CR13626: a novel oral brain penetrant tyrosine kinase inhibitor that reduces tumor growth and prolongs survival in a mouse model of glioblastoma.

Glioblastoma multiforme (GBM) is the most malignant primary brain cancer. Despite aggressive treatments currently there is no cure for GBM. Many challenges should be considered for the development of new therapeutical agents for glioblastoma, including appropriate target selectivity and pharmacokinetics. Several mutations and alterations of key cellular pathways including tyrosine kinases (TKs) are involved in malignant transformation and tumor progression. Thus, the targeting of multiple pathways and the development of innovative combination drug regimens is expected to yield improved therapies. Moreover, the abilities to cross the blood-brain barrier (BBB) reaching effective concentrations in brain and to remain into this tissue avoiding the effects of efflux transporters are also critical issues in the development of new therapeutics for GBM. CR13626 is a novel brain penetrant small molecule able to potently inhibit in vitro the activity of EGFR, VEGFR2 (aka KDR), Fyn, Yes, Lck, HGK (aka MAP4K4) and RET kinases relevant for GBM development. CR13626 shows good oral bioavailability (72%) and relevant brain penetration (brain/plasma ratio of 1.4). In an orthotopic xenograft glioblastoma mouse model, oral treatment with CR13626 results in a time-dependent reduction of tumor growth, leading to a significant increase of animal survival. The unique properties of CR13626 warrant its further investigation as a potential new drug candidate in glioblastoma.

Pharmacological characterisation of CR6086, a potent prostaglandin E2 receptor 4 antagonist, as a new potential disease-modifying anti-rheumatic drug.

BACKGROUND: Prostaglandin E2 (PGE2) acts via its EP4 receptor as a cytokine amplifier (e.g., interleukin [IL]-6) and induces the differentiation and expansion of inflammatory T-helper (Th) lymphocytes. These mechanisms play a key role in the onset and progression of rheumatoid arthritis (RA). We present the pharmacological characterisation of CR6086, a novel EP4 receptor antagonist, and provide evidence for its potential as a disease-modifying anti-rheumatic drug (DMARD). METHODS: CR6086 affinity and pharmacodynamics were studied in EP4-expressing HEK293 cells by radioligand binding and cyclic adenosine monophosphate (cAMP) production, respectively. In immune cells, IL-6 and vascular endothelial growth factor (VEGF) expression were analysed by RT-PCR, and IL-23 and IL-17 release were measured by enzyme-linked immunosorbent assay (ELISA). In collagen-induced arthritis (CIA) models, rats or mice were immunised with bovine collagen type II. Drugs were administered orally (etanercept and methotrexate intraperitoneally) starting at disease onset. Arthritis progression was evaluated by oedema, clinical score and histopathology. Anti-collagen II immunoglobulin G antibodies were measured by ELISA. RESULTS: CR6086 showed selectivity and high affinity for the human EP4 receptor (Ki = 16.6 nM) and functioned as a pure antagonist (half-maximal inhibitory concentration, 22 nM) on PGE2-stimulated cAMP production. In models of human immune cells in culture, CR6086 reduced key cytokine players of RA (IL-6 and VEGF expression in macrophages, IL-23 release from dendritic cells, IL-17 release from Th17 cells). In the CIA model of RA in rats and mice, CR6086 significantly improved all features of arthritis: severity, histology, inflammation and pain. In rats, CR6086 was better than the selective cyclooxygenase-2 inhibitor rofecoxib and at least as effective as the Janus kinase inhibitor tofacitinib. In mice, CR6086 and the biologic DMARD etanercept were highly effective, whereas the non-steroidal anti-inflammatory drug naproxen was ineffective. Importantly, in a study of CR6086/methotrexate, combined treatment greatly improved the effect of a fully immunosuppressive dose of methotrexate. CONCLUSIONS: CR6086 is a novel, potent EP4 antagonist showing favourable immunomodulatory properties, striking DMARD effects in rodents, and anti-inflammatory activity targeted to immune-mediated inflammatory diseases and distinct from the general effects of cyclooxygenase inhibitors. These results support the clinical development of CR6086, both as a stand-alone DMARD and as a combination therapy with methotrexate. The proof-of-concept trial in patients with RA is ongoing.

