Master protocols explained: basket, umbrella, and platform trials in clinical research

Most clinical trials answer one question at a time. One study drug is tested against one condition, in one group of participants, under one protocol. A master protocol works differently. It is a single overarching study framework that runs several related substudies at once, sharing eligibility screening, data systems, and often a single control group across all of them. That structure lets researchers test more than one study intervention, or study more than one condition, without building a separate trial for every question.

The U.S. Food and Drug Administration (FDA) describes a master protocol as a protocol with multiple substudies designed to evaluate one or more medical products in one or more diseases within a coordinated study structure. Three formats fall under this umbrella term: basket trials, umbrella trials, and platform trials. Each has a distinct purpose, and each shows up more often in current clinical research than in the past.

What a master protocol actually is

A master protocol is best understood as a shared framework rather than a single experiment. Traditional trials use a two-arm design: participants are randomly assigned to receive the study intervention or a comparison such as standard care or placebo, and a fixed number of people are studied over a fixed period. That model works well for a clear single question, but it is slow and resource-intensive when many candidate products or many participant subgroups need to be studied.

A master protocol solves that by holding common elements steady across substudies. The screening process, informed consent structure, safety oversight, data collection systems, and often a single shared control group are defined once at the framework level. New substudies plug into that framework rather than starting from scratch. Master protocols are not usually used for the earliest tests of a study drug in humans; a workable dose is typically established first through smaller, focused studies such as Phase 0 clinical trials.

Three formats sit under the master protocol category. Each answers a different type of question.

Basket trials: one study intervention, many conditions

A basket trial studies one investigational product across multiple diseases or conditions that share a common feature. That feature is usually a biomarker, which is a measurable biological signal, such as a specific gene change, a protein level, or another indicator that can be detected through a test. If several different diseases share the same underlying biomarker, one product designed to act on that biomarker can be studied across all of them at once.

A helpful way to picture this format is a single key that fits several different locks because the locks share the same internal shape. In cancer research, for example, a product designed to act on a specific genetic change may be studied in participants with lung, colon, thyroid, or other tumor types at the same time, regardless of where the cancer began, as long as the target genetic change is present.

Basket trials are common in oncology because tumor biology is often defined by genetic changes rather than by the organ where the tumor started. They are also being explored in inflammatory and rare diseases where a shared biological pathway links otherwise different conditions. Many basket trials are early-phase and exploratory, designed to look for early signals of activity across several conditions before larger confirmatory studies begin. Identifying candidates for these studies often depends on biomarker testing, which determines whether a person's condition carries the specific feature the study is looking for.

Umbrella trials: many study interventions, one condition

An umbrella trial flips the basket concept. Instead of one product across many conditions, an umbrella trial studies multiple products against a single condition, usually sorting participants into subgroups based on biomarker results. The image is many different keys tested against one lock to see which one fits best.

Under one shared framework for a single disease, each biomarker-defined subgroup is matched to the product most likely to help it. Someone with one genetic profile may be assigned to one substudy arm, while someone with a different profile may be assigned to another. In many umbrella designs, participants within each subgroup are then randomly assigned to receive the study product or a comparison, and a single control group can serve several product arms. Whether participants know which arm they are on depends on whether the trial is open-label or blinded.

Umbrella trials are useful when a single disease is known to have several distinct biological subtypes, each potentially responsive to a different approach. Breast cancer, lung cancer, and some blood cancers are common examples, though the design is also being applied outside oncology as biomarker science expands.

Platform trials: an ongoing framework that adapts over time

A platform trial studies multiple study interventions against a single disease within a perpetual framework that has no fixed end date. The defining feature is adaptivity. New study arms can be added when new candidate products emerge, and existing arms can be dropped when data show that an intervention is not working. A shared control group serves all the arms simultaneously.

