What the Trial Actually Did
The idea behind adaptive cancer therapy is counterintuitive enough that it needs stating plainly: give less of a drug, on purpose, and the cancer may take longer to become resistant to it.
The pilot study that put that idea into patients was run at Moffitt Cancer Center in men with metastatic castration-resistant prostate cancer, and reported in Nature Communications in 2017 by Jingsong Zhang, Jessica Cunningham, Joel Brown and Robert Gatenby. Moffitt describes it as a pilot trial in 17 patients. The 2017 paper reported an interim analysis of that cohort.
The dosing rule was specific. Patients took abiraterone until their PSA, a blood marker of prostate cancer activity, fell by more than 50 percent from baseline. Treatment then stopped. When PSA rose back toward baseline, treatment restarted, and the cycle repeated.
The reasoning comes from evolutionary biology rather than pharmacology. Tumors contain a mix of drug-sensitive and drug-resistant cells. Treating continuously at maximum dose kills the sensitive cells efficiently, which removes the competition holding the resistant ones back. Keeping a population of sensitive cells alive, the theory goes, keeps resistant cells in check. As Gatenby put it, current strategies applying therapy at maximum tolerated dose until progression "are often not evolutionarily optimal."
A practical side effect is that patients receive less total drug, which also lowers cost.
What the Numbers Show
This is where reporting on adaptive therapy frequently goes wrong, so the figures deserve care.
With standard continuous dosing, the 2017 paper cited radiographic progression occurring at a median of about 16.5 months.
In 2022, Moffitt reported updated results in eLife after four additional years of follow-up. Patients on adaptive dosing had a median time to cancer progression of 33.5 months, compared with 14.3 months for patients treated with standard continuous therapy until progression. Median overall survival was 58.5 months versus 31.3 months. Every patient in the standard-treatment group had progressed and died by the time of that report, while four patients on adaptive therapy remained alive with no evidence of progression.
The difference in time to progression is therefore roughly 19 months, not 40. Claims of a 40-month advantage circulate but do not match the published figures, and anyone encountering that number should treat it with suspicion.
Two limitations belong here rather than at the end. This was a pilot trial of a small number of patients, not a randomized study. And the comparison group was not created by randomly assigning men to one approach or the other, which is the design that allows a fair comparison.
The Published Objection
Adaptive therapy has an unusual feature for a widely discussed idea: a formal methodological critique published in the same journal as the original report.
In Nature Communications in 2021, a critique argued that the way the trial's results were reported and compared to other data did not support the conclusion being drawn. Its summary was blunt: "the evidence for adaptive therapy being superior to continuous therapy still does not exist." The paper contained no new data and instead examined how the existing data had been analyzed and presented, with particular attention to comparisons against historical figures.
Gatenby and colleagues published a response the same year. They noted that all patients in the comparison cohort had progressed while four remained on adaptive therapy, and that the median time to progression in the adaptive group remained consistent with what the preliminary report had predicted. They also addressed comparability between the groups, reporting similar Gleason scores.
For readers, the useful takeaway is not who won that exchange. It is that the disagreement is about evidence quality rather than about whether the biology is interesting, and that it remains unresolved in the literature.
Why Randomized Trials Are Only Starting Now
The obvious next step after a promising pilot is a randomized trial, and the reason that took years is worth understanding.
In their 2021 response, the Moffitt authors explained that their original plan to confirm the findings with a randomized study was complicated because the standard of care shifted, with abiraterone moving into earlier use in metastatic castration-sensitive disease. A trial designed against the old standard would have been testing the wrong comparison.
They reported launching a second adaptive therapy trial, registered as NCT03511196, in metastatic castration-sensitive prostate cancer using the same evolutionary model.
Separately, a Phase II randomized controlled trial called ANZadapt is testing patient-specific adaptive versus continuous abiraterone or enzalutamide in metastatic castration-resistant prostate cancer, running in the Netherlands and Australia, with time to treatment failure as its primary endpoint.
Adaptive dosing approaches have also been incorporated into trials in ovarian cancer and BRAF-mutant melanoma, so the concept is being tested beyond prostate cancer.
MedicalDaily Evidence Check and What Patients Should Take From This
Study type: pilot clinical trial, not randomized, with a comparison cohort rather than randomly assigned controls. Participants: a small group of men with metastatic castration-resistant prostate cancer, described by Moffitt as 17. Published in: Nature Communications in 2017, with updated results in eLife in 2022. What it found: longer median time to progression, 33.5 months versus 14.3, and longer median overall survival, 58.5 months versus 31.3. What it did not prove: that adaptive dosing is superior to continuous dosing, a point argued formally in a published critique. What readers should know: randomized trials are underway and have not reported.
For a patient with prostate cancer, adaptive dosing is not something to request based on this trial. It is a research approach being tested, and the pauses in treatment are governed by protocol-defined PSA thresholds and monitoring that only a trial or a specialist center can provide. Stopping or interrupting a cancer medication outside that structure is not adaptive therapy; it is an untreated interval.
Anyone interested should ask their oncologist whether a trial is open to them and what the eligibility criteria are. Asking whether a treatment plan follows continuous or intermittent dosing, and why, is also a reasonable question in any consultation.
Nobody should pause, reduce, or stop a prescribed cancer therapy based on a news article. Those decisions belong to the treating oncologist.
The confirmed facts are the published outcomes of a small pilot trial and the existence of a formal published dispute about what they establish. Those most affected are men with advanced prostate cancer following this research. The reasonable action is a conversation about trial eligibility. The central uncertainty is whether randomized trials confirm the benefit. The next expected development is results from the randomized studies now running.
Frequently Asked Questions
What is adaptive therapy? A dosing approach that pauses and restarts a cancer drug based on a patient's own tumor markers, aiming to slow the development of drug resistance.
How many patients were in the original trial? Moffitt describes it as a pilot trial in 17 patients with metastatic castration-resistant prostate cancer. It was not a randomized study.
What were the results? Median time to progression was 33.5 months on adaptive dosing versus 14.3 months on standard treatment, with median overall survival of 58.5 versus 31.3 months.
Did it show a 40-month advantage? No. That figure does not match the published data. The reported difference in median time to progression is roughly 19 months.
Why do some researchers dispute the findings? A published critique argued the reporting and the comparisons with historical data do not support a conclusion of superiority. The authors responded defending their analysis.
Is adaptive therapy available to patients now? It is a research approach. Randomized trials are underway in prostate cancer, and adaptive dosing is being tested in ovarian cancer and melanoma.
Can I ask my doctor to pause my treatment this way? Discuss it, but do not act alone. Protocol-defined thresholds and monitoring are what make this an intervention rather than an untreated gap.
