Tyrosine kinases in KMT2A/MLL-rearranged acute leukemias as potential therapeutic targets to overcome cancer drug resistance

Aim:The main goal of this study was to elucidate at the transcript level the tyrosine kinase expression profiles of primary leukemia cells from mixed lineage leukemia 1 gene rearranged(KMT2A/MLL-R+)acute myeloid leukemia(AML)and acute lymphoblastic leukemia(ALL)patients.Methods:We evaluated protein tyrosine kinase(PTK)gene expression profiles of primary leukemic cells in KMT2A/MLL-R+AML and ALL patients using publicly available archived datasets.Results:Our studies provided unprecedented evidence that the genetic signatures of KMT2A/MLL-R+AML and ALL cells are characterized by transcript-level overexpression of specific PTK.In infants,children and adults with KMT2A/MLL-R+ALL,as well as pediatric patients with KMT2A/MLL-R+AML,the gene expression levels for FLT3,BTK,SYK,JAK2/JAK3,as well as several SRC family PTK were differentially amplified.In adults with KMT2A/MLLR+AML,the gene expression levels for SYK,JAK family kinase TYK2,and the SRC family kinases FGR and HCK were differentially amplified.Conclusion:These results provide new insights regarding the clinical potential of small molecule inhibitors of these PTK,many of which are already FDA/EMA-approved for other indications,as components of innovative multimodality treatment platforms against KMT2A/MLL-R+acute leukemias.

Identification and targeting of CD22ΔE12 as a molecular RNAi target to overcome drug resistance in high-risk B-lineage leukemias and lymphomas

Aim:CD22ΔE12 as an oncogenic driver lesion in aggressive and drug-resistant B-precursor acute lymphoblastic leukemia(BPL)cells.The purpose of the present study was to identify the CD22ΔE12-specific signature transcriptome in human BPL cells and evaluate the clinical potential of a nanoscale formulation of CD22ΔE12-siRNA as an RNAi therapeutic against drug-resistant BPL.CD22ΔE12-siRNA nanoparticles significantly improved the event-free survival(EFS)outcome of NOD/SCID(NS)mice challenged with human BPL xenograft cells.Methods:Gene expression and translational bioinformatics methods were applied to examine the expression of the CD22ΔE12-specific signature transcriptome in human BPL cells in subsets of BPL patients.Survival analysis for mice challenged with BPL cells and treated with CD22ΔE12 siRNA was performed using standard methods.Results:Leukemia cells from CD22ΔE12-Tg mice exhibit gene and protein expression profiles consistent with constitutive activation of multiple signaling networks,mimicking the profiles of relapsed BPL patients as well as newly diagnosed high-risk patients with BCR-ABL+/Philadelphia chromosome(Ph)+BPL as well as Ph-like BPL.A nanoscale formulation of CD22ΔE12-siRNA abrogated the in vivo clonogenicity of the leukemia-initiating leukemic cell fraction in xenograft specimens derived from patients with relapsed BPL and significantly improved the EFS outcome of NS mice challenged with drug-resistant human BPL xenograft cells.Conclusion:The CD22-RNAi technology is applicable to all BPL patients both high risk and standard risk.That is because CD22ΔE12 is a characteristic feature of drug-resistant leukemic clones that escape chemotherapy and cause relapse in both high risk and low risk subgroups of patients.The technology therefore has the potential(1)for prevention of relapses by selectively killing the clones that are most likely to escape chemotherapy and cause relapse as well(2)for treatment of relapses in BPL.This research project may also lead to innovative salvage regimens against other forms of CD22ΔE12-positive relapsed B-lineage leukemias and lymphomas.

Cancer drug resistance in multiple myeloma

INTRODUCTION Multiple myeloma(MM)is the second most common hematologic malignancy after non-Hodgkin’s lymphoma.Intrinsic and acquired drug resistance of cancer cells to standard drugs is a major obstacle for a more successful survival outcome of MM patients treated on contemporary clinical protocols.The primary purpose of this special issue on“Drug Targets and Resistance Mechanisms in Multiple Myeloma”was to collect new and transformative information regarding new insights about the mechanisms of drug resistance in MM and the role of the tumor microenvironment in treatment failures.

Wilms’tumor gene(WT1)is strongly expressed in high-risk subsets of pediatric acute lymphoblastic leukemia

Aim:The purpose of the present study was to perform a comprehensive analysis of WT1 gene expression in high-risk pediatric acute lymphoblastic leukemia(ALL).Methods:We performed a meta-analysis of WT1 gene expression for normal hematopoietic cells vs.primary leukemia cells from 801 pediatric ALL samples deposited in the Oncomine database combined with an in-depth gene expression analysis using our in-house database of gene expression profiles of primary leukemia cells from 1416 pediatric ALL cases.We also examined the expression of WT1 in primary leukemic cells from 299 T-lineage ALL patients in the Oncomine database and 189 T-lineage ALL patients in the archived datasets GSE13159,GSE13351,and GSE13159.Results:Our data provide unprecedented evidence that primary leukemia cells from patients with MLL gene rearrangements(MLL-R)express highest levels of WT1 expression within the high-risk subsets of pediatric B-lineage ALL.Notably,MLL-R^(+)patients exhibited>6-fold higher expression levels of the WT1 gene compared to the other B-lineage ALL subtypes combined(P<0.0001).Our findings in 97 MLL-R^(+)infant B-lineage ALL cases uniquely demonstrated that WT1 is expressed at 1.5-4.2-fold higher levels in MLL-R^(+)infant leukemia cells than in normal hematopoietic cells and revealed that WT1 expression level was substantially higher in steroid-resistant infant leukemia cells when compared to non-leukemic healthy bone marrow cells.Furthermore,our study demonstrates for the first time that the WT1-regulated EWSR1,TP53,U2AF2,and WTAP genes(i.e.,WT1 interactome)were differentially upregulated in MLL-R^(+)leukemia cells illustrating that the MLL-regulatory pathway is aberrantly upregulated in MLL-R^(+)pediatric B-lineage ALL.These novel insights provide a compelling rationale for targeting WT1 in second line treatment of MLL-R^(+)pediatric B-lineage ALL,including MLL-R^(+)infant ALL.Furthermore,our study is the first to demonstrate that leukemia cells from 370 Ph-like patients had significantly higher WT1 expression when compared to normal hematopoietic cells.Finally,our findings demonstrate for the first time that chemotherapy-resistant primarily leukemic cells from relapsed B-lineage ALL patients exhibit higher expression levels of WT1 than primary leukemia cells from newly diagnosed B-lineage ALL patients(P=0.001).Conclusion:Our findings indicate that the WT1 gene product may serve as a target for immunotherapy in high risk/poor prognosis subsets of newly diagnosed as well as relapsed pediatric B-lineage ALL.Our findings also significantly expand the current knowledge of WT1 expression in T-lineage ALL and provide new evidence that WT1 gene and its interactome are expressed in T-lineage ALL cells at significantly higher levels than in normal hematopoietic cells.This previously unknown differential expression profile uniquely indicates that the protein product of WT1 would be an attractive molecular target for treatment of T-lineage ALL as well.