A useful analogy is an ongoing tournament in which competitors can enter and leave while the tournament itself keeps running. Rather than closing a trial and opening a new one every time a new candidate becomes available, researchers add the candidate as another arm within the existing platform. Interim analyses, planned looks at accumulating data before the study is complete, guide these decisions.

Platform trials became widely visible during the COVID-19 pandemic, when large adaptive platform studies of hospitalized patients identified which interventions reduced deaths and which did not, sometimes within months. The same design is now used in cancer, inherited neurological diseases, and other areas. Platform trials benefit from advances in artificial intelligence and data analytics, which help researchers analyze accumulating results and match candidates to substudies more quickly than manual review would allow.

Why master protocols matter for study participants

For someone considering clinical trial participation, master protocols offer several practical differences from traditional single-question trials.

The first is access. A single screening process, including any biomarker testing, can open the door to several possible substudies rather than just one. If a person does not qualify for one arm, they may still qualify for another within the same framework.

The second is biomarker-driven matching. Rather than being grouped only by diagnosis, participants can be matched to the substudy most relevant to the biology of their condition. This is especially meaningful in cancer and in conditions where different subtypes respond differently to different approaches.

The third is a smaller share of participants receiving placebo or standard-care comparisons. Because a single control group can serve several product arms, fewer people overall are assigned to the comparison group than would be needed if each product were studied in its own separate trial.

The fourth is faster answers. When ineffective arms can be dropped early and effective ones can be identified sooner, useful findings can reach patients more quickly than a series of separate trials would allow.

These designs are also more complex, and participants sometimes need to work through more information than they would for a traditional trial. Reading the study documents carefully is important, and there are resources on how to read an informed consent form that can help.

How pre-screening and matching fit into master protocols

Master protocols usually begin with a shared screening step. That step often includes biomarker or molecular testing to determine which substudy or arm a person may qualify for. Because master protocols involve multiple substudies with different eligibility rules, the matching process can be more detailed than in a traditional single-arm trial.

DecenTrialz supports the earliest stages of that process. AI-assisted matching narrows the search across active studies to identify substudies that may fit a person's condition, medical history, and location. Registered nurses then complete a pre-screening conversation to gather additional information and confirm whether a person appears to meet the initial criteria for a specific substudy.

That is where the DecenTrialz role ends. The registered nurse pre-screens only. Final eligibility determination, informed consent, the full study walk-through, and enrollment are always handled by the research site team at the study location. Master protocol substudies can involve additional testing and detailed protocol conversations at the site, and those steps belong to the site clinicians and study coordinators. To explore active clinical studies and begin the pre-screening process, visit DecenTrialz.

Common questions about joining a master protocol study

Will participants receive a placebo?

Sometimes, depending on the substudy design. Master protocols are structured so that fewer participants overall are assigned to the control group, since one control group can serve several product arms. Whether placebo is used at all depends on the specific substudy and the condition being studied.

Can a person choose which arm to join?

Generally no. Arm assignment is based on biomarker results and, in randomized substudies, on random allocation. Some designs allow participants to consent to only a subset of substudies, and the informed consent process explains what is possible.

Are master protocols only for cancer?

No. Oncology remains the most common use, but master protocols are now applied in infectious disease, neurology, inherited conditions, and inflammatory disease research.

Are these studies more complex than traditional trials?

The framework is more complex behind the scenes, and the consent conversation may cover more possibilities. From the participant side, the day-to-day experience of study visits, procedures, and follow-up is often similar to a traditional trial, since each substudy operates within its own protocol.

Who oversees safety in a master protocol?

The same regulatory and ethical protections that govern other clinical research apply, including institutional review board oversight and data safety monitoring. Because master protocols can generate safety data across several arms at once, monitoring is often built to review that information continuously.

Master protocols are one of the clearest examples of how clinical trial design has evolved to keep pace with biology and technology. For participants, they can mean broader access, more precise matching, and a faster path from research to results.

To learn more about active clinical studies and start a pre-screening conversation with a registered nurse, visit DecenTrialz.