THP

Say it: tee-aitch-PEE

Docetaxel, trastuzumab and pertuzumab

THP is a chemotherapy medicine plus two HER2 targeted antibodies, and it is the usual first treatment for HER2 positive breast cancer that has spread.

Also called: THP chemo, docetaxel Herceptin Perjeta, HP plus docetaxel, pertuzumab trastuzumab docetaxel, THP with Phesgo, paclitaxel HP

What it is

HER2 is a protein that drives some breast cancers to grow. Trastuzumab and pertuzumab block HER2 in two different ways, and docetaxel kills dividing cancer cells. For cancer that has spread, the goal is to shrink it and keep it under control for as long as possible. After the chemotherapy part ends, the antibodies usually continue on their own.

Often used for

• HER2 positive breast cancer that has spread (first treatment)
• HER2 positive breast cancer that came back
• HER2 positive early breast cancer before surgery (some cases)

Paclitaxel in place of docetaxel

Some people get weekly paclitaxel instead of docetaxel, which can cause less fluid buildup and fewer low blood counts.

HP maintenance

After chemotherapy stops, trastuzumab and pertuzumab continue every 3 weeks for as long as they keep working. People with hormone receptor positive cancer often add hormone pills.

With Phesgo (shot form)

Trastuzumab and pertuzumab can be given together as one shot under the skin, which takes minutes instead of hours.

The medicines in this plan

Docetaxel

Taxane chemotherapy. Given through a vein over about 1 hour on day 1, usually for about 6 cycles.

Trastuzumab

Antibody that blocks HER2. Given through a vein or as a shot on day 1 of each cycle; the first dose takes longer.

Pertuzumab

Antibody that blocks HER2 in a different spot than trastuzumab. Given through a vein on day 1 of each cycle.

How you get it

THP is given in an outpatient infusion clinic every 21 days. The first visit can take 4 to 5 hours, and later ones are shorter. Docetaxel is usually given for about 6 cycles (about 4 months), then the two antibodies continue alone every 3 weeks as long as they help. Your schedule may be different.

A typical cycle

Day before

Start dexamethasone pills, as prescribed, to prevent reactions and fluid buildup from docetaxel.

Day 1

Blood tests, then pertuzumab, trastuzumab and docetaxel through a vein, with time to watch for reactions.

Days 2 to 10

Diarrhea, tiredness and body aches are most likely. Blood counts are lowest around days 7 to 10.

Days 11 to 21

Recovery. Visit and blood tests before the next cycle.

After chemotherapy

Trastuzumab and pertuzumab every 3 weeks, with scans every few months.

Common side effects and what helps

• Diarrhea, very common with pertuzumab. Keep loperamide at home and drink lots of fluids.
• Hair loss during docetaxel. It grows back after docetaxel stops.
• Tiredness. Short walks and rest help.
• Low white blood cell counts. Wash hands often and stay away from sick people.
• Rash, dry skin and nail changes. Moisturize daily and keep nails short.
• Tingling or numbness in fingers and toes. Tell your team if it gets worse.
• Swelling of the legs from fluid. Take your steroid doses and report sudden weight gain.
• Mouth sores and taste changes. Rinse often and choose soft, mild foods.

Call your care team right away if you have

• A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills
• Diarrhea 4 or more times a day above normal, or with dizziness
• Shortness of breath, swelling of the legs, or a racing heartbeat
• Chills, rash, wheezing or face swelling during or after an infusion
• Vomiting or you cannot keep fluids down
• New cough or trouble breathing

Good to know

• Trastuzumab and pertuzumab can weaken the heart. You will have a heart ultrasound (echocardiogram) before starting and about every 3 months.
• You will have blood tests before each cycle during chemotherapy.
• These medicines can harm an unborn baby. Use reliable birth control during treatment and for 7 months after the last dose.
• Scans are done every few months to check how the cancer is responding.

At home

• Keep loperamide at home and start it at the first loose stool, as your team instructs.
• Drink plenty of fluids every day.
• Use alarms so you do not miss dexamethasone doses.
• Check your temperature if you feel unwell.
• Weigh yourself a few times a week to catch fluid buildup early.

Questions to ask

• How many cycles of docetaxel will I get?
• How long will I stay on trastuzumab and pertuzumab?
• Can I get the shot form (Phesgo)?
• Should I also take hormone pills?
• How often will I have scans and heart tests?

Breast cancer

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.