New Series of Molecular Diagnostic Reference Standards

Horizon Diagnostics, a division of Horizon Discovery, has launched a suite of genetically-defined fixed formalin, paraffin embedded (FFPE) cell line standards, containing defined stoichiometric ratios of the seven variants of the K-Ras oncogene, for which testing is required to determine individual drug treatment regimens for colorectal cancer patients.

The FFPE standards are launched following the company’s release of genetically defined genomic DNA (gDNA) standards. Whilst the gDNA controls were primarily designed to support the validation of new diagnostic assays, the FFPE standards more closely recapitulate the way in which tumor biopsies are embedded for testing, not only enabling controlling for assay sensitivity, but also for the bench-work processing of the biopsy.

According to Dr Paul Morrill, Commercial Director of the reagents division at Horizon Discovery, “variability in DNA extraction from tumor biopsies is currently a source of error in many diagnostic laboratories, and due to the lack of means of standardization, is a major cause of false negative and positive results. The availability of our genetically defined FFPE standards can help to identify false positive and false negative results when they occur, and thereby directly improve the clinical outcomes for patients. Quality assurance for cancer diagnostics is key to ensuring that the right drug is given to the right patient at the right time.”

The FFPE product launch forms part of a broader strategy by the company to develop a range of control reagents to support companion diagnostics in cancer and other disease areas. The FFPE standards, along with gDNA controls and FFPE tumor grafts, are designed to improve the accuracy of genetic testing across the full range of platform technologies from immunohistochemistry (IHC), to molecular, to cytogenetic based tests.

At the heart of these products lies Horizon Discovery’s precision gene-editing technology, which uses recombinant adeno-associated viral vectors to reconstitute gene mutations in human cell lines, just as they occur in patients. Having begun with a primary focus on modeling somatic point mutations (single base-pair substitutions) involved in the proliferation of malignancies, the company is now modeling more complex mutations such as fusion translocations.

Horizon’s ability to routinely engineer genetic mutations into a variety of tissue types in order to develop reference standards comes at a time when an increasing understanding of the molecular drivers of cancer is enabling the development of ‘targeted’ biological therapeutics. These targeted drugs implicitly require a patient’s tumor to be tested for the molecular markers corresponding to the drug, which in turn is driving the development of a large number of ‘companion’ diagnostic tests. As inhibitors for many of the major molecular pathways have already been developed, new agents increasingly target ‘rare’ mutations which occur in a small subset of patients with the particular disease. For example, Pfizer’s recently approved drug, Crizotinib, targets a mutation that is only present in 2-4% of non-small cell lung cancer patients. These rare mutations are equally hard to find in established cell lines or tissue samples, which poses a difficulty for diagnostic manufacturers who require biological material containing the mutation of interest to validate their diagnostic tests.

Mr Joshua Kapp, Business Development Manager, said: “The ability to accurately reconstitute rare mutations using our technology will become increasingly valuable as these mutations become harder to find in clinical samples. Furthermore, our ability to stoichiometrically define the percentage of mutant alleles in our control material represents a gold-standard for manufacturers to validate the sensitivity of their new assays, and for laboratories to apply routine quality controls down to individual batches.”

The suite of FFPE K-Ras mutation standards forms part of a more extensive panel of FFPE products covering additional mutations such as B-Raf, EGFR, PI3Ka and AKT1, all important markers in lung and colon cancer. The FFPE standards are supplied as sections in Eppendorf tubes, and each section contains a defined percentage of mutant alleles (50%).