How epigenetics is moving from niche curiosity to clinical reality
Two decades ago, epigenetics was a niche field. Today it underlies FDA-approved cancer drugs, a growing menu of diagnostic tests, and a clinical pipeline of more than 2,000 clinical trials. In our recent CAS Insights webinar, Gene Expression, Edited: How Epigenetics is Changing Biomedical Science, co-produced with ACS Webinars, three panelists mapped how the field arrived here and where it's headed.
- Dr. Kavita Iyer (CAS) presented a landscape analysis derived from the CAS Content Collection™.
- Dr. Saverio Alberti (University of Messina, Italy) traced the mechanistic link between epigenetic regulation and genome instability.
- Dr. Jean-Pierre Issa (President and CEO, Coriell Institute for Medical Research) walked through the clinical implications.
A maturing field
Dr. Iyer opened with a landscape analysis of the epigenetic field derived from the CAS Content Collection™, which contains nearly 150,000 publications related to epigenetics. There's a steady rise over the last 20 years, with the most striking signal being in the patent literature, where publications nearly doubled between 2023 and 2025. This is a strong indicator of growing commercial interest.
Of the four core mechanisms (DNA methylation, chromatin remodeling, histone modification, and non-coding RNA), DNA methylation dominates by volume, but non-coding RNA is the fastest-growing area, with microRNA leading, long non-coding RNA emerging over the last decade, and circular RNA gaining momentum since 2019. The U.S. dominates the patent landscape, with much of the activity concentrated in precision diagnostics. On the therapeutic side, nChroma Bio is advancing a CRISPR-Cas-based epigenetic platform with its lead candidate CRM-1001 reaching Phase I/II trials.
The clinical pipeline reflects how quickly the field has matured. There are roughly 2,200 epigenetic clinical trials at clinicaltrials.gov and 13 FDA-approved drugs, dominated by HDAC and IDH inhibitors. Sixty-two percent of trials are for previously approved drugs being repositioned or combined, and the modality mix is diversifying beyond HDAC and DNMT inhibitors to include BET and KDM inhibitors, CRISPR-based silencers (such as TUNE-401 for chronic hepatitis B), epigenetic PROTACs, RIPTACs, and antisense oligonucleotides.
Epigenetics, genome stability, and the cancer connection
Dr. Alberti picked up the mechanistic thread, focusing on how DNA methylation and histone methylation drive genome instability and tumor progression. He started with a deceptively simple observation: the deamination of 5-methylcytosine to thymine is the most frequent mutation in the human genome. Epigenetic marks aren't a parallel layer of regulation. They feed directly into the mutational machinery.
His group's selection experiments showed that DNA methylation comes in two flavors: one tight and immovable (like the methylation locking down HLA class I genes in trophoblast), and one flexible, where cellular selection can shift expression. The flexible kind is the one cancer exploits. Mutated p53 (present in roughly half of all human cancers) turned out to be a major regulator of cytosine methylation levels, which drives the gene amplification that fuels tumor growth.
That principle ran through the rest of his talk. Two-thirds of the genes involved in body-plan development are also implicated in cancer. The major players in DNA repair (BRCA1, BRCA2, p53, MYC, CHK1, CHK2, ATM, ATR) are all oncogenes. The same chromatin opening that allows repair proteins to access damaged DNA also exposes the genome to corruption. Cancer hijacks systems that evolution built for survival and uses them for unchecked growth. Dr. Alberti's group leveraged this insight to identify a seven-gene panel that drives breast cancer progression.
From mechanism to clinic
Dr. Issa carried the story into the clinic. Epigenetics, he explained, plays three distinct but mechanistically related roles in the body: defining cellular identity (Waddington's 1950s framing), allowing phenotypic variation between genetically identical individuals, and silencing the "dark matter" of repetitive elements. All three go wrong in cancer.
On the biomarker side, the most clinically useful application today is tumor classification. Most prominently, the use of DNA methylation patterns to type brain tumors from very small samples, now increasingly a standard of care. SEPT9 methylation in plasma and the multi-marker Cologuard stool test are FDA-approved tools for colon cancer screening, and cell-free DNA methylation panels are advancing for early detection and recurrence monitoring.
On the therapeutic side, the field traces back to the discovery that the cytosine analogs azacitidine and decitabine (originally developed as chemotherapy) are powerful DNA methylation inhibitors. Both are now standard-of-care for hematologic malignancies. Dr. Issa shared two surprises from his own lab's screening work: a class of calcium channel modulators turned out to have unsuspected epigenetic activity, and a natural-compound screen inspired by the longevity difference between queen bees and worker bees (driven by epigenetic compounds in royal jelly) yielded the first known CDK9 kinase inhibitor with epigenetic activity.
He also offered a critique of how the field tests these drugs. In his first decitabine clinical trial, doses 10 to 15 times lower than the conventional maximum produced more responses, not fewer. Epigenetic drugs, he argued, need to be dosed for target engagement rather than maximum tolerated toxicity. Additionally, they have rarely been tested in chemotherapy-naive solid-tumor patients, which may be more a problem of testing than of biology.
Aging, plasticity, and a call for skepticism
All three talks discussed that the epigenome changes with age, and not just in cancer. Dr. Issa's group showed that the rate at which the epigenome drifts correlates with organismal lifespan (fast in mice, slow in humans). The underlying mechanism appears to be random errors accumulating in stem cells over time, generating diversity that can both fuel cancer evolution and degrade normal tissue function. The rate can be slowed by caloric restriction (in mice and primates, at least) and accelerated by chronic inflammation and microbiome disruption.
In closing, Dr. Issa pushed back on a phrase that gets attached too easily to epigenetics: plastic.
Cellular identity, X-chromosome inactivation, and CpG-island methylation are exquisitely stable. Some mechanisms (histone modifications, sparse non-promoter methylation) are more dynamic and may underlie phenomena like transient chemotherapy resistance. However, not every epigenetic state is plastic, and conflating them is one of the field's recurring sources of confusion.
Final thoughts
The three closing reflections captured where the field sits today. Dr. Iyer noted that epigenetics has shifted from niche curiosity to a tractable druggable space, with CRISPR-Cas epigenetic platforms among the most exciting near-term developments. Dr. Alberti pointed to cancer cell heterogeneity (itself driven by epigenetic variation) as the next major frontier for understanding and treating tumors. Dr. Issa, drawing on 30 years in the field, added that much of what circulates as "epigenetic" is speculation rather than data, and a healthy dose of skepticism is essential when reading new claims.
Watch the full webinar
To hear directly from Dr. Iyer, Dr. Alberti, and Dr. Issa, including the full landscape analysis, mechanism slides, and Q&A, watch the recording on demand via ACS Webinars.
For more information, see the CAS Insights Report, The future of epigenetics: Emerging technologies and clinical applications.
