Discovery of CA-4948, an Orally Bioavailable IRAK4 Inhibitor for Treatment of Hematologic Malignancies.

Small molecule potent IRAK4 inhibitors from a novel bicyclic heterocycle class were designed and synthesized based on hits identified from Aurigene's compound library. The advanced lead compound, CA-4948, demonstrated good cellular activity in ABC DLBCL and AML cell lines. Inhibition of TLR signaling leading to decreased IL-6 levels was also observed in whole blood assays. CA-4948 demonstrated moderate to high selectivity in a panel of 329 kinases as well as exhibited desirable ADME and PK profiles including good oral bioavailability in mice, rat, and dog and showed >90% tumor growth inhibition in relevant tumor models with excellent correlation with in vivo PD modulation. CA-4948 was well tolerated in toxicity studies in both mouse and dog at efficacious exposure. The overall profile of CA-4948 prompted us to select it as a clinical candidate for evaluation in patients with relapsed or refractory hematologic malignancies including non-Hodgkin lymphoma and acute myeloid leukemia.

Debio 0617B Inhibits Growth of STAT3-Driven Solid Tumors through Combined Inhibition of JAK, SRC, and Class III/V Receptor Tyrosine Kinases.

Tumor survival, metastases, chemoresistance, and escape from immune responses have been associated with inappropriate activation of STAT3 and/or STAT5 in various cancers, including solid tumors. Debio 0617B has been developed as a first-in-class kinase inhibitor with a unique profile targeting phospho-STAT3 (pSTAT3) and/or pSTAT5 in tumors through combined inhibition of JAK, SRC, ABL, and class III/V receptor tyrosine kinases (RTK). Debio 0617B showed dose-dependent inhibition of pSTAT3 in STAT3-activated carcinoma cell lines; Debio 0617B also showed potent antiproliferative activity in a panel of cancer cell lines and in patient-derived tumor xenografts tested in an in vitro clonogenic assay. Debio 0617B showed in vivo efficacy by inhibiting tumor growth in several mouse xenograft models. To increase in vivo efficacy and STAT3 inhibition, Debio 0617B was tested in combination with the EGFR inhibitor erlotinib in a non-small cell lung cancer xenograft model. To evaluate the impact of in vivo STAT3 blockade on metastases, Debio 0617B was tested in an orthotopic tumor model. Measurement of primary tumor weight and metastatic counts in lung tissue demonstrated therapeutic efficacy of Debio 0617B in this model. These data show potent activity of Debio 0617B on a broad spectrum of STAT3-driven solid tumors and synergistic activity in combination with EGFR inhibition. Mol Cancer Ther; 15(10); 2334-43. ©2016 AACR.

Increased c-Jun-NH2-kinase signaling in neurofibromatosis-1 heterozygous microglia drives microglia activation and promotes optic glioma proliferation.

Neurofibromatosis-1 (NF1) is a common tumor predisposition syndrome in which affected individuals develop benign and malignant tumors. Previous studies from our laboratory and others have shown that benign tumor formation in Nf1 genetically engineered mice (GEM) requires a permissive tumor microenvironment. In the central nervous system, Nf1 loss in glia is insufficient for glioma formation unless coupled with Nf1 heterozygosity in the brain. Our subsequent studies identified Nf1+/- microglia as a critical cellular determinant of optic glioma growth in Nf1 GEM. Using NF1 as an experimental paradigm to further characterize the role of microglia in glioma growth, we first examined the properties of Nf1+/- microglia in vitro and in vivo. Nf1+/- microglia exhibit increased proliferation and motility and express elevated levels of genes associated with microglia activation. We further show that Nf1+/- microglia harbor high levels of activated c-Jun-NH(2)-kinase (JNK) without any significant changes in Akt, mitogen-activated protein kinase (MAPK), or p38-MAPK activity. In contrast, Nf1-/- astrocytes do not exhibit increased JNK activation. SP600125 inhibition of JNK activity in Nf1+/- microglia results in amelioration of the increased proliferation and motility phenotypes and reduces the levels of expression of activated microglia-associated transcripts. Moreover, SP600125 treatment of Nf1 optic glioma-bearing GEM results in reduced optic glioma proliferation in vivo. Collectively, these findings suggest that Nf1+/- microglia represent a good model system to study the role of specialized microglia in brain tumorigenesis and identify a unique Nf1 deregulated pathway for therapeutic studies aimed at abrogating microenvironmental signals that promote brain tumor growth.

