Detect MSI in CRC with 1-Hour Molecular Test

The FDA has given Premarket Approval to the IdyllaTM CDx MSI test in patients with microsatellite instability-high (MSI-H) colorectal cancer (CRC) who may benefit from the receipt of nivolumab (Opdivo) with or without ipilimumab (Yervoy), according to a news release from the assay’s developer, Biocartis.1

The assay, which was designed to be used on the IdyllaTM platform, qualitatively detects a series of monomorphic biomarkers including ACVR2A, BTBD7, DIDO1, MRE11, RYR3, SEC31A, and SULF2. By detecting these biomarkers, the test can detect MSI in CRC tissue samples. A single-use cartridge, it delivers results in under 3 hours following less than 3 minutes of hands-on time.

“Achieving FDA approval for our Idylla™ CDx MSI Test represents a key milestone for Biocartis," Michael Korn, MD, chief medical and scientific officer at Biocartis, said in the news release.1 “It underscores our commitment to helping [patients with cancer] receive the right therapy without delay, and the recent [phase 3] CheckMate-8HW data [NCT04008030] reinforce the critical importance of accurate MSI-H/deficient mismatch repair [dMMR] testing in colorectal cancer. With its speed, accuracy, and automation, the Idylla™ CDx MSI Test offers a powerful solution that enables clinicians to make timely, confident, and data-driven treatment decisions when every moment counts.”

The IdyllaTM CDx MSI test was used in the phase 3 CheckMate-8HW trial, in which adult patients with immunotherapy-naïve MSI-H/dMMR CRC were randomly assigned to receive nivolumab alone or with ipilimumab.2 Specifically, patients were treated with 240 mg of nivolumab and 1 mg/kg of ipilimumab intravenously every 3 weeks for the first 12 weeks and 480 mg of nivolumab 4 weeks thereafter in the combination arm; those in the monotherapy arm received 240 mg of intravenous nivolumab every 2 weeks for 12 weeks followed by 480 mg of nivolumab every 4 weeks thereafter.

The results therein found that the nivolumab combination exhibited a significant progression-free survival (PFS) benefit vs nivolumab alone, with median values of not reached (95% CI, 53.8-not estimable [NE]) and 39.3 months (95% CI, 22.1-NE), respectively (HR, 0.62; 95% CI, 0.48-0.81; P = .0003).

Additionally, the PFS rates at 12, 24, and 36 months in the combination vs the nivolumab monotherapy arms were 76% (95% CI, 71%-80%) vs 63% (95% CI, 57%-68%), 71% (95% CI, 65%-76%) vs 56% (95% CI, 49%-61%), and 68% (95% CI, 62%-73%) vs 51% (95% CI, 45%-57%), respectively. Prespecified subgroup analyses showed that PFS generally favored nivolumab plus ipilimumab vs nivolumab alone.

Results from the phase 3 trial supported the FDA approval of nivolumab plus ipilimumab in patients with unresectable or metastatic MSI-H/dMMR CRC in April 2025.3

The test was used to assess the trial’s primary efficacy population of patients with MSI-H/dMMR disease. Specifically, the trial’s co-primary end points included PFS per RECIST v1.1 criteria for the nivolumab combination vs chemotherapy in the population, and PFS for the combination vs nivolumab alone across all lines of therapy.

According to the assay’s developers, the Idylla™ CDx MSI Test will be made available across the US soon, with availability in other non-US markets forthcoming.

“The approval of this new MSI companion diagnostic for patients with colorectal cancer is a meaningful achievement from our collaboration with Biocartis and a strong reflection of our Precision Medicine strategy at Bristol Myers Squibb,” Sarah Hersey, vice president of Precision Medicine, Bioanalytical and Translational Sciences at Bristol Myers Squibb, said in the release.1 “Rapid and accurate diagnosis is crucial to enabling access to appropriate therapeutic approaches, and this latest advancement exemplifies our commitment to delivering innovative, targeted solutions that have the potential to improve outcomes for patients.”