Combined Casein Kinase II inhibition and epigenetic modulation in acute B-lymphoblastic leukemia

Background: The tumor suppressor protein phosphatase and tensin homolog (PTEN) is a key regulator of the PI3K/AKT pathway which is frequently altered in a variety of tumors including a subset of acute B-lymphoblastic leukemias (B-ALL). While PTEN mutations and deletions are rare in B-ALL, promoter hypermethylation and posttranslational modifications are the main pathways of PTEN inactivation. Casein Kinase II (CK2) is often upregulated in B-ALL and phosphorylates both PTEN and DNA methyltransferase 3A, resulting in increased PI3K/AKT signaling and offering a potential mechanism for further regulation of tumor-related pathways. Methods: Here, we evaluated the effects of CK2 inhibitor CX-4945 alone and in combination with hypomethylating agent decitabine on B-ALL proliferation and PI3K/AKT pathway activation. We further investigated if CX-4945 intensified decitabine-induced hypomethylation and identified aberrantly methylated biological processes after CK2 inhibition. In vivo tumor cell proliferation in cell line and patient derived xenografts was assessed by longitudinal full body bioluminescence imaging and peripheral blood flow cytometry of NSG mice. Results: CX-4945 incubation resulted in CK2 inhibition and PI3K pathway downregulation thereby inducing apoptosis and anti-proliferative effects. CX-4945 further affected methylation patterns of tumor-related transcription factors and regulators of cellular metabolism. No overlap with decitabine-affected genes or processes was detected. Decitabine alone revealed only modest anti-proliferative effects on B-ALL cell lines, however, if combined with CX-4945 a synergistic inhibition was observed. In vivo assessment of CX-4945 in B-ALL cell line xenografts resulted in delayed proliferation of B-ALL cells. Combination with DEC further decelerated B-ALL expansion significantly and decreased infiltration in bone marrow and spleen. Effects in patient-derived xenografts all harboring a t(4;11) translocation were heterogeneous. Conclusions: We herein demonstrate the anti-leukemic potential of CX-4945 in synergy with decitabine in vitro as well as in vivo identifying CK2 as a potentially targetable kinase in B-ALL

In vivo vaccination with cell line-derived whole tumor lysates: neoantigen quality, not quantity matters

Background!#!Cancer vaccines provide a complex source of neoantigens. Still, increasing evidence reveals that the neoantigen quality rather than the quantity is predictive for treatment outcome.!##!Methods!#!Using the preclinical Mlh1!##!Results!#!Both tumor cell lysates delayed tumor formation in the prophylactic setting, with the A7450 T1 M1 lysate being more effective in decelerating tumor growth than the 328 lysate (median overall survival: 37 vs. 25 weeks). Comparable results were achieved in therapeutic setting and could be traced back to antigen-driven immune stimulation. Reactive T cells isolated from A7450 T1 M1-treated mice recognized autologous Mlh1!##!Conclusions!#!By applying two tumor cell lysates we demonstrate that neoantigen quality outranks quantity. This should be considered prior to designing cancer vaccine-based combination approaches

Molecular Characterization of the Response to Conventional Chemotherapeutics in Pro-B-ALL Cell Lines in Terms of Tumor Relapse

Little is known about optimally applying chemotherapeutic agents in a specific temporal sequence to rapidly reduce the tumor load and to improve therapeutic efficacy. The clinical optimization of drug efficacy while reducing side effects is still restricted due to an incomplete understanding of the mode of action and related tumor relapse mechanisms on the molecular level. The molecular characterization of transcriptomic drug signatures can help to identify the affected pathways, downstream regulated genes and regulatory interactions related to tumor relapse in response to drug application. We tried to outline the dynamic regulatory reprogramming leading to tumor relapse in relapsed MLL-rearranged pro-B-cell acute lymphoblastic leukemia (B-ALL) cells in response to two first-line treatments: dexamethasone (Dexa) and cytarabine (AraC). We performed an integrative molecular analysis of whole transcriptome profiles of each treatment, specifically considering public knowledge of miRNA regulation via a network-based approach to unravel key driver genes and miRNAs that may control the relapse mechanisms accompanying each treatment. Our results gave hints to the crucial regulatory roles of genes leading to Dexa-resistance and related miRNAs linked to chemosensitivity. These genes and miRNAs should be further investigated in preclinical models to obtain more hints about relapse processes