NMS-E973, a novel synthetic inhibitor of Hsp90 with activity against multiple models of drug resistance to targeted agents, including intracranial metastases.

PURPOSE: Recent developments of second generation Hsp90 inhibitors suggested a potential for development of this class of molecules also in tumors that have become resistant to molecular targeted agents. Disease progression is often due to brain metastases, sometimes related to insufficient drug concentrations within the brain. Our objective was to identify and characterize a novel inhibitor of Hsp90 able to cross the blood-brain barrier (BBB). EXPERIMENTAL DESIGN: Here is described a detailed biochemical and crystallographic characterization of NMS-E973. Mechanism-based anticancer activity was described in cell models, including models of resistance to kinase inhibitors. Pharmacokinetics properties were followed in plasma, tumor, liver, and brain. In vivo activity and pharmacodynamics, as well as the pharmacokinetic/pharmacodynamic relationships, were evaluated in xenografts, including an intracranially implanted melanoma model. RESULTS: NMS-E973, representative of a novel isoxazole-derived class of Hsp90 inhibitors, binds Hsp90α with subnanomolar affinity and high selectivity towards kinases, as well as other ATPases. It possesses potent antiproliferative activity against tumor cell lines and a favorable pharmacokinetic profile, with selective retention in tumor tissue and ability to cross the BBB. NMS-E973 induces tumor shrinkage in different human tumor xenografts, and is highly active in models of resistance to kinase inhibitors. Moreover, consistent with its brain penetration, NMS-E973 is active also in an intracranially implanted melanoma model. CONCLUSIONS: Overall, the efficacy profile of NMS-E973 suggests a potential for development in different clinical settings, including tumors that have become resistant to molecular targeted agents, particularly in cases of tumors which reside beyond the BBB.

Labeling protocols for in vivo tracking of human skeletal muscle cells (HSkMCs) by magnetic resonance and bioluminescence imaging.

PURPOSE: We propose herein labeling protocols for multimodal in vivo visualization of human skeletal muscle cells (HSkMCs) by MRI and BLI to investigate the survival, localization, and proliferation/differentiation of these cells in cell-mediated therapy. PROCEDURES: HSkMCs were labeled with different quantities of Endorem® and transfection agents or infected with lentiviral vector expressing the luciferase gene under the myogenin promoter. Cells were evaluated before and after intra-arterial injection in NUDE mice with N2-induced muscle inflammation. RESULTS: Neither iron labeling nor infection affected cell features; the number of iron-positive cells increased proportionally to the iron content in the medium and in the presence of transfection agents. Loaded cells were detected for up to 1 month by MRI and 2 months by BLI. CONCLUSIONS: These protocols could be used to visualize new stem cells, in vivo and over time, in preclinical studies of cell-based treatments for myopathies of different etiologies.

In vivo imaging of lymph node migration of MNP- and (111)In-labeled dendritic cells in a transgenic mouse model of breast cancer (MMTV-Ras).

PURPOSE: The authors present a protocol for the in vivo evaluation, using different imaging techniques, of lymph node (LN) homing of tumor-specific dendritic cells (DCs) in a murine breast cancer model. PROCEDURES: Bone marrow DCs were labeled with paramagnetic nanoparticles (MNPs) or (111)In-oxine. Antigen loading was performed using tumor lysate. Mature DCs were injected into the footpads of transgenic tumor-bearing mice (MMTV-Ras) and DC migration was tracked by magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT). Ex vivo analyses were performed to validate the imaging data. RESULTS: DC labeling, both with MNPs and with (111)In-oxine, did not affect DC phenotype or functionality. MRI and SPECT allowed the detection of iron and (111)In in both axillary and popliteal LNs. Immunohistochemistry and γ-counting revealed the presence of DCs in LNs. CONCLUSIONS: MRI and SPECT imaging, by allowing in vivo dynamic monitoring of DC migration, could further the development and optimization of efficient anti-cancer vaccines.

Efficacy of PHA-848125, a cyclin-dependent kinase inhibitor, on the K-Ras(G12D)LA2 lung adenocarcinoma transgenic mouse model: evaluation by multimodality imaging.

K-ras is the most frequently mutated oncogene in non-small cell lung cancer (NSCLC), the most common form of lung cancer. Recent studies indicate that NSCLC patients with mutant K-ras do not respond to epidermal growth factor receptor inhibitors. In the attempt to find alternative therapeutic regimes for such patients, we tested PHA-848125, an oral pan cyclin-dependent kinase inhibitor currently under evaluation in phase II clinical trial, on a transgenic mouse model, K-Ras(G12D)LA2, which develops pulmonary cancerous lesions reminiscent of human lung adenocarcinomas. We used magnetic resonance imaging and positron emission tomography to follow longitudinally disease progression and evaluate therapeutic efficacy in this model. Treatment of K-Ras(G12D)LA2 mice with 40 mg/kg twice daily for 10 days with PHA-848125 induced a significant tumor growth inhibition at the end of treatment (P < 0.005) and this was accompanied by a reduction in the cell membrane turnover, as seen by 11C-Choline-positron emission tomography (P < 0.05). Magnetic resonance imaging data were validated versus histology and the mechanism of action of the compound was verified by immunohistochemistry, using cyclin-dependent kinase-related biomarkers phospho-Retinoblastoma and cyclin A. In this study, multimodality imaging was successfully used for the preclinical assessment of PHA-848125 therapeutic efficacy on a lung adenocarcinoma mouse model. This compound induced a volumetric and metabolic anticancer effect and could represent a valid therapeutic approach for NSCLC patients with mutant K-ras.

Magnetic resonance imaging and histopathological characterization of prostate tumors in TRAMP mice as model for pre-clinical trials.

BACKGROUND: The Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) develops progressive forms of prostate cancer. Due to the lack of a validated non-invasive methodology, pathology has been so far the most common parameter evaluated in efficacy studies. METHODS: We studied by magnetic resonance imaging (MRI) 210 mice that were repeatedly measured up to 33 weeks of age in order to stage prostate tumors and follow pathological progression in single animals. A pre-clinical trial with doxorubicin was also performed. RESULTS: Progressive forms of cancer (well and poorly differentiated (PD) adenocarcinomas) were easily recognized on MR images and MRI findings were validated against histopathological analysis. Age at tumor onset was different for the two tumoral forms. Doxorubicin treatment caused a strong reduction in tumor volume. CONCLUSIONS: Prostate cancer in TRAMP mice is multifocal and heterogeneous: a non-invasive methodology such as MRI facilitates the rational design of translational pre-clinical trials in this widely used animal model.