated protein kinase (MAPK) pathway and the phosphoinositide 3-kinase (PI3K)-Akt pathway, we showed that IL-15 stimulation directly led to CD56 upregulation. In conclusion, these results underscore the previously neglected importance of CD56 expression on immune cells, benefiting current and future immune therapeutic options.

Rebound Thrombocytosis after Induction Chemotherapy is a Strong Biomarker for Favorable Outcome in AML Patients

Whereas the molecular events underlying acute myeloid leukemia (AML) are increasingly identified, dynamics of hematologic recovery following induction chemotherapy remain mysterious. Platelet recovery may vary between incomplete and excess recovery among patients achieving remission. We analyzed platelet recovery after the first induction cycle in 291 consecutive AML patients. We defined excess platelet rebound (EPR) as platelet increase above 500 G/L. We observed EPR in 120 (41.2%) patients. EPR+ patients had lower platelets at diagnosis, higher marrow infiltration, more frequently NPM1 mutations, and were associated with ELN favorable risk. Absence of EPR correlated with complex karyotypes, ELN intermediate-I and adverse risk, and therapy-related AML. Overall survival was better in EPR+ patients than EPR- (median 125 vs 41 months; p = 0.04), as was disease-free survival. By multivariate analysis, EPR+ was an independent parameter associated with favorable survival. Plasma thrombopoietin (TPO) levels at diagnosis indicated EPR+ (p < 0.0001), while GATA-1, GATA-2, and MPL mRNA expression did not differ between EPR+ and EPR- patients. Finally, transcription factors blocking early megakaryopoiesis were upregulated in EPR- patients, while NFE2 involved in late megakaryocyte differentiation was increased in EPR+ patients. Our work identifies mechanisms involved in platelet recovery after induction chemotherapy.