Assessing the efficacy of molecularly targeted agents on cell line-based platforms by using system identification

BACKGROUND: Molecularly targeted agents (MTAs) are increasingly used for cancer treatment, the goal being to improve the efficacy and selectivity of cancer treatment by developing agents that block the growth of cancer cells by interfering with specific targeted molecules needed for carcinogenesis and tumor growth. This approach differs from traditional cytotoxic anticancer drugs. The lack of specificity of cytotoxic drugs allows a relatively straightforward approach in preclinical and clinical studies, where the optimal dose has usually been defined as the "maximum tolerated dose" (MTD). This toxicity-based dosing approach is founded on the assumption that the therapeutic anticancer effect and toxic effects of the drug increase in parallel as the dose is escalated. On the contrary, most MTAs are expected to be more selective and less toxic than cytotoxic drugs. Consequently, the maximum therapeutic effect may be achieved at a "biologically effective dose" (BED) well below the MTD. Hence, dosing study for MTAs should be different from cytotoxic drugs. Enhanced efforts to molecularly characterize the drug efficacy for MTAs in preclinical models will be valuable for successfully designing dosing regimens for clinical trials. RESULTS: A novel preclinical model combining experimental methods and theoretical analysis is proposed to investigate the mechanism of action and identify pharmacodynamic characteristics of the drug. Instead of fixed time point analysis of the drug exposure to drug effect, the time course of drug effect for different doses is quantitatively studied on cell line-based platforms using system identification, where tumor cells' responses to drugs through the use of fluorescent reporters are sampled over a time course. Results show that drug effect is time-varying and higher dosages induce faster and stronger responses as expected. However, the drug efficacy change along different dosages is not linear; on the contrary, there exist certain thresholds. This kind of preclinical study can provide valuable suggestions about dosing regimens for the in vivo experimental stage to increase productivity

Fluorescence enhanced optical tomography on breast phantoms with measurements using a gain modulated intensified CCD imaging system

Fluorescence-enhanced optical imaging using near-infrared (NIR) light developed for in-vivo molecular targeting and reporting of cancer provides promising opportunities for diagnostic imaging. However, prior to the administration of unproven contrast agents, the benefits of fluorescence-enhanced optical imaging must be assessed in feasibility phantom studies. A novel intensified charge-coupled device (ICCD) imaging system has been developed to perform 3-D fluorescence tomographic imaging in the frequency-domain using near-infrared contrast agents. This study is unique since it (i) employs a large tissue-mimicking phantom (~1087 cc), which is shaped and sized to resemble a female breast and part of the extended chest wall region, and (ii) enables rapid data acquisition in the frequency-domain by using a gain-modulated ICCD camera. Diagnostic 3-D fluorescence-enhanced optical tomography is demonstrated using 0.5-1 cc single and multiple targets contrasted from their surrounding by ??M concentrations of Indocyanine green (ICG) in the breast-shaped phantom (10 cm diameter), under varying conditions of target-to-background absorption contrast ratios (1:0 and 100:1) and target depths (up to 3 cm deep). Boundary surface fluorescence measurements of referenced amplitude and phase shift were used along with the coupled diffusion equation of light propagation in order to perform 3-D image reconstructions using the approximate extended Kalman filter (AEKF) algorithm, and hence differentiate the target from the background based on fluorescent optical contrast. Detection of single and multiple targets is demonstrated under various conditions of target depths (up to 2 cm deep), absorption optical contrast ratio (1:0 and 100:1), target volumes (0.5-1 cc), and multiple targets (up to three 0.5 cc targets). The feasibility of 3-D image reconstructions from simultaneous multiple point excitation sources are presented. Preliminary lifetime imaging studies with 1:2 and 2:1 optical contrast in fluorescence lifetime of the contrast agents is also demonstrated. The specificity of the optical imager is further assessed from homogeneous phantom studies containing no fluorescently contrasted targets. While nuclear imaging currently provides clinical diagnostic opportunities using radioactive tracers, molecular targeting of tumors using non-ionizing NIR contrast agents tomographically imaged using the frequency-domain ICCD imaging system could possibly become a new method of diagnostic imaging

Precision Medicine in Solid Tumors

In the era of precision medicine, the use of molecularly targeted therapies in selected patients has led to a paradigm change in cancer treatment. Multiple studies have demonstrated the benefits of therapies that are chosen based on the molecular profile of the tumor and also from the liquid biopsy. With genomics' increasing ability, a routine transcriptomics analysis of advanced/metastatic cancers is now feasible in most cancer hospitals, including community cancer centers. This is an unprecedented shift in the management of cancers irrespective of their organ types, which not only improved the outcome but also opened several new avenues in research and practice, such as immune-check-point inhibitors, tumor-TME co-evolution in the development of resistance, longitudinal liquid biopsies, biomarkers screening and the management of electronic medical records.This book brings together these crucial areas of investigation. The research presented here attempts to address the current issues to provoke thoughts for the future. The future of precision medicine will have to embrace a shift from in vitro, in vivo/PDX models for the mechanistic study to a more functional test based on the scientific interrogation of genomic data, in the form of functional precision medicine. We will also have to combat the element of noise in the multitudes of data and impart the regulatory structure to make judicious use of the data. The expectations for functional precision medicine are high. We aspire to witness a tremendous improvement in patient outcomes, from better to best, down the road that will match the clinical guidelines

