ASCO Now Supportive of Functional Precision Medicine: What Oncologists Should Know

For more than two decades, many oncologists have associated the American Society of Clinical Oncology (ASCO) with opposition to ex vivo functional drug testing. That landscape has now changed. In July 2026, ASCO issued a Clinical Notice with an unusually clear statement:

“ASCO officially clarifies its support for the advancement of functional precision medicine (FPM) to improve clinical outcomes for patients with cancer.” [1]

At the same time, ASCO formally archived its 2004 assessment and 2011 update on chemotherapy sensitivity and resistance assays, clarified that they no longer represent active ASCO policy, and stated that they should not be used to guide clinical or insurance-coverage decisions regarding modern functional precision medicine.  

In fact, ASCO states that the functional testing available today is fundamentally different from the assays evaluated two decades ago. Modern platforms can use improved tissue-processing methods, three-dimensional cultures, and clinically relevant measurements of treatment response.  

Randomized trials have also moved the evidence beyond analytical plausibility: assay-guided treatment improved median progression-free survival from 3 to 11 months in platinum-resistant ovarian cancer and median overall survival from 7.5 to 12 months in recurrent glioblastoma.[2,3] Interestingly, just by guiding the choice of already accepted guideline-compliant standard of care treatments.  

These studies demonstrate that measuring drug response directly in a patient's live tumor can significantly improve patient outcomes and platforms that can test the whole spectrum of legacy chemotherapies to the latest targeted therapies may be even more effective in identifying the most effective therapy for cancer patients.

The NCI is now pushing functional precision medicine forward

Only three weeks after ASCO's Clinical Notice, National Cancer Institute (NCI) Director Anthony Letai, MD, PhD, devoted an NCI Cancer Currents article to functional precision medicine.  His description of the underlying concept was strikingly straightforward:

“If you want to know whether a drug will work, why not expose a person’s living cancer cells directly to the therapy…” [4]

Letai noted that several NCI-Designated Cancer Centers are already conducting feasibility studies and clinical trials using functional precision medicine and specifically highlighted ASCO's recent support for advancing the field. And the NCI has gone beyond commentary. In July 2026, it convened a dedicated workshop bringing together academia, biotechnology, pharmaceutical companies, regulators, and patient advocates to accelerate translation of functional precision oncology into clinical practice.

Where functional profiling may be useful

Functional profiling deserves consideration when:

• a patient is already undergoing a resection or biopsy that can provide viable tumor tissue; 

• disease has progressed following standard therapy; 

• several reasonable treatments are available without a clear evidence-based hierarchy; or

• additional patient-specific evidence could help distinguish among chemotherapy, targeted therapies, off-label treatments, or clinical-trial options.

In short, pathology identifies the disease, genomics and other biomarkers provide validated rationales for potential targets, and guidelines describe reasonable and cost-effective evidence-based options. 

Functional precision medicine adds something different: empirical evidence showing how the individual patient's living tumor actually responds when exposed to selected treatments.

Choosing a platform

Not all functional profiling approaches are equivalent, so oncologists may want to consider three practical aspects:

How well does the assay preserve and reflect the patient's tumor? Native 3D tumor models preserve more of the original tumor architecture and microenvironment than expanded organoids, while both are biologically more physiologically relevant than conventional single cell cultures.

What is actually measured? Cancer treatments do not all work the same way. Many functional tests look mainly at whether a drug quickly kills tumor cells (cytotoxicity). That works well for many chemotherapies such as carboplatin or doxorubicin. But it can miss drug effects of drugs that work mainly by stopping cancer cells from growing (antiproliferation) such as gemcitabine, irinotecan, and many novel target therapies. Thus, tests that measure both tumor-cell killing and growth suppression can not only evaluate a broader range of treatment options but may be more accurate in evaluating their potential clinical benefit.

Can results be returned in time to guide treatment? Most functional profiling assays can provide results within about 7–10 days. Some approaches, however, require an additional culture or expansion step which can extend turnaround time to several weeks. Thus, oncologists should also consider whether the expected turnaround time fits the patient’s clinical situation.

For practical clinical use, the ideal functional profiling platform therefore preserves the patient's native tumor biology as much as possible, measures complementary treatment effects, and returns results quickly enough to guide the next treatment decision.

What has changed for Oncologists?

ASCO's previous assessments are no longer an argument against modern functional profiling. Instead, ASCO now explicitly supports advancing functional precision medicine, while the NCI is actively working to move the field toward broader clinical implementation. For an oncologist facing a difficult treatment decision, this creates an important opportunity: 

When several treatments are medically reasonable, functional profiling can provide additional patient-specific evidence, direct observation of how that patient's live tumor responds to those therapies.

Thus, if a patient asks about functional profiling, or if additional evidence could help distinguish among otherwise reasonable treatment options, modern functional precision medicine deserves consideration.

References

1. American Society of Clinical Oncology. ASCO Clinical Notice: ASCO Clarification on the Status of Functional Precision Medicine (FPM). July 14, 2026.

2. Herzog TJ, et al. NPJ Precision Oncology. 2023;4:101025.

3. Ranjan T, et al. Cell Reports Medicine. 2025;9:86. 

4. Letai A.Could Functional Precision Medicine Be the New Precision Oncology? National Cancer Institute. August 6, 2026.