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Testing Drugs on Living Cancer Cells: What NCI Means by Functional Precision Medicine
NCI's director has described an approach that exposes a person's own living cancer cells to drugs to see what happens. Here is what that would involve, what stands in the way, and why it is not available today.
Original commentary from the Cancer Explained editorial team.
Please note: this page is educational only — it is not medical advice, and it does not speculate about anyone’s health beyond reliable public reporting. For questions about your own health, talk with your healthcare team.
Most of what is called precision medicine in cancer today works by reading. A sample of the tumor is tested. The genes and proteins in it are read. If a known fault turns up, there may be a drug aimed at that fault.
NCI director Anthony Letai wrote a Cancer Currents post on the National Cancer Institute's site. He described a different idea. He put the question simply: "If you want to know whether a drug will work, why not expose a person's living cancer cells directly to the therapy and observe what happens?"
That approach is called functional precision medicine. This page explains what it would mean. Just as important, it explains what it does not mean for anyone being treated today.
Reading the tumor versus testing it
Today's approach is the reading one. NCI describes precision medicine as "an approach to medical care in which disease prevention, diagnosis, and treatment are tailored to the genes, proteins, and other substances in your body." NCI says that in cancer care it means "using biomarker and other tests to select treatments that are most likely to help you, while at the same time sparing you from getting treatments that are not likely to help."
The functional idea adds a step. Take living cancer cells from the person. Put possible drugs on them. Then watch which ones actually kill the cells. Letai compares it to what labs already do with germs. They grow the sample, try different antibiotics on it and see which one works.
He notes the approach was attempted in the 1980s and 1990s. In his view, two things have changed since then. There are now hundreds of approved cancer drugs worth testing. And there are newer tools to make sense of the results, such as single-cell analysis and artificial intelligence.
Why it is not available at the clinic
The post describes an NCI workshop in July 2026. Three obstacles came out of it. They are worth knowing. Each one is a reason this is not something to ask for next week.
The cells are usually already dead. Biopsy samples are usually put into formalin. This preservative kills cells right away. It is what makes standard lab testing of tissue possible. Testing drugs on cells means keeping some tissue alive instead. That has to be done in a way that is ethical and does not harm the diagnosis.
Labs do not yet do it the same way. Labs would need shared rules for handling, shipping and storing living samples. Then a result in one lab would mean the same as a result in another.
Coverage and guidelines have not caught up. Insurance and medical guidelines would need to accept such tests. They would also need a plan for when a result points to a drug not approved for that cancer.
Several NCI-designated cancer centers are running early studies to see if it can work. The post says routine use for hard-to-treat cancers may be possible in about five years. In research terms, that is a goal, not a schedule.
What this does not mean
- It is not a test anyone can ask for as part of standard care. It is being studied. The obstacles above are the reason.
- It is not a replacement for genomic testing. Biomarker testing on tumor tissue is the established route today, and NCI's guidance on it is unchanged.
- It does not promise a right answer. NCI's warnings about precision medicine still apply. "Biomarker tests don't help everyone who gets them." Cancer cells in one tumor are not all the same. And a test is "a snapshot of the changes at one point in time."
- It is not evidence that any particular drug works. Cells in a dish are not a person. A drug that kills cancer cells on a plate has not been shown to help anyone. Clinical trials exist to find that out.
- It has nothing to do with commercial "personalised" tests sold direct to patients. This is NCI describing a research direction, not endorsing a product.
What to ask a healthcare team
- Has my cancer had biomarker or molecular testing, and what did it show?
- If standard options are running short, what clinical trials might I be eligible for?
- Is any research of this kind happening at a center I could reach?
- What would we use to judge whether a treatment is working for me?
How this article was prepared
An AI-assisted editorial system helped prepare this page. It used a Cancer Currents message from the National Cancer Institute's director on functional precision medicine. It also used NCI patient pages on precision medicine and targeted therapy. Each was opened on the source-check date shown above. No named medical reviewer has reviewed it unless one is listed.
Cancer Explained is published by the National Cancer Information Foundation. It is not medical advice and does not suggest a test or treatment.
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Put the story in context
Prevention, possible warning signs, screening, and diagnosis
This story relates to Precision medicine and biomarker testing. The information below is general: it does not reveal anything else about a public person’s health, and not every point applies to every cancer. Personal advice depends on age, symptoms, family history, exposures, and medical history.
Prevention and risk reduction
Not every cancer can be prevented. Avoiding tobacco, protecting skin from ultraviolet radiation, limiting alcohol, staying active, and receiving recommended HPV or hepatitis B vaccination can lower the risk of certain cancers. A risk factor is not a prediction or a cause in one individual.
Symptoms and possible early signs
Possible signs vary and are often caused by conditions other than cancer. Changes worth discussing include a new lump, unexplained bleeding or weight loss, a persistent cough, lasting bowel or bladder changes, a changing skin spot, or symptoms that persist or worsen. Some early cancers cause no symptoms.
Screening and early detection
Screening looks for certain cancers before symptoms begin. Recommended tests exist only for some cancers and depend on age and risk. Screening can have benefits and harms; it is not the same as evaluating a new symptom, and there is no single routine scan or blood test that reliably screens for every cancer.
How cancer is diagnosed
Diagnosis may involve a history and exam, imaging, laboratory tests, and often a biopsy. Pathology can identify the cancer type and may test biomarkers that guide treatment. Symptoms, screening results, tumor markers, or online stories alone cannot confirm cancer.
A public story may encourage questions, but it should not be used to estimate your risk or choose testing. Contact a healthcare professional about a persistent or concerning change. Seek urgent care for severe or rapidly worsening symptoms.