What is TUKYSA?

TUKYSA is a prescription medicine used with the medicine trastuzumab to treat adults with RAS wild-type human epidermal growth factor receptor-2 (HER2) positive colorectal cancer that has spread to other parts of the body (metastatic), or cannot be removed by surgery, and who have received treatment with fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy and it did not work or is no longer working.

This use is approved based on a clinical study that measured how many patients had a tumor response and how long that response lasted. Studies are ongoing to confirm the benefit of TUKYSA for this use.

It is not known if TUKYSA is safe and effective in children.

Could TUKYSA be right for me?

The TUKYSA regimen is chemotherapy-free. Although HER2-targeted therapies are not chemotherapy, they can affect normal cells and cause side effects, some of which may be serious.

TUKYSA was studied in a clinical trial called MOUNTAINEER. It included 84 people with RAS wild-type, HER2 positive (HER2+) colorectal cancer that could not be removed by surgery (unresectable) or had spread to other parts of the body (metastatic). To participate in this study, these adults must have:

• Previously received fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy (some patients had also received immunotherapy)
• Had tumors that were both RAS wild-type and HER2+
• Never received any therapy that targets HER2

The trial only studied people receiving TUKYSA and trastuzumab. Because they were not directly compared with people receiving any other treatment for RAS wild-type, HER2+ metastatic colorectal cancer, no conclusions can be drawn about the relative effectiveness of TUKYSA + trastuzumab and other treatments.

What were the results in the clinical trial?

In a clinical trial with the TUKYSA regimen,*

• 38% of people (32 out of 84) saw their tumors shrink or disappear
  • 35% of people had a partial response, which means that the amount of cancer in the body, or the size of the tumor, decreased after treatment
  • 3.6% of people had a complete response, which means that all signs of cancer were gone after treatment. This doesn’t mean that cancer was cured
• For the 32 of 84 patients who responded to the TUKYSA regimen,* the median length of time that tumors continued to respond to treatment was 12.4 months

Median: The middle number in a group of numbers that are listed from lowest to highest; also called midpoint.

*TUKYSA regimen: TUKYSA, trastuzumab. The TUKYSA regimen may not work for everyone.

What are the possible side effects of TUKYSA?

The most common side effects of TUKYSA (tucatinib) and trastuzumab were:

• diarrhea
• tiredness
• rash
• nausea
• stomach-area (abdomen) pain
• infusion-related reactions
• fever

These are not all the possible side effects of TUKYSA and trastuzumab. Be sure to tell your healthcare provider about any side effects you have.

How do I take TUKYSA?

TUKYSA (tucatinib) is an oral treatment. Take each dose about 12 hours apart and at the same times every day. Take TUKYSA with or without food. Swallow TUKYSA tablets whole. Do not chew, crush, or split TUKYSA tablets before swallowing. Do not take TUKYSA tablets if they are broken, cracked, or damaged. If you vomit or miss a dose of TUKYSA, take your next dose at your regular time. Your healthcare provider may change your dose of TUKYSA if needed.

TUKYSA is prescribed with another medicine called trastuzumab. Trastuzumab is given intravenously every 21 days.

Do I need tests with TUKYSA?

Your healthcare provider will test your blood to check your liver function before starting and every 3 weeks during treatment with TUKYSA (tucatinib), or as needed. These tests may be performed when you go in for your trastuzumab treatment. Based on the test results, your healthcare provider may change your dose of TUKYSA, temporarily stop, or permanently stop treatment with TUKYSA.

If you are a female who can become pregnant, your healthcare provider will do a pregnancy test before starting TUKYSA.