# Unmask hidden antigens with a short epigenetic course before immunotherapy

Source: https://onco.cc/ideas/idea-bio2-epigenetic-priming-cold-tumours/  
OnCo record `idea-bio2-epigenetic-priming-cold-tumours` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Low doses of drugs that change how DNA is packaged can make cancer cells display more of what marks them as abnormal, potentially waking up immunotherapy in cold tumours.

## Summary

Hypomethylating agents de-repress endogenous retroviruses and cancer-testis antigens and induce viral mimicry through interferon signalling, and HDAC or EZH2 inhibition can restore antigen presentation machinery. Trials combining epigenetic agents with checkpoint blockade in colorectal and lung cancer have been mostly small, with variable schedules and no pharmacodynamic gating. Dose and schedule, rather than the concept, are probably the reason for inconsistency.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: A pharmacodynamically gated low-dose epigenetic priming schedule, confirmed by an interferon signature and antigen re-expression on biopsy, raises response to checkpoint blockade in mismatch-repair-proficient colorectal cancer above the near-zero baseline.
- Rationale: Viral mimicry is a well-replicated mechanism in human cells, and the constraint is achieving priming exposure without lymphotoxicity. Gating escalation on a measured interferon response is the discipline previous combination trials lacked.
- Proposed test: A phase 1b with mandatory paired biopsies where dose escalation is gated on interferon signature induction rather than tolerability alone, and expansion only if priming is demonstrated.
- Maturity: early-clinical
- Actor: research

## Sources

- Bottleneck evidence (No one can predict who responds to immunotherapy): Haslam & Prasad (JAMA Network Open 2019): https://doi.org/10.1001/jamanetworkopen.2019.2535

## Connected records

- ideas: [Making microsatellite-stable colorectal cancer immunotherapy-responsive](https://onco.cc/ideas/idea-immunotherapy-mss-crc/)
- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/)
- technologies: [DNA methylation profiling](https://onco.cc/technologies/methylation-profiling/), [Epigenetic drugs (HDAC, DNMT, EZH2, IDH, menin, BET)](https://onco.cc/technologies/epigenetic-drugs/), [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- targets: [EZH2](https://onco.cc/targets/ezh2/)
- drugs: [Azacitidine](https://onco.cc/drugs/azacitidine/), [Decitabine + cedazuridine (oral)](https://onco.cc/drugs/decitabine-cedazuridine/), [Mevrometostat](https://onco.cc/drugs/mevrometostat/)
- terms: [Hot vs cold tumours](https://onco.cc/terms/cold-vs-hot/), [Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)](https://onco.cc/terms/msi/)
- bottlenecks: [Cold tumours and the immunosuppressive microenvironment](https://onco.cc/bottlenecks/b-tme-immunosuppression/), [No one can predict who responds to immunotherapy](https://onco.cc/bottlenecks/b-immunotherapy-response/), [Too many combinations to test](https://onco.cc/bottlenecks/b-combination-space/)
- key papers: [Estimation of the Percentage of US Patients With Cancer Who Are Eligible for and Respond to Checkpoint Inhibitor Immunotherapy Drugs](https://onco.cc/key-papers/paper-haslam-jama-netw-open/), [Expression of EZH2 and Ki-67 in colorectal cancer and associations with treatment response and prognosis](https://onco.cc/key-papers/paper-ezh2-colorectal-br-j-cancer-2009/)

---
JSON: https://onco.cc/api/v1/entities/idea-bio2-epigenetic-priming-cold-tumours.json