For years, it has been common practice to analyze tissue biopsies from cancer patients by routine FFPE immunohistochemistry (IHC). Yet, with the advent of precision medicine, oncology is increasingly dependent on molecular testing to determine the most appropriate treatment.
In an oncology setting, molecular testing typically involves dissecting tissue from pathology slides for analysis by next-generation sequencing (NGS) or PCR. However, current tissue dissection methods present challenges associated with sample impurity, poor yield, or incompatibility with automation—all of which can impact the accuracy and completeness of downstream results.
The AVENIO Millisect System semi-automates precise FFPE tissue dissection to increase tumor yield from complex tumors >250 µM in diameter and minimize contamination by non-desired tissue. This enhanced precision may translate to a reduction in false-negative results for more actionable tumor insights, while the digitally assisted workflow ensures that sample dissection is both consistent and traceable.
Current tissue dissection methods are widely recognized as being either too crude for precise molecular analyses or too complex for frequent clinical use. At one end of the scale, manual dissection is a familiar and inexpensive method that provides acceptable end results in cases where the sample mainly comprises whole tumor.
However, manual dissection is labor intensive and lacks precision, which can lead to contamination of samples with adjacent normal tissue. Manual dissection is also prone to inconsistency, especially for small (<300 µm) or heterogeneous target areas. A significant percentage of samples harvested by manual dissection are rejected following genetic analysis, likely due to insufficient yield and quality of tumor cells.
Laser capture microdissection (LCM) is at the other end of the scale, allowing for isolation of areas of interest as small as a single cell. But while LCM is high in precision and resolution, it is unsuitable for routine clinical use since it is low-throughput and relatively time consuming.
Further shortcomings of LCM are that it is both complicated and expensive. This method also risks losing precious sample material due to burning, lack of adherence, or degradation. For these reasons, a better tissue dissection method is required by labs wishing to perform NGS or PCR on tumor regions of interest.
The AVENIO Millisect System is a benchtop instrument that overcomes the many limitations of current tissue dissection methods. The compact system—comprising the instrument (Figure 1), single-use plastic milling tips (available in three different blade sizes), and software—enables precise and consistent recovery of tissue regions of interest for molecular pathology.
Figure 1. AVENIO Millisect Tissue Dissection System.
To initiate a tissue dissection workflow, molecular pathology labs simply load up to four slides (one stained, annotated reference slide and three unstained serial slides) on to the stage and prompt the AVENIO Millisect System to capture pre-dissection digital images. The digital software then enables alignment and mapping of the reference image’s annotated region(s) onto the unstained slides such that a dissecting path is computed automatically.
Next, the AVENIO Millisect System loads an appropriately sized milling tip (selected by the end user and loaded on to the instrument deck) and fills it with dissection fluid. The milling tip then moves to the dissecting position, where it lowers on to the slide. As the rotating cutting blade moves over the region of interest, it displaces the tissue, which is aspirated into the lower portion of the milling tip.
When the dissection is complete, another set of high-resolution images is captured to document that the region of interest has been milled from the unstained serial slide(s). The displaced tissue is then dispensed from the milling tip into a collection vial for further analysis by PCR or NGS. The digital software ensures complete traceability and reporting throughout the dissection process, with every detail of the job being documented for later review.
Using the efficient, consistent workflow described above, the AVENIO Millisect System semi-automates precise tissue dissection to increase tumor yield and reduce collection of non-desired tissue in downstream sequencing or PCR. Published studies have demonstrated its ability to increase actionable tumor information and reduce false negative results.1,2 To learn more, visit the Roche Sequencing website.
1. Geiersbach, K., et al 2016. Cancer Genet. 209:42-49
2. Gustafson, H., et al 2016. Integr Cancer Sci Therap. 3(4):500-503