Expression profiling identifies a molecular signature of reactive astrocytes stimulated by cyclic AMP or proinflammatory cytokines.

Specialized glia, termed reactive astrocytes, accompany numerous pathologic conditions affecting the central nervous system, including stroke, multiple sclerosis, and neoplasia. To better define this important cell type, we employed high-density microarray gene expression profiling using two in vitro models of reactive gliosis (stimulation with dbcAMP or IL-1beta/IFNgamma). We identified 44 differentially expressed transcripts common to both in vitro models and demonstrated that a subset of these genes are also differentially expressed in response to experimental autoimmune encephalomyelitis and focal cerebral ischemia in vivo. Moreover, this pattern of differential gene expression is not observed in hyperproliferating or neoplastic glia.

Spatiotemporal differences in CXCL12 expression and cyclic AMP underlie the unique pattern of optic glioma growth in neurofibromatosis type 1.

Astrocytoma (glioma) formation in neurofibromatosis type 1 (NF1) occurs preferentially along the optic pathway during the first decade of life. The molecular basis for this unique pattern of gliomagenesis is unknown. Previous studies in mouse Nf1 optic glioma models suggest that this patterning results from cooperative effects of Nf1 loss in glial cells and the action of factors derived from the surrounding Nf1+/- brain. Because CXCL12 is a stroma-derived growth factor for malignant brain tumors, we tested the hypothesis that CXCL12 functions in concert with Nf1 loss to facilitate NF1-associated glioma growth. Whereas CXCL12 promoted cell death in wild-type astrocytes, it increased Nf1-/- astrocyte survival. This increase in Nf1-/- astrocyte survival in response to CXCL12 was due to sustained suppression of intracellular cyclic AMP (cAMP) levels. Moreover, the ability of CXCL12 to suppress cAMP and increase Nf1-/- astrocyte survival was a consequence of mitogen-activated protein/extracellular signal-regulated kinase kinase-dependent inhibition of CXCL12 receptor (CXCR4) desensitization. In support of an instructive role for CXCL12 in facilitating optic glioma growth, we also show that CXCL12 expression along the optic pathway is higher in infant children and young mice and is associated with low levels of cAMP. CXCL12 expression declines in multiple brain regions with increasing age, correlating with the age-dependent decline in glioma growth in children with NF1. Collectively, these studies provide a mechanism for the unique pattern of NF1-associated glioma growth.

Neurofibromatosis-1 (Nf1) heterozygous brain microglia elaborate paracrine factors that promote Nf1-deficient astrocyte and glioma growth.

The tumor microenvironment is considered to play an important role in tumor formation and progression by providing both negative and positive signals that influence tumor cell growth. We and others have previously shown that brain tumor (glioma) formation in Nf1 genetically engineered mice requires a microenvironment composed of cells heterozygous for a targeted Nf1 mutation. Using NF1 as a model system to understand the contribution of the tumor microenvironment to glioma formation, we show that Nf1+/- brain microglia produce specific factors that promote Nf1-/- astrocyte growth in vitro and in vivo and identify hyaluronidase as one of these factors in both genetically engineered Nf1 mouse and human NF1-associated optic glioma. We further demonstrate that blocking hyaluronidase ameliorates the ability of Nf1+/- microglia to increase Nf1-/- astrocyte proliferation and that hyaluronidase increases Nf1-/- astrocyte proliferation in an MAPK-dependent fashion. Lastly, inhibiting microglia activation in genetically engineered Nf1 mice significantly reduces mouse optic glioma proliferation in vivo. Collectively, these studies identify Nf1+/- microglia as an important stromal cell type that promotes Nf1-/- astrocyte and optic glioma growth relevant to the pathogenesis of NF1-associated brain tumors and suggest that future brain therapies might be directed against paracrine factors produced by cells in the tumor microenvironment.