Experimental pharmacology of glucosamine sulfate.

Several clinical studies demonstrated that glucosamine sulfate (GS) is effective in controlling osteoarthritis (OA), showing a structure-modifying action. However, little is known about the molecular mechanism(s) by which GS exerts such action and about the effects of GS at a tissue level on osteoarthritic cartilage and other joint structures. Here we provide mechanistic evidence suggesting that in vitro GS attenuates NF-κB activation at concentrations in the range of those observed after GS administration to volunteers and patients, thus strengthening previous findings. Furthermore, we describe the effects of GS at a tissue level on the progression of the disease in a relevant model of spontaneous OA, the STR/ort mouse. In this model, the administration of GS at human corresponding doses was associated with a significant decrease of OA scores. Histomorphometry showed that the lesion surface was also significantly decreased, while the number of viable chondrocytes within the matrix was significantly increased. GS improved the course of OA in the STR/Ort mouse, by delaying cartilage breakdown as assessed histologically and histomorphometrically.

Synthesis, pharmacophore modeling and in vitro activity of 10,11-dihydrodibenzo[b,f]oxepine-4-carboxamide derivatives as novel and potent antagonists of the prostaglandin EP4 receptor.

The construction of a EP(4) antagonists pharmacophore model and the discovery of a highly potent oxepinic series of EP(4) antagonists is discussed. Compound 1a exhibits an excellent selectivity profile toward EP(2) receptor subtype and low cytochrome P450 inhibition potential.

Expression studies in gliomas and glial cells do not support a tumor suppressor role for LGI1.

Disruptions of LGI1 in glioblastoma (GBM) cell lines and LGI1 mutations in families with autosomal dominant epilepsy imply a role for LGI1 in glial cells as well as in neurons. Although we and others could not find LGI1 mutations in malignant gliomas, our initial studies appeared to support the idea that LGI1 is poorly expressed or absent in these tumors. Microarray data suggested that LGI1 could be involved in the control of matrix metalloproteinases, and we found that tumors derived from U87 glioblastoma cells overexpressing LGI1 were less aggressive than U87 control tumors. To our surprise, we observed that LGI1 expression after differentiation of murine neural stem cells was robust in neurons but negligible in glial cells, in agreement with immunohistochemistry studies on rodent brain. This observation could suggest that the variable levels of LGI1 expression in gliomas reflect the presence of neurons entrapped within the tumor. To test this hypothesis, we investigated LGI1 expression in parallel with expression of the neuronal marker NEF3 by real-time PCR on 30 malignant gliomas. Results showed a strong, positive correlation between the expression levels of these two genes (P < 0.0001). Thus, our data confirm that LGI1 is involved in cell-matrix interactions but suggest that its expression is not relevant in glial cells, implying that its role as a tumor suppressor in gliomas should be reconsidered.

The neural progenitor-restricted isoform of the MARK4 gene in 19q13.2 is upregulated in human gliomas and overexpressed in a subset of glioblastoma cell lines.

Alterations of 19q13 are frequently observed in glial neoplasms, suggesting that this region harbors at least one gene involved in gliomagenesis. Following our previous studies on structural 19q chromosome rearrangements in gliomas, we have undertaken a detailed FISH analysis of the breakpoints and identified a 19q13.2 intrachromosomal amplification of the MAP/microtubule affinity-regulating kinase 4 (MARK4) gene in three primary glioblastoma cell lines. Recent data suggest that this gene is involved in the Wnt-signaling pathway. We observed that the expression of the alternatively spliced MARK4L isoform is upregulated in both fresh and cultured gliomas and overexpressed in all of the above three glioblastoma cell lines. Interestingly, we also found that MARK4L expression is restricted to undifferentiated neural progenitor cells or proliferating glial precursor cells, whereas its expression is downregulated during glial differentiation. Perturbation of expression using antisense oligonucleotides against MARK4 in glioblastoma cell lines, consistently induced a decreased proliferation of tumor cells. Taken together, these data show that MARK4, which is normally expressed in neural progenitors, is re-expressed in gliomas and may become a key target of intrachromosomal amplification upon 19q rearrangements.