Advanced MSI-H/dMMR colorectal cancer (CRC)
A FIRST TREATMENT OPTION, USED ALONE, FOR CERTAIN PEOPLE THAT HAVE ADVANCED MSI-H/dMMR COLORECTAL CANCER
IT’S TRU. KEYTRUDA.

Understanding KEYTRUDA
KEYTRUDA is an FDA-approved immunotherapy. Learn how KEYTRUDA works with your immune system.
What to know about side effects. Consult your doctor right away if you experience any.
Looking for information on what to expect while taking KEYTRUDA? Explore resources and find local support.
Is KEYTRUDA right for you?
KEYTRUDA is a prescription medicine used to treat a kind of cancer called colon or rectal cancer. KEYTRUDA may be used when your cancer has spread or cannot be removed by surgery (advanced colon or rectal cancer), and has been shown by a laboratory test to be microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR).
Biomarker testing may help determine your treatment plan
In colorectal cancer, there are biomarkers, including MSI/MMR, that may help determine what treatment is right for you. If your test results come back as MSI-H or dMMR, it may help your doctor determine your treatment plan.
MSI = microsatellite instability
MMR = mismatch repair
MSI-H = microsatellite instability-high
dMMR = mismatch repair deficient
What do MSI-H and dMMR mean?
- MSI-H stands for microsatellite instability-high. Errors in the DNA repair system can lead to errors in genetic patterns that are normally repeated, called microsatellites. MSI-H means that there is a high amount of instability (errors) in a tumor.
- dMMR stands for mismatch repair deficient (incomplete). This occurs when the DNA repair system is not working correctly, which may lead to a buildup of errors in the genetic patterns.
- Even if you don’t know your status, your doctor may. Talk to your doctor about your MSI/MMR status.
How does a biomarker test work and why have one?
- A tissue sample (biopsy) of your tumor is taken, and your doctor orders the test.
- A biomarker test can determine whether there is a high amount of instability (changes), or “MSI-High” (MSI-H), or the cancer is mismatch repair deficient (dMMR).
- Knowing your MSI/MMR status is important when deciding on a treatment plan. When the results are available, your doctor will go over the results with you and let you know what your treatment options may be.
What can I do after testing?
- Talk with your doctor to discuss treatment options based on your results. You may begin treatment with KEYTRUDA if you and your doctor have decided it’s right for you.
Clinical Trial Results
KEYTRUDA can be used alone as a first treatment and has been proven to reduce the risk of cancer spreading, growing, or getting worse compared to chemotherapy
A clinical trial compared people with microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) advanced colorectal cancer who received KEYTRUDA to those who received chemotherapy.
- All 307 people in the trial had MSI-H/dMMR advanced colorectal cancer that was previously untreated
- 153 people who received 200 mg of KEYTRUDA every 3 weeks were compared to 154 people who received chemotherapy every 2 weeks
KEYTRUDA reduced the risk of cancer spreading, growing, or getting worse by 40% compared to chemotherapy
- Half of the people on KEYTRUDA were alive without their cancer spreading, growing, or getting worse at 16.5 months, compared to 8.2 months for people on chemotherapy
- Cancer did not progress in 46% of people receiving KEYTRUDA compared to 27% of people receiving chemotherapy
The trial did not show a meaningful difference in how long people who received KEYTRUDA lived compared to how long people who received chemotherapy lived
- 59% (91 out of 153) of people treated with KEYTRUDA were alive at the time of patient follow-up
- 49% (76 out of 154) of people treated with chemotherapy were alive at the time of patient follow-up
Talk to your doctor to learn more about these clinical trial results.
More people saw their tumors shrink
Duration of responses
Of the people who responded to KEYTRUDA:
- 75% of people continued to respond for 12 months or longer compared to 37% of people who responded to chemotherapy
- 43% of people continued to respond for 24 months or longer compared to 18% of people who responded to chemotherapy
Response durations for the responding patients on KEYTRUDA ranged from 2.3+ to 41.4+ months (median not reached) compared to 2.8 to 37.5+ months for patients on chemotherapy (median 10.6 months).