Antibody Drug Conjugates

Overview

An antibody drug conjugate (ADC) is a newer type of cancer treatment that works like a guided delivery system. It has three parts: an antibody (a lab-made protein that looks for a specific marker found on some cancer cells), a chemical linker (a small connector), and a payload (a strong cell-killing medicine, often a type of chemotherapy). Because the antibody sticks to the cancer cell, the payload is carried more directly to the cancer, while healthy cells are exposed to less of it. ADCs are usually given through a drip into a vein, and sometimes under the skin, in cycles with rest periods in between.

ADCs are not common in the general population, because they are only used to treat certain cancers. Among people receiving cancer treatment, however, they are becoming much more widely used. You may hear them called 'smart chemotherapy' or 'guided chemotherapy' in the media.

ADCs are used in adults, and sometimes in teenagers and children in specialist centres, for particular cancers that carry a specific marker on the cancer cells. Suitability depends on the exact type of cancer, what treatments you have already had, your blood counts, your heart, your eyes and your general fitness. Your oncology team makes this decision with you, one person at a time.

Symptoms

Common symptoms

• Tiredness and low energy, especially in the days after each treatment
• Feeling sick or being sick, usually in the first few days after treatment
• Loose stools or constipation
• Hair thinning or loss with some types of ADC
• Sore mouth or mouth ulcers
• Numbness, tingling or unusual feelings in hands and feet (nerve irritation)
• Dry eyes, blurred vision or eye irritation
• Rash, dry skin or sensitivity to sunlight
• Lower blood counts, which can mean more infections, bruising or breathlessness
• A mild reaction during the drip, such as chills, flushing or itching

Symptoms in children

• Children and teenagers may feel very tired and lose their appetite during treatment
• Fever can appear quickly because blood counts can drop, and in children this needs checking the same day
• Mouth sores and sore throats can make eating and drinking hard, so watch for signs of dehydration
• Nerve tingling may show up as clumsiness, dropping things or refusing to walk, rather than being described as numbness
• Children may not describe eye problems clearly, so mention any rubbing of eyes, sensitivity to light or new squinting to the care team

Symptoms in older adults

• Tiredness and weakness can build up over cycles and affect walking and balance, so falls prevention matters
• Low blood counts may cause more breathlessness and dizziness than in younger people
• Dry eyes, blurred vision and eye discomfort are important to report early, especially if you already have eye conditions
• Dehydration from sickness or diarrhoea can develop faster, particularly if you take water tablets or blood pressure medicines
• Memory, confusion or new drowsiness should always be checked, as infections can present differently in older age

Causes

Main causes

• ADCs are a treatment, not a disease, so they do not have causes in the usual sense
• They are prescribed when a cancer carries a particular marker on its cells that the antibody part can recognise
• They are also used when other treatments have stopped working, or when a newer option looks safer or more effective for you
• The side effects happen because the payload can still affect some healthy tissue, especially skin, eyes, nerves, gut, lungs and bone marrow

Risk factors

• Having a cancer type for which an ADC is approved and available
• Cancer cells testing positive for the matching marker
• Previous treatments such as chemotherapy, which can affect your blood counts and nerves
• Existing lung problems, which raise the chance of lung inflammation with certain ADCs
• Existing eye problems such as dry eye, which can make eye side effects more likely
• Existing nerve tingling from earlier treatment or conditions like diabetes
• Heart problems, which matter for some ADC types
• Being older or frail, which can make side effects harder to cope with

When to see a doctor

See a doctor urgently if:

• Any fever, shivering or feeling suddenly very unwell between treatments
• Breathing problems, a new cough, or breathlessness that gets worse
• Severe diarrhoea, vomiting, or signs of dehydration such as dizziness and dark urine
• Eye pain, redness or changes in vision
• New or worsening numbness, tingling or weakness in your hands or feet
• A rash that is spreading or blistering, or skin that peels
• Bleeding or bruising more easily than usual

Book a routine appointment if:

• Mild sickness, loose stools or constipation that is not settling with the advice you were given
• Sore mouth, taste changes or appetite loss
• Dry, itchy or sun-sensitive skin
• Tiredness that is affecting your daily life
• Hair thinning and questions about scalp care
• Worry or low mood that is lasting more than a couple of weeks
• Any question about your treatment schedule, travel plans or vaccines

Diagnosis

ADCs are not diagnosed, they are prescribed. The decision starts with your cancer team reviewing your cancer type, the results of tests on your cancer tissue, your blood tests, your heart and eye health, and what treatments you have already had. They then discuss whether an ADC is likely to help you, and explain the benefits and risks so you can decide together.

Tests that may be done

• A biopsy or tissue sample tested for markers on the cancer cells
• Blood tests to check blood counts, liver and kidney function
• A heart scan or heart tracing before and during certain ADCs
• An eye check if the ADC you are offered can affect the eyes
• Scans such as CT, MRI or PET to see where the cancer is and to track response
• Pregnancy test where relevant, as these treatments are not suitable in pregnancy
• Regular blood tests during treatment, usually before each cycle

What to expect at your appointment

Expect a conversation rather than a single test. Your team will explain what the treatment is aiming for, how often you will attend, what side effects to watch for, and who to contact. You will usually have a treatment plan in writing, plus a 24-hour contact number for your cancer unit. You can bring someone with you, ask for more time, and ask the same question more than once. Saying yes is your choice, and you can ask what the alternatives are.

