FDA Grants Premarket Approval to Idylla CDx MSI Test for MSI-H CRC

The FDA has granted premarket approval to the fully automated, cartridge-based, “sample-to-result” Idylla CDx MSI Test, a companion diagnostic test for identifying eligible patients with microsatellite instability–high (MSI-H) colorectal cancer (CRC) who may benefit from treatment with nivolumab (Opdivo) as monotherapy or in combination with ipilimumab (Yervoy).1

“The approval of this new MSI companion diagnostic for patients with CRC 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, stated in a news release. “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.”

The Idylla CDx MSI Test was designed to be used on the Idylla Platform. This qualitative test can detect a panel of 7 monomorphic biomarkers (ACVR2A, BTBD7, DIDO1, MRE11, RYR3, SEC31A, and SULF2) that are indicative of MSI in samples of CRC tissue. This test can be run with less than 3 minutes of hands-on time and can deliver results in less than 3 hours.

“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, added in the news release. “It underscores our commitment to helping oncology patients receive the right therapy without delay, and the recent [phase 3] CheckMate 8HW [trial (NCT04008030)] data reinforce the critical importance of accurate MSI-H/dMMR testing in CRC. 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.”

What Was the Design of CheckMate 8HW?

The multicenter, open-label trial randomly assigned patients with immunotherapy-naive unresectable or metastatic CRC with known MSI-H or mismatch repair–deficient (dMMR) status in a 2:2:1 fashion to receive treatment with nivolumab monotherapy (n = 353), nivolumab plus ipilimumab (n = 354), or investigator’s choice of chemotherapy (n = 132).2 In the first-line setting, the trial compared nivolumab plus ipilimumab vs chemotherapy. Across all lines of therapy, the trial compared nivolumab plus ipilimumab vs nivolumab monotherapy.

Where Does Nivolumab Currently Fit Into the MSI-H CRC Treatment Paradigm?

Notably, nivolumab plus ipilimumab was FDA approved on April 8, 2025, for the treatment of adult and pediatric patients 12 years of age or older who have dMMR or MSI-H unresectable or metastatic CRC.3 On the same date, the FDA also converted the accelerated approval of nivolumab monotherapy to a regular approval for the treatment of adult and pediatric patients 12 years of age or older who have MSI-H or dMMR metastatic CRC and have progressed following treatment with fluoropyrimidine, oxaliplatin, and irinotecan.

The efficacy of nivolumab was assessed in CheckMate 8HW, which showed that patients with dMMR/MSI-H metastatic CRC who received first-line nivolumab plus ipilimumab achieved a median progression-free survival (PFS) that was not reached (NR; 95% CI, 38.4 months-not estimable [NE]) vs 5.8 months (95% CI, 4.4-7.8) among those who received chemotherapy (HR, 0.21; 95% CI, 0.14-0.32; P < .0001). Additionally, across all lines of therapy, the median PFS was NR (95% CI, 53.8 months-NE) with nivolumab plus ipilimumab vs 39.3 months (95% CI, 22.1-NE) with nivolumab monotherapy (HR, 0.62; 95% CI, 0.48-0.81; P = .0003).

References

1. Biocartis receives FDA approval for the Idylla CDx MSI Test. News release. Biocartis Group of Companies. September 15, 2025. Accessed September 15, 2025. https://www.biocartis.com/sites/default/files/2025-09/msi-cdx_pma_-_press_release_-_sep2025.pdf
2. Andre T, Elez E, Lenz H-J, et al. First results of nivolumab (NIVO) plus ipilimumab (IPI) vs NIVO monotherapy for microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) metastatic colorectal cancer (mCRC) from CheckMate 8HW. J Clin Oncol. 2025;43(suppl 4):LBA143. doi:10.1200/JCO.2025.43.4_suppl.LBA143
3. FDA approves nivolumab with ipilimumab for unresectable or metastatic MSI-H or dMMR colorectal cancer. FDA. April 8, 2025. Accessed September 15, 2025. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-nivolumab-ipilimumab-unresectable-or-metastatic-msi-h-or-dmmr-colorectal-cancer