HER2 testing by Micro-array, resolving tough diagnostic questions
Accurate reporting of HER2 (ERBB2) gene copy number status in newly diagnosed breast and gastric cancers is critical for selecting patients predicted to respond to anti-HER2 therapy. In current clinical practice, tumors are evaluated for HER2 positivity by protein-based immunohistochemistry (IHC) and/or chromosome 17-based fluorescence in situ hybridization (FISH). In the majority of cases, these testing modalities provide a clearly actionable “positive” or “negative” answer. However, in an estimated 10- to 20% of breast and gastric cancers, both IHC and FISH tests are reported as “equivocal” providing the clinician with no guidance as to the potential effectiveness of targeted anti-HER2 therapy for the patient.
Array-based comparative genomic hybridization (aCGH) provides an alternative molecular testing method for determining HER2 status in breast cancer and resolution of these tough double equivocal specimens. This DNA-based technology uses fluorescently labeled test and reference DNA probes hybridized to a DNA microarray to produce a high-resolution view of the HER2 amplicon in context of the entirety of chromosome 17. The p arm, q arm, and centromere region are subjectively and objectively visualized by CGH revealing, in many cases, complex chromosome 17 rearrangements such as centromere amplification, p arm loss, and additional amplified loci.
PacificDx is pleased to offer HI-RES HER2 testing by aCGH as a tech-only service to the greater clinical community. Please contact us at http://pacificdx.com/contacts/ or 949-812-6944 for referral information.
PacificDx presenting at the Association of Genetic Technologists 41st Annual Meeting
PacificDx employees Aditi Khurana and Dr. Cynthe Sims recently attended the 41st Annual Meeting of the Association of Genetic Technologists. The meeting provided PacificDx with the opportunity to present three posters covering PacificDx’s latest developments at the laboratory. Dr. Sims presented results and information about PacificDx’s HI-Res HER2 test for Breast Cancers that are equivocal for both IHC and FISH testing. This unique assay provides a clear resolution to these difficult clinical cases. Ms Khurana presented two posters, the first one discussing the clinical validation of a Novel four color PDGFR/KIT/RET/CC4 FISH probe set that can be utilized to detect both RET gene rearrangements and PDGFR/KIT amplifications on the same slide; efficiently utilizing limited FFPE material. The second poster explained the use of tools from an open source Bioinformatics tool called Galaxy for the development and validation of an in house pipeline to analyze NGS data.
The 41st AGT meeting was geared towards topics of laboratory techniques, new developments in the clinical genomic testing and technical workshops where professionals could exchange ideas regarding latest developments and challenges in their labs. The meeting was an excellent opportunity for professional development and Dr. Sims volunteered her expertise in molecular sciences to serve as a microarray workshop moderator and as a round-table discussion leader regarding the topic of clinical microarrays.