The breakthroughs in genomic testing give the promise of an understanding of the unique biology of an individual patient’s cancer. Tumor profiling, which combines test results from techniques such as immunohistochemistry (IHC), fluorescent in situ hybridization (FISH), polymerase chain reaction (PCR) and next-generation sequencing (NGS), is becoming increasingly available to oncologists. The proliferation of these technologies, while exciting, presents several challenges to widespread adoption in the clinic. HTG Molecular Diagnostics, Inc. is focused on delivering on the promise of these tumor profiling breakthroughs through reduced usage of precious tissue specimens, platform consolidation, and optimization of testing efficiency.
Challenges In Tumor Profiling Today
Challenge #1: low tissue availability for tumor profiling
Most tumor profiling testing today is performed on formalin-fixed paraffin-embedded (FFPE) tissue samples. Historically, five to ten slides in total were consumed in the complete diagnostic workup for each tumor. With the advent of new molecular techniques there are additional demands for tissue, and the molecular tests on the market today require much more than a single slide. For example, in order to effectively manage the treatment of advanced non-small cell lung cancer (NSCLC) patients, oncologists need to know the histological subtype of the tumor, the EGFR mutation status, and the ALK translocation status. If a local laboratory sends specimens to centralized laboratories for all three of these characterizations, as much as 100 microns (20 unstained FFPE slides) of tumor tissue may be required.
The growing number of specialized tumor-profiling tests, and their appetite for FFPE tissue, is in direct conflict with the trend towards smaller, less-invasive testing approaches. Large surgical resections are giving way to core needle biopsies and fine-needle aspirates.
Challenge #2: platform proliferation
In NSCLC, it is common for each test (Histology, EGFR, ALK) to be performed using a different testing methodology such as IHC, sequencing, and FISH, respectively. Because the sample is split and the results are aggregated later, a complete report cannot be compiled until the results from all different testing methodologies have been reported.
Challenge #3: inefficiencies in testing
Today, every molecular diagnostic test for FFPE tissue (with the exclusion of FISH) requires extraction of nucleic acids. Extraction of nucleic acids from FFPE tissue is a multi-step complex technique requiring multiple manual pipetting procedures by highly trained molecular technicians, and several of these manual steps require technician wait time as the samples are being centrifuged or column-separated. Because the extraction process requires the isolation of nucleic acids from other cellular material, each separation step results in partial specimen loss as well the introduction of biases as the losses are not equal across all nucleic acids being extracted.
Solution #1: preservation of precious tumor tissues
The HTG Edge platform enables multi-parameter tumor profiling on a single platform from exceedingly small FFPE specimens.
The sample input for sequencing-based HTG assays is a single 5 micron FFPE tissue slide. HTG envisions a single tumor profiling product that provides histological classification of the tumor (squamous versus nonsquamous), DNA mutation status (including EGFR), and gene rearrangement status (including ALK) from a single unstained slide. Allowing for an H&E to aid in macrodissection of the tumor cells, only 10 microns of tissue thickness (2 slides) will be required.
We believe that the HTG approach creates opportunities for new treatment approaches in cancers where initial diagnostic biopsies do not yield sufficient tissue for current tumor profiling methods.
Solution #2: platform consolidation
HTG’s chemistry allows consolidation of multiple tumor profiling techniques to a single platform with a greatly simplified workflow. Testing capabilities of the platform, in various stages of research and development, include:
- DNA mutations
- RNA expression
- Gene fusions and rearrangements
- Protein expression
- Copy number variation
In lung cancer, we envision the consolidation of histological classification, DNA mutation status (including EGFR), and gene rearrangement status (including ALK) to a single testing workflow:
Solution #3: testing efficiencies
HTG assays do not require extraction of nucleic acids. Our customers simply macro-dissect the area of interest from an unstained slide, lyse the sample using the proprietary HTG lysis buffer, and load the sample on the automated processor. This workflow eliminates the multiple manual steps associated with conventional molecular techniques, dramatically reducing technician time and proficiency requirements.
HTG’s Vision For Tumor Profiling
We believe there is significant and growing demand for improvement of tumor profiling through reduced usage of precious tissue specimens, platform consolidation, and optimization of testing efficiency. Lung cancer is an area in which we are initially focused, and we plan to develop a single solution that provides testing for:
- Fusions and rearrangements (including ALK)
- Hotspot mutations (including EGFR)
- Histology classification
Our broader approach to tumor profiling includes solutions for breast, lung, prostate, colon and thyroid cancers and may include testing for microRNA expression.
 Genomic Health OncotypeDX Breast http://breast-cancer.oncotypedx.com/en-US/Professional-Invasive/Ordering/~/media/Files/ODX-Breast/GHI020-INTPathologyReport.pdf
NanoString Prosigna http://ltd.aruplab.com/Tests/Pub/2010248
Foundation Medicine FoundationOne http://www.foundationone.com/docs/FoundationOne_specimen-preparation-instructions.pdf
LabCorp HistoPlus http://www.genecentric.com/wp-content/uploads/2013/01/HistoPlus-Lung-Cancer.pdf
Qiagen Therascreen EGFR test http://www.legacyhealth.org/for-health-professionals/refer-a-patient/laboratory-services/test-table/egfr-mutation-analysis-by-pcr.aspx
Vysis ALK FISH https://www.labcorp.com/wps/wcm/connect/IntOncologyLib/integratedoncology/home/our+services/oncology+testing/alk-testing