# Train the bone marrow to make better anti-tumour immune cells

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

## TL;DR

Certain vaccines and fungal sugars reprogramme the bone marrow so it produces more aggressive immune cells for months. That could be used before immunotherapy.

## Summary

Trained immunity (epigenetic reprogramming of haematopoietic progenitors by BCG or beta-glucan) produces durable changes in myeloid output and reduced tumour growth in mouse models, and BCG's efficacy in bladder cancer is the oldest immunotherapy in use. Priming the marrow before checkpoint therapy or cell therapy is a cheap, generic intervention that has never been formally tested in solid tumours.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Systemic beta-glucan or BCG priming before checkpoint blockade shifts circulating monocyte epigenetic and functional profiles and increases response rates in cold tumours.
- Rationale: The mechanism operates upstream, on progenitor cells, so it could change the whole myeloid compartment rather than one tumour. Both priming agents are cheap, widely available and have decades of safety data.
- Proposed test: A randomised window trial measuring monocyte functional and epigenetic reprogramming after priming, with tumour myeloid composition on biopsy as the mechanistic endpoint before any efficacy trial.
- Maturity: preclinical-evidence
- Actor: research

## Sources

- Bottleneck evidence (Cold tumours and the immunosuppressive microenvironment): Haslam & Prasad, Estimation of the percentage of US patients eligible for and responding to checkpoint inhibitors (JAMA Netw Open 2019): https://doi.org/10.1001/jamanetworkopen.2019.2535

## Connected records

- cancers: [Bladder & urothelial cancer](https://onco.cc/cancers/urothelial/), [Colorectal cancer](https://onco.cc/cancers/colorectal/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/), [Intravesical therapy (BCG, chemotherapy, devices, gene and viral therapy)](https://onco.cc/technologies/bcg-and-intravesical-therapy/)
- drugs: [Intravesical BCG](https://onco.cc/drugs/bcg-intravesical/)
- terms: [Hot vs cold tumours](https://onco.cc/terms/cold-vs-hot/)
- bottlenecks: [Cold tumours and the immunosuppressive microenvironment](https://onco.cc/bottlenecks/b-tme-immunosuppression/), [No incentive to repurpose cheap drugs](https://onco.cc/bottlenecks/b-generic-repurposing/)
- 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/)

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