A trial looking at pregabalin and radiotherapy for pain caused by secondary cancer in the bones

Who can enter

You can enter this trial if you

• Have bone pain caused by secondary cancer
• Have pain that scores 4 or above on a 0 to 10 pain scale
• Are due to have radiotherapy for your bone pain
• Are well enough to take part in the trial
• Are at least 18 years old

You cannot enter this trial if you

• Are having other treatment for your cancer that may help to reduce the pain in your bones
• Are having radiotherapy that involves a large area of your body
• Are having radiotherapy to your spine
• Are having drugs called bisphosphonates to control your pain (you can enter the trial if you were taking a bisphosphonate as part of your cancer treatment before you got bone pain)
• Have kidney problems
• Are already taking pregabalin or a similar drug called gabapentin

Trial design

The trial has two different periods. The first one is called the ‘Run In’ period. It will last between 1 day and 2 weeks. During this period, your doctors and nurses will assess your pain and try to make sure that you are having the type and dose of painkiller that works best for you.

At the end of this period, your doctor or nurse will do a pain assessment. If you have a score of 4 or more on a 0 to 10 pain scale, you will go on to the next phase of the trial. This is called the ‘Assessment’ period.

At this point, you will be put into one of 2 treatment groups by a computer. Neither you, nor your doctor will be able to decide which group you go in. And you will not know which group you are in, as both groups will have treatment that looks the same. This is called a ‘double blind’ trial. Everybody taking part will have radiotherapy, and then

• People in group 1 will have pregabalin tablets twice a day for 4 weeks
• People in group 2 will have dummy tablets (placebos) twice a day for 4 weeks

The doctors can increase the dose of your tablets each week.

By the 4th week you will be having the maximum dose. During this period, your doctors will not change any other pain medicine you take, but you can take extra painkillers for breakthrough pain. The trial team will assess your pain each week. If you have any side effects, the doctors may not increase your dose.

At the end of 4 weeks, your doctor or nurse will do another pain assessment. Then they will explain how to reduce the dose of your tablets each day for a week, until you stop the tablets altogether. They do this because you may feel dizzy or drowsy if you stop taking pregabalin too quickly.

The trial team will ask you if they can take 2 blood samples to study how your genes may affect your response to the drug and any side effects you have. These blood tests are optional. If you don’t want to give the blood samples for research, you don’t have to. You can still take part in the trial.

Hospital visits

If you take part in this trial, you will have between 2 and 4 extra hospital visits. The trial doctors will thoroughly assess your pain and side effects from any painkillers at the end of the Run In period, and again at the end of the trial. You have to go to hospital for both of these assessments.

During the 4 weeks you take the pregabalin tablets, the trial team will assess your pain each week. But they may be able to do this by phone, so that you don’t have to go to hospital every week.

Side effects

The most common side effects of pregabalin are feeling sick (nausea) or feeling drowsy. The trial team can reduce the dose of the drug if you have bad side effects.

There is more information about the side effects of radiotherapy for bone pain on CancerHelp UK.