Contributions
Abstract: EP395
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Leukemia relapse is the main cause of treatment failure in leukemia.Natural killer (NK) cell is effective lymphocytes and play irreplaceable role in anti-leukemia procession. However,whether the status of NK cells affects recurrence is rarely discussed.
Aims
To evaluate the prognostic impact of NK-cells exhaustion in relapsed patients, and explore its impact due to NKG2A over expression
Methods
We perform analyses on 72 bone marrow samples, enrolled from 12 health donors (HC) and 30 AML patients who had experienced first hematological relapse after HSCT (Relapse) as well as 30 matched AML patients in remission (CR), to detect NK-cells phenotype,cytotoxicity, proliferation as well as RNA-sequences in the above group. The cytotoxicity and cytokine secretion of NK cells was determined using CD107a expression and IFN-γ production against K562 or THP-1 cell line as targets. In each of the above groups, NK cells were sorted for killing AML blasts to detect NK lysis function.
NK cells or blocking the NKG2A receptor NK cells were xenografted into NPG mice with or without leukemia to detect NK cells survival in vivo. NK cells sorted from spleen were used for cytotoxicity assessment of anti-leukemia in vitro. And tumor burden in NPG mice was monitored by using in vivo imaging system.
Results
The results declared that exhausted NK-cells expansion showed with naïve phenotype which CD56bright(P=0.0002)and NKG2A receptor(P=0.00346)overexpression in AML relapsed patients. Although there existed NK-cells expansion in AML relapsed patients with the frequency of KI67+NK cells significantly higher(P=0.002),the cell cycle of NK cells was stagnated in G1 stage in AML relapse patients(P<0.0001) compared to those patients in CR group. After 48 hours of co-incubation, NK-cells sorted from relapsed patients resulted in significantly less leukemia blasts apoptosis(P=0.0245) in vitro. Further-more, NK cells display compromised cytotoxicity of CD107a degranulation (P=0.0008) and IFN-γproduction（P=0.0167）in the presence of K562 target cells ex vivo. The RNA-seq data show NK-cells exhaustion is followed up down-regulation of the transcription factors T-bet(P=0.0122)and up-regulation of the cyclin D2(P=0.0035).
Among the 30 AML relapsed patients, only 21 patients received chemotherapy and/or DLI treatment, of which 13 patients were treated effectively and the rest were ineffective.Surprisingly, in these patients with curative effects after treatment, the proportion of NKG2A+NK cells sharp dipped(P=0.0075), and the IFN-γproduction(P=0.0263）also improved, comparing with their data on relapsed time one by one. Whatever, in patients who have failed treatment, the expression of NKG2A is further up-regulated(P=0.0075), and the function of NK cells remains unchanged, corresponding to their data on first relapsed time one by one.
In immunodeficiency mice model with adoptive NK cells infusion, we found that NK-cells exhausted with elevated NKG2A expression(P<0.005)and limited anti-leukemia function(P<0.05)and shorter persistent time in leukemia-infiltration mice compared with those mice without leukemia(P<0.05).Meanwhile, in immunodeficient mice with leukemia-burden, infusion of NK cells blocking NKG2A receptor can significantly reduce tumor burden(P<0.001)and improve the long-term survival rate of mice compared to those xenografted with untreated NK cells(P<0.001).
Conclusion
NK-cells exhaustion is associated with relapse in AML patients. NKG2A receptor blocking could rescue NK cells exhaustion and may be considered as a penitential effective therapy to improve the therapy efficacy for relapsed AML patients.
Keyword(s): Antibody targeting, NK cell, NK receptor, Relapsed acute myeloid leukemia
Abstract: EP395
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Leukemia relapse is the main cause of treatment failure in leukemia.Natural killer (NK) cell is effective lymphocytes and play irreplaceable role in anti-leukemia procession. However,whether the status of NK cells affects recurrence is rarely discussed.
Aims
To evaluate the prognostic impact of NK-cells exhaustion in relapsed patients, and explore its impact due to NKG2A over expression
Methods
We perform analyses on 72 bone marrow samples, enrolled from 12 health donors (HC) and 30 AML patients who had experienced first hematological relapse after HSCT (Relapse) as well as 30 matched AML patients in remission (CR), to detect NK-cells phenotype,cytotoxicity, proliferation as well as RNA-sequences in the above group. The cytotoxicity and cytokine secretion of NK cells was determined using CD107a expression and IFN-γ production against K562 or THP-1 cell line as targets. In each of the above groups, NK cells were sorted for killing AML blasts to detect NK lysis function.
NK cells or blocking the NKG2A receptor NK cells were xenografted into NPG mice with or without leukemia to detect NK cells survival in vivo. NK cells sorted from spleen were used for cytotoxicity assessment of anti-leukemia in vitro. And tumor burden in NPG mice was monitored by using in vivo imaging system.
Results
The results declared that exhausted NK-cells expansion showed with naïve phenotype which CD56bright(P=0.0002)and NKG2A receptor(P=0.00346)overexpression in AML relapsed patients. Although there existed NK-cells expansion in AML relapsed patients with the frequency of KI67+NK cells significantly higher(P=0.002),the cell cycle of NK cells was stagnated in G1 stage in AML relapse patients(P<0.0001) compared to those patients in CR group. After 48 hours of co-incubation, NK-cells sorted from relapsed patients resulted in significantly less leukemia blasts apoptosis(P=0.0245) in vitro. Further-more, NK cells display compromised cytotoxicity of CD107a degranulation (P=0.0008) and IFN-γproduction（P=0.0167）in the presence of K562 target cells ex vivo. The RNA-seq data show NK-cells exhaustion is followed up down-regulation of the transcription factors T-bet(P=0.0122)and up-regulation of the cyclin D2(P=0.0035).
Among the 30 AML relapsed patients, only 21 patients received chemotherapy and/or DLI treatment, of which 13 patients were treated effectively and the rest were ineffective.Surprisingly, in these patients with curative effects after treatment, the proportion of NKG2A+NK cells sharp dipped(P=0.0075), and the IFN-γproduction(P=0.0263）also improved, comparing with their data on relapsed time one by one. Whatever, in patients who have failed treatment, the expression of NKG2A is further up-regulated(P=0.0075), and the function of NK cells remains unchanged, corresponding to their data on first relapsed time one by one.
In immunodeficiency mice model with adoptive NK cells infusion, we found that NK-cells exhausted with elevated NKG2A expression(P<0.005)and limited anti-leukemia function(P<0.05)and shorter persistent time in leukemia-infiltration mice compared with those mice without leukemia(P<0.05).Meanwhile, in immunodeficient mice with leukemia-burden, infusion of NK cells blocking NKG2A receptor can significantly reduce tumor burden(P<0.001)and improve the long-term survival rate of mice compared to those xenografted with untreated NK cells(P<0.001).
Conclusion
NK-cells exhaustion is associated with relapse in AML patients. NKG2A receptor blocking could rescue NK cells exhaustion and may be considered as a penitential effective therapy to improve the therapy efficacy for relapsed AML patients.
Keyword(s): Antibody targeting, NK cell, NK receptor, Relapsed acute myeloid leukemia