Treatment

ADCs are given in treatment cycles, often every few weeks. Most people receive them as an outpatient, either through a drip into a vein or as an injection under the skin, depending on the medicine. Your team monitors you during and after each dose, adjusts the schedule if side effects appear, and may pause or stop treatment if the balance of benefit and harm changes. Supportive care is a big part of treatment: medicines to prevent sickness, mouth care, skin care, eye drops, and prompt treatment of infection.

Self-care at home

• Keep a simple daily note of temperature, bowel habits, how tired you feel, and any new tingling or eye symptoms, and bring it to appointments
• Drink enough fluid, especially if you have sickness or loose stools, and ask your team how much is right for you
• Wash your hands often and avoid close contact with people who have infections while your blood counts are low
• Use gentle, unperfumed skin products and a high-factor sunscreen, and cover up in the sun
• Use lubricating eye drops if your team advises them, and rest your eyes from screens
• Clean your teeth gently with a soft brush and rinse with the mouthwash your team recommends
• Tell your team about any other medicines, supplements or herbal products before you start them
• Ask before having any vaccines, dental work or travel, and carry your treatment card if you are given one

Medical treatments

Your cancer team may use an antibody drug conjugate on its own or alongside other cancer treatments. Alongside this, they offer supportive medicines to prevent and treat sickness, manage diarrhoea or constipation, protect the mouth, soothe eyes, ease nerve discomfort and treat infection. Some people need blood transfusions, growth-factor injections to lift blood counts, or a short stay in hospital. If side effects are troublesome, the team may lower the dose, delay a cycle, or switch to a different treatment. All of these decisions are made with you and reviewed regularly.

When is surgery considered?

Surgery is not part of ADC treatment itself. However, some people have surgery before or after a course of ADCs as part of their overall cancer plan, and your team will explain if and when that applies to you.

Living with this condition

Life during ADC treatment tends to follow a rhythm: a few days around each dose when you feel more tired or queasy, then a gradual return to your normal. Plan demanding tasks for the days you usually feel best, keep shopping and appointments flexible, and accept offers of help. Keep your cancer unit's contact number somewhere easy to find, and check in with them rather than waiting for your next appointment if something changes.

Lifestyle tips

• Pace yourself and build short rests into the day rather than one long crash
• Keep gentle movement going, such as short walks, even on tired days
• Avoid alcohol if your liver tests are not stable, or ask your team what is safe for you
• Protect your skin from the sun with clothing, a hat and sunscreen
• Keep your home smoke-free and avoid breathing in fumes, dust or mould
• Keep a small bag ready for hospital visits with medicines, a phone charger and a snack
• Ask your employer or school about flexible hours and rest breaks

Diet and exercise

There is no special diet that treats cancer, but eating well helps you cope with treatment. Aim for regular small meals with protein at each one, such as eggs, beans, fish, chicken, dairy or fortified plant alternatives, plus fruit and vegetables you can tolerate. If food tastes odd, try cold or bland foods and ask to see a dietitian for free advice. For movement, aim for what you can do comfortably and build up slowly: a short daily walk, light housework, or gentle strength work with bands. If you have nerve symptoms or balance problems, ask about physiotherapy, and stop any activity that causes chest pain or dizziness.

Mental health and emotional wellbeing

It is very common to feel anxious, low or worn down during cancer treatment. Waiting for scan results, coping with side effects and juggling family life can all take a toll, and that is not a sign of weakness. Tell your team how you are feeling, because practical help and talking therapies are available and often make a real difference. If you ever have thoughts of harming yourself, please reach out straight away: contact your cancer team or family doctor urgently, call your local emergency number, or contact a crisis line in your country. You deserve support, and help is available at any hour.

Prevention

ADCs are a treatment, not a condition, so there is nothing to prevent. What you can do is reduce the chance of serious side effects and make treatment safer. Report symptoms early, attend your blood tests and check-ups, follow eye and skin care advice, and tell your team about every other medicine or supplement you take.

Screening programmes

Routine cancer screening for your age and sex is still worthwhile, because finding a cancer earlier usually means more treatment options. If you are being treated with an ADC, you will also have regular monitoring tests such as blood counts, heart checks or eye checks, which act as an early warning system for side effects.

Complications

If left untreated

• If the cancer itself is not treated, it can grow and spread, causing pain, tiredness and other problems
• If side effects of treatment are not reported, they can become serious, for example an infection when blood counts are low
• Untreated lung inflammation can cause lasting breathing problems, so a new cough or breathlessness needs checking
• Untreated eye side effects can, in rare cases, affect vision, so early review matters
• Ongoing nerve tingling can affect grip, walking and daily tasks if it is not managed

Long-term outlook

ADCs have changed the outlook for several cancers, including some that were previously hard to treat, and research is moving quickly. Many people have good responses and are able to stay on treatment with manageable side effects. Response varies from person to person, and your team will review how things are going with scans and tests. Whatever your situation, there is support available, and it is reasonable to ask your team what they hope the treatment will achieve for you.

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