How long a new drug takes to go through clinical trials

This page has information about the things that can affect how long a new drug takes to go through clinical trials.

Drug testing and licensing

All new drugs and treatments have to be thoroughly tested before they are licensed and available for patients.

It takes time for a new drug to go through the various stages of testing. This process is often called from the bench to the bedside.

A new drug is first studied in the laboratory. If the drug looks promising, it is carefully studied in people.

New drugs are only prescribed and used as part of standard treatment for cancer after they have gone through clinical trials.

Timing of testing

There is no typical length of time it takes for a drug to be tested and approved. It might take 10 to 15 years or more to complete all 3 phases of clinical trials before the licensing stage. But this time span varies a lot.

Factors that affect drugs licensing time

There are many factors that affect how long it takes for a drug to be licensed.

The type of cancer

Clinical trials for rarer cancers often take longer to recruit. This is because there are fewer patients available to take part.

Several different countries may need to collaborate to recruit enough patients. So this can make the trial take longer to organise and set up. But an international trial recruits more quickly and so is likely be quicker in the long run.

The type of treatment

Trials are easier to run that use standard ways of giving treatment. These standard ways include giving a drug as tablets or through a vein (by drip). If a trial uses standard delivery methods, more hospitals are likely to be able to take part.

Some new treatments need special equipment or specially trained staff, and have to take place in specialised centres. So it may take longer to recruit the number of patients they need for the trial.

The number of patients needed

Trials are designed to look at various things. The research team may want to find out if a new treatment is better than current treatment. Or they may want to check that the treatment is no worse than the current treatment. Or they may need to find out how much better a new drug works.

The number of patients in a trial has to be enough to be able to find these things out. The results, or data, are looked at statistically (called statistical analysis). If the trial doesn’t recruit enough patients, the results may not be reliable.

The length of treatment

It is quicker to get results about treatment that is a single dose or short course, compared to a drug that you take for months or even years.

The follow up period

Research teams follow the progress of all patients in clinical trials for some time after treatment. This is to see how well the treatment works over a longer period and to find out more about long term side effects.

Follow up periods can range from a few months to more than 10 years, depending on the type of treatment and the group of patients tested.

An example of results being available quickly might be a new treatment for advanced cancer that extends life by a few months.

Some trials looking at whether a new treatment is better at stopping cancer coming back need follow up for at least several years.

Trials looking at preventing cancer may take a very long time.

Any problems with the new treatment

There may be problems with new drugs or treatments that the researchers won't know about until they run the trials. There could be unexpected side effects or reactions to treatment. Or there may be difficulties in giving the treatment to patients.

Problems with the new treatment can lengthen the trial period.

Related information

How clinical trials are planned and organised

How clinical trials are supervised

Find a clinical trial

Clinical trial results

Last reviewed

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Find a trial

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