A spinal fluid test may show if treatment is working
Original title: Cerebrospinal fluid and plasma circulating tumor DNA dynamics as a biomarker of response during trastuzumab deruxtecan treatment in patients with breast cancer with leptomeningeal disease.
How far along is this research?
- Lab cells
- Animals
- Review
- Tested in people
This was tested in people. That is the most reliable kind of research we share.
It was tried in a small group of people in a trial, not in everyday care.
The short version
A test on spinal fluid may show early whether a drug is helping.
What was studied. Doctors tested spinal fluid and blood from seven patients in a trial of the drug trastuzumab deruxtecan. All had breast cancer that had spread to the lining of the brain and spinal cord.
What they found. Tumor DNA was found in the spinal fluid of every patient at the start. In blood it was found in only two of six samples at the start. Spinal fluid tumor DNA dropped within 1 to 2 cycles of the drug, and those drops went along with longer control of the disease on scans.
What this means, and what it doesn't
What it could mean: A spinal fluid test might one day tell your care team early if a drug is working. That could mean less waiting and guessing between scans. Blood tests looked less useful for disease in the brain lining.
What it doesn't mean: This is not a new treatment and it is not a cure. It was a small study of seven patients, done to see if the test works at all. The test is not part of normal care, and your doctor cannot order it this way today. It also cannot say how any one person will do. Larger studies are needed first.
Source: PubMed, October 13, 2026 · Read the original
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