On February 21, the U.S. Food and Drug Administration (FDA) approved FoundationOne CDx to be used as a companion diagnostic to identify patients with microsatellite instability–high (MSI-H) status solid tumors who may be appropriate candidates for treatment with pembrolizumab. FoundationOne CDx is the first and only FDA-approved companion diagnostic to aid in identifying patients with MSI-H solid tumors for whom treatment with pembrolizumab may be appropriate.
In tumors that are defined as MSI-H, the DNA repair mechanisms are faulty, and as a result, tumor cells can acquire a significant number of mutations that can make them recognizable by the immune system. MSI-H status is more commonly found in colorectal, endometrial, and gastrointestinal cancers, but it can also be seen in other types of cancer. Pembrolizumab was granted accelerated approval to treat certain patients with MSI-H solid tumors in May 2017, making it the first targeted therapy approved to treat patients based on a genomic signature, instead of where the tumor originated in the body.
About FoundationOne CDx
FoundationOne CDx is a next-generation sequencing–based in vitro diagnostic device for detection of substitutions, insertion and deletion alterations (indels), and copy number alterations in 324 genes and select gene rearrangements, as well as genomic signatures including microsatellite instability and tumor mutational burden using DNA isolated from formalin-fixed, paraffin-embedded tumor tissue specimens. FoundationOne CDx is for prescription use only and is intended as a companion diagnostic to identify patients who may benefit from treatment with certain targeted therapies in accordance with their approved therapeutic product labeling. Additionally, FoundationOne CDx is intended to provide tumor mutation profiling to be used by qualified health-care professionals in accordance with professional guidelines in oncology for patients with solid malignant neoplasms. Use of the test does not guarantee a patient will be matched to a treatment; a negative result does not rule out the presence of an alteration.
