Evaluating gene fusions in solid tumors - Clinical experience using an RNA based 53 gene next-generation sequencing panel.

Given the known association of gene fusions with solid tumor morbidity and the need to clarify the role of fusions in therapeutic, prognostic and diagnostic outcomes, we reviewed the positive yield rate for fusions in solid tumors using cases that were referred to our laboratory for clinical testing. We retrospectively evaluated results from 183 solid tumor samples that were received during a 24 month period for testing using the FusionSeq™ assay, an RNA-based Next Generation Sequencing (NGS) panel of 53 genes known to form fusions in solid tumors. Positive yield rate (actionable fusions) was evaluated for all samples tested, as a correlate for clinical utility. Twenty five fusions (actionable, variants of uncertain significance - VUS, and benign) were identified, of which 7 were classified as actionable gene fusions, resulting in an overall positive yield rate of ∼3.8% (7/183). Sixteen mostly novel fusions were classified and reported as VUSs. Five fusion events were classified as false positives, occurring due to mispriming or wild-type read through while 2 were classified as likely benign. Additionally 68% of fusions (17 of 25) detected in our study were present in prostate, colorectal, and gynecological cancers, suggesting that the frequency of fusions identified is dependent on specific tumor type. The high number of novel fusions identified highlights the potential for fusions in precision medicine.

Technical and Regulatory Considerations for Taking Liquid Biopsy to the Clinic: Validation of the JAX PlasmaMonitorTM Assay.

The standard of care in oncology has been genomic profiling of tumor tissue biopsies for the treatment and management of disease, which can prove to be quite challenging in terms of cost, invasiveness of procedure, and potential risk for the patient. As the number of available drugs in oncology continues to increase, so too does the demand for technologies and testing applications that can identify genomic alterations targetable by these new therapies. Liquid biopsies that use a blood draw from the diseased patient may offset the many disadvantages of the invasive procedure. However, as with any new technology or finding in the clinical field, the clinical utility of an analytical test such as that of the liquid biopsy has to be established. Here, we review the clinical testing space for liquid biopsy offerings and elucidate the technical and regulatory considerations to develop such an assay, using our recently validated PlasmaMonitorTM test.

Retrospective genotype-phenotype analysis in a 305 patient cohort referred for testing of a targeted epilepsy panel.

PURPOSE: Epilepsy is a diverse neurological condition with extreme genetic and phenotypic heterogeneity. The introduction of next-generation sequencing into the clinical laboratory has made it possible to investigate hundreds of associated genes simultaneously for a patient, even in the absence of a clearly defined syndrome. This has resulted in the detection of rare and novel mutations at a rate well beyond our ability to characterize their effects. This retrospective study reviews genotype data in the context of available phenotypic information on 305 patients spanning the epileptic spectrum to identify established and novel patterns of correlation. METHODS: Our epilepsy panel comprising 377 genes was used to sequence 305 patients referred for genetic testing. Qualifying variants were annotated with phenotypic data obtained from either the test requisition form or supporting clinical documentation. Observed phenotypes were compared with established phenotypes in OMIM, published literature and the ILAEs 2010 report on genetic testing to assess congruity with known gene aberrations. RESULTS: We identified a number of novel and recognized genetic variants consistent with established epileptic phenotypes. Forty-one pathogenic or predicted deleterious variants were detected in 39 patients with accompanying clinical documentation. Twenty-five of these variants across 15 genes were novel. Furthermore, evaluation of phenotype data for 194 patients with variants of unknown significance in genes with autosomal dominant and X-linked disease inheritance elucidated potentially disease-causing variants that were not currently characterized in the literature. CONCLUSIONS: Assessment of key genotype-phenotype correlations from our cohort provide insight into variant classification, as well as the importance of including ILAE recommended genes as part of minimum panel content for comprehensive epilepsy tests. Many of the reported VUSs are likely genuine pathogenic variants driving the observed phenotypes, but not enough evidence is available for assertive classifications. Similar studies will provide more utility via mounting independent genotype-phenotype data from unrelated patients. The possible outcome would be a better molecular diagnostic product, with fewer indeterminate reports containing only VUSs.

Genomic Profiling of Two Histologically Distinct Rare Urothelial Cancers in a Clinical Setting to Identify Potential Therapeutic Options for Treatment and Management of Disease.

Molecular profiling of urothelial cancers for therapeutic and prognostic potential has been very limited due to the absence of cancer-specific targeted therapies. We describe here 2 clinical cases with a histological diagnosis of an invasive sarcomatoid and a poorly differentiated carcinoma favoring urothelial with some neuroendocrine differentiation, two of the rarer types of urothelial cancers, which were evaluated for mutations in 212 genes for single-nucleotide variants and copy-number variants and 53 genes for fusions associated with solid tumors. In both cases, we identified variants in 2 genes, ARID1A and CDKN2A, indicative of the role of dysregulation of chromatin remodeling and cell cycle control as being common features of bladder cancer, consistent with the proposed model of tumorigenesis in these rare, highly aggressive pathological subtypes. The presence of a KRAS mutation in the poorly differentiated cancer and a TP53 mutation in the sarcomatoid tumor is indicative of a distinctive profile and adds a potential layer of molecular stratification to these rarer histological subtypes. We present a comparative analysis of the histological, clinical, and molecular profile of both cases and discuss the potential to delineate these tumors at the molecular level keeping in mind the possible therapeutic implications.