Our results demonstrate dual antitumoral and bone-protective effects of PIM447. This fact, together with the very strong synergy exhibited with standard-of-care treatments, supports the future clinical development of this drug in multiple myeloma. Clin Cancer Res; 23(1); 225-38. ©2016 AACR.

BackgroundThe aim of this article is to present an optimized acquisition and analysis protocol for the echocardiographic evaluation of left ventricle (LV) remodeling in a mouse model of myocardial infarction (MI).Methodology13 female DBA/2J mice underwent permanent occlusion of the left anterior descending (LAD) coronary artery leading to MI. Mice echocardiography was performed using a Vevo 770 (Visualsonics, Canada) before infarction, and 7, 14, 30, 60, 90 and 120 days after LAD ligation. LV systolic function was evaluated using different parameters, including the fractional area change (FAC%) computed in four high-temporal resolution B-mode short axis images taken at different ventricular levels, and in one parasternal long axis. Pulsed wave and tissue Doppler modes were used to evaluate the diastolic function and Tei Index for global cardiac function. The echocardiographic measurements of infarct size were validated histologically using collagen deposition labeled by Sirius red staining. All data was analyzed using Shapiro-Wilk and Student's t-tests.Principal FindingsOur results reveal LV dilation resulting in marked remodeling an severe systolic dysfunction, starting seven days after MI (LV internal apical diameter, basal = 2.82±0.24, 7d = 3.49±0.42; p<0.001. End-diastolic area, basal = 18.98±1.81, 7d = 22.04±2.11; p<0.001). A strong statistically significant negative correlation exists between the infarct size and long-axis FAC% (r = −0.946; R2 = 0.90; p<0.05). Moreover, the measured Tei Index values confirmed significant post-infarction impairment of the global cardiac function (basal = 0.46±0.07, 7d = 0.55±0.08, 14 d = 0.57±0.06, 30 d = 0.54±0.06, 60 d = 0.54±0.07, 90 d = 0.57±0.08; p<0.01).Conclusions/SignificanceIn summary, we have performed a complete characterization of LV post-infarction remodeling in a DBA/2J mouse model of MI, using parameters adapted to the particular characteristics of the model In the future, this well characterized model will be used in both investigative and pharmacological studies that require accurate quantitative monitoring of cardiac recovery after myocardial infarction.

Stem cell-derived cardiomyocytes (CMs) are often electrophysiologically immature and heterogeneous, which represents a major barrier to their in vitro and in vivo application. Therefore, the purpose of this study was to examine whether Neuregulin-1b (NRG-1b) treatment could enhance in vitro generation of mature ''workingtype'' CMs from induced pluripotent stem (iPS) cells and assess the regenerative effects of these CMs on cardiac tissue after acute myocardial infarction (AMI). With that purpose, adult mouse fibroblast-derived iPS from a-MHC-GFP mice were derived and differentiated into CMs through NRG-1b and/or dimethyl sulfoxide (DMSO) treatment. Cardiac specification and maturation of the iPS was analyzed by gene expression array, quantitative real-time polymerase chain reaction, immunofluorescence, electron microscopy, and patch-clamp techniques. In vivo, the iPS-derived CMs or culture medium control were injected into the peri-infarct region of hearts after coronary artery ligation, and functional and histology changes were assessed from 1 to 8 weeks post-transplantation. On differentiation, the iPS displayed early and robust in vitro cardiogenesis, expressing cardiac-specific genes and proteins. More importantly, electrophysiological studies demonstrated that a more mature ventricular-like cardiac phenotype was achieved when cells were treated with NRG-1b and DMSO compared with DMSO alone. Furthermore, in vivo studies demonstrated that iPS-derived CMs were able to engraft and electromechanically couple to heart tissue, ultimately preserving cardiac function and inducing adequate heart tissue remodeling. In conclusion, we have demonstrated that combined treatment with NRG-1b and DMSO leads to efficient differentiation of iPS into ventricular-like cardiac cells with a higher degree of maturation, which are capable of preserving cardiac function and tissue viability when transplanted into a mouse model of AMI.

Interleukin-15 (IL-15) is a cell growth-factor that regulates lymphocyte function and homeostasis. Its strong immunostimulatory activity coupled with an apparent lack of toxicity makes IL-15 an exciting candidate for cancer therapy, somehow limited by its short half-life in circulation. To increase IL-15 bioavailability we constructed a recombinant adeno-associated vector expressing murine IL-15 (AAV-mIL15) in the liver. Mice injected with AAV-mIL15 showed sustained and vector dose-dependent levels of IL-15/IL-15Rα complexes in serum, production of IFN-γ and activation of CD8+ T-cells and macrophages. The antitumoral efficacy of AAV-mIL15 was tested in a mouse model of metastatic colorectal cancer established by injection of MC38 cells. AAV-mIL15 treatment slightly inhibits MC38 tumor-growth and significantly increases the survival of mice. However, mIL-15 sustained expression was associated with development of side effects like hepatosplenomegaly, liver damage and the development of haematological stress, which results in the expansion of hematopoietic precursors in the bone marrow. To elucidate the mechanism, we treated IFN-γ receptor-, RAG1-, CD1d- and μMT-deficient mice and performed adoptive transfer of bone marrow cells from WT mice to RAG1-defcient mice. We demonstrated that the side effects of murine IL-15 administration were mainly mediated by IFN-γ-producing T-cells.ConclusionIL-15 induces the activation and survival of effector immune cells that are necessary for its antitumoral activity; but, long-term exposure to IL-15 is associated with the development of important side effects mainly mediated by IFN-γ-producing T-cells. Strategies to modulate T-cell activation should be combined with IL-15 administration to reduce secondary adverse events while maintaining its antitumoral effect.

Drug efficacy in the central nervous system (CNS) requires an additional step after crossing the blood-brain barrier. Therapeutic agents must reach their targets in the brain to modulate them; thus, the free drug concentration hypothesis is a key parameter for in vivo pharmacology. Here, we report the impact of neurodegeneration (Alzheimer's disease (AD) and Parkinson's disease (PD) compared with healthy controls) on the binding of 10 known drugs to postmortem brain tissues from animal models and humans. Unbound drug fractions, for some drugs, are significantly different between healthy and injured brain tissues (AD or PD). In addition, drugs binding to brain tissues from AD and PD animal models do not always recapitulate their binding to the corresponding human injured brain tissues. These results reveal potentially relevant implications for CNS drug discovery.