The transforming growth factor-beta (TGF-beta) superfamily of ligands has a pivotal role in the regulation of a wide variety of physiological processes from development to pathogenesis. Since the discovery of the prototypic member, TGF-beta, almost 20 years ago, there have been tremendous advances in our understanding of the complex biology of this superfamily. Deregulation of TGF-beta has been implicated in the pathogenesis of a variety of diseases, including cancer and fibrosis. Here we present the rationale for evaluating TGF-beta signalling inhibitors as cancer therapeutics, the structures of small-molecule inhibitors that are in development and the targeted drug discovery model that is being applied to their development.

The ICF syndrome (i̲mmunodeficiency, c̲entromeric region instability, f̲acial anomalies) is a unique DNA methylation deficiency disease diagnosed by an extraordinary collection of chromosomal anomalies specifically in the vicinity of the centromeres of chromosomes 1 and 16 (Chr1 and Chr16) in mitogen-stimulated lymphocytes. These aberrations include decondensation of centromere-adjacent (qh) heterochromatin, multiradial chromosomes with up to 12 arms, and whole-arm deletions. We demonstrate that lymphoblastoid cell lines from two ICF patients exhibit these Chr1 and Chr16 anomalies in 61% of the cells and continuously generate 1qh or 16qh breaks. No other consistent chromosomal abnormality was seen except for various telomeric associations, which had not been previously noted in ICF cells. Surprisingly, multiradials composed of arms of both Chr1 and Chr16 were favored over homologous associations and cells containing multiradials with 3 or >4 arms almost always displayed losses or gains of Chr1 or Chr16 arms from the metaphase. Our results suggest that decondensation of 1qh and 16qh often leads to unresolved Holliday junctions, chromosome breakage, arm missegregation, and the formation of multiradials that may yield more stable chromosomal abnormalities, such as translocations. These cell lines maintained the abnormal hypomethylation in 1qh and 16qh seen in ICF tissues. The ICF-specific hypomethylation occurs in only a small percentage of the genome, e.g., ICF brain DNA had 7% less 5-methylcytosine than normal brain DNA. The ICF lymphoblastoid cell lines, therefore, retain not only the ICF-specific pattern of chromosome rearrangements, but also of targeted DNA hypomethylation. This hypomethylation of heterochromatic DNA sequences is seen in many cancers and may predispose to chromosome rearrangements in cancer as well as in ICF.

Pyrazole-based inhibitors of the transforming growth factor-beta type I receptor kinase domain (TbetaR-I) are described. Examination of the SAR in both enzyme- and cell-based in vitro assays resulted in the emergence of two subseries featuring differing selectivity versus p38 MAP kinase. A common binding mode at the active site has been established by successful cocrystallization and X-ray analysis of potent inhibitors with the TbetaR-I receptor kinase domain.

Chromosomal abnormalities have major biologic and prognostic implications in leukemias. Cytogenetic information in typically hypoproliferative multiple myeloma (MM) is limited because of difficulties in obtaining analyzable metaphases. In this study, karyotypes and other known prognostic factors were analyzed in 155 newly diagnosed MM patients, entered on an intensive treatment program with two autotransplants. Complete remission (CR), event-free (EFS) and overall survival (OS) were analyzed using standard statistical methods. Abnormal cytogenetics were found in 39% of patients and were associated with a significantly lower CR rate (27% v 48%; P = .008). EFS and OS were inferior in patients with either partial or complete deletion of chromosome 13 or 11q abnormalities (“unfavorable” karyotype) when compared with the remaining patients (P < .001) who, as a group, had a similar prognosis irrespective of cytogenetic findings, ie, inevaluable, normal, or abnormal but without an “unfavorable” karyotype. The patients with abnormalities of both chromosomes 11 and 13 had a dismal prognosis with median EFS and OS of only 11 and 12 months, respectively. Significant associations were noted between an “unfavorable” karyotype and IgA isotype, elevated levels of beta-2 microglobulin (B2M, > or = 3 mg/L) and age > 60 years. On multivariate regression analysis, the absence of an “unfavorable” karyotype was the most significant variable associated with prolonged EFS and OS (P = .0001 and .0002, respectively). Other independent favorable variables were age less than 60 years, C-reactive protein (CRP) < or = 0.4 mg/dL and bone marrow plasmacytosis < or = 50% before treatment. On a multivariate analysis without cytogenetics, these same three standard parameters were identified as the only favorable variables. Patients not having all three standard favorable variables had a significantly lower CR rate (P = .03), EFS (P = .0001), and OS (P = .002) if an unfavorable karyotype was detected. We conclude that, in this program of uniformly treated MM patients, a poor prognosis was associated predominantly with abnormalities of chromosomes 11 and 13.

Transforming growth factor-beta (TGF-β) signaling regulates a wide range of biological processes. TGF-β plays an important role in tumorigenesis and contributes to the hallmarks of cancer, including tumor proliferation, invasion and metastasis, inflammation, angiogenesis, and escape of immune surveillance. There are several pharmacological approaches to block TGF-β signaling, such as monoclonal antibodies, vaccines, antisense oligonucleotides, and small molecule inhibitors. Galunisertib (LY2157299 monohydrate) is an oral small molecule inhibitor of the TGF-β receptor I kinase that specifically downregulates the phosphorylation of SMAD2, abrogating activation of the canonical pathway. Furthermore, galunisertib has antitumor activity in tumor-bearing animal models such as breast, colon, lung cancers, and hepatocellular carcinoma. Continuous long-term exposure to galunisertib caused cardiac toxicities in animals requiring adoption of a pharmacokinetic/pharmacodynamic-based dosing strategy to allow further development. The use of such a pharmacokinetic/pharmacodynamic model defined a therapeutic window with an appropriate safety profile that enabled the clinical investigation of galunisertib. These efforts resulted in an intermittent dosing regimen (14 days on/14 days off, on a 28-day cycle) of galunisertib for all ongoing trials. Galunisertib is being investigated either as monotherapy or in combination with standard antitumor regimens (including nivolumab) in patients with cancer with high unmet medical needs such as glioblastoma, pancreatic cancer, and hepatocellular carcinoma. The present review summarizes the past and current experiences with different pharmacological treatments that enabled galunisertib to be investigated in patients.