Identification Of Molecular Therapeutic Targets Research Articles

Genome-Based Medicine for Acute Myeloid Leukemia: Study and Targeting of Molecular Alterations and Use of Minimal Residual Disease as a Biomarker

Acute myeloid leukemia (AML) is a highly heterogeneous hematologic malignancy characterized by the clonal proliferation of hematopoietic stem and progenitor cells (HSPCs) and blockade of differentiation and proliferation of immature myeloid cells that accumulate in bone marrow at the expense of normal hematopoiesis. AMLs originate from the expansion of HSPCs progressively acquiring somatic mutations. The development of high-throughput sequencing techniques has helped to discover the genetic heterogeneity and complexity of AMLs, revise diagnostic and prognostic criteria, and to identify new therapeutic targets. These studies have allowed the identification of several recurrent driver mutations and the definition of a rational molecular classification of these tumors. In parallel, the development of techniques for the determination of single-cell mutational profiling has considerably contributed to understanding the clonal heterogeneity and evolution of AMLs. The acquisition of these genetic data coupled with the identification of molecular therapeutic targets has determined a considerable expansion of the therapeutic armamentarium, with the development of several new drugs highly active against specific AML subtypes. These developments have increased the interest and the need for sensitive techniques for the identification of minimal residual disease, the population of leukemia cells that survives despite morphological remission and causes disease relapse.

Return of comprehensive tumour genomic profiling results to advanced cancer patients: a qualitative study.

PurposeThe introduction of comprehensive tumour genomic profiling (CGP) into clinical oncology allows the identification of molecular therapeutic targets. However, the potential complexity of genomic results and their implications may cause confusion and distress for patients undergoing CGP. We investigated the experience of advanced cancer patients receiving CGP results in a research setting.MethodsSemi-structured interviews with 37 advanced cancer patients were conducted within two weeks of patients receiving CGP results. Interviewees were purposively sampled based on CGP result, cancer type, age and gender to ensure diversity. Themes were derived from interview transcripts using a framework analysis approach.ResultsWe identified six themes: (1) hoping against the odds; (2) managing expectations; (3) understanding is cursory; (4) communication of results is cursory; (5) genomics and incurable cancer; and (6) decisions about treatment.ConclusionDespite enthusiasm regarding CGP about the hope it provides for new treatments, participants experienced challenges in understanding results, and acceptance of identified treatments was not automatic. Support is needed for patients undergoing CGP to understand the implications of testing and cope with non-actionable results.

Abstract 825: Identification of molecular therapeutic targets that enhance the antitumor activity of neratinib in breast cancer cells

Abstract Background: Aberrant expression of members of the ErbB family of receptor tyrosine kinases and its downstream pathways is known to play pivotal roles in breast cancer malignancy. HER2-positive breast cancer has an aggressive nature that is driven by HER2 gene amplification. Inflammatory breast cancer is a rare but the most aggressive clinical subtype of breast cancer. Triple-negative breast cancer is an aggressive receptor subtype of breast cancer. More than 30% of cases of each of these groups express EGFR. Emerging therapeutic resistance continues to be a challenge in recurrent and/or metastatic disease. Neratinib is a potent irreversible EGFR, HER2, and HER4 tyrosine kinase inhibitor that blocks signal transduction generated via these receptors. In this study, we sought to identify the optimal targets in different subtypes of breast cancer and synergistic partners to maximize the antitumor effect of neratinib against breast cancer cells in vitro and in vivo. Methods: Expression of EGFR and HER2 was assessed via Western blot in 31 breast cancer cell lines, including HER2-targeted drug-resistant cell lines (14 triple-negative breast cancer and 10 HER2-positive). The antiproliferative effects of neratinib were measured using cell proliferation and anchorage-independent colony-formation (soft agar) assays. A reverse-phase protein array was used to profile and validate the signaling networks induced by neratinib-based treatment. To identify the synergistic targets, RNA interference screening of a 779-kinome library was performed under multicellular tumor spheroid culture conditions. Results: In vitro proliferation data demonstrated that neratinib had a nanomolar range of half-maximal inhibitory concentrations in most of the tested cell lines, including T-DM1-resistant HER-2 breast cancer cell lines. Neratinib inhibited colony formation in a dose-dependent manner (P = 0.0001). Reverse-phase protein array data revealed that the efficacy of neratinib correlated with phosphorylated EGFR (R2 = 0.6055) or phosphorylated HER2 (R2 = 0.6734) expression level. Statistical analysis identified the 25 most relevant targets in the RNA interference screening, which we will validate for combinational antitumor effects with neratinib in in vitro and in vivo studies. Conclusion: We determined the efficacy of neratinib and identified target molecules to enhance neratinib efficacy in different breast cancer subtype cell lines with ErbB alterations. Our data inform new combined treatment strategies with neratinib for breast cancer that will lead to innovative designs using optimized neratinib combinations in clinical trials. Citation Format: Bora Lim, Jangsoon Lee, Troy Pearson, Liu Huey, Minha Hwang, Kuicheon Choi, Francesca Avogadri-Connors, Richard E. Cutler, Debu Tripathy, Naoto T. Ueno. Identification of molecular therapeutic targets that enhance the antitumor activity of neratinib in breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 825.

