High iASPP (PPP1R13L) expression is an independent predictor of adverse clinical outcome in acute myeloid leukemia (AML).

Apoptosis-stimulating proteins of p53 (ASPPs) are a family of proteins that modulate key tumor suppressor pathways via direct interaction with p53. Deregulation of these proteins promotes cancer development and impairs sensitivity to systemic (chemo)therapy and radiation. In this study, we describe that the inhibitor of ASPP (iASPP) is frequently highly expressed in acute myeloid leukemia (AML) and that overexpression correlates with a poor clinical outcome.

Evaluation of apoptosis stimulating protein of TP53-1 (ASPP1/PPP1R13B) to predict therapy resistance and overall survival in acute myeloid leukemia (AML).

ASPP1 (PPP1R13B) belongs to a family of p53-binding proteins and enhances apoptosis by stimulation of p53-transactivation of selected proapoptotic target genes. It is preferentially expressed in hematopoietic stem cells (HSC) and together with p53 preserves the genomic integrity of the HSC pool. Consequently, dysfunction of ASPP1 has been associated with malignant transformation and development of acute lymphoblastic leukemias and lymphomas - whereas methylation of the promoter region is linked to reduced transcription and ultimately attenuated expression of ASPP1.

Alternative splicing of Apoptosis Stimulating Protein of TP53-2 (ASPP2) results in an oncogenic isoform promoting migration and therapy resistance in soft tissue sarcoma (STS).

Background: Metastatic soft tissue sarcoma (STS) are a heterogeneous group of malignancies which are not curable with chemotherapy alone. Therefore, understanding the molecular mechanisms of sarcomagenesis and therapy resistance remains a critical clinical need. ASPP2 is a tumor suppressor, that functions through both p53-dependent and p53-independent mechanisms.

ASPP2κ Is Expressed In Human Colorectal Carcinoma And Promotes Chemotherapy Resistance And Tumorigenesis.

Alternative splicing is a common physiologic mechanism to generate numerous distinct gene products from one gene locus, which can result in unique gene products with differing important functional outcomes depending on cell context. Aberrant alternative splicing is a hallmark of cancer that can contribute to oncogenesis and aggressiveness of the disease as well as resistance to therapy. However, aberrant splicing might also result in novel targets for cancer therapy.

Alternative splicing of the tumor suppressor ASPP2 results in a stress-inducible, oncogenic isoform prevalent in acute leukemia.

Background: Apoptosis-stimulating Protein of TP53-2 (ASPP2) is a tumor suppressor enhancing TP53-mediated apoptosis via binding to the TP53 core domain. TP53 mutations found in cancers disrupt ASPP2 binding, arguing for an important role of ASPP2 in TP53-mediated tumor suppression. We now identify an oncogenic splicing variant, ASPP2κ, with high prevalence in acute leukemia.

A Phase II Study Alternating Erlotinib With Second-line mFOLFOX6 or FOLFIRI for Metastatic Colorectal Cancer.

Background: Based on our pre-clinical data, we hypothesized that sequencing chemotherapy with erlotinib would increase the tumor response rate in patients with metastatic colorectal cancer.

Patients And Methods: A phase II trial (planned n=58) using second-line therapy for metastatic colorectal cancer with either oxaliplatin-based (mFOLFOX6) or irinotecan-based (FOLFIRI) combination chemotherapy and 100 mg erlotinib daily on days 3-8 after each infusion (days 1 and 2) every 14 days. The primary endpoint was the response rate compared to the historical response rate.

Dasatinib overrides the differentiation blockage in a patient with mutant- D816V positive CBFβ-MYH11 leukemia.

Activating D816V mutations are frequently found in CBF AML, which predicts for an unfavorable outcome. Dasatinib is a potent inhibitor of wildtype and mutant-KIT isoforms - including D816V. We now provide proof of antileukemic efficacy in a patient with relapsing mutant- D816V CBF AML.

Crenolanib is a type I tyrosine kinase inhibitor that inhibits mutant D816 isoforms prevalent in systemic mastocytosis and core binding factor leukemia.

Activating D816 mutations of the class III receptor tyrosine kinase are associated with the majority of patients with systemic mastocytosis (SM), but also core binding factor (CBF) AML, making mutations attractive therapeutic targets for the treatment of these cancers. Crenolanib is a potent and selective inhibitor of wild-type as well as mutant isoforms of the class III receptor tyrosine kinases FLT3 and PDGFRα/β. Notably, crenolanib inhibits constitutively active mutant-FLT3 isoforms resulting from amino acid substitutions of aspartic acid at codon 835, which is homologous to codon 816 in the gene - suggesting sensitivity against mutant-KIT D816 isoforms as well.

Dronabinol has preferential antileukemic activity in acute lymphoblastic and myeloid leukemia with lymphoid differentiation patterns.

Background: It has been previously demonstrated in several cancer models, that Dronabinol (THC) may have anti-tumor activity--however, controversial data exists for acute leukemia. We have anecdotal evidence that THC may have contributed to disease control in a patient with acute undifferentiated leukemia.

Methods: To test this hypothesis, we evaluated the antileukemic efficacy of THC in several leukemia cell lines and native leukemia blasts cultured ex vivo.

Attenuated expression of apoptosis stimulating protein of p53-2 (ASPP2) in human acute leukemia is associated with therapy failure.

Inactivation of the p53 pathway is a universal event in human cancers and promotes tumorigenesis and resistance to chemotherapy. Inactivating p53 mutations are uncommon in non-complex karyotype leukemias, thus the p53-pathway must be inactivated by other mechanisms. The Apoptosis Stimulating Protein of p53-2 (ASPP2) is a damage-inducible p53-binding protein that enhances apoptosis at least in part through a p53-mediated pathway.

Cell cycle-dependent activity of the novel dual PI3K-MTORC1/2 inhibitor NVP-BGT226 in acute leukemia.

Background: Dysregulation of the PI3Kinase/AKT pathway is involved in the pathogenesis of many human malignancies. In acute leukemia, the AKT pathway is frequently activated, however mutations in the PI3K/AKT pathway are uncommon. In some cases, constitutive AKT activation can be linked to gain-of-function tyrosine kinase (TK) mutations upstream of the PI3K/AKT pathway.

Quizartinib (AC220) is a potent second generation class III tyrosine kinase inhibitor that displays a distinct inhibition profile against mutant-FLT3, -PDGFRA and -KIT isoforms.

Background: Activating mutations of class III receptor tyrosine kinases (RTK) FLT3, PDGFR and KIT are associated with multiple human neoplasms including hematologic malignancies, for example: systemic mast cell disorders (KIT), non-CML myeloproliferative neoplasms (PDGFR) and subsets of acute leukemias (FLT3 and KIT). First generation tyrosine kinase inhibitors (TKI) are rapidly being integrated into routine cancer care. However, the expanding spectrum of TK-mutations, bioavailability issues and the emerging problem of primary or secondary TKI-therapy resistance have lead to the search for novel second generation TKIs to improve target potency and to overcome resistant clones.

N terminus of ASPP2 binds to Ras and enhances Ras/Raf/MEK/ERK activation to promote oncogene-induced senescence.

The ASPP2 (also known as 53BP2L) tumor suppressor is a proapoptotic member of a family of p53 binding proteins that functions in part by enhancing p53-dependent apoptosis via its C-terminal p53-binding domain. Mounting evidence also suggests that ASPP2 harbors important nonapoptotic p53-independent functions. Structural studies identify a small G protein Ras-association domain in the ASPP2 N terminus.