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U.S. FDA Approves FoundationOne®CDx as a Companion Diagnostic for KEYTRUDA® (pembrolizumab) to Identify Patients with Microsatellite Instability-High (MSI-H) Solid Tumors

Foundation Medicine’s tissue-based comprehensive genomic profiling test is now the first and only FDA-approved companion diagnostic to aid in identifying patients with MSI-H solid tumors who may benefit from immunotherapy

CAMBRIDGE, Mass.--(BUSINESS WIRE)-- Foundation Medicine, Inc. today announced that it received approval from the U.S. Food and Drug Administration (FDA) for 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 for treatment with Merck’s KEYTRUDA® (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 KEYTRUDA 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.1 KEYTRUDA 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.

“Immunotherapy has huge promise as a potential treatment option for patients with advanced cancer; however, identifying those who may benefit is complex and requires high-quality diagnostics,” said Mia Levy, M.D., Ph.D., chief medical officer at Foundation Medicine. “Not only could this approval allow more patients to benefit from KEYTRUDA, but it also underscores an important shift toward tumor-agnostic cancer care.”

Foundation Medicine is committed to providing oncologists and patients with the insights they need to make informed treatment decisions. This FDA approval of FoundationOne CDx to identify patients with MSI-H solid tumors, and its previous approval of the test to identify patients with TMB-H solid tumors who may benefit from treatment with KEYTRUDA, reinforces the assay’s analytical and clinical validity for guiding immunotherapy treatment decisions and therapy development. This is the third tumor agnostic companion diagnostic approval for FoundationOne CDx, which now has 26 companion diagnostic claims and two group claims across 27 targeted therapies.

“We’re proud to see this collaboration with Foundation Medicine, which drew on the deep scientific expertise of both organizations, result in another companion diagnostic approval for use in identifying patients who may be appropriate for KEYTRUDA,” said Eric Rubin, senior vice president, early-stage development, clinical oncology, Merck Research Laboratories.

About Foundation Medicine

Foundation Medicine is a molecular information company dedicated to a transformation in cancer care in which treatment is informed by a deep understanding of the genomic changes that contribute to each patient's unique cancer. The company offers a full suite of comprehensive genomic profiling assays to identify the molecular alterations in a patient’s cancer and match them with relevant targeted therapies, immunotherapies and clinical trials. Foundation Medicine’s molecular information platform aims to improve day-to-day care for patients by serving the needs of clinicians, academic researchers and drug developers to help advance the science of molecular medicine in cancer. For more information, please visit or follow Foundation Medicine on Twitter (@FoundationATCG).

Foundation Medicine® and FoundationOne ® are registered trademarks of Foundation Medicine, Inc.

KEYTRUDA® is a registered trademark of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.

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 (CNAs) in 324 genes and select gene rearrangements, as well as genomic signatures including microsatellite instability (MSI) and tumor mutational burden (TMB) using DNA isolated from formalin-fixed, paraffin-embedded (FFPE) 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. Some patients may require a biopsy. For a full list of targeted therapies for which FoundationOne CDx is indicated as a companion diagnostic, please visit

Source: Foundation Medicine

1 National Cancer Institute. “MSI-H Cancer.”

Foundation Medicine:
Erin Smith, 262-914-2779

Source: Foundation Medicine

February 22, 2022