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Kadcyla (ado-trastuzumab emtansine)
Starting Kadcyla can bring up a lot of questions, for you and for the people who love you. Here you'll find what to expect, how to feel your best day to day and where to get help, so you can focus on your life and time together.
ℹ️ General information to help you and your loved ones talk with your care team, not medical advice. Read our disclaimer.
Antibody-drug conjugate (HER2-directed) · Used for: Breast cancer
💉 Given by IV or injection · Antibody-drug conjugate (HER2-directed)
The quick guide
What it is: Antibody-drug conjugate (HER2-directed).
How it's given: An IV infusion every 3 weeks.
How it works: Kadcyla is trastuzumab linked to a chemo drug, delivering chemo right to HER2-positive cells. Used after surgery when cancer remains, and for metastatic HER2+ breast cancer.
Side effects you may notice, and what helps at home
| Side effect | What can help |
|---|---|
| Fatigue (extreme tiredness) | Short walks and planned rest. |
| Nausea and vomiting (CINV) | Small bland meals; take anti-nausea medicine as prescribed. |
| Neutropenia (low blood counts and infection risk) (Low platelets) | Wash hands often; check your temperature if you feel unwell. |
| Muscle pain | Tell your care team; they can help. |
| Neuropathy (numbness and tingling) (Numbness or tingling) | Protect hands and feet; tell your team early. |
Not everyone gets these. Your team may suggest other ways to manage them.
Call your care team now if you have:
- ⚠️ Boxed warning (FDA's most serious): Liver damage, heart problems and harm to an unborn baby. Don't confuse Kadcyla with plain trastuzumab.
- Yellow skin or eyes or dark urine
- Bleeding or easy bruising
- Shortness of breath or leg swelling
Call 911 for trouble breathing, chest pain or signs of stroke.
🗓 What to expect
1️⃣ Before you start
- Ask your team for a written schedule and an after-hours phone number.
- Bring a list of all your medicines and supplements.
2️⃣ During each infusion
- You'll get the medicine through an IV in a clinic; nurses check you during the infusion.
- Tell the nurse right away about chills, itching, flushing or trouble breathing.
- Bring a snack, water and something to pass the time.
3️⃣ Between doses
- Watch for the side effects below and use the checklist.
- Keep up with blood tests and visits.
- Call your team for anything in the red box.
✅ Side-effect checklist
Print this and check off what you notice so you can tell your team.
| Side effect | Noticed? | Notes for my team |
|---|---|---|
| Fatigue (extreme tiredness) | ☐ | |
| Nausea and vomiting (CINV) | ☐ | |
| Neutropenia (low blood counts and infection risk) | ☐ | |
| Muscle pain | ☐ | |
| Neuropathy (numbness and tingling) | ☐ |
Help paying for Kadcyla (ado-trastuzumab emtansine)
Kadcyla (ado-trastuzumab emtansine) is made by Genentech (Roche).
Official manufacturer program:
- Genentech Access Solutions: Insurance help, copay assistance and the Genentech Patient Foundation for free medicine.
Copay cards are usually only for people with commercial (job or marketplace) insurance. If you have Medicare or Medicaid, look at free-drug programs and these independent foundations:
- PAN Foundation: Copays and coinsurance, including for people with Medicare, when a disease fund is open.
- HealthWell Foundation: Grants for copays, deductibles and premiums when a fund is open.
- CancerCare Co-Payment Assistance Foundation: Help with treatment copays for insured people under income limits.
- Good Days: Copay help and some travel costs.
- NeedyMeds: Free database of assistance programs, open to anyone.
📋 Medicare: Medicare Part B usually covers drugs given by infusion in a doctor's office or hospital outpatient clinic. You typically pay 20% after the Part B deductible. See Medicare and your cancer drugs.
More: Help from drug makers · Our guide to paying for cancer treatment.
❓ Questions you and your loved ones can ask
- What is the goal of this treatment for me?
- How will we know if it's working?
- Which side effects should I call about right away, and what number do I call after hours?
- Which medicines, vitamins or supplements should I avoid?
- Will this affect my ability to work, drive or care for my family?
- What will this cost me, and who can help me with coverage?
Support for you and your family
- Susan G. Komen: Breast care helpline, treatment assistance and education
- Living Beyond Breast Cancer: Helpline, peer support and programs for metastatic breast cancer
- CancerCare: Free counseling, support groups and financial help
- Cancer Support Community: Support groups, a helpline and the MyLifeLine online community
Questions people often ask
How does Kadcyla work?
Kadcyla is trastuzumab linked to a chemo drug, delivering chemo right to HER2-positive cells.
How is Kadcyla given?
An IV infusion every 3 weeks.
📄 The official FDA label for Kadcyla (ado-trastuzumab emtansine), including its patient information section, is on DailyMed.
Written by the Cancer Side Effects Guide team from FDA labels and leading cancer centers. Not medical advice. · Last updated: October 15, 2026 · How we write