Molecular tumour boards and molecular diagnostics for patients with cancer in the Netherlands: experiences, challenges, and aspirations.

Advances in molecular tumour diagnostics and the number of targeted therapies increase rapidly. Molecular tumour boards (MTBs) are designated to interpret these data and provide clinical recommendations. Not all patients with cancer have access to advice of an MTB. We aimed to determine the current status, opportunities, and challenges of the organisation of MTBs in the Netherlands. We interviewed several stakeholders about their experiences with an MTB, using template analysis. Most clinicians and patient representatives underscore the significance of an MTB, because it can stimulate rational treatment options, enrolment in clinical trials, and interdisciplinary knowledge transfer. Health insurance companies and financial managers are concerned about increasing costs. Registries to assess the clinical benefit of MTBs, guidelines on quality control, financial agreements, and logistical resources are lacking. The national organisation of MTBs and a registry of molecular and clinical data are important issues to address.

Preserved genetic diversity in organoids cultured from biopsies of human colorectal cancer metastases.

Tumor organoids are 3D cultures of cancer cells. They can be derived from the tumor of each individual patient, thereby providing an attractive ex vivo assay to tailor treatment. Using patient-derived tumor organoids for this purpose requires that organoids derived from biopsies maintain the genetic diversity of the in vivo tumor. In this study tumor biopsies were obtained from 14 patients with metastatic colorectal cancer (i) to test the feasibility of organoid culture from metastatic biopsy specimens and (ii) to compare the genetic diversity of patient-derived tumor organoids and the original tumor biopsy. Genetic analysis was performed using SOLiD sequencing for 1,977 cancer-relevant genes. Copy number profiles were generated from sequencing data using CopywriteR. Here we demonstrate that organoid cultures can be established from tumor biopsies of patients with metastatic colorectal cancer with a success rate of 71%. Genetic analysis showed that organoids reflect the metastasis from which they were derived. Ninety percent of somatic mutations were shared between organoids and biopsies from the same patient, and the DNA copy number profiles of organoids and the corresponding original tumor show a correlation of 0.89. Most importantly, none of the mutations that were found exclusively in either the tumor or organoid culture are in driver genes or genes amenable for drug targeting. These findings support further exploration of patient-derived organoids as an ex vivo platform to personalize anticancer treatment.

Predicting clinical benefit from everolimus in patients with advanced solid tumors, the CPCT-03 study.

BACKGROUND: In this study, our aim was to identify molecular aberrations predictive for response to everolimus, an mTOR inhibitor, regardless of tumor type. METHODS: To generate hypotheses about potential markers for sensitivity to mTOR inhibition, drug sensitivity and genomic profiles of 835 cell lines were analyzed. Subsequently, a multicenter study was conducted. Patients with advanced solid tumors lacking standard of care treatment options were included and underwent a pre-treatment tumor biopsy to enable DNA sequencing of 1,977 genes, derive copy number profiles and determine activation status of pS6 and pERK. Treatment benefit was determined according to TTP ratio and RECIST. We tested for associations between treatment benefit and single molecular aberrations, clusters of aberrations and pathway perturbation. RESULTS: Cell line screens indicated several genes, such as PTEN (P = 0.016; Wald test), to be associated with sensitivity to mTOR inhibition. Subsequently 73 patients were included, of which 59 started treatment with everolimus. Response and molecular data were available from 43 patients. PTEN aberrations, i.e. copy number loss or mutation, were associated with treatment benefit (P = 0.046; Fisher's exact test). CONCLUSION: Loss-of-function aberrations in PTEN potentially represent a tumor type agnostic biomarker for benefit from everolimus and warrants further confirmation in subsequent studies.

Systematic analysis of chromatin interactions at disease associated loci links novel candidate genes to inflammatory bowel disease.

BACKGROUND: Genome-wide association studies (GWAS) have revealed many susceptibility loci for complex genetic diseases. For most loci, the causal genes have not been identified. Currently, the identification of candidate genes is predominantly based on genes that localize close to or within identified loci. We have recently shown that 92 of the 163 inflammatory bowel disease (IBD)-loci co-localize with non-coding DNA regulatory elements (DREs). Mutations in DREs can contribute to IBD pathogenesis through dysregulation of gene expression. Consequently, genes that are regulated by these 92 DREs are to be considered as candidate genes. This study uses circular chromosome conformation capture-sequencing (4C-seq) to systematically analyze chromatin-interactions at IBD susceptibility loci that localize to regulatory DNA. RESULTS: Using 4C-seq, we identify genomic regions that physically interact with the 92 DRE that were found at IBD susceptibility loci. Since the activity of regulatory elements is cell-type specific, 4C-seq was performed in monocytes, lymphocytes, and intestinal epithelial cells. Altogether, we identified 902 novel IBD candidate genes. These include genes specific for IBD-subtypes and many noteworthy genes including ATG9A and IL10RA. We show that expression of many novel candidate genes is genotype-dependent and that these genes are upregulated during intestinal inflammation in IBD. Furthermore, we identify HNF4α as a potential key upstream regulator of IBD candidate genes. CONCLUSIONS: We reveal many novel and relevant IBD candidate genes, pathways, and regulators. Our approach complements classical candidate gene identification, links novel genes to IBD and can be applied to any existing GWAS data.