Clinical trials versus expanded access
In one sentence
A clinical trial studies a treatment under a research protocol, while expanded access uses an investigational product for treatment outside a trial under applicable safeguards.
The intuition
A trial is a planned way to learn whether a treatment helps and how it harms. Expanded access is a way to consider treatment for someone who cannot use a suitable trial route. Both involve uncertainty, but their primary purposes differ.
Neither is a reservation for a dose. The treating team, product supplier and relevant review bodies each have a part to play.
How it works
A clinical trial follows a research protocol. It defines eligibility, treatment groups, monitoring and the outcomes being studied. Participants may be randomized; joining does not always mean receiving the investigational product.
Expanded access, also called compassionate use, permits treatment use of an investigational product outside a trial in qualifying circumstances. U.S. criteria include serious or immediately life-threatening illness, no comparable or satisfactory alternative, a favorable enough anticipated benefit–risk balance, and no interference with the product's clinical development.
An Investigational New Drug (IND) application is the regulatory submission supporting investigation or expanded-access use of a drug. A single-patient IND is one expanded-access route, rather than a competing category. An access protocol may also be submitted under an existing IND. An IND number is not a marketing approval or proof of benefit.
The product supplier must agree to supply the treatment and supporting information. A treating physician needs a feasible treatment and monitoring plan. Food and Drug Administration (FDA) authorization, applicable institutional review board (IRB) review, and informed consent form part of the expanded-access process. Special procedures apply in emergencies.
| Question | Clinical trial | Expanded access |
|---|---|---|
| Primary purpose | Answer research questions | Treat a qualifying patient outside a trial |
| Entry | Protocol eligibility and an available site/cohort | Clinical criteria, supplier agreement and applicable reviews |
| Treatment assignment | Defined by protocol; may be randomized | Defined in the access treatment plan |
| What it can establish | Depends on design and conduct | Does not replace a controlled efficacy study |
Why it matters in cancer
A trial result and an access approval answer different questions. A trial may offer structured monitoring while preserving uncertainty about treatment benefit. Expanded access may make treatment possible without supplying the evidence that it improves outcomes in a particular disease.
Worked example
A fictional patient cannot join a relevant trial because the cohort is closed. That fact alone does not establish expanded-access eligibility. The clinician still evaluates alternatives and risk, the supplier decides whether it can provide product, and the required reviews must support the proposed use.
Common confusions
- “Compassionate use” does not mean treatment is known to work.
- A supplier's agreement does not replace clinician and regulatory review.
- A new personalized formulation does not automatically inherit another formulation's evidence or access authorization.
- Federal Right to Try is a separate pathway with its own patient and product criteria. It does not compel a manufacturer to supply a drug.
Related concepts
Sources and scope
U.S. source check: October 9, 2026. Expert and learner review remain pending. The example is fictional.
Timing correction: For a non-emergency single-patient IND, FDA says treatment may begin 30 days after receipt or earlier if FDA notifies the physician that it may proceed, subject to applicable reviews and consent. Emergency use may be authorized rapidly before the follow-up written submission. These rules are not a promised end-to-end preparation or manufacturing time.
- FDA: expanded access overview — criteria and categories.
- FDA: how physicians request single-patient expanded access — supplier agreement and emergency versus non-emergency timing.
- FDA: expanded access information for institutional review boards — review and consent responsibilities.
- FDA: Right to Try — separate statutory pathway and supply limitations.