The SEAMARK clinical trial is exploring potential treatment options for people with metastatic colorectal cancer (or mCRC). Tomorrow’s breakthroughs start today with you.

The SEAMARK study is being conducted to compare the effectiveness of a combination of 3 study medicines compared to 1 study medicine when given to people with mCRC.

Your participation in the SEAMARK clinical trial can help advance a potential treatment option for people with metastatic CRC. Thank you for taking the time to learn more.

Who may participate

Thank you for your interest in the SEAMARK clinical research study. We’re looking for approximately 104 people who have been diagnosed with metastatic colorectal cancer (also known as colon cancer or rectal cancer). To participate, you may not have received prior systemic therapy. ‘Systemic therapy’ is a term for treatments that travel through your entire body in order to target cancer cells wherever they are.

You will need to meet a few other criteria to take part in this study. The study team can explain these to you if you choose to learn more. 


Metastatic colorectal cancer



Molecular Type

MSI-H or dMMR and BRAF V600E mutation

Each clinical study has its own guidelines for who can participate, called eligibility criteria. However, only the research study staff can determine if you qualify to enroll in the study.

What to expect

To see if you may qualify for the SEAMARK study, you will attend one or more screening visits at the study clinic. You will be asked health-related questions and will have several study assessments, tests, and procedures to help determine if the study is a good fit for you.

If you’re eligible, you will be randomly placed in either Group A or Group B. Randomly assigning you to one of these 2 groups helps to avoid bias in the study.

  • Group A participants will receive the study medicines: encorafenib, cetuximab, and pembrolizumab
  • Group B participants will receive the study medicine: pembrolizumab

Researchers can learn about the safety and effectiveness of the 3 study medicines when given together by comparing the experiences of participants in Group A with those who only receive pembrolizumab, in Group B. If you qualify and choose to take part, the study team will discuss these details with you.

Length of study treatment

About 24 months (2 years)

Number of study visits

Group A – 1 visit every 2 weeks Group B – 1 visit every 6 weeks

Long-term follow up

1 study visit, and 1 phone call every 3 months for about 2-3 years

What does participation involve?

You will attend study visits for about 2 years. Exactly how long you participate depends on how you respond to the study medicines. You and the study doctor will decide what is best for you and if you should stop treatment at any time. Additionally, if you are in Group A you may continue to receive some of the study medicines after 2 years until you or your doctor decide to stop treatment.

During this study,you will have certain tests, procedures, and assessments. What happens at each study visit will vary and some study visits may take longer than others. Assessments may include blood samples, physical exams, tumor samples, and questionnaires about your health and quality of life. The study team will explain these details to you.

About the study medicines

There are 3 study medicines involved in this study. All participants will receive pembrolizumab by IV (intravenous infusion) once every 6 weeks. However, participants in Group A will also take encorafenib capsules once a day by mouth and will receive cetuximab by IV once every 2 weeks.

The study medicines are designed to work in different ways. Specifically,

  • Pembrolizumab may help your immune system kill cancer cells
  • Encorafenib and cetuximab target cancerous BRAF proteins and potentially slow down the growth of cancer cells

Frequently Asked Questions

What are MSI-H or dMMR and BRAF V600E molecular types?

Mutations are changes in the DNA of some cancer cells that can be targeted with certain therapies. BRAF V600E is a mutation found in some patients with mCRC. Mutations or deficiencies in the DNA repair mechanisms are known as microsatellite high (MSI-H) and/or deficient mismatch repair (dMMR). If you are not sure whether your cancer has these changes in the DNA, the study team will run some tests to confirm before you participate

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What is an intravenous (IV) infusion?

An intravenous (IV) infusion is a needle attached to a bag that holds the study drug (pembrolizumab), delivering the drug into the vein.

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Is taking part in this clinical trial voluntary?

Yes, participation in clinical trials is completely voluntary: taking part in a trial is your choice. You are free to stop being in this trial at any time and for any reason and it will not affect your future medical care in any way.

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Are there any risks or benefits?

It is possible your condition or health may improve, worsen, or stay the same. If your health gets worse, the study team and the study doctor will help you decide what to do, which may mean stopping your participation in the study.

Participant safety is the top priority of this clinical trial. Before you participate, you will be provided with an informed consent document that explains the potential risks and benefits in detail. Your health will also be monitored by the study team while in the study.

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