Properties and ionic mechanisms of action potential adaptation, restitution, and accommodation in canine epicardium

Computational models of cardiac myocytes are important tools for understanding ionic mechanisms of arrhythmia. This work presents a new model of the canine epicardial myocyte that reproduces a wide range of experimentally observed rate-dependent behaviors in cardiac cell and tissue, including action potential (AP) duration (APD) adaptation, restitution, and accommodation. Model behavior depends on updated formulations for the 4-aminopyridine-sensitive transient outward current (I(to1)), the slow component of the delayed rectifier K(+) current (I(Ks)), the L-type Ca(2+) channel current (I(Ca,L)), and the Na(+)-K(+) pump current (I(NaK)) fit to data from canine ventricular myocytes. We found that I(to1) plays a limited role in potentiating peak I(Ca,L) and sarcoplasmic reticulum Ca(2+) release for propagated APs but modulates the time course of APD restitution. I(Ks) plays an important role in APD shortening at short diastolic intervals, despite a limited role in AP repolarization at longer cycle lengths. In addition, we found that I(Ca,L) plays a critical role in APD accommodation and rate dependence of APD restitution. Ca(2+) entry via I(Ca,L) at fast rate drives increased Na(+)-Ca(2+) exchanger Ca(2+) extrusion and Na(+) entry, which in turn increases Na(+) extrusion via outward I(NaK). APD accommodation results from this increased outward I(NaK). Our simulation results provide valuable insight into the mechanistic basis of rate-dependent phenomena important for determining the heart's response to rapid and irregular pacing rates (e.g., arrhythmia). Accurate simulation of rate-dependent phenomena and increased understanding of their mechanistic basis will lead to more realistic multicellular simulations of arrhythmia and identification of molecular therapeutic targets.

Growth of cancer cell lines under stem cell-like conditions has the potential to unveil therapeutic targets

Malignant tumors comprise a small proportion of cancer-initiating cells (CIC), capable of sustaining tumor formation and growth. CIC are the main potential target for anticancer therapy. However, the identification of molecular therapeutic targets in CIC isolated from primary tumors is an extremely difficult task. Here, we show that after years of passaging under differentiating conditions, glioblastoma, mammary carcinoma, and melanoma cell lines contained a fraction of cells capable of forming spheroids upon in vitro growth under stem cell-like conditions. We found an increased expression of surface markers associated with the stem cell phenotype and of oncogenes in cell lines and clones cultured as spheroids vs. adherent cultures. Also, spheroid-forming cells displayed increased tumorigenicity and an altered pattern of chemosensitivity. Interestingly, also from single retrovirally marked clones, it was possible to isolate cells able to grow as spheroids and associated with increased tumorigenicity. Our findings indicate that short-term selection and propagation of CIC as spheroid cultures from established cancer cell lines, coupled with gene expression profiling, represents a suitable tool to study and therapeutically target CIC: the notion of which genes have been down-regulated during growth under differentiating conditions will help find CIC-associated therapeutic targets.