Three sequencing methods tested on archival breast tumor DNA methylation

DNA methylation profiling can now be carried out on archived hospital tissue using three different sequencing approaches, according to a study published in Clinical Epigenetics. Researchers compared whole-genome bisulfite sequencing, enzymatic-methylation sequencing (EM-seq), and the biomodal duet multiomics solution evoC kit on residual triple-negative breast cancer tissue that had been formalin-fixed, paraffin-embedded, and macrodissected for clinical use.

Formalin-fixed, paraffin-embedded, or FFPE, tissue is a mainstay of retrospective molecular studies because it preserves tissue architecture and comes from extensive clinically annotated archives. The trade-off is chemical: the fixation process fragments and degrades nucleic acids, which often limits how much molecular information can be recovered from stored samples.

Newer enzymatic methods, including EM-seq and the evoC kit, use enzyme-based chemistry instead and have emerged as alternatives for methylation analysis.

The study team characterized all three methods on low-input FFPE residual samples from triple-negative breast cancer, an aggressive subtype that lacks targetable alterations. The authors note that triple-negative breast cancer carries a high risk of local and distant recurrence, with most metastatic progression occurring within three years of diagnosis.

The central finding is one of feasibility rather than a single winning method. The researchers report that applying all three sequencing approaches to low-input FFPE residual triple-negative breast cancer samples is feasible, meaning each chemistry produced usable data from degraded archival material.

Alongside feasibility, the study highlights method-specific trade-offs that should be weighed when selecting a sequencing strategy. Because the three approaches differ in chemistry, the choice among them affects how methylation and copy-number information can be extracted from limited, degraded DNA, although the published abstract does not detail the specific performance differences between the kits.

The authors conclude that these findings support a streamlined framework for combined genetic and epigenetic profiling of archival FFPE residual triple-negative breast cancer samples and for future cohort expansion.

The article was published on 11 September 2026 as an open-access research paper, with the shared early version subject to further edits before the final version of record.

Subject of Research: Comparing three DNA methylation sequencing methods on archival FFPE triple-negative breast cancer tissue

Article Title: A comparison of methods for analyzing DNA methylation from clinical archival macrodissected formalin-fixed paraffin-embedded tissue

Article References: Gopal, N. E. K., Dawe, M., Batra, H., Espin-Garcia, O., McCready, D., Bedard, P. L., Cescon, D. W., Pugh, T. J., & Done, S. J. (2026). A comparison of methods for analyzing DNA methylation from clinical archival macrodissected formalin-fixed paraffin-embedded tissue. Clinical Epigenetics. https://doi.org/10.1186/s13148-026-02239-1

Image Credits: AI Generated

DOI: 10.1186/s13148-026-02239-1

Keywords: DNA methylation, FFPE tissue, whole-genome bisulfite sequencing, EM-seq, evoC, triple-negative breast cancer, epigenetics, archival tissue, macrodissection, sequencing methods, comparison, methods