Foundation Medicine has received the US FDA approval for its FoundationOne CDx as a companion diagnostic to detect cancer patients eligible for treatment with Merck’s Keytruda (pembrolizumab) .

The US agency has approved the CDx to identify patients with Microsatellite Instability High (MSI-H) status solid tumours who are eligible to receive treatment with the medicine.

Keytruda is a humanised antibody that blocks the interaction between programmed death receptor-1 (PD-1) and its ligands, PD-L1 and PD-L2.

The drug is used to treat melanoma, lung cancer, head and neck cancer, Hodgkin lymphoma, stomach cancer, cervical cancer, and certain types of breast cancer.

FoundationOne is the first and only CDx approved by the FDA to identify patients with MSI-H solid tumours who are eligible for treatment with Keytruda, said the company.

Foundation Medicine chief medical officer Mia Levy said: “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.

“Not only could this approval allow more patients to benefit from KEYTRUDA, but it also underscores an important shift toward tumor-agnostic cancer care.”

MSI-H tumours are characterised by faulty DNA repair mechanisms, which allows tumour cells to acquire significant mutations that makes them identifiable by the immune system.

The MSI-H status is often identified in colorectal, endometrial and gastrointestinal cancers, but it can also be seen in other types of cancer.

In May 2017, Keytruda has received accelerated approval to treat certain patients with MSI-H solid tumours.

FoundationOne CDx is a next-generation sequencing based in vitro diagnostic device, used to identify patients who may benefit from treatment with certain targeted therapies.

Also, it provides tumour mutation profiling for health care professionals, pursuant to professional guidelines in oncology, for patients with solid malignant neoplasms.

The current FDA approval builds on the previous approval of the test to identify patients with TMB-H solid tumours who may benefit from treatment with Keytruda

Merck Research Laboratories clinical oncology early-stage development senior vice president Eric Rubin said: “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.”