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Merck & Co. will work with Promega to develop the biological analysis company’s microsatellite instability technology into an official, on-label companion diagnostic for its Keytruda immunotherapy in solid tumors.

The global collaboration will start with its eyes on regulatory approvals in the U.S. and China, plus the possibility of expanding its work into additional territories.

Promega’s diagnostic platform aims to measure the accumulation of insertion or deletion errors in genetic code, also known as indels, caused by the deficient proteins in the mismatch-repair system that fail to catch them, and are found in certain types of cancers.

“Unlike other DNA-based, molecular screening options, Promega MSI technology uses five monomorphic mononucleotides, which is recommended by the National Cancer Institute,” said Jeff Bacher, a senior research scientist at Promega.

“Our test uses a sensitive and specific panel of markers for detection of MSI status and offers valuable insight to help inform physicians on how best to treat patients with cancer including those likely to benefit from immune checkpoint inhibitor treatment,” Bacher said. Keytruda was the first therapy approved by the FDA to treat solid tumors in any organ of the body, based instead on the cancer’s genetic code and MSI status.

Promega’s PCR-based testing methods have been used as a lab-developed test and in research use only for acquiring MSI status since 2004, though it was recently granted innovation status and priority review by China’s National Medical Products Administration.

“It is gratifying to see our MSI technology have such meaning within the oncology community,” said Bill Linton, president and CEO of the Madison, Wisconsin-based company. “Promega developed this technology well over a decade ago and our long-term commitment to R&D helped evolve its use.”

In addition to the Merck collaboration, Promega said it plans pursue regulatory clearances for a separate MSI in vitro diagnostic in the U.S., China and Europe, with the goal of commercial launches in the first half of next year.