# Flush dormant cells out of bone marrow, then kill them

Source: https://onco.cc/ideas/idea-bio2-cxcr4-mobilise-then-kill/  
OnCo record `idea-bio2-cxcr4-mobilise-then-kill` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Sleeping cancer cells hide in bone marrow where drugs cannot reach them. Pushing them into the bloodstream on purpose, then treating, might clear them.

## Summary

Disseminated tumour cells occupy the CXCL12-CXCR4 haematopoietic niche, which shields them from chemotherapy. Plerixafor is an approved CXCR4 antagonist used to mobilise stem cells. A deliberate mobilise-then-treat schedule (plerixafor followed within a day by an antibody-drug conjugate or T-cell engager while cells are in circulation) is testable with agents that already exist.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Plerixafor-induced mobilisation followed promptly by an antigen-directed agent reduces bone marrow disseminated tumour cell counts by at least 80% in patients who have detectable cells, versus the agent alone.
- Rationale: The same manoeuvre improves chemosensitivity in acute myeloid leukaemia trials of CXCR4 blockade. If niche protection is why adjuvant therapy fails to clear disseminated cells, breaking the niche should be measurable directly in a marrow aspirate.
- Proposed test: A single-arm mechanistic trial in breast cancer patients with marrow-positive disseminated cells: serial aspirates and CTC counts before and after plerixafor plus an approved ADC. Kill the idea if counts do not fall.
- Maturity: preclinical-evidence
- Actor: research

## Sources

- Bottleneck evidence (Metastasis is understood least and studied last): Dillekås et al., Are 90% of deaths from cancer caused by metastases? (Cancer Medicine 2019): https://doi.org/10.1002/cam4.2474

## Connected records

- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [Antibody-drug conjugate (ADC)](https://onco.cc/technologies/adc/), [MRD / molecular residual disease testing](https://onco.cc/technologies/mrd-testing/), [T-cell engagers (bispecific)](https://onco.cc/technologies/t-cell-engager/)
- terms: [Minimal / molecular residual disease (MRD)](https://onco.cc/terms/mrd/)
- bottlenecks: [Dormant cells and minimal residual disease](https://onco.cc/bottlenecks/b-dormancy-mrd/), [Metastasis is understood least and studied last](https://onco.cc/bottlenecks/b-metastasis-biology/)
- key papers: [Are 90% of deaths from cancer caused by metastases?](https://onco.cc/key-papers/paper-dillekas-cancer-med/)

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