Molecular Biomarkers for the Evaluation of Colorectal Cancer: Guideline From the American Society for Clinical Pathology, College of American Pathologists, Association for Molecular Pathology, and American Society of Clinical Oncology

OBJECTIVES: - To develop evidence-based guideline recommendations through a systematic review of the literature to establish standard molecular biomarker testing of colorectal cancer (CRC) tissues to guide epidermal growth factor receptor (EGFR) therapies and conventional chemotherapy regimens. METHODS: - The American Society for Clinical Pathology, College of American Pathologists, Association for Molecular Pathology, and American Society of Clinical Oncology convened an expert panel to develop an evidence-based guideline to establish standard molecular biomarker testing and guide therapies for patients with CRC. A comprehensive literature search that included more than 4,000 articles was conducted. RESULTS: - Twenty-one guideline statements were established. CONCLUSIONS: - Evidence supports mutational testing for EGFR signaling pathway genes, since they provide clinically actionable information as negative predictors of benefit to anti-EGFR monoclonal antibody therapies for targeted therapy of CRC. Mutations in several of the biomarkers have clear prognostic value. Laboratory approaches to operationalize CRC molecular testing are presented

Small Molecule Hsp90 Modulator and Neuregulin-induced Peripheral Demyelination

Abstract Modulating molecular chaperones is emerging as an attractive approach to treat neurodegenerative diseases associated with protein aggregation, diabetic peripheral neuropathy (DPN) and possibly, demyelinating neuropathies. KU-32 is a small molecule inhibitor of heat shock protein 90 (Hsp90) and reverses sensory deficits associated with myelinated fiber dysfunction in DPN. Additionally, KU-32 prevented the loss of myelinated internodes induced by treating myelinated Schwann cell-dorsal root ganglia sensory neuron co-cultures with neuregulin-1 Type 1 (NRG1). Since KU-32 decreased NRG1-induced demyelination in an Hsp70-dependent manner, the goal of the current study was to clarify how Hsp70 may be mechanistically linked to preventing demyelination. The activation of p42/p44 MAPK and induction of the transcription factor c-jun function as negative regulators of myelination. NRG1 activated MAPK, induced c-jun expression and promoted a loss of myelin segments in DRG explants isolated from both wild type and Hsp70 KO mice. Although KU-32 did not block the activation of MAPK, it blocked c-jun induction and protected against a loss of myelinated segments in wildtype (WT) mice. KU-32 did not prevent the NRG1-dependent induction of c-jun and loss of myelin segments in explants from Hsp70 KO mice. Over-expression of Hsp70 in myelinated DRG explants prepared from WT or Hsp70 KO mice was sufficient to block the induction of c-jun and the loss of myelin segments induced by NRG1. Lastly, inhibiting the proteasome prevented KU-32 from decreasing c-jun levels. Collectively, these data support that Hsp70 induction is sufficient to prevent NRG1-induced demyelination by enhancing the proteasomal degradation of c-jun

Photoacoustic image guidance and tissue characterization in cardiovascular applications

Collectively, cardiovascular diseases continue to be the leading cause of death, across nations and across decades. Improved diagnostic imaging methods offer promise to alleviate the morbidity associated with these diseases. Photoacoustic (PA) imaging is one such method, poised to make a significant impact on cardiovascular imaging, both as a research tool, as well as a clinical imaging modality. Offering the potential of molecular imaging in real-time, PA methods have been demonstrated in proof-of-concept studies tracking myocyte calcium dynamics. These results open the door to non-invasive longitudinal assessment of cardiac electrophysiological function, with implications for drug and contrast agent development. PA image guidance has also been extended to the characterization of cardiac radiofrequency ablation lesions. This method has been demonstrated to utilize endogenous chromophore changes resulting from ablation for the generation of depth-resolved tissue characterization maps, capable of assessing lesion extent. The technique has been subsequently validated by assessing high-intensity focused ultrasound ablation lesions in myocardium, with the hope for offering thermographic capabilities as well. While PA imaging offers such promise in cardiac ablation procedures, it is also in the process of clinical translation for image guidance and characterization in coronary artery disease applications. Research has shown, using Monte Carlo optical modeling, that using a simple dual-wavelength PA imaging technique has great potential for successful visualization of atherosclerotic plaques across multiple tissue types and at clinically relevant multiple millimeters of depth. Collectively these results offer a suite of PA imaging tools with the potential for molecular and thermographic imaging across a broad range of cardiovascular applications.Biomedical Engineerin

Ultrasound Imaging

This book provides an overview of ultrafast ultrasound imaging, 3D high-quality ultrasonic imaging, correction of phase aberrations in medical ultrasound images, etc. Several interesting medical and clinical applications areas are also discussed in the book, like the use of three dimensional ultrasound imaging in evaluation of Asherman's syndrome, the role of 3D ultrasound in assessment of endometrial receptivity and follicular vascularity to predict the quality oocyte, ultrasound imaging in vascular diseases and the fetal palate, clinical application of ultrasound molecular imaging, Doppler abdominal ultrasound in small animals and so on