ideasIdea
Flush dormant cells out of bone marrow, then kill them
Sleeping cancer cells hide in bone marrow where drugs cannot reach them. Pushing them into the bloodstream on purpose, then treating, might clear them.
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.
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.
What would test it
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
Who has to act
research
Cost to try
Medium ($1M to $50M)
Years to first evidence
7
Bottlenecks it attacks
- Metastasis is understood least and studied last · Metastasis causes about nine in ten cancer deaths but gets a small fraction of research money and almost no trials of its own.
- Dormant cells and minimal residual disease · After a 'successful' treatment, cells can sleep for years then relapse. We can barely detect them and cannot target them.