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Kadclya® (Trastuzumab Emtansine) 

Information leaflet on Kadclya® (Trastuzumab Emtansine)

This leaflet provides information for patients having treatment with Kadcyla. The leaflet will explain what Kadcyla is and when and how it is given. It will also tell you about common side effects that you may experience.  Contact telephone numbers and details of how to obtain further information on Kadcyla are given at the end of the leaflet.

What is Kadcyla and how does it work?

Kadcyla is made of 2 different drugs which work in combination: 

  1. A monoclonal antibody drug: this attaches itself to HER 2 receptors and stops cancer cells from dividing and growing. HER-2 (human epidermal growth factor 2) receptors are found on the outside of some cancer cells and it stimulates their growth. 
  2. A chemotherapy drug: This also stops cells from growing and dividing    

How often will I receive Kadcyla?

For this treatment to be most effective, it is given at specific time intervals. It usual to have Kadcyla every 3 weeks. The exact number of treatments you will receive will be discussed with you. 

How often will I see the specialist team?

We will let you how often you will need to be reviewed, this will either be in the outpatient clinic or a telephone review. You will need a blood test before each treatment.  At each visit the nurse who gives your Kadcyla will check how you are feeling and discuss any problems you may have. 

How is Kadcyla given?

Kadcyla is given through a drip into a vein in the back of your hand or arm. However, sometimes, if your veins are difficult to find, it may be suggested that a fine tube called a PICC is inserted into a large vein in your upper arm. This will remain in place throughout the course of your treatment.  Your doctor or nurse will discuss this further with you, if required. We have a leaflet that tells you more about PICC lines.

Where will my treatment be given?

Your treatment may be in one of the day case treatment areas at Velindre or a hospital closer to your home.  

How long will my appointment take?

Your first Kadcyla is given more slowly and we will observe you for approximately 1.5 hours after the infusion to check you are ok.  Your first appointment may take approximately 4 hours.  

Your second Kadcyla treatment will be given slightly quicker. This appointment with take approximately to 2.5 hours.

Can I bring relatives and friends with me? 

You are welcome to bring someone to stay with you during your treatment. Space is limited so there is not usually room for more than one person.  Treatment areas are not suitable for young children.

What are the possible side effects? 

Most people tolerate Kadcyla treatment very well, with very few side effects.  However, there are a number of possible side effects which can occur. The doctors, nurses and pharmacy team can give you advice or answer any questions you may have.

Reactions during the treatment 

Some patients may experience a reaction at the time the Kadcyla is given. This is why the first treatment is given more slowly.  A nurse will monitor you closely during the treatment. 

If you experience any of the following during the treatment please tell your nurse straight away:

•    Feeling hot and feverish
•    Develop a temperature
•    Chills or shivering
•    Headache
•    Dizziness or faintness
•    Problems with breathing
•    Rash or itching
•    Feeling sick or vomiting
•    Swelling of face/mouth ( this is rare) 
•    Pain in back, abdomen or chest

If any of these occur we will slow down or stop the Kadcyla until you feel better. If needed, we will give you medication to help with the symptoms .The treatment can then start again, often without any further problems.

Sometimes patients can experience a temperature/shivering/feeling sick at home after the infusion on the first day. If this occurs, ring the treatment helpline. The telephone number is at the end of the leaflet. 


You are at an increased risk of picking up infections because your white blood cells which help fight infections can be reduced by this treatment.  
If you develop an infection whilst your white blood cells are low, you are at risk of sepsis, this can be life threatening. 

Contact Velindre Cancer Centre immediately if you develop any signs of infection, for example flu like symptoms or a temperature above 37.5°centigrade.  The telephone number is at the end of the leaflet.

Effects on the nerves of your hands and feet

Kadcyla can affect the nerves of your hands and feet.  This may lead to a loss of sensation, tingling or pins and needles.  If this occurs please tell your doctor or nurse at your next clinic visit.

These symptoms may increase as you have more cycles of chemotherapy. If you have these symptoms, it is important to be extra careful when exposing your hands and feet to hot or cold temperatures. These symptoms usually go away within a few months of finishing your treatment. 

Myalgia (pain in the muscles)

Some patients may experience myalgia which is muscle or joint pain.  This can sometimes be severe but will only last for a few days.  If you already have painkillers at home you may find they relieve the pain.  If this does not work please contact Velindre Cancer Centre.  The telephone numbers are at the end of the leaflet.

Skin and tissue damage

Some chemotherapy drugs may damage the skin and surrounding area if they leak outside of your vein.  This is known as extravasation.  It is extremely rare but it is important that you tell us immediately if you notice any swelling, pain or burning at the site of the drip.  If this occurs whilst the chemotherapy is being given, tell your nurse.  If you notice pain, swelling or redness when you’re at home please contact us immediately the telephone number is at the end of the leaflet

Heart problems

Kadcyla treatment may cause some heart problems. These will usually get better when Kadcyla treatment is stopped or has completed. Your doctor will discuss this with you and arrange for your heart function to be tested before you start Kadcyla. Your heart function will be monitored every 3 - 4 months for the first year of treatment. We will also check your blood pressure and monitor your weight regularly.  

If you already have a heart condition or you take any heart medication, please tell your Velindre doctor before you start treatment with Kadcyla. If you do develop heart problems whilst on Kadcyla it may be treated with tablets. It is very important not to stop taking any tablets you have been given for heart problems without discussing it with your Velindre doctor or specialist nurse. 

If at any time during your treatment you develop a new or worsening problem with shortness of breath- especially at rest, a cough, chest tightness, fluid retention (swelling) in your arms or legs, palpitations (heart flutter or irregular heart beat), feel dizzy or lightheaded, please contact the treatment helpline. The telephone number is at the end of the leaflet. 
However, if you experience any chest pain, ring 999.

Lung problems: 

A small number of patients may develop lung problems, if you feel short of breath at rest, develop a new persistent cough or chest tightness ring the treatment helpline. The telephone number is at the end of the leaflet.

Feeling sick: 

If you feel sick after your treatment, anti-sickness medication can help. Ring the treatment helpline if you feel sick and need anti-sickness medication or the medication isn’t helping. 

Feeling feverish : 

If you feel shivery/cold/ feverish on the evening of your treatment, you can take paracetamol 4-6 hours apart, maximum of 8 in 24 hours. If you need 8 in 24 hours however, ring the treatment helpline. 

Other common side effects you may experience in the first few days after treatment include:

  • Diarrhoea 
  • Constipation
  • Tiredness
  • Headaches  
  • Dizziness
  • Abdominal pain
  • Difficulty sleeping. 
  • Sore mouth
  • Mouth sores
  • Altered taste

These side effects usually only last a few days. If you feel very unwell or want further advice please contact Velindre Cancer Centre. The telephone number is at the end of the leaflet.

Anaemia and low platelets: 

If you feel tired, short of breath or notice excessive bruising or bleeding, ring the treatment helpline. This would normally be expected in patients having chemotherapy with Kadcyla. 

Blood clots

A diagnosis of cancer can increase your risk of developing a blood clot (thrombosis), and having cancer treatment may increase this risk further.  It is important to tell your doctor immediately if you have symptoms such as pain, redness and swelling in your leg, or breathlessness and chest pain.  

Blood clots can be very serious.  However, most clots can usually be successfully treated with drugs to thin the blood.  Your doctor or nurse can give you more information.

Other information

It is important you do not become pregnant whilst having Kadcyla treatment, and for 7 months after completing the treatment. Breastfeeding is not recommended during treatment and for a minimum of 6 months following completion of treatment. 

Taking other medication with Kadcyla?

Kadcyla can remain in your body for up to 6 months after you finish treatment.  During this time you should tell your doctor or pharmacist that you have had Kadcyla before starting any new medicines.
Do not take over the counter medication, herbal or alternative medicines. 

Sometimes cancer drugs can have very serious side effects which rarely can be life threatening. It is important to inform Velindre cancer centre if you are concerned about any side-effects.  The telephone number is at the end of the leaflet.

Manufacturer’s patient information leaflets

Velindre leaflets provide information about very common and commonly reported side-effects (we are unable to list all of the common side effects), for more information regarding these and the less common side-effects please refer to the manufacturers patient information leaflets, obtained from Velindre pharmacy and/or on the internet at Sometimes patients may find these leaflets difficult to read however. Please ask if you would like a copy from your doctor or from Velindre pharmacy

Contact telephone numbers

Velindre Cancer Centre 029 2061 5888
If you are unwell at home and need immediate advice at any time of the day or night ask for the treatment helpline

Pharmacy department 029 2061 5888 ext 6223
Monday – Friday 9am – 5pm for queries about your medicines

Macmillan freephone Helpline 0808 808 0000

Tenovus freephone 0808 808 1010
cancer helpline 

This information is also available in Welsh

This leaflet was written by health professionals.  The information contained in this leaflet is evidence based.  The leaflet has been approved by doctors, nurses, pharmacists and patients.  It is reviewed and updated every 2 years.

Written May 2020