Contributions
Abstract: S864
Type: Oral Presentation
Presentation during EHA23: On Saturday, June 16, 2018 from 16:30 - 16:45
Location: Room A4
Background
The most frequent chromosomal rearrangement in childhood B acute lymphoblastic leukemia (B-ALL) is the reciprocal translocation t(12;21)(p13;q22) (ETV6-RUNX1). Although the presence of ETV6-RUNX1 appears to be a strong independent predictor factor of a favorable prognosis, relapses still occur in the 10% of patients, usually near the end of treatment and occasionally many years later. A distinctive marker able to distinguish, already at diagnosis, ETV6-RUNX1 patients at risk of relapse is still missing.
Aims
To identify new potential biomarker and/or therapeutic targets that could predict and/or prevent already at the moment of diagnosis ETV6-RUNX1 patients’ relapse.
Methods
By Reverse Phase Protein Arrays (RPPA) we performed the phosphoproteomic profiling of pediatric ETV6-RUNX1 B-ALL patients. We evaluated by MTT assay the effects of treatment with selected inhibitors in cell lines and primary samples. We assessed by phosphoflow the phosphorylation of SYK.
Results
We performed a phosphoproteomic profiling at diagnosis of 62 pediatric ETV6-RUNX1 B-ALL patients. We analysed the activation status of several signaling pathways and we identified SYK as hyperactivated (SYK Y525) in patients who will experience relapse (n=11) compared to non-relapsed ones (n=51, p=0.02). Total SYK and SYK RNA were not differentially expressed in the two subgroups. We also evaluated the activation of SYK at relapse occurrence and we observed an increase of SYK Y525 compared to diagnosis (n=8, p=0.009). SYK is a non-receptor tyrosine kinase which mediates signal transduction downstream of a variety of transmembrane receptors including classical immunoreceptors such as the B-cell receptor. Thus, we first functionally validated SYK as a new therapeutic target by treatment of cell lines and primary cells from pediatric ETV6-RUNX1 patients with SYK inhibitors. We treated t(12;21) REH, AT-1 and AT-2 cell lines, that display SYK hyperphosphorylation, with Entospletinib, Fostamatinib and PRT-060318. After 48hours of treatment, all the compounds were able to decrease both cell proliferation and SYK Y525 phosphorylation. We also tested inhibitors in combination with conventional chemotherapeutic compounds (Vincristine, Dexamethasone and Cytarabine-Ara-C), and Entospletinib resulted the one with the best synergistic effect. This result was also confirmed combining all the three chemotherapeutic compounds (VDA) together with Entospletinib. We also validated SYK as a therapeutic target by treating primary cells from t(12;21) patients at diagnosis with Entospletinib and VDA alone or in combination. At diagnosis we observed an augmented response to Entospletinib in samples from patients who will experience relapse (n=3) compared to non relapsed ones (n=7, p=0.03), and more importantly an increased cell death with Entospletinib+VDA compared to VDA alone (p= 0.1) in patients who will relapse. Finally, we are now setting up the analysis of activated SYK by phosphoflow to validate it as a prognostic marker. We will screen an independent cohort of t(12;21) patients, and preliminary results seem to confirm what previously observed by RPPA.
Conclusion
SYK is hyperactivated in t(12;21) B-ALL patients who will experience relapse and also at relapse occurrence. Its inhibition using Entospletinib, a phase 2 inhibitor for Chronic Lymphocytic Leukemia treatment, is able to potentiate the effects of conventional chemotherapeutics. Thus, SYK could be considered as a new potential marker of relapse occurrence and as a new therapeutic target for t(12;21) pediatric patients.
Session topic: 1. Acute lymphoblastic leukemia – Biology & Translational Research
Keyword(s): B cell acute lymphoblastic leukemia, Relapse, TEL-AML1
Abstract: S864
Type: Oral Presentation
Presentation during EHA23: On Saturday, June 16, 2018 from 16:30 - 16:45
Location: Room A4
Background
The most frequent chromosomal rearrangement in childhood B acute lymphoblastic leukemia (B-ALL) is the reciprocal translocation t(12;21)(p13;q22) (ETV6-RUNX1). Although the presence of ETV6-RUNX1 appears to be a strong independent predictor factor of a favorable prognosis, relapses still occur in the 10% of patients, usually near the end of treatment and occasionally many years later. A distinctive marker able to distinguish, already at diagnosis, ETV6-RUNX1 patients at risk of relapse is still missing.
Aims
To identify new potential biomarker and/or therapeutic targets that could predict and/or prevent already at the moment of diagnosis ETV6-RUNX1 patients’ relapse.
Methods
By Reverse Phase Protein Arrays (RPPA) we performed the phosphoproteomic profiling of pediatric ETV6-RUNX1 B-ALL patients. We evaluated by MTT assay the effects of treatment with selected inhibitors in cell lines and primary samples. We assessed by phosphoflow the phosphorylation of SYK.
Results
We performed a phosphoproteomic profiling at diagnosis of 62 pediatric ETV6-RUNX1 B-ALL patients. We analysed the activation status of several signaling pathways and we identified SYK as hyperactivated (SYK Y525) in patients who will experience relapse (n=11) compared to non-relapsed ones (n=51, p=0.02). Total SYK and SYK RNA were not differentially expressed in the two subgroups. We also evaluated the activation of SYK at relapse occurrence and we observed an increase of SYK Y525 compared to diagnosis (n=8, p=0.009). SYK is a non-receptor tyrosine kinase which mediates signal transduction downstream of a variety of transmembrane receptors including classical immunoreceptors such as the B-cell receptor. Thus, we first functionally validated SYK as a new therapeutic target by treatment of cell lines and primary cells from pediatric ETV6-RUNX1 patients with SYK inhibitors. We treated t(12;21) REH, AT-1 and AT-2 cell lines, that display SYK hyperphosphorylation, with Entospletinib, Fostamatinib and PRT-060318. After 48hours of treatment, all the compounds were able to decrease both cell proliferation and SYK Y525 phosphorylation. We also tested inhibitors in combination with conventional chemotherapeutic compounds (Vincristine, Dexamethasone and Cytarabine-Ara-C), and Entospletinib resulted the one with the best synergistic effect. This result was also confirmed combining all the three chemotherapeutic compounds (VDA) together with Entospletinib. We also validated SYK as a therapeutic target by treating primary cells from t(12;21) patients at diagnosis with Entospletinib and VDA alone or in combination. At diagnosis we observed an augmented response to Entospletinib in samples from patients who will experience relapse (n=3) compared to non relapsed ones (n=7, p=0.03), and more importantly an increased cell death with Entospletinib+VDA compared to VDA alone (p= 0.1) in patients who will relapse. Finally, we are now setting up the analysis of activated SYK by phosphoflow to validate it as a prognostic marker. We will screen an independent cohort of t(12;21) patients, and preliminary results seem to confirm what previously observed by RPPA.
Conclusion
SYK is hyperactivated in t(12;21) B-ALL patients who will experience relapse and also at relapse occurrence. Its inhibition using Entospletinib, a phase 2 inhibitor for Chronic Lymphocytic Leukemia treatment, is able to potentiate the effects of conventional chemotherapeutics. Thus, SYK could be considered as a new potential marker of relapse occurrence and as a new therapeutic target for t(12;21) pediatric patients.
Session topic: 1. Acute lymphoblastic leukemia – Biology & Translational Research
Keyword(s): B cell acute lymphoblastic leukemia, Relapse, TEL-AML1