See the DrugPatentWatch profile for Pembrolizumab
What does “pembrolizumab MSI-High” mean?
Pembrolizumab is an immunotherapy drug (a PD-1 inhibitor) used for certain cancers that are classified as MSI-High (also called “MSI-high” or “dMMR” in some contexts). MSI-High tumors have defects in mismatch repair, which tends to create many abnormal DNA sequences (“neoantigens”) that the immune system can recognize. Pembrolizumab is used in cancers where regulators have approved it for MSI-High or dMMR disease. [1]
Which cancers are treated with pembrolizumab when they’re MSI-High?
MSI-High/dMMR is a biomarker that can apply across multiple tumor types. The broad concept is that pembrolizumab may be offered when a cancer is MSI-High/dMMR and meets the specific treatment setting defined by clinical approvals for that cancer type. [1]
How do MSI-High and dMMR relate?
MSI-High and dMMR are closely linked. MSI-High refers to a high level of microsatellite instability detected by tumor testing. dMMR refers to mismatch repair deficiency detected by mismatch repair protein loss and/or related assays. Many regulatory and clinical frameworks treat MSI-High and dMMR as equivalent or interchangeable eligibility criteria for immunotherapy based on the same underlying biology. [1]
How is MSI-High tested before using pembrolizumab?
Patients typically get tumor testing to determine whether the tumor is MSI-High (and/or dMMR). Testing is usually done on tumor tissue and relies on either molecular assays for microsatellite instability and/or immunohistochemistry for mismatch repair proteins, depending on local practice and the lab/assay used for eligibility. [1]
What outcomes do people look for in MSI-High treated with pembrolizumab?
Patients and clinicians generally focus on whether pembrolizumab can shrink tumors and help control the disease for longer periods, since MSI-High/dMMR cancers often respond better to PD-1 blockade than MSI-stable tumors. The exact benefit depends on cancer type and line of therapy (first-line vs later lines), which determines the approved indication and expected results. [1]
Common questions patients ask
People commonly ask what “MSI-High” means for prognosis, whether pembrolizumab works even if there are limited options, and what testing is needed to confirm eligibility. They also ask how long treatment lasts and what side effects to watch for, since immunotherapies can cause immune-related side effects that affect organs like the lungs, liver, gut, skin, thyroid, and more. [1]
Sources
- https://www.nccn.org/