A study looking at an anaesthetic tablet to help treat cancer related nerve pain (KPS)

Who can enter

You can enter this study if you

• Have nerve (‘neuropathic’) pain related to cancer or its treatment that reaches a certain level on various pain assessments
• Have tried a medication that strengthens the action of your existing painkillers (an ‘adjuvant analgesic’), for example gabapentin or amitriptyline
• Are willing to use reliable contraception if there is any chance that you could become pregnant
• Are at least 18 years of age

You cannot enter this study if you

• Have had a type of radiotherapy or chemotherapy that may cause nerve pain within 6 weeks of joining the study
• Are likely to have a change in your cancer treatment during the study, which may alter the pain you are having
• Have had fits (seizures) in the last 2 years
• Have had a stroke or any other disease that affects the blood supply to or within your brain (cerebrovascular disease)
• Are taking a type of medication to control your heartbeat called a ‘class 1 anti-arrhythmic’, for example lidocaine or flecainide – you can check this with your doctor
• Have high blood pressure (your lower reading is over 100mmHg)
• Are sensing things that are not really there (hallucinating)
• Have a condition that makes you lose touch with reality (psychotic disorder), or you have difficulty learning, understanding and remembering information (cognitive impairment)

Trial design

This study will recruit 214 patients into 2 groups. This is a randomised study. The people taking part are put into treatment groups by a computer. Neither you nor your doctor will be able to decide or know which group you are in. This is called a ‘double blind’ study.

Everyone will continue taking their regular pain medication throughout the study. Half of those taking part will also take ketamine tablets. The other half will take a dummy (placebo) tablet.

The first part of the study is to make sure that you are already having the best possible standard treatment for your pain. The study team will assess your pain and regular pain medication each day, for up to 2 weeks. They may alter your current doses, or your medication, if needed. If the study doctor and you then feel that your pain is better, you will finish at this point. If you both feel that your pain is still not controlled, you will enter the second stage of the study.

You will then be put into one of 2 groups by computer. You will continue your regular pain medication. If you are in group 1, you will also take ketamine tablets. If you are in group 2, you will take a dummy (placebo) tablet. You take the study medication 4 times per day. During this stage, your regular medication stays the same. But the study team may alter the dose of your study medication depending on the results of your pain assessments. The team will phone you every day during this stage, which may last up to 2 weeks. You will also complete a booklet each day for the rest of the study to record your pain and medication.

Once your pain and any side effects are controlled as well as possible, you continue your regular and study medication for 16 days. The study team will either contact or see you every 4 days during this time.

Throughout the study you will help the team gather information about your treatment and how you are feeling. They will use tests including pain scales and a quality of life questionnaire.

The study team will also ask if you would be willing to give a blood sample at the beginning and the end of the study. These may help researchers understand more about how genes affect our response to pain and medication. You do not have to do this. You can still enter the study if you say no.

While you are on the study, it is important that you do not take any new medications without speaking to your study doctor. This includes medication that you can buy without a prescription at a chemist or supermarket. If your GP or hospital doctor wants you to take new medication you must tell them about this study, and that you may be taking ketamine.

Hospital visits

When you start the study, you will see the study team and complete some pain assessments. If you have agreed to give some blood samples, you will do this too.

If you remain in the study after the first stage, you will see the team again to receive your study medication.

During the final 16 days of the study, the team will either contact or see you every 4 days. They will talk to you about your medication, and assess your pain using

• Simple pain tests, for example trailing fine hairs across your skin
• 4 short pain scales
• 3 short questionnaires, asking about your pain and how you are feeling

These 5 visits will last about an hour. On your final visit you give your second study blood sample, if you have agreed to this. If necessary during this final stage, the study doctor or nurse may be able to phone you or come to your home instead of you going to the hospital or clinic.

When you have finished the study you will continue to see your specialist cancer team in the same way as before.

Side effects

A low dose of ketamine can cause nightmares and sensing things that are not really there (hallucination). If you have either of these side effects, you can talk to your study doctor or nurse - there is other medication that can help.