Contribute to HER2-positive metastatic colorectal cancer treatment research

About the MOUNTAINEER-03 Study

The MOUNTAINEER‑03 clinical research study is evaluating if a study drug combination works compared to standard therapy for HER2‑positive, normal RAS cancer of the colon or rectum that is locally advanced, unresectable, or metastatic. Metastatic means the cancer has spread to other parts of the body, such as the lung or brain. Unresectable means the cancer cannot be removed by surgery. Locally advanced means the cancer has grown outside of the body part where it started but has not yet spread to other parts of the body.¹

To participate, a person cannot have previously received any treatment for metastatic colorectal cancer. However, it is permitted to receive a maximum of 2 doses of mFOLFOX6 in the metastatic setting before enrolling in the study. Participants may have received treatment for earlier stage colorectal cancer.

This clinical research study will aim to find out how the investigational study drug combination works compared to the current standard of care for those living with normal RAS, HER2‑positive metastatic colorectal cancer. This study will also test which side effects happen when participants take this combination of drugs.

Who Can Take Part?

Participants may be able to take part in the clinical research study if they:

• Are aged 18 and older
• Have cancer of the colon or rectum that is locally advanced (has grown outside of the body part where it started but has not yet spread to other parts of the body), unresectable (can’t be removed by surgery), or metastatic (has spread to other parts of the body)
• Have cancer that is RAS normal and HER2-positive

This is not a complete list of eligibility criteria. There will be additional health-related questions and some medical tests to confirm eligibility for the clinical research study.

Why Participate?

People who qualify and decide to participate in the clinical research study may help advance medical knowledge about normal RAS, HER2‑positive metastatic colorectal cancer.

Clinical Research Study Participation and Safety

While the clinical research study is ongoing, a team of study doctors and nurses at the study site will closely monitor participants’ health. A study team member is available to answer questions or concerns throughout the clinical research study.

There are also risks involved in the MOUNTAINEER‑03 Study, including possible side effects from study treatment. This study drug combination may have little, if any, benefit to participants. Your cancer prognosis may or may not improve by taking part in the MOUNTAINEER‑03 Study.

Participation is voluntary, and participants are free to withdraw at any time, for any reason. The study doctor may discuss options for follow-up even if a participant is no longer receiving the investigational study drug. This follow-up is important because it helps us to understand how the investigational study drug works over time.

About HER2 and RAS

You will be tested for 2 types of genetic mutations—HER2 and RAS—to determine whether you are eligible to participate in the MOUNTAINEER-03 Study.

RAS

Your doctor may also test for mutations in a group of genes called rat sarcoma viral oncogene homolog (RAS) genes. Mutations in RAS genes can cause cancer cells to grow and spread.⁵

The results of testing may show:⁵

• A normal RAS gene, also known as RAS wild-type (RAS WT)
• An abnormal RAS gene, also known as a mutated RAS gene

Determining your RAS status can help your doctor choose an appropriate treatment for your colorectal cancer.

Frequently Asked Questions

Why is the MOUNTAINEER-03 Study being conducted?⁶

The MOUNTAINEER-03 Study is being conducted to evaluate if a study drug combination works when given with the standard therapy compared to standard therapy alone for HER2-positive colorectal cancer that is locally advanced, unresectable, or metastatic. To participate, a person cannot have previously received any treatment for metastatic colorectal cancer. However, it is permitted to receive a maximum of 2 doses of mFOLFOX6 in the metastatic setting before enrolling in the study. Participants may have received treatment for earlier stage colorectal cancer.

Who is conducting MOUNTAINEER-03?

Pfizer is performing the MOUNTAINEER-03 Study.

If participants qualify, how do they decide if MOUNTAINEER-03 is right for them?

Deciding to participate in a clinical research study is an important and personal decision. Before agreeing to participate, the study team will review all aspects of the clinical research study with potential participants. They will be given a document called an Informed Consent Form that provides, in writing, the clinical research study’s purpose, assessments, procedures, benefits, risks, and precautions. They will have the opportunity to ask questions and are encouraged to speak with their own physician to decide if taking part is right for them.

Do participants have to pay anything to take part?

Some study-related care and investigational study drug costs may be covered. Participants may be reimbursed for expenses relating to attending study appointments such as travel, as per local regulations. The study team can provide more information.

Is there a placebo in this clinical research study?

No, all participants will receive either the investigational drug therapy or the standard therapy.

What are the therapies in this clinical research study?

The investigational drug therapy includes:

Investigational study drug (tucatinib)

+

Investigational study drug (trastuzumab)

+

Standard chemotherapy (mFOLFOX6: modified infusional fluorouracil, leucovorin, oxaliplatin)

The standard therapy includes:

Standard chemotherapy (mFOLFOX6)

The study doctor may also add one of the following:

bevacizumab

or

cetuximab

Is participation voluntary?

Yes, participation in any clinical research study is completely voluntary. If someone decides to participate, they will be able to choose to stop taking part at any time and for any reason. If they choose to stop taking part, this will not affect their medical care and they will still receive the standard of care treatment. They should talk to their study doctor about leaving the clinical research study so that they can schedule a final evaluation. The study doctor may discuss options for follow-up even if one is no longer receiving the investigational study drug. This follow-up is important because it helps us to understand how the investigational study drug works over time.