TH: paclitaxel and trastuzumab
- Medical Review: Karthik V. Giridhar, MD
TH (paclitaxel and trastuzumab) is a chemotherapy regimen used to treat HER2-positive early-stage breast cancer. It is a combination of two medicines:
- Paclitaxel (Taxol) – a type of chemotherapy medicine called a taxane
- Trastuzumab (Herceptin) – a type of targeted therapy called a monoclonal antibody
Sometimes this regimen is offered with another taxane, docetaxel (Taxotere), instead of paclitaxel. It would still be called TH in this case. Ask your care team to explain why they recommend one taxane over another.
How TH works
Paclitaxel works by damaging the structure or the “skeleton” that supports cancer cells. This stops the cancer cells from growing and dividing. Docetaxel (Taxotere) works in a similar way and is sometimes used instead of paclitaxel.
Trastuzumab works by attaching to the HER2 proteins on the surface of HER2-positive cancer cells, and blocks the signals that cause the cancer cells to multiply. After attaching to cancer cells, it can also alert the immune system to kill them.
Who gets TH
TH may be used to treat people diagnosed with smaller HER2-positive early-stage breast cancers:
- The tumors are usually smaller than 2 centimeters.
- The cancer has not traveled to the lymph nodes.
TH is given after surgery as adjuvant therapy.
You and your doctor will discuss the best chemotherapy treatment for your situation.
How TH is given
TH is usually given by vein through an intravenous line or a port, once a week for 12 weeks.
This is typically followed by 9 months of treatment with trastuzumab alone, given once every 3 weeks.
The trastuzumab can also be given as an injection called Herceptin Hylecta instead of an intravenous infusion. This way of giving trastuzumab is faster than an infusion.
Side effects and things to remember
Different medicines have different side effects. You may not have every side effect related to each medicine of the combination therapy.
TH tends to cause fewer serious side effects than other combination regimens for HER2-positive breast cancer that contain multiple chemotherapy medicines plus trastuzumab. Side effects of TH may include:
- Hair loss
- Fatigue
- Diarrhea
- Neutropenia, or low white blood cell count, which can make infections more likely
- Infusion reaction
- Anemia, or low red blood cell count
- Neuropathy (numbness or tingling in the hands or feet)
Heart problems are a rare but serious side effect of trastuzumab. These include congestive heart failure, when the heart muscle weakens and doesn’t pump blood well. Your doctor will check your heart before you start treatment and every several months during treatment. Be sure to tell your doctor if you have ever had heart problems.
Also tell your doctor about any medicines you are taking, including vitamins, herbal supplements, and over-the counter-medicines, to make sure they will not interfere with your chemotherapy treatment.
Contact your doctor right away if you develop a fever or other symptoms of an infection such as a sore throat or chills.
Talk to your doctor, pharmacist, or nurse about all your side effects so that they can help you manage them. You can also visit Side effects for more information.
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Reviewed and updated: August 10, 2026
Reviewed by: Karthik V. Giridhar, MD
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