US-based biotechnology company Promega has teamed up with British pharmaceutical company GSK to develop and market a microsatellite instability (MSI) companion diagnostic (CDx) IVD kit.

The CDx IVD kit will be designed to identify adult cancer patients with MSI-H solid tumours who may be eligible for treatment with GSK’s anti-cancer medication Jemperli (dostarlimab-gxly).

MSI is a genetic condition caused by the accumulation of mutations in short repetitive DNA sequences, known as microsatellites.

The MSI-High (MSI-H) tumours often present elevated response rates for immune checkpoint inhibitor (ICI) therapies, such as anti-PD-1 monoclonal antibody (mAb) drugs.

Jemperli is an anti-PD-1 mAb medication, approved for patients with mismatch repair deficient (dMMR) recurrent or advanced solid tumours, who were previously treated.

Recently, the UK Medicines and Healthcare products Regulatory Agency (MHRA) has expanded the indication of Jemperli to include certain types of endometrial cancer in adults.

The CDx IVD kit development is part of GSK’s post-marketing commitment to the FDA, to support the safe and effective use of Jemperli in patients with MSI-H solid tumours.

The future CDx indication will use Promega’s PCR-based five-marker MSI panel with Jemperli.

Promega global clinical market director Alok Sharma said: “This collaboration underscores our commitment to enabling patient access to targeted therapies.

“The results of our MSI biomarker test will be a critical step to identifying patients who may be eligible to receive this drug marketed by GSK.”

Promega has more than 19 years of experience in MSI research, and its PCR method has been extensively used in clinical research across the world.

Its OncoMate MSI Dx Analysis System has been approved in the US as an IVD medical device to determine MSI status in colorectal cancer tumours.

Last year, Promega partnered with Fujifilm Cellular Dynamics, a biotech company focused on human-induced pluripotent stem cell (iPSC) technologies, to advance novel assay development for drug discovery.