Small molecules to regulate the GH/IGF1 axis by inhibiting the growth hormone receptor synthesis

Growth hormone (GH) and insulin-like growth factor-1 (IGF1) play an important role in mammalian development, cell proliferation and lifespan. Especially in cases of tumor growth there is an urgent need to control the GH/IGF1 axis. In this study we screened a 38,480-compound library, and in two consecutive rounds of analogues selection, we identified active lead compounds based on the following criteria: inhibition the GH receptor (GHR) activity and its downstream effectors Jak2 and STAT5, and inhibition of growth of breast and colon cancer cells. The most active small molecule (BM001) inhibited both the GH/IGF1 axis and cell proliferation with an IC50 of 10-30 nM of human cancer cells. BM001 depleted GHR in human lymphoblasts. In preclinical xenografted experiments, BM001 showed a strong decrease in tumor volume in mice transplanted with MDA-MB-231 breast cancer cells. Mechanistically, the drug acts on the synthesis of the GHR. Our findings open the possibility to inhibit the GH/IGF1 axis with a small molecule.

The Identification of Small Molecule Inhibitors That Reduce Invasion and Metastasis of Aggressive Cancers

Transformed epithelial cells can activate programs of epithelial plasticity and switch from a sessile, epithelial phenotype to a motile, mesenchymal phenotype. This process is linked to the acquisition of an invasive phenotype and the formation of distant metastases. The development of compounds that block the acquisition of an invasive phenotype or revert the invasive mesenchymal phenotype into a more differentiated epithelial phenotype represent a promising anticancer strategy. In a high-throughput assay based on E-cadherin (re)induction and the inhibition of tumor cell invasion, 44,475 low molecular weight (LMW) compounds were screened. The screening resulted in the identification of candidate compounds from the PROAM02 class. Selected LMW compounds activated E-cadherin promoter activity and inhibited cancer cell invasion in multiple metastatic human cancer cell lines. The intraperitoneal administration of selected LMW compounds reduced the tumor burden in human prostate and breast cancer in vivo mouse models. Moreover, selected LMW compounds decreased the intra-bone growth of xenografted human prostate cancer cells. This study describes the identification of the PROAM02 class of small molecules that can be exploited to reduce cancer cell invasion and metastases. Further clinical evaluation of selected candidate inhibitors is warranted to address their safety, bioavailability and antitumor efficacy in the management of patients with aggressive cancers.

Abstract 3768: Targeting of epithelial-to-mesenchyme transition by a novel small molecule inhibitor attenuates prostate and breast cancer invasiveness and bone metastases

Transformed epithelial cells can activate embryonic programs of epithelial plasticity and switch from a sessile, epithelial phenotype to a motile, mesenchymal phenotype also referred to as epithelial-to-mesenchymal transition (EMT). EMT is associated with poor prognosis in patients with osteotropic cancers. E-cadherin (CDH1) is an essential homotypic cell adhesion molecule that is often down regulated during this process.

EMT-like processes are increasingly linked to therapy resistance and metastasis-initiating cells, thus providing the rationale for the development of novel small-molecule inhibitors that a) block the acquisition of an invasive phenotype in osteotropic cancer cells via EMT or b) revert their invasive, mesenchymal phenotype into epithelial phenotype (MET) by upregulation of CDH1 expression.

High throughput screening of >43,000 LMW compounds, followed by compound design & optimization in vitro led to the identification ten candidate therapeutic compounds. These compounds displayed significant inhibitory effects on cancer cell invasion (>80%) and induced E-cadherin (re)expression, most likely through interference with the binding of transcriptional repressors to the CDH1 E-box elements. We identified a unique compound, OCD155, can effectively and dose-dependently block the acquisition of an invasive phenotype in osteotropic prostate and breast cancer cells (PC-3M-Pro4luc2 and MDA-MB-231/Bluc). When tested in our in vivo models of prostate and breast cancer bone metastasis, treatment of mice with OCD155 strongly and dose-dependently inhibited skeletal metastasis (number of metastases, tumor burden) according to preventive and curative protocols. At the dosages tested, no adverse effects of OCD155 were observed (body weight, liver toxicity parameters). To the best of our knowledge, our studies are the first to demonstrate the efficacy of new small molecule EMT inhibitor in the treatment of experimental skeletal metastasis.

Citation Format: Jan Kroon, Onno van Hooij, Eugenio Zoni, Maaike van der Mark, Geertje van der Horst, Johan Tijhuis, Cindy van Rijt-van de Westerlo, Gerald Verhaegh, Henk Viëtor, Antoine Wellink, Peter Maas, Jack Schalken, Gabri van der Pluijm. Targeting of epithelial-to-mesenchyme transition by a novel small molecule inhibitor attenuates prostate and breast cancer invasiveness and bone metastases. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3768.

Detection of mutant NPM1 mRNA in acute myeloid leukemia using custom gene expression arrays

Mutations in the gene encoding nucleophosmin (NPM1) carry a prognostic value for patients with acute myeloid leukemia (AML). Various techniques are currently being used to detect these mutations in routine molecular diagnostics. Incorporation of accurate NPM1 mutation detection on a gene expression platform would enable simultaneous detection with various other expression biomarkers. Here we present an array-based mutation detection using custom probes for NPM1 WT mRNA and NPM1 type A, B, and D mutant mRNA. This method was 100% accurate on a training cohort of 505 newly diagnosed unselected AML cases. Validation on an independent cohort of 143 normal-karyotype AML cases revealed no false-negative results, and one false positive (sensitivity 100.0% and specificity 98.7%). Based on this, we conclude that this method provides a reliable method for NPM1 mutation detection. The method can be applied to other genes/mutations as long as the mutant alleles are sufficiently highly expressed.

Detection of CEBPA double mutants in acute myeloid leukemia using a custom gene expression array

Double (bi-allelic) mutations in the gene encoding the CCAAT/enhancer-binding protein-alpha (CEBPA) transcription factor have a favorable prognostic impact in acute myeloid leukemia (AML). Double mutations in CEBPA can be detected using various techniques, but it is a notoriously difficult gene to sequence due to its high GC-content. Here we developed a two-step gene expression classifier for accurate and standardized detection of CEBPA double mutations. The key feature of the two-step classifier is that it explicitly removes cases with low CEBPA expression, thereby excluding CEBPA hypermethylated cases that have similar gene expression profiles as a CEBPA double mutant, which would result in false-positive predictions. In the second step, we have developed a 55 gene signature to identity the true CEBPA double-mutation cases. This two-step classifier was tested on a cohort of 505 unselected AML cases, including 26 CEBPA double mutants, 12 CEBPA single mutants, and seven CEBPA promoter hypermethylated cases, on which its performance was estimated by a double-loop cross-validation protocol. The two-step classifier achieves a sensitivity of 96.2% (95% confidence interval [CI] 81.1 to 99.3) and specificity of 100.0% (95% CI 99.2 to 100.0). There are no false-positive detections. This two-step CEBPA double-mutation classifier has been incorporated on a microarray platform that can simultaneously detect other relevant molecular biomarkers, which allows for a standardized comprehensive diagnostic assay. In conclusion, gene expression profiling provides a reliable method for CEBPA double-mutation detection in patients with AML for clinical use.

Antenatal care in pregnancies at risk of alloimmune thrombocytopenia: report of 19 cases in 16 families

OBJECTIVE

To assess accuracy of a management program in patients at risk for alloimmune thrombocytopenia (NAITP) and to describe perinatal outcomes.

STUDY DESIGN

Nineteen fetuses at risk of thrombocytopenia were identified using obstetric history, HLA type of the mother and fetal phenotyping in cases where paternal heterozygozity for the offending antigen was present. Cordocentesis was timed according to obstetric history and performed with safety precautions to prevent haemorrhage. High dose intravenous gamma globulin (IVIG) was administered to the mother in cases with a fetal platelet count < 100 x 10(9)/l.

RESULTS

The platelet antagonisms were distributed as follows: HPA-1a in 15 patients, HPA-5a in two, HPA-3a in one, with one further woman who had antibodies against a private antigen. All multigravidas (N = 18) had previously given birth to an infant with NAITP and two of those infants had experienced severe bleeding. Two fetuses were negative for the offending antigen. The median and mean platelet count at first cordocentesis was 26 and 75 x 10(9)/l respectively (range 3-276). A total of 46 cordocentesis were carried out, of which 37 were followed by platelet transfusions. Bleeding complications were not observed. IVIG was administered to eight mothers and two fetuses responded. Nine infants were delivered by caesarean section (CS) and 10 vaginally at a mean gestational age of 37 weeks (range 34-41). The median and mean platelet count at birth was 141.5 and 140 x 10(9)/l, respectively (range 36-314). Ultrasound examination, both ante- and postnatally, revealed no intracranial haemorrhages. There was one procedure related neonatal death and one infant suffered from convulsions in the neonatal period due to a sinus thrombosis, possibly related to the platelet transfusions.

CONCLUSIONS

When obstetric history is taken into account cordocentesis in NAITP can be postponed. Safety recommendations described in this study allow cordocentesis without bleeding complications. However, our study does not support routine cordocentesis in patients with a history of NAITP. Both the risks of cordocentesis, and the lack of prospective data on the magnitude of the risk of intrauterine or peripartal bleeding, should be considered.