Histology independent therapies (HITs)

Histology independent therapies (HITs) are a new type of cancer treatment.

They are a type of cancer treatment called targeted therapy. Targeted therapies are drugs that find and attack cancer cells. They target something in or around the cancer cell that is helping it grow and survive. There are many different types of targeted therapy.

Different targeted therapies are used to treat different cancer types. Some targeted therapies are only effective if the cancer cell has a certain gene change (see ‘Gene changes’ heading below).

Cancers are usually treated according to where they start in the body. For example, bowel cancer is treated with drugs that have been shown, in clinical trials, to work on bowel cancer cells. Even if the bowel cancer cells have spread to other parts of the body, such as the lungs or liver, they are still bowel cancer cells. So you would be given drugs that treat bowel cancer.

HITs are different to other targeted therapies. This is because they can be used to treat any type of cancer that has a certain gene change. For example, there is a gene change called NTRK gene fusion, which can be found in over 20 different types of cancer.

HIT drugs can treat any cancer with this gene change. Doctors will choose this type of treatment based on the gene change, rather than on where in the body the cancer started. If the cancer cells have the NTRK gene fusion, then the drugs may be used.

Other HIT drugs are being developed that may be effective for cancers that have different gene changes.

Histology independent therapies (HITs) can treat certain cancers that start in the organs of the body. HITs are not currently used to treat blood cancers such as leukaemia or lymphoma. This is because they are not effective at treating these types of cancer.

You may be offered treatment with a HIT drug if you have a cancer that has a specific gene change. Currently, there are 2 HIT drugs available in the UK through the NHS. These are larotrectinib and entrectinib. They may be used to treat people with a cancer that has a gene change called NTRK gene fusion.

Testing for a gene variant

If your cancer doctor thinks a histology independent therapy (HIT) drug is a possible treatment for you, they will arrange a test on the cancer cells to see if they have the gene variant.

Your doctors may be able to test a sample of the tissue they took from the cancer when you were first diagnosed. This is called a biopsy. Sometimes they need to take another sample. They will explain if they need to do this and how they will take the sample.

The NTRK gene fusion has been found in some very rare cancers. It is only found very occasionally in more common cancers. Your cancer doctor can tell you more about this and how likely it is that you might have a tumour with the NTRK fusion.

Like other cancer treatments, histology independent therapies (HITs) can cause side effects. You may have side effects while you are taking the drugs.

The side effects you get will depend on which drug you are taking. Different drugs cause different side effects. The drugs may also affect different people in different ways. Talk to your cancer doctor, specialist nurse or pharmacist if you have any side effects.

Some side effects are mild and can be easily treated. Other side effects can be harder to manage. But these can often be reduced or controlled in some way. Your doctor, nurse or pharmacist may prescribe drugs to help control them.

Side effects of HIT drugs may include the following:

• An increased risk of infection – this is because the drugs may reduce the number of white blood cells in your blood. Your healthcare team will give you advice about this.
• Feeling sick (nausea) – your doctor can give you anti-sickness drugs to help.
• Constipation – your healthcare team can advise you about how to manage this.
• Feeling tired (fatigue) – try to pace yourself and allow time to rest.
• Effects on the nervous system – the treatment may make you feel dizzy or unsteady. Some people may have mood changes, memory problems or feel confused. Contact the hospital straight away if you have any of these effects.

Some cancer treatments may cause long-term side effects. Because HIT drugs are a new treatment, we do not yet know whether there are long-term side effects, or what they might be. Your doctors and nurses will monitor you regularly. You should tell them about any new symptoms or side effects.

Before you go to an appointment, it can help to prepare any questions you would like to ask. You may also find it helpful to do the following:

• Take notes during your appointments so you can read them later.
• Record the conversation so you can listen to it later. You should always ask for permission to record a conversation first.
• Ask your healthcare team for a copy of any letters that have the details of your discussions.
• Ask someone to come with you to your hospital appointments, such as a family member or friend. They can support you by making notes or asking questions.

Here are some questions that you may want to ask your cancer doctor or specialist nurse:

• What tests do I need?
• Am I eligible for this treatment? If not, are there other treatments I can have?
• How often will I have this treatment?
• Will I need any other tests before or after treatment?
• What are the side effects of this treatment?
• Are there possible long-term side effects of this treatment?
• What can I do to support myself?

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• use plain English
• explain medical words
• use short sentences
• use illustrations to explain text
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