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Research and new methods

Phase II: does it work?

Phase II trials test whether a medicine found safe in phase I actually works in a specific disease, and study safety in more people.

Last updated: ~1 min read
Three doctors studying an X-ray image together
Figure 1.Doctors reviewing results together

01Short answer

Usually tens to hundreds of people take part, all with the same disease or the same genetic change. The response is measured: remission, fewer blasts or negative MRD. Sometimes phase II is comparative (randomised). A successful phase II is encouraging but does not yet prove the medicine is better than standard care; phase III usually shows that. In rare diseases, a strong phase II result can sometimes support accelerated approval.

02Simple explanation

Effect is tested.

One disease group.

Response is measured.

Not yet proof.

03Scientific explanation

NCI: phase II trials study whether a new treatment works on a certain type of cancer.

NCI: new treatments are tested step by step, from the laboratory to clinical trials; only those proven safe and beneficial become standard care.

04What happens in the body?

Response rate

The share of participants who respond to treatment.

A target
Figure 2.A target — Phase II: does it work?

Accelerated approval

Conditional approval based on early data in serious diseases.

A shrinking cluster
Figure 3.A shrinking cluster.

How to read the news

Research news brings hope, but not every advance suits everyone. Look at who it was tested in, at what phase and in how many people.

Talk to your doctor

Show your doctor what you have read; they will explain how it relates to your diagnosis and treatment. Do not change your treatment on your own.

05From research news to a conversation: four steps

Read, check, ask, decide together.

Read — From a trusted source.1ReadFrom a trusted source.
Check — Phase, participants, result.2CheckPhase, participants, result.
Ask — Show your doctor.3AskShow your doctor.
Decide — Together, without rushing.4DecideTogether, without rushing.
SourceA trusted site.
DoctorA personal explanation.
SafetyNot changing treatment yourself.

06Key points at a glance

TopicIn brief
Response rateThe share of participants who respond to treatment.
Accelerated approvalConditional approval based on early data in serious diseases.
How to read the newsResearch news brings hope, but not every advance suits everyone. Look at who it was tested in, at what phase and in how many people.
Talk to your doctorShow your doctor what you have read; they will explain how it relates to your diagnosis and treatment. Do not change your treatment on your own.

07Key terms

Response rate
The percentage of participants who benefit.
Endpoint
The main result a trial measures.
Clinical trial
Testing a new treatment with volunteers.
Evidence
A result confirmed by reliable research.

08Key points

  • Measure.
  • Compare.
  • Confirm.
  • Check the source.
  • Talk to your doctor.

09Frequently asked questions

A phase II result was in the news; is the medicine ready?

Not yet; more testing may be needed.

Who takes part?

Usually people with a specific disease or mutation.

Is this advance right for me?

Only your treating doctor can say, based on your diagnosis, stage and condition.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. A phase II result was in the news; is the medicine ready?

  2. Who takes part?

  3. Is this advance right for me?

My questions

12Sources

  1. National Cancer Institute. Phases of Clinical Trials
  2. National Cancer Institute. NCI Dictionary of Cancer Terms: phase II clinical trial
  3. National Cancer Institute. What Are Clinical Trials?
  4. National Cancer Institute. Using Trusted Resources
  5. National Cancer Institute. NCI Dictionary of Cancer Terms: randomized clinical trial
  6. National Cancer Institute. NCI Dictionary of Cancer Terms: overall survival
  7. National Cancer Institute. NCI Dictionary of Cancer Terms: somatic mutation
  8. National Cancer Institute. NCI Dictionary of Cancer Terms: targeted therapy
  9. National Cancer Institute. NCI Dictionary of Cancer Terms: biomarker
  10. National Cancer Institute. NCI Dictionary of Cancer Terms: precision